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flutter / third_party / libpng / 38734eeb45276c429e1c98d8394dbfcc2b79cc16 / . / libpng.3
blob: c04a23f1e7a0e12d36e8d4fc102b2f4580a1fcd7 [file] [log] [blame]
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]1.TH LIBPNG 3 "March 3, 2011"
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]2.SH NAME
Glenn Randers-Pehrson7c969f32011-02-19 15:58:03 -0600[diff] [blame]3libpng \- Portable Network Graphics (PNG) Reference Library 1.5.2beta03
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4.SH SYNOPSIS
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]5\fI\fB
6
7\fB#include <png.h>\fP
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9\fI\fB
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]10
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]11\fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]13\fI\fB
14
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]15\fBvoid png_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]17\fI\fB
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Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]19\fBvoid png_build_grayscale_palette (int \fP\fIbit_depth\fP\fB, png_colorp \fIpalette\fP\fB);\fP
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21\fI\fB
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23\fBpng_voidp png_calloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
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25\fI\fB
26
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]27\fBvoid png_chunk_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]29\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]31\fBvoid png_chunk_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]32
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]33\fI\fB
34
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]35\fBvoid png_chunk_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]36
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]37\fI\fB
38
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]39\fBvoid png_convert_from_struct_tm (png_timep \fP\fIptime\fP\fB, struct tm FAR * \fIttime\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]40
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]41\fI\fB
42
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]43\fBvoid png_convert_from_time_t (png_timep \fP\fIptime\fP\fB, time_t \fIttime\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]44
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]45\fI\fB
46
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]47\fBpng_charp png_convert_to_rfc1123 (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fIptime\fP\fB);\fP
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]48
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]49\fI\fB
50
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]51\fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]52
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]53\fI\fB
54
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]55\fBpng_structp png_create_read_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]56
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]57\fI\fB
58
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]59\fBpng_structp png_create_read_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]60
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]61\fI\fB
62
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]63\fBpng_structp png_create_write_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]64
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]65\fI\fB
66
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]67\fBpng_structp png_create_write_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
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69\fI\fB
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71\fBvoid png_data_freer (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIfreer\fP\fB, png_uint_32 \fImask)\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]72
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]73\fI\fB
74
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]75\fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]77\fI\fB
78
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]79\fBvoid png_destroy_read_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fP\fIinfo_ptr_ptr\fP\fB, png_infopp \fIend_info_ptr_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]81\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]83\fBvoid png_destroy_write_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]85\fI\fB
86
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]87\fBvoid png_err (png_structp \fIpng_ptr\fP\fB);\fP
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89\fI\fB
90
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]91\fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]93\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]95\fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]97\fI\fB
98
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]99\fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]101\fI\fB
102
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]103\fBvoid png_free_default (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]104
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]105\fI\fB
106
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]107\fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]108
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]109\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]111\fBpng_byte png_get_bit_depth (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]112
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]113\fI\fB
114
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]115\fBpng_uint_32 png_get_bKGD (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]116
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]117\fI\fB
118
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]119\fBpng_byte png_get_channels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]120
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]121\fI\fB
122
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]123\fBpng_uint_32 png_get_cHRM (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, double \fP\fI*green_y\fP\fB, double \fP\fI*blue_x\fP\fB, double \fI*blue_y\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]124
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]125\fI\fB
126
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]127\fBpng_uint_32 png_get_cHRM_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_uint_32 \fP\fI*green_x\fP\fB, png_uint_32 \fP\fI*green_y\fP\fB, png_uint_32 \fP\fI*blue_x\fP\fB, png_uint_32 \fI*blue_y\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]128
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]129\fI\fB
130
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]131\fBpng_uint_32 png_get_chunk_cache_max (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]132
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]133\fI\fB
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Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]135\fI\fB
136
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]137\fBpng_alloc_size_t png_get_chunk_malloc_max (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]138
139\fI\fB
140
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]141\fBpng_byte png_get_color_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]142
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]143\fI\fB
144
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]145\fBpng_uint_32 png_get_compression_buffer_size (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]146
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]147\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]149\fBpng_byte png_get_compression_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]150
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]151\fI\fB
152
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]153\fBpng_byte png_get_copyright (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]154
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]155\fI\fB
156
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]157\fBpng_uint_32 png_get_current_row_number \fI(png_const_structp\fP\fB);\fP
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159\fI\fB
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161\fBpng_byte png_get_current_pass_number \fI(png_const_structp\fP\fB);\fP
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163\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]165\fBpng_voidp png_get_error_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]166
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]167\fI\fB
168
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]169\fBpng_byte png_get_filter_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]170
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]171\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]173\fBpng_uint_32 png_get_gAMA (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]174
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]175\fI\fB
176
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]177\fBpng_uint_32 png_get_gAMA_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]178
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]179\fI\fB
180
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]181\fBpng_byte png_get_header_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]182
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]183\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]185\fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]186
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]187\fI\fB
188
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]189\fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]190
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]191\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]193\fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]194
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]195\fI\fB
196
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]197\fBpng_uint_32 png_get_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*width\fP\fB, png_uint_32 \fP\fI*height\fP\fB, int \fP\fI*bit_depth\fP\fB, int \fP\fI*color_type\fP\fB, int \fP\fI*interlace_type\fP\fB, int \fP\fI*compression_type\fP\fB, int \fI*filter_type\fP\fB);\fP
198
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]199\fI\fB
200
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]201\fBpng_uint_32 png_get_image_height (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]202
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]203\fI\fB
204
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]205\fBpng_uint_32 png_get_image_width (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]206
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]207\fI\fB
208
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]209\fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP
210
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]211\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]212
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]213\fBpng_byte png_get_interlace_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]214
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]215\fI\fB
216
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]217\fBpng_const_bytep png_get_io_chunk_name (png_structp \fIpng_ptr\fP\fB);\fP
218
219\fI\fB
220
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]221\fBpng_uint_32 png_get_io_chunk_type (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona63dbed2011-01-22 08:51:19 -0600[diff] [blame]222
223\fI\fB
224
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]225\fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP
226
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]227\fI\fB
228
Glenn Randers-Pehrsona63dbed2011-01-22 08:51:19 -0600[diff] [blame]229\fBpng_uint_32 png_get_io_state (png_structp \fIpng_ptr\fP\fB);\fP
230
231\fI\fB
232
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]233\fBpng_byte png_get_libpng_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]234
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]235\fI\fB
236
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]237\fBpng_voidp png_get_mem_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]238
239\fI\fB
240
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]241\fBpng_uint_32 png_get_oFFs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]242
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]243\fI\fB
244
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]245\fBpng_uint_32 png_get_pCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fI*purpose\fP\fB, png_int_32 \fP\fI*X0\fP\fB, png_int_32 \fP\fI*X1\fP\fB, int \fP\fI*type\fP\fB, int \fP\fI*nparams\fP\fB, png_charp \fP\fI*units\fP\fB, png_charpp \fI*params\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]246
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]247\fI\fB
248
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]249\fBpng_uint_32 png_get_pHYs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]250
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]251\fI\fB
252
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]253\fBfloat png_get_pixel_aspect_ratio (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]254
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]255\fI\fB
256
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]257\fBpng_uint_32 png_get_pHYs_dpi (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]258
259\fI\fB
260
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]261\fBpng_fixed_point png_get_pixel_aspect_ratio_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]262
263\fI\fB
264
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]265\fBpng_uint_32 png_get_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]266
267\fI\fB
268
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]269\fBpng_uint_32 png_get_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]270
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]271\fI\fB
272
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]273\fBpng_voidp png_get_progressive_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]274
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]275\fI\fB
276
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]277\fBpng_uint_32 png_get_PLTE (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]278
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]279\fI\fB
280
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]281\fBpng_byte png_get_rgb_to_gray_status (png_const_structp \fIpng_ptr)
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]282
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]283\fBpng_uint_32 png_get_rowbytes (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]284
285\fI\fB
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]286
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]287\fBpng_bytepp png_get_rows (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]288
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]289\fI\fB
290
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]291\fBpng_uint_32 png_get_sBIT (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]292
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]293\fI\fB
294
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]295\fBvoid png_get_sCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, double* \fP\fIwidth\fP\fB, double* \fIheight\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]296
297\fI\fB
298
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]299\fBvoid png_get_sCAL_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_fixed_pointp \fP\fIwidth\fP\fB, png_fixed_pointp \fIheight\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]300
301\fI\fB
302
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]303\fBvoid png_get_sCAL_s (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_charpp \fP\fIwidth\fP\fB, png_charpp \fIheight\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]304
305\fI\fB
306
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]307\fBpng_bytep png_get_signature (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]308
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]309\fI\fB
310
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]311\fBpng_uint_32 png_get_sPLT (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fI*splt_ptr\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]312
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]313\fI\fB
314
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]315\fBpng_uint_32 png_get_sRGB (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int \fI*file_srgb_intent\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]316
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]317\fI\fB
318
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]319\fBpng_uint_32 png_get_text (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]320
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]321\fI\fB
322
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]323\fBpng_uint_32 png_get_tIME (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]324
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]325\fI\fB
326
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]327\fBpng_uint_32 png_get_tRNS (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans_alpha\fP\fB, int \fP\fI*num_trans\fP\fB, png_color_16p \fI*trans_color\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]328
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]329\fI\fB
330
331\fB/* This function is really an inline macro. \fI*/
332
333\fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP
334
335\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]336
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]337\fBpng_uint_32 png_get_uint_31 (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIbuf\fP\fB);\fP
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]338
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]339\fI\fB
340
341\fB/* This function is really an inline macro. \fI*/
342
343\fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP
344
345\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]346
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]347\fBpng_uint_32 png_get_unknown_chunks (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]348
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]349\fI\fB
350
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]351\fBpng_voidp png_get_user_chunk_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]352
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]353\fI\fB
354
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]355\fBpng_uint_32 png_get_user_height_max (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]356
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]357\fI\fB
358
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]359\fBpng_voidp png_get_user_transform_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]360
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]361\fI\fB
362
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]363\fBpng_uint_32 png_get_user_width_max (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]364
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]365\fI\fB
366
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]367\fBpng_uint_32 png_get_valid (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]368
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]369\fI\fB
370
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]371\fBfloat png_get_x_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]372
373\fI\fB
374
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]375\fBpng_fixed_point png_get_x_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]376
377\fI\fB
378
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]379\fBpng_int_32 png_get_x_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]380
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]381\fI\fB
382
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]383\fBpng_int_32 png_get_x_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]384
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]385\fI\fB
386
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]387\fBpng_uint_32 png_get_x_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]388
389\fI\fB
390
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]391\fBpng_uint_32 png_get_x_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]392
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]393\fI\fB
394
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]395\fBfloat png_get_y_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]396
397\fI\fB
398
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]399\fBpng_fixed_point png_get_y_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]400
401\fI\fB
402
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]403\fBpng_int_32 png_get_y_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]404
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]405\fI\fB
406
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]407\fBpng_int_32 png_get_y_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]408
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]409\fI\fB
410
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]411\fBpng_uint_32 png_get_y_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]412
413\fI\fB
414
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]415\fBpng_uint_32 png_get_y_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]416
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]417\fI\fB
418
Glenn Randers-Pehrsonc1bfe682002-03-06 22:08:00 -0600[diff] [blame]419\fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
420
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]421\fI\fB
422
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]423\fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
424
425\fI\fB
426
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]427\fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]428
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]429\fI\fB
430
Glenn Randers-Pehrsonf98726a2010-02-19 09:54:53 -0600[diff] [blame]431\fBvoid png_longjmp (png_structp \fP\fIpng_ptr\fP\fB, int \fIval\fP\fB);\fP
432
433\fI\fB
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Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]435\fBpng_voidp png_malloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]436
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]437\fI\fB
438
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]439\fBpng_voidp png_malloc_default (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
440
441\fI\fB
442
443\fBpng_voidp png_malloc_warn (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
444
445\fI\fB
446
447\fBpng_uint_32 png_permit_mng_features (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fImng_features_permitted\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]448
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]449\fI\fB
450
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]451\fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP
452
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]453\fI\fB
454
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]455\fBpng_size_t png_process_data_pause \fP\fI(png_structp\fP\fB, int \fIsave\fP\fB);\fP
456
457\fI\fB
458
459\fBpng_uint_32 png_process_data_skip \fI(png_structp\fP\fB);\fP
460
461\fI\fB
462
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]463\fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP
464
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]465\fI\fB
466
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]467\fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
468
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]469\fI\fB
470
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]471\fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
472
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]473\fI\fB
474
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]475\fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
476
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]477\fI\fB
478
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]479\fBvoid png_read_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]480
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]481\fI\fB
482
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]483\fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP
484
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]485\fI\fB
486
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]487\fBvoid png_read_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_bytepp \fP\fIdisplay_row\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
488
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]489\fI\fB
490
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]491\fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
492
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]493\fI\fB
494
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]495\fBint png_reset_zstream (png_structp \fIpng_ptr\fP\fB);\fP
496
497\fI\fB
498
499\fBvoid png_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]500
501\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]502
503\fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP
504
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]505\fI\fB
506
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]507\fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP
508
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]509\fI\fB
510
511\fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
512
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]513\fI\fB
Glenn Randers-Pehrson67864af2004-08-28 23:30:07 -0500[diff] [blame]514
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]515\fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP
516
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]517\fI\fB
518
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]519\fBvoid png_set_background_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, png_uint_32 \fIbackground_gamma\fP\fB);\fP
520
521\fI\fB
522
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]523\fBvoid png_set_benign_errors (png_structp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
524
525\fI\fB
526
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]527\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
528
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]529\fI\fB
530
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]531\fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP
532
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]533\fI\fB
534
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]535\fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP
536
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]537\fI\fB
538
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]539\fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\fB, png_uint_32 \fP\fIgreen_y\fP\fB, png_uint_32 \fP\fIblue_x\fP\fB, png_uint_32 \fIblue_y\fP\fB);\fP
540
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]541\fI\fB
542
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]543\fBvoid png_set_chunk_cache_max (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIuser_chunk_cache_max\fP\fB);\fP
544
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]545\fI\fB
546
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]547\fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
548
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]549\fI\fB
550
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]551\fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
552
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]553\fI\fB
554
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]555\fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
556
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]557\fI\fB
558
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]559\fBvoid png_set_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]560
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]561\fI\fB
562
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]563\fBvoid png_set_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]564
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]565\fI\fB
566
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]567\fBvoid png_set_crc_action (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcrit_action\fP\fB, int \fIancil_action\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]568
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]569\fI\fB
570
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]571\fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]572
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]573\fI\fB
574
Glenn Randers-Pehrsond08b6bd2011-02-19 15:50:17 -0600[diff] [blame]575\fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsonc85f5f62011-02-13 05:56:07 -0600[diff] [blame]576
577\fI\fB
578
Glenn Randers-Pehrsond08b6bd2011-02-19 15:50:17 -0600[diff] [blame]579\fBvoid png_set_expand_16 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]580
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]581\fI\fB
582
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]583\fBvoid png_set_expand_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]584
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]585\fI\fB
586
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]587\fBvoid png_set_filler (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]588
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]589\fI\fB
590
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]591\fBvoid png_set_filter (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImethod\fP\fB, int \fIfilters\fP\fB);\fP
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]592
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]593\fI\fB
594
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]595\fBvoid png_set_filter_heuristics (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_doublep \fP\fIfilter_weights\fP\fB, png_doublep \fIfilter_costs\fP\fB);\fP
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]596
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]597\fI\fB
598
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]599\fBvoid png_set_filter_heuristics_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_fixed_point_p \fP\fIfilter_weights\fP\fB, png_fixed_point_p \fIfilter_costs\fP\fB);\fP
600
601\fI\fB
602
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]603\fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]604
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]605\fI\fB
606
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]607\fBvoid png_set_gamma (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIscreen_gamma\fP\fB, double \fIdefault_file_gamma\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]608
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]609\fI\fB
610
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]611\fBvoid png_set_gamma_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIscreen_gamma\fP\fB, png_uint_32 \fIdefault_file_gamma\fP\fB);\fP
612
613\fI\fB
614
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]615\fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]616
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]617\fI\fB
618
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]619\fBvoid png_set_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIfile_gamma\fP\fB);\fP
620
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]621\fI\fB
622
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]623\fBvoid png_set_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]624
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]625\fI\fB
626
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]627\fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]628
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]629\fI\fB
630
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]631\fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]632
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]633\fI\fB
634
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]635\fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]636
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]637\fI\fB
638
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]639\fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]640
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]641\fI\fB
642
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]643\fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP
644
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]645\fI\fB
646
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]647\fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]648
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]649\fI\fB
650
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]651\fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]652
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]653\fI\fB
654
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]655\fBvoid png_set_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIinterlace_type\fP\fB, int \fP\fIcompression_type\fP\fB, int \fIfilter_type\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]656
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]657\fI\fB
658
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]659\fBvoid png_set_keep_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIkeep\fP\fB, png_bytep \fP\fIchunk_list\fP\fB, int \fInum_chunks\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]660
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]661\fI\fB
662
Glenn Randers-Pehrson1e6ed732009-11-20 22:06:56 -0600[diff] [blame]663\fBjmp_buf* png_set_longjmp_fn (png_structp \fP\fIpng_ptr\fP\fB, png_longjmp_ptr \fP\fIlongjmp_fn\fP\fB, size_t \fIjmp_buf_size\fP\fB);\fP
664
665\fI\fB
666
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]667\fBvoid png_set_chunk_malloc_max (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIuser_chunk_cache_max\fP\fB);\fP
668
669\fI\fB
670
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]671\fBvoid png_set_compression_buffer_size (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
672
673\fI\fB
674
675\fBvoid png_set_mem_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]676
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]677\fI\fB
678
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]679\fBvoid png_set_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIoffset_x\fP\fB, png_uint_32 \fP\fIoffset_y\fP\fB, int \fIunit_type\fP\fB);\fP
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]680
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]681\fI\fB
682
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]683\fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]684
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]685\fI\fB
686
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]687\fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]688
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]689\fI\fB
690
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]691\fBvoid png_set_palette_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]692
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]693\fI\fB
694
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]695\fBvoid png_set_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, png_charpp \fIparams\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]696
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]697\fI\fB
698
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]699\fBvoid png_set_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIres_x\fP\fB, png_uint_32 \fP\fIres_y\fP\fB, int \fIunit_type\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]700
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]701\fI\fB
702
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]703\fBvoid png_set_progressive_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIprogressive_ptr\fP\fB, png_progressive_info_ptr \fP\fIinfo_fn\fP\fB, png_progressive_row_ptr \fP\fIrow_fn\fP\fB, png_progressive_end_ptr \fIend_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]704
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]705\fI\fB
706
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]707\fBvoid png_set_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]708
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]709\fI\fB
710
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]711\fBvoid png_set_quantize (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_quantize\fP\fB);\fP
712
713\fI\fB
714
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]715\fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]716
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]717\fI\fB
718
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]719\fBvoid png_set_read_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_read_status_ptr \fIread_row_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]720
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]721\fI\fB
722
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]723\fBvoid png_set_read_user_chunk_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_chunk_ptr\fP\fB, png_user_chunk_ptr \fIread_user_chunk_fn\fP\fB);\fP
724
725\fI\fB
726
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]727\fBvoid png_set_read_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIread_user_transform_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]728
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]729\fI\fB
730
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]731\fBvoid png_set_rgb_to_gray (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIerror_action\fP\fB, double \fP\fIred\fP\fB, double \fIgreen\fP\fB);\fP
732
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]733\fI\fB
734
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]735\fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_uint_32 \fP\fIred\fP\fB, png_uint_32 \fIgreen\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]736
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]737\fI\fB
738
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]739\fBvoid png_set_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytepp \fIrow_pointers\fP\fB);\fP
740
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]741\fI\fB
742
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]743\fBvoid png_set_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fIsig_bit\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]744
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]745\fI\fB
746
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]747\fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
748
749\fI\fB
750
751\fBvoid png_set_sCAL_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_fixed_point \fP\fIwidth\fP\fB, png_fixed_point \fIheight\fP\fB);\fP
752
753\fI\fB
754
755\fBvoid png_set_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_charp \fP\fIwidth\fP\fB, png_charp \fIheight\fP\fB);\fP
756
757\fI\fB
758
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]759\fBvoid png_set_shift (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fItrue_bits\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]760
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]761\fI\fB
762
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]763\fBvoid png_set_sig_bytes (png_structp \fP\fIpng_ptr\fP\fB, int \fInum_bytes\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]764
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]765\fI\fB
766
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]767\fBvoid png_set_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fP\fIsplt_ptr\fP\fB, int \fInum_spalettes\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]768
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]769\fI\fB
770
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]771\fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]772
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]773\fI\fB
774
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]775\fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]776
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]777\fI\fB
778
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]779\fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]780
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]781\fI\fB
782
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]783\fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]784
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]785\fI\fB
786
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]787\fBvoid png_set_strip_error_numbers (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIstrip_mode\fP\fB);\fP
788
789\fI\fB
790
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]791\fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]792
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]793\fI\fB
794
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]795\fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]796
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]797\fI\fB
798
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]799\fBvoid png_set_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]800
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]801\fI\fB
802
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]803\fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]804
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]805\fI\fB
806
Glenn Randers-Pehrsonf3c51e42011-01-15 10:25:25 -0600[diff] [blame]807\fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans_alpha\fP\fB, int \fP\fInum_trans\fP\fB, png_color_16p \fItrans_color\fP\fB);\fP
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]808
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]809\fI\fB
810
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]811\fBvoid png_set_tRNS_to_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]812
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]813\fI\fB
814
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]815\fBpng_uint_32 png_set_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkp \fP\fIunknowns\fP\fB, int \fP\fInum\fP\fB, int \fIlocation\fP\fB);\fP
816
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]817\fI\fB
818
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]819\fBvoid png_set_unknown_chunk_location (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIchunk\fP\fB, int \fIlocation\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]820
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]821\fI\fB
822
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]823\fBvoid png_set_user_limits (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIuser_width_max\fP\fB, png_uint_32 \fIuser_height_max\fP\fB);\fP
824
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]825\fI\fB
826
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]827\fBvoid png_set_user_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_transform_ptr\fP\fB, int \fP\fIuser_transform_depth\fP\fB, int \fIuser_transform_channels\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]828
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]829\fI\fB
830
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]831\fBvoid png_set_write_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fP\fIwrite_data_fn\fP\fB, png_flush_ptr \fIoutput_flush_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]832
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]833\fI\fB
834
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]835\fBvoid png_set_write_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_write_status_ptr \fIwrite_row_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]836
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]837\fI\fB
838
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]839\fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]840
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]841\fI\fB
842
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]843\fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]844
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]845\fI\fB
846
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]847\fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]848
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]849\fI\fB
850
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]851\fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]852
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]853\fI\fB
854
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]855\fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]856
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]857\fI\fB
858
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]859\fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]860
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]861\fI\fB
862
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]863\fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]864
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]865\fI\fB
866
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]867\fBvoid png_write_chunk_start (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]868
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]869\fI\fB
870
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]871\fBvoid png_write_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]872
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]873\fI\fB
874
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]875\fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]876
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]877\fI\fB
878
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]879\fBvoid png_write_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]880
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]881\fI\fB
882
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]883\fBvoid png_write_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]884
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]885\fI\fB
886
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]887\fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
888
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]889\fI\fB
890
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]891\fBvoid png_write_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]892
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]893\fI\fB
894
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]895\fBvoid png_write_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]896
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]897\fI\fB
898
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]899\fBvoid png_write_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]900
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]901\fI\fB
902
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]903\fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP
904
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]905\fI\fB
906
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]907\fBvoidpf png_zalloc (voidpf \fP\fIpng_ptr\fP\fB, uInt \fP\fIitems\fP\fB, uInt \fIsize\fP\fB);\fP
908
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]909\fI\fB
910
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]911\fBvoid png_zfree (voidpf \fP\fIpng_ptr\fP\fB, voidpf \fIptr\fP\fB);\fP
912
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]913\fI\fB
914
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]915.SH DESCRIPTION
916The
917.I libpng
918library supports encoding, decoding, and various manipulations of
919the Portable Network Graphics (PNG) format image files. It uses the
920.IR zlib(3)
921compression library.
Glenn Randers-Pehrson557b2562010-10-17 12:55:04 -0500[diff] [blame]922Following is a copy of the libpng-manual.txt file that accompanies libpng.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]923.SH LIBPNG.TXT
Glenn Randers-Pehrson557b2562010-10-17 12:55:04 -0500[diff] [blame]924libpng-manual.txt - A description on how to use and modify libpng
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]925
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]926 libpng version 1.5.2beta03 - March 3, 2011
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]927 Updated and distributed by Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]928 <glennrp at users.sourceforge.net>
Glenn Randers-Pehrson9f45c8e2011-01-15 19:35:03 -0600[diff] [blame]929 Copyright (c) 1998-2011 Glenn Randers-Pehrson
Glenn Randers-Pehrson037023b2009-06-24 10:27:36 -0500[diff] [blame]930
Glenn Randers-Pehrsonbfbf8652009-06-26 21:46:52 -0500[diff] [blame]931 This document is released under the libpng license.
Glenn Randers-Pehrsonc332bbc2009-06-25 13:43:50 -0500[diff] [blame]932 For conditions of distribution and use, see the disclaimer
Glenn Randers-Pehrson037023b2009-06-24 10:27:36 -0500[diff] [blame]933 and license in png.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]934
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]935 Based on:
936
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]937 libpng versions 0.97, January 1998, through 1.5.2beta03 - March 3, 2011
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]938 Updated and distributed by Glenn Randers-Pehrson
Glenn Randers-Pehrson9f45c8e2011-01-15 19:35:03 -0600[diff] [blame]939 Copyright (c) 1998-2011 Glenn Randers-Pehrson
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]940
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]941 libpng 1.0 beta 6 version 0.96 May 28, 1997
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]942 Updated and distributed by Andreas Dilger
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]943 Copyright (c) 1996, 1997 Andreas Dilger
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]944
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]945 libpng 1.0 beta 2 - version 0.88 January 26, 1996
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]946 For conditions of distribution and use, see copyright
947 notice in png.h. Copyright (c) 1995, 1996 Guy Eric
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]948 Schalnat, Group 42, Inc.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]949
950 Updated/rewritten per request in the libpng FAQ
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]951 Copyright (c) 1995, 1996 Frank J. T. Wojcik
952 December 18, 1995 & January 20, 1996
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]953
954.SH I. Introduction
955
956This file describes how to use and modify the PNG reference library
957(known as libpng) for your own use. There are five sections to this
958file: introduction, structures, reading, writing, and modification and
959configuration notes for various special platforms. In addition to this
960file, example.c is a good starting point for using the library, as
961it is heavily commented and should include everything most people
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]962will need. We assume that libpng is already installed; see the
963INSTALL file for instructions on how to install libpng.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]964
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]965For examples of libpng usage, see the files "example.c", "pngtest.c",
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]966and the files in the "contrib" directory, all of which are included in
967the libpng distribution.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]968
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]969Libpng was written as a companion to the PNG specification, as a way
970of reducing the amount of time and effort it takes to support the PNG
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]971file format in application programs.
972
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]973The PNG specification (second edition), November 2003, is available as
974a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at
975<http://www.w3.org/TR/2003/REC-PNG-20031110/
976The W3C and ISO documents have identical technical content.
977
978The PNG-1.2 specification is available at
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]979<http://www.libpng.org/pub/png/documents/>. It is technically equivalent
980to the PNG specification (second edition) but has some additional material.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]981
982The PNG-1.0 specification is available
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]983as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]984W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
985
986Some additional chunks are described in the special-purpose public chunks
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]987documents at <http://www.libpng.org/pub/png/documents/>.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]988
989Other information
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]990about PNG, and the latest version of libpng, can be found at the PNG home
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]991page, <http://www.libpng.org/pub/png/>.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]992
993Most users will not have to modify the library significantly; advanced
994users may want to modify it more. All attempts were made to make it as
995complete as possible, while keeping the code easy to understand.
996Currently, this library only supports C. Support for other languages
997is being considered.
998
999Libpng has been designed to handle multiple sessions at one time,
1000to be easily modifiable, to be portable to the vast majority of
1001machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
1002to use. The ultimate goal of libpng is to promote the acceptance of
1003the PNG file format in whatever way possible. While there is still
1004work to be done (see the TODO file), libpng should cover the
1005majority of the needs of its users.
1006
1007Libpng uses zlib for its compression and decompression of PNG files.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1008Further information about zlib, and the latest version of zlib, can
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]1009be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1010The zlib compression utility is a general purpose utility that is
1011useful for more than PNG files, and can be used without libpng.
1012See the documentation delivered with zlib for more details.
1013You can usually find the source files for the zlib utility wherever you
1014find the libpng source files.
1015
1016Libpng is thread safe, provided the threads are using different
1017instances of the structures. Each thread should have its own
1018png_struct and png_info instances, and thus its own image.
1019Libpng does not protect itself against two threads using the
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]1020same instance of a structure.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1021
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1022.SH II. Structures
1023
1024There are two main structures that are important to libpng, png_struct
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1025and png_info. Both are internal structures that are no longer exposed
1026in the libpng interface (as of libpng 1.5.0).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1027
1028The png_info structure is designed to provide information about the
1029PNG file. At one time, the fields of png_info were intended to be
1030directly accessible to the user. However, this tended to cause problems
1031with applications using dynamically loaded libraries, and as a result
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]1032a set of interface functions for png_info (the png_get_*() and png_set_*()
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1033functions) was developed.
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]1034
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1035The png_struct structure is the object used by the library to decode a
1036single image. As of 1.5.0 this structure is also not exposed.
1037
1038Almost all libpng APIs require a pointer to a png_struct as the first argument.
1039Many (in particular the png_set and png_get APIs) also require a pointer
1040to png_info as the second argument. Some application visible macros
1041defined in png.h designed for basic data access (reading and writing
1042integers in the PNG format) break this rule, but it's almost always safe
1043to assume that a (png_struct*) has to be passed to call an API function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1044
1045The png.h header file is an invaluable reference for programming with libpng.
1046And while I'm on the topic, make sure you include the libpng header file:
1047
1048#include <png.h>
1049
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1050.SS Types
1051
1052The png.h header file defines a number of integral types used by the
1053APIs. Most of these are fairly obvious; for example types corresponding
1054to integers of particular sizes and types for passing color values.
1055
1056One exception is how non-integral numbers are handled. For application
1057convenience most APIs that take such numbers have C (double) arguments,
1058however internally PNG, and libpng, use 32 bit signed integers and encode
1059the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
1060macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
1061which is simply (png_int_32).
1062
1063All APIs that take (double) arguments also have an matching API that
1064takes the corresponding fixed point integer arguments. The fixed point
1065API has the same name as the floating point one with _fixed appended.
1066The actual range of values permitted in the APIs is frequently less than
1067the full range of (png_fixed_point) (-21474 to +21474). When APIs require
1068a non-negative argument the type is recorded as png_uint_32 above. Consult
1069the header file and the text below for more information.
1070
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]1071Special care must be take with sCAL chunk handling because the chunk itself
1072uses non-integral values encoded as strings containing decimal floating point
1073numbers. See the comments in the header file.
1074
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1075.SS Configuration
1076
1077The main header file function declarations are frequently protected by C
1078preprocessing directives of the form:
1079
1080 #ifdef PNG_feature_SUPPORTED
1081 declare-function
1082 #endif
1083
1084The library can be built without support for these APIs, although a
1085standard build will have all implemented APIs. Application programs
1086should check the feature macros before using an API for maximum
1087portability. From libpng 1.5.0 the feature macros set during the build
1088of libpng are recorded in the header file "pnglibconf.h" and this file
1089is always included by png.h.
1090
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]1091If you don't need to change the library configuration from the default skip to
1092the next section ("Reading").
1093
1094Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all
1095of the build project files in the 'projects' directory simply copy
1096scripts/pnglibconf.h.prebuilt to pnglibconf.h. This means that these build
1097systems do not permit easy auto-configuration of the library - they only
1098support the default configuration.
1099
1100The easiest way to make minor changes to the libpng configuration when
1101auto-configuration is supported is to add definitions to the command line
1102using (typically) CPPFLAGS. For example:
1103
1104CPPFLAGS=-DPNG_NO_FLOATING_ARITHMETIC
1105
1106will change the internal libpng math implementation for gamma correction and
1107other arithmetic calculations to fixed point, avoiding the need for fast
1108floating point support. The result can be seen in the generated pnglibconf.h -
1109make sure it contains the changed feature macro setting.
1110
1111If you need to make more extensive configuration changes - more than one or two
1112feature macro settings - you can either add -DPNG_USER_CONFIG to the build
1113command line and put a list of feature macro settings in pngusr.h or you can set
1114DFA_XTRA (a makefile variable) to a file containing the same information in the
1115form of 'option' settings.
1116
1117A. Changing pnglibconf.h
1118
1119A variety of methods exist to build libpng. Not all of these support
1120reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be
1121rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand.
1122
1123Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt and changing
1124the lines defining the supported features, paying very close attention to the
1125'option' information in scripts/pnglibconf.dfa that describes those features and
1126their requirements. This is easy to get wrong.
1127
1128B. Configuration using DFA_XTRA
1129
1130Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later
1131variant such as 'nawk' or 'gawk', is available. The configure build will
1132automatically find an appropriate awk and build pnglibconf.h.
1133scripts/pnglibconf.mak contains a set of make rules for doing the same thing if
1134configure is not used, and many of the makefiles in the scripts directory use
1135this approach.
1136
1137When rebuilding simply write new file containing changed options and set
1138DFA_XTRA to the name of this file. This causes the build to append the new file
1139to the end of scripts/pnglibconf.dfa. pngusr.dfa should contain lines of the
1140following forms:
1141
1142everything = off
1143
1144This turns all optional features off. Include it at the start of pngusr.dfa to
1145make it easier to build a minimal configuration. You will need to turn at least
1146some features on afterward to enable either reading or writing code, or both.
1147
1148option feature on
1149option feature off
1150
1151Enable or disable a single feature. This will automatically enable other
1152features required by a feature that is turned on or disable other features that
1153require a feature which is turned off. Conflicting settings will cause an error
1154message to be emitted by awk.
1155
1156setting feature default value
1157
1158Changes the default value of setting 'feature' to 'value'. There are a small
1159number of settings listed at the top of pnglibconf.h, they are documented in the
1160source code. Most of these values have performance implications for the library
1161but most of them have no visible effect on the API. Some can also be overridden
1162from the API.
1163
1164C. Configuration using PNG_USR_CONFIG
1165
1166If -DPNG_USR_CONFIG is added to the CFLAGS when pnglibconf.h is built the file
1167pngusr.h will automatically be included before the options in
1168scripts/pnglibconf.dfa are processed. pngusr.h should contain only macro
1169definitions turning features on or off or setting settings.
1170
1171Apart from the global setting "everything = off" all the options listed above
1172can be set using macros in pngusr.h:
1173
1174#define PNG_feature_SUPPORTED
1175
1176is equivalent to:
1177
1178option feature on
1179
1180#define PNG_NO_feature
1181
1182is equivalent to:
1183
1184option feature off
1185
1186#define PNG_feature value
1187
1188is equivalent to:
1189
1190setting feature default value
1191
1192Notice that in both cases, pngusr.dfa and pngusr.h, the contents of the
1193pngusr file you supply override the contents of scripts/pnglibconf.dfa
1194
1195If confusing or incomprehensible behavior results it is possible to
1196examine the intermediate file pnglibconf.dfn to find the full set of
1197dependency information for each setting and option. Simply locate the
1198feature in the file and read the C comments that precede it.
1199
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1200.SH III. Reading
1201
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1202We'll now walk you through the possible functions to call when reading
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1203in a PNG file sequentially, briefly explaining the syntax and purpose
1204of each one. See example.c and png.h for more detail. While
1205progressive reading is covered in the next section, you will still
1206need some of the functions discussed in this section to read a PNG
1207file.
1208
1209.SS Setup
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1210
1211You will want to do the I/O initialization(*) before you get into libpng,
1212so if it doesn't work, you don't have much to undo. Of course, you
1213will also want to insure that you are, in fact, dealing with a PNG
1214file. Libpng provides a simple check to see if a file is a PNG file.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1215To use it, pass in the first 1 to 8 bytes of the file to the function
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]1216png_sig_cmp(), and it will return 0 (false) if the bytes match the
1217corresponding bytes of the PNG signature, or nonzero (true) otherwise.
1218Of course, the more bytes you pass in, the greater the accuracy of the
1219prediction.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1220
1221If you are intending to keep the file pointer open for use in libpng,
1222you must ensure you don't read more than 8 bytes from the beginning
1223of the file, and you also have to make a call to png_set_sig_bytes_read()
1224with the number of bytes you read from the beginning. Libpng will
1225then only check the bytes (if any) that your program didn't read.
1226
1227(*): If you are not using the standard I/O functions, you will need
1228to replace them with custom functions. See the discussion under
1229Customizing libpng.
1230
1231
1232 FILE *fp = fopen(file_name, "rb");
1233 if (!fp)
1234 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1235 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1236 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1237
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1238 fread(header, 1, number, fp);
Glenn Randers-Pehrsonc9442291999-01-06 21:50:16 -0600[diff] [blame]1239 is_png = !png_sig_cmp(header, 0, number);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1240
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1241 if (!is_png)
1242 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1243 return (NOT_PNG);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1244 }
1245
1246
1247Next, png_struct and png_info need to be allocated and initialized. In
1248order to ensure that the size of these structures is correct even with a
1249dynamically linked libpng, there are functions to initialize and
1250allocate the structures. We also pass the library version, optional
1251pointers to error handling functions, and a pointer to a data struct for
1252use by the error functions, if necessary (the pointer and functions can
1253be NULL if the default error handlers are to be used). See the section
1254on Changes to Libpng below regarding the old initialization functions.
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]1255The structure allocation functions quietly return NULL if they fail to
1256create the structure, so your application should check for that.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1257
1258 png_structp png_ptr = png_create_read_struct
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1259 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1260 user_error_fn, user_warning_fn);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1261
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1262 if (!png_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1263 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1264
1265 png_infop info_ptr = png_create_info_struct(png_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1266
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1267 if (!info_ptr)
1268 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1269 png_destroy_read_struct(&png_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1270 (png_infopp)NULL, (png_infopp)NULL);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1271 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1272 }
1273
1274 png_infop end_info = png_create_info_struct(png_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1275
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1276 if (!end_info)
1277 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1278 png_destroy_read_struct(&png_ptr, &info_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1279 (png_infopp)NULL);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1280 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1281 }
1282
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]1283If you want to use your own memory allocation routines,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1284use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]1285png_create_read_struct_2() instead of png_create_read_struct():
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1286
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]1287 png_structp png_ptr = png_create_read_struct_2
1288 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
1289 user_error_fn, user_warning_fn, (png_voidp)
1290 user_mem_ptr, user_malloc_fn, user_free_fn);
1291
1292The error handling routines passed to png_create_read_struct()
1293and the memory alloc/free routines passed to png_create_struct_2()
1294are only necessary if you are not using the libpng supplied error
1295handling and memory alloc/free functions.
1296
1297When libpng encounters an error, it expects to longjmp back
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1298to your routine. Therefore, you will need to call setjmp and pass
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1299your png_jmpbuf(png_ptr). If you read the file from different
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1300routines, you will need to update the jmpbuf field every time you enter
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1301a new routine that will call a png_*() function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1302
1303See your documentation of setjmp/longjmp for your compiler for more
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1304information on setjmp/longjmp. See the discussion on libpng error
1305handling in the Customizing Libpng section below for more information
1306on the libpng error handling. If an error occurs, and libpng longjmp's
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1307back to your setjmp, you will want to call png_destroy_read_struct() to
1308free any memory.
1309
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1310 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1311 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1312 png_destroy_read_struct(&png_ptr, &info_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1313 &end_info);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1314 fclose(fp);
1315 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1316 }
1317
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1318If you would rather avoid the complexity of setjmp/longjmp issues,
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]1319you can compile libpng with PNG_NO_SETJMP, in which case
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1320errors will result in a call to PNG_ABORT() which defaults to abort().
1321
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]1322You can #define PNG_ABORT() to a function that does something
1323more useful than abort(), as long as your function does not
1324return.
1325
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1326Now you need to set up the input code. The default for libpng is to
1327use the C function fread(). If you use this, you will need to pass a
1328valid FILE * in the function png_init_io(). Be sure that the file is
1329opened in binary mode. If you wish to handle reading data in another
1330way, you need not call the png_init_io() function, but you must then
1331implement the libpng I/O methods discussed in the Customizing Libpng
1332section below.
1333
1334 png_init_io(png_ptr, fp);
1335
1336If you had previously opened the file and read any of the signature from
1337the beginning in order to see if this was a PNG file, you need to let
1338libpng know that there are some bytes missing from the start of the file.
1339
1340 png_set_sig_bytes(png_ptr, number);
1341
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]1342You can change the zlib compression buffer size to be used while
1343reading compressed data with
1344
1345 png_set_compression_buffer_size(png_ptr, buffer_size);
1346
1347where the default size is 8192 bytes. Note that the buffer size
1348is changed immediately and the buffer is reallocated immediately,
1349instead of setting a flag to be acted upon later.
1350
Glenn Randers-Pehrson9dd1cdf2011-01-06 21:42:36 -0600[diff] [blame]1351If you want CRC errors to be handled in a different manner than
1352the default, use
1353
1354 png_set_crc_action(png_ptr, crit_action, ancil_action);
1355
1356The values for png_set_crc_action() say how libpng is to handle CRC errors in
1357ancillary and critical chunks, and whether to use the data contained
1358therein. Note that it is impossible to "discard" data in a critical
1359chunk.
1360
1361Choices for (int) crit_action are
1362 PNG_CRC_DEFAULT 0 error/quit
1363 PNG_CRC_ERROR_QUIT 1 error/quit
1364 PNG_CRC_WARN_USE 3 warn/use data
1365 PNG_CRC_QUIET_USE 4 quiet/use data
1366 PNG_CRC_NO_CHANGE 5 use the current value
1367
1368Choices for (int) ancil_action are
1369 PNG_CRC_DEFAULT 0 error/quit
1370 PNG_CRC_ERROR_QUIT 1 error/quit
1371 PNG_CRC_WARN_DISCARD 2 warn/discard data
1372 PNG_CRC_WARN_USE 3 warn/use data
1373 PNG_CRC_QUIET_USE 4 quiet/use data
1374 PNG_CRC_NO_CHANGE 5 use the current value
1375
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1376.SS Setting up callback code
1377
1378You can set up a callback function to handle any unknown chunks in the
1379input stream. You must supply the function
1380
Glenn Randers-Pehrson81ce8892011-01-24 08:04:37 -0600[diff] [blame]1381 read_chunk_callback(png_structp png_ptr,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1382 png_unknown_chunkp chunk);
1383 {
1384 /* The unknown chunk structure contains your
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1385 chunk data, along with similar data for any other
1386 unknown chunks: */
1387
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1388 png_byte name[5];
1389 png_byte *data;
1390 png_size_t size;
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1391
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1392 /* Note that libpng has already taken care of
1393 the CRC handling */
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1394
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1395 /* put your code here. Search for your chunk in the
1396 unknown chunk structure, process it, and return one
1397 of the following: */
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1398
1399 return (-n); /* chunk had an error */
1400 return (0); /* did not recognize */
1401 return (n); /* success */
1402 }
1403
1404(You can give your function another name that you like instead of
1405"read_chunk_callback")
1406
1407To inform libpng about your function, use
1408
1409 png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
1410 read_chunk_callback);
1411
1412This names not only the callback function, but also a user pointer that
1413you can retrieve with
1414
1415 png_get_user_chunk_ptr(png_ptr);
1416
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1417If you call the png_set_read_user_chunk_fn() function, then all unknown
1418chunks will be saved when read, in case your callback function will need
1419one or more of them. This behavior can be changed with the
1420png_set_keep_unknown_chunks() function, described below.
1421
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]1422At this point, you can set up a callback function that will be
1423called after each row has been read, which you can use to control
1424a progress meter or the like. It's demonstrated in pngtest.c.
1425You must supply a function
1426
Glenn Randers-Pehrson81ce8892011-01-24 08:04:37 -0600[diff] [blame]1427 void read_row_callback(png_structp png_ptr,
1428 png_uint_32 row, int pass);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]1429 {
1430 /* put your code here */
1431 }
1432
1433(You can give it another name that you like instead of "read_row_callback")
1434
1435To inform libpng about your function, use
1436
1437 png_set_read_status_fn(png_ptr, read_row_callback);
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1438
John Bowler59010e52011-02-16 06:16:31 -0600[diff] [blame]1439When this function is called the row has already been completely processed and
1440the 'row' and 'pass' refer to the next row to be handled. For the
1441non-interlaced case the row that was just handled is simply one less than the
1442passed in row number, and pass will always be 0. For the interlaced case the
1443same applies unless the row value is 0, in which case the row just handled was
1444the last one from one of the preceding passes. Because interlacing may skip a
1445pass you cannot be sure that the preceding pass is just 'pass-1', if you really
1446need to know what the last pass is record (row,pass) from the callback and use
1447the last recorded value each time.
1448
1449As with the user transform you can find the output row using the
1450PNG_ROW_FROM_PASS_ROW macro.
1451
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1452.SS Unknown-chunk handling
1453
1454Now you get to set the way the library processes unknown chunks in the
1455input PNG stream. Both known and unknown chunks will be read. Normal
1456behavior is that known chunks will be parsed into information in
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1457various info_ptr members while unknown chunks will be discarded. This
1458behavior can be wasteful if your application will never use some known
1459chunk types. To change this, you can call:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1460
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]1461 png_set_keep_unknown_chunks(png_ptr, keep,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1462 chunk_list, num_chunks);
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1463 keep - 0: default unknown chunk handling
1464 1: ignore; do not keep
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1465 2: keep only if safe-to-copy
1466 3: keep even if unsafe-to-copy
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1467
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1468 You can use these definitions:
1469 PNG_HANDLE_CHUNK_AS_DEFAULT 0
1470 PNG_HANDLE_CHUNK_NEVER 1
1471 PNG_HANDLE_CHUNK_IF_SAFE 2
1472 PNG_HANDLE_CHUNK_ALWAYS 3
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1473
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1474 chunk_list - list of chunks affected (a byte string,
1475 five bytes per chunk, NULL or '\0' if
1476 num_chunks is 0)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1477
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1478 num_chunks - number of chunks affected; if 0, all
Glenn Randers-Pehrsondff799e2004-08-07 21:42:49 -0500[diff] [blame]1479 unknown chunks are affected. If nonzero,
1480 only the chunks in the list are affected
1481
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1482Unknown chunks declared in this way will be saved as raw data onto a
1483list of png_unknown_chunk structures. If a chunk that is normally
1484known to libpng is named in the list, it will be handled as unknown,
1485according to the "keep" directive. If a chunk is named in successive
1486instances of png_set_keep_unknown_chunks(), the final instance will
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1487take precedence. The IHDR and IEND chunks should not be named in
1488chunk_list; if they are, libpng will process them normally anyway.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1489
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1490Here is an example of the usage of png_set_keep_unknown_chunks(),
1491where the private "vpAg" chunk will later be processed by a user chunk
1492callback function:
1493
1494 png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
1495
1496 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
1497 png_byte unused_chunks[]=
1498 {
1499 104, 73, 83, 84, (png_byte) '\0', /* hIST */
1500 105, 84, 88, 116, (png_byte) '\0', /* iTXt */
1501 112, 67, 65, 76, (png_byte) '\0', /* pCAL */
1502 115, 67, 65, 76, (png_byte) '\0', /* sCAL */
1503 115, 80, 76, 84, (png_byte) '\0', /* sPLT */
1504 116, 73, 77, 69, (png_byte) '\0', /* tIME */
1505 };
1506 #endif
1507
1508 ...
1509
1510 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
1511 /* ignore all unknown chunks: */
1512 png_set_keep_unknown_chunks(read_ptr, 1, NULL, 0);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1513
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1514 /* except for vpAg: */
1515 png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1516
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1517 /* also ignore unused known chunks: */
1518 png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
1519 (int)sizeof(unused_chunks)/5);
1520 #endif
1521
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]1522.SS User limits
1523
1524The PNG specification allows the width and height of an image to be as
1525large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
1526Since very few applications really need to process such large images,
1527we have imposed an arbitrary 1-million limit on rows and columns.
1528Larger images will be rejected immediately with a png_error() call. If
1529you wish to override this limit, you can use
1530
1531 png_set_user_limits(png_ptr, width_max, height_max);
1532
1533to set your own limits, or use width_max = height_max = 0x7fffffffL
1534to allow all valid dimensions (libpng may reject some very large images
1535anyway because of potential buffer overflow conditions).
1536
1537You should put this statement after you create the PNG structure and
1538before calling png_read_info(), png_read_png(), or png_process_data().
1539If you need to retrieve the limits that are being applied, use
1540
1541 width_max = png_get_user_width_max(png_ptr);
1542 height_max = png_get_user_height_max(png_ptr);
1543
1544The PNG specification sets no limit on the number of ancillary chunks
1545allowed in a PNG datastream. You can impose a limit on the total number
1546of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with
1547
1548 png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
1549
1550where 0x7fffffffL means unlimited. You can retrieve this limit with
1551
1552 chunk_cache_max = png_get_chunk_cache_max(png_ptr);
1553
Glenn Randers-Pehrson8f5846f2009-10-31 21:31:08 -0500[diff] [blame]1554This limit also applies to the number of buffers that can be allocated
1555by png_decompress_chunk() while decompressing iTXt, zTXt, and iCCP chunks.
1556
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]1557You can also set a limit on the amount of memory that a compressed chunk
1558other than IDAT can occupy, with
1559
1560 png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
1561
1562and you can retrieve the limit with
1563
1564 chunk_malloc_max = png_get_chunk_malloc_max(png_ptr);
1565
1566Any chunks that would cause either of these limits to be exceeded will
1567be ignored.
1568
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1569.SS The high-level read interface
1570
1571At this point there are two ways to proceed; through the high-level
1572read interface, or through a sequence of low-level read operations.
1573You can use the high-level interface if (a) you are willing to read
1574the entire image into memory, and (b) the input transformations
1575you want to do are limited to the following set:
1576
1577 PNG_TRANSFORM_IDENTITY No transformation
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1578 PNG_TRANSFORM_STRIP_16 Strip 16-bit samples to
1579 8 bits
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1580 PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1581 PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit
1582 samples to bytes
1583 PNG_TRANSFORM_PACKSWAP Change order of packed
1584 pixels to LSB first
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1585 PNG_TRANSFORM_EXPAND Perform set_expand()
1586 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1587 PNG_TRANSFORM_SHIFT Normalize pixels to the
1588 sBIT depth
1589 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
1590 to BGRA
1591 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
1592 to AG
1593 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
1594 to transparency
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1595 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
Glenn Randers-Pehrson99708d52009-06-29 17:30:00 -0500[diff] [blame]1596 PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
1597 to RGB (or GA to RGBA)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1598
1599(This excludes setting a background color, doing gamma transformation,
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]1600quantizing, and setting filler.) If this is the case, simply do this:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1601
1602 png_read_png(png_ptr, info_ptr, png_transforms, NULL)
1603
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]1604where png_transforms is an integer containing the bitwise OR of some
1605set of transformation flags. This call is equivalent to png_read_info(),
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1606followed the set of transformations indicated by the transform mask,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1607then png_read_image(), and finally png_read_end().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1608
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1609(The final parameter of this call is not yet used. Someday it might point
1610to transformation parameters required by some future input transform.)
1611
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]1612You must use png_transforms and not call any png_set_transform() functions
1613when you use png_read_png().
1614
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1615After you have called png_read_png(), you can retrieve the image data
1616with
1617
1618 row_pointers = png_get_rows(png_ptr, info_ptr);
1619
1620where row_pointers is an array of pointers to the pixel data for each row:
1621
1622 png_bytep row_pointers[height];
1623
1624If you know your image size and pixel size ahead of time, you can allocate
1625row_pointers prior to calling png_read_png() with
1626
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1627 if (height > PNG_UINT_32_MAX/png_sizeof(png_byte))
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]1628 png_error (png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1629 "Image is too tall to process in memory");
1630
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]1631 if (width > PNG_UINT_32_MAX/pixel_size)
1632 png_error (png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1633 "Image is too wide to process in memory");
1634
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1635 row_pointers = png_malloc(png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1636 height*png_sizeof(png_bytep));
1637
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1638 for (int i=0; i<height, i++)
1639 row_pointers[i]=NULL; /* security precaution */
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1640
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1641 for (int i=0; i<height, i++)
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1642 row_pointers[i]=png_malloc(png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1643 width*pixel_size);
1644
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]1645 png_set_rows(png_ptr, info_ptr, &row_pointers);
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1646
1647Alternatively you could allocate your image in one big block and define
1648row_pointers[i] to point into the proper places in your block.
1649
1650If you use png_set_rows(), the application is responsible for freeing
1651row_pointers (and row_pointers[i], if they were separately allocated).
1652
1653If you don't allocate row_pointers ahead of time, png_read_png() will
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1654do it, and it'll be free'ed by libpng when you call png_destroy_*().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1655
1656.SS The low-level read interface
1657
1658If you are going the low-level route, you are now ready to read all
1659the file information up to the actual image data. You do this with a
1660call to png_read_info().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1661
1662 png_read_info(png_ptr, info_ptr);
1663
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1664This will process all chunks up to but not including the image data.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1665
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1666.SS Querying the info structure
1667
1668Functions are used to get the information from the info_ptr once it
1669has been read. Note that these fields may not be completely filled
1670in until png_read_end() has read the chunk data following the image.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1671
1672 png_get_IHDR(png_ptr, info_ptr, &width, &height,
1673 &bit_depth, &color_type, &interlace_type,
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]1674 &compression_type, &filter_method);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1675
1676 width - holds the width of the image
1677 in pixels (up to 2^31).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1678
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1679 height - holds the height of the image
1680 in pixels (up to 2^31).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1681
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1682 bit_depth - holds the bit depth of one of the
1683 image channels. (valid values are
1684 1, 2, 4, 8, 16 and depend also on
1685 the color_type. See also
1686 significant bits (sBIT) below).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1687
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1688 color_type - describes which color/alpha channels
1689 are present.
1690 PNG_COLOR_TYPE_GRAY
1691 (bit depths 1, 2, 4, 8, 16)
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1692 PNG_COLOR_TYPE_GRAY_ALPHA
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1693 (bit depths 8, 16)
1694 PNG_COLOR_TYPE_PALETTE
1695 (bit depths 1, 2, 4, 8)
1696 PNG_COLOR_TYPE_RGB
1697 (bit_depths 8, 16)
1698 PNG_COLOR_TYPE_RGB_ALPHA
1699 (bit_depths 8, 16)
1700
1701 PNG_COLOR_MASK_PALETTE
1702 PNG_COLOR_MASK_COLOR
1703 PNG_COLOR_MASK_ALPHA
1704
Glenn Randers-Pehrson2cb633b2011-01-21 08:31:29 -0600[diff] [blame]1705 interlace_type - (PNG_INTERLACE_NONE or
1706 PNG_INTERLACE_ADAM7)
1707
1708 compression_type - (must be PNG_COMPRESSION_TYPE_BASE
1709 for PNG 1.0)
1710
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]1711 filter_method - (must be PNG_FILTER_TYPE_BASE
1712 for PNG 1.0, and can also be
1713 PNG_INTRAPIXEL_DIFFERENCING if
1714 the PNG datastream is embedded in
1715 a MNG-1.0 datastream)
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1716
1717 Any or all of interlace_type, compression_type, or
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1718 filter_method can be NULL if you are
1719 not interested in their values.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1720
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1721 Note that png_get_IHDR() returns 32-bit data into
1722 the application's width and height variables.
1723 This is an unsafe situation if these are 16-bit
1724 variables. In such situations, the
1725 png_get_image_width() and png_get_image_height()
1726 functions described below are safer.
1727
1728 width = png_get_image_width(png_ptr,
1729 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1730
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1731 height = png_get_image_height(png_ptr,
1732 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1733
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1734 bit_depth = png_get_bit_depth(png_ptr,
1735 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1736
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1737 color_type = png_get_color_type(png_ptr,
1738 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1739
Glenn Randers-Pehrson2cb633b2011-01-21 08:31:29 -0600[diff] [blame]1740 interlace_type = png_get_interlace_type(png_ptr,
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1741 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1742
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1743 compression_type = png_get_compression_type(png_ptr,
1744 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1745
Glenn Randers-Pehrson2cb633b2011-01-21 08:31:29 -0600[diff] [blame]1746 filter_method = png_get_filter_type(png_ptr,
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1747 info_ptr);
1748
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1749 channels = png_get_channels(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1750
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1751 channels - number of channels of info for the
1752 color type (valid values are 1 (GRAY,
1753 PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
1754 4 (RGB_ALPHA or RGB + filler byte))
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1755
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1756 rowbytes = png_get_rowbytes(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1757
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1758 rowbytes - number of bytes needed to hold a row
1759
1760 signature = png_get_signature(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1761
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1762 signature - holds the signature read from the
1763 file (if any). The data is kept in
1764 the same offset it would be if the
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1765 whole signature were read (i.e. if an
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1766 application had already read in 4
1767 bytes of signature before starting
1768 libpng, the remaining 4 bytes would
1769 be in signature[4] through signature[7]
1770 (see png_set_sig_bytes())).
1771
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1772These are also important, but their validity depends on whether the chunk
1773has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
1774png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
1775data has been read, or zero if it is missing. The parameters to the
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]1776png_get_<chunk> are set directly if they are simple data types, or a
1777pointer into the info_ptr is returned for any complex types.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1778
1779 png_get_PLTE(png_ptr, info_ptr, &palette,
1780 &num_palette);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1781
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1782 palette - the palette for the file
1783 (array of png_color)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1784
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1785 num_palette - number of entries in the palette
1786
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]1787 png_get_gAMA(png_ptr, info_ptr, &file_gamma);
Glenn Randers-Pehrson27742382011-01-27 09:37:34 -0600[diff] [blame]1788 png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1789
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]1790 file_gamma - the gamma at which the file is
1791 written (PNG_INFO_gAMA)
1792
1793 int_file_gamma - 100,000 times the gamma at which the
1794 file is written
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1795
1796 png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1797
Glenn Randers-Pehrson27742382011-01-27 09:37:34 -0600[diff] [blame]1798 file_srgb_intent - the rendering intent (PNG_INFO_sRGB)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1799 The presence of the sRGB chunk
1800 means that the pixel data is in the
1801 sRGB color space. This chunk also
1802 implies specific values of gAMA and
1803 cHRM.
1804
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1805 png_get_iCCP(png_ptr, info_ptr, &name,
1806 &compression_type, &profile, &proflen);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1807
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]1808 name - The profile name.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1809
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]1810 compression_type - The compression type; always
1811 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
1812 You may give NULL to this argument to
1813 ignore it.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1814
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]1815 profile - International Color Consortium color
1816 profile data. May contain NULs.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1817
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]1818 proflen - length of profile data in bytes.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1819
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1820 png_get_sBIT(png_ptr, info_ptr, &sig_bit);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1821
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1822 sig_bit - the number of significant bits for
1823 (PNG_INFO_sBIT) each of the gray,
1824 red, green, and blue channels,
1825 whichever are appropriate for the
1826 given color type (png_color_16)
1827
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]1828 png_get_tRNS(png_ptr, info_ptr, &trans_alpha,
1829 &num_trans, &trans_color);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1830
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]1831 trans_alpha - array of alpha (transparency)
1832 entries for palette (PNG_INFO_tRNS)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1833
Glenn Randers-Pehrsonf3c51e42011-01-15 10:25:25 -0600[diff] [blame]1834 num_trans - number of transparent entries
1835 (PNG_INFO_tRNS)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1836
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]1837 trans_color - graylevel or color sample values of
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]1838 the single transparent color for
1839 non-paletted images (PNG_INFO_tRNS)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1840
1841 png_get_hIST(png_ptr, info_ptr, &hist);
1842 (PNG_INFO_hIST)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1843
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1844 hist - histogram of palette (array of
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1845 png_uint_16)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1846
1847 png_get_tIME(png_ptr, info_ptr, &mod_time);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1848
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1849 mod_time - time image was last modified
1850 (PNG_VALID_tIME)
1851
1852 png_get_bKGD(png_ptr, info_ptr, &background);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1853
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1854 background - background color (PNG_VALID_bKGD)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1855 valid 16-bit red, green and blue
1856 values, regardless of color_type
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1857
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1858 num_comments = png_get_text(png_ptr, info_ptr,
1859 &text_ptr, &num_text);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1860
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1861 num_comments - number of comments
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1862
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1863 text_ptr - array of png_text holding image
1864 comments
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1865
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1866 text_ptr[i].compression - type of compression used
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1867 on "text" PNG_TEXT_COMPRESSION_NONE
1868 PNG_TEXT_COMPRESSION_zTXt
1869 PNG_ITXT_COMPRESSION_NONE
1870 PNG_ITXT_COMPRESSION_zTXt
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1871
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1872 text_ptr[i].key - keyword for comment. Must contain
1873 1-79 characters.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1874
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1875 text_ptr[i].text - text comments for current
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]1876 keyword. Can be empty.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1877
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1878 text_ptr[i].text_length - length of text string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1879 after decompression, 0 for iTXt
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1880
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1881 text_ptr[i].itxt_length - length of itxt string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1882 after decompression, 0 for tEXt/zTXt
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1883
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1884 text_ptr[i].lang - language of comment (empty
1885 string for unknown).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1886
Glenn Randers-Pehrson73d57cb2002-03-25 18:49:08 -0600[diff] [blame]1887 text_ptr[i].lang_key - keyword in UTF-8
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1888 (empty string for unknown).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1889
Glenn Randers-Pehrson8f5846f2009-10-31 21:31:08 -0500[diff] [blame]1890 Note that the itxt_length, lang, and lang_key
1891 members of the text_ptr structure only exist
1892 when the library is built with iTXt chunk support.
1893
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1894 num_text - number of comments (same as
1895 num_comments; you can put NULL here
1896 to avoid the duplication)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1897
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1898 Note while png_set_text() will accept text, language,
1899 and translated keywords that can be NULL pointers, the
1900 structure returned by png_get_text will always contain
1901 regular zero-terminated C strings. They might be
1902 empty strings but they will never be NULL pointers.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1903
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1904 num_spalettes = png_get_sPLT(png_ptr, info_ptr,
1905 &palette_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1906
1907 num_spalettes - number of sPLT chunks read.
1908
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1909 palette_ptr - array of palette structures holding
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1910 contents of one or more sPLT chunks
1911 read.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1912
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1913 png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1914 &unit_type);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1915
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1916 offset_x - positive offset from the left edge
1917 of the screen
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1918
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1919 offset_y - positive offset from the top edge
1920 of the screen
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1921
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1922 unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
1923
1924 png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1925 &unit_type);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1926
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1927 res_x - pixels/unit physical resolution in
1928 x direction
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1929
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1930 res_y - pixels/unit physical resolution in
1931 x direction
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1932
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1933 unit_type - PNG_RESOLUTION_UNKNOWN,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1934 PNG_RESOLUTION_METER
1935
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1936 png_get_sCAL(png_ptr, info_ptr, &unit, &width,
1937 &height)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1938
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1939 unit - physical scale units (an integer)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1940
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1941 width - width of a pixel in physical scale units
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1942
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1943 height - height of a pixel in physical scale units
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1944 (width and height are doubles)
1945
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1946 png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
1947 &height)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1948
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1949 unit - physical scale units (an integer)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1950
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1951 width - width of a pixel in physical scale units
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1952
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1953 height - height of a pixel in physical scale units
1954 (width and height are strings like "2.54")
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1955
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1956 num_unknown_chunks = png_get_unknown_chunks(png_ptr,
1957 info_ptr, &unknowns)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1958
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1959 unknowns - array of png_unknown_chunk
1960 structures holding unknown chunks
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1961
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1962 unknowns[i].name - name of unknown chunk
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1963
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1964 unknowns[i].data - data of unknown chunk
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1965
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1966 unknowns[i].size - size of unknown chunk's data
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1967
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1968 unknowns[i].location - position of chunk in file
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1969
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1970 The value of "i" corresponds to the order in which the
1971 chunks were read from the PNG file or inserted with the
1972 png_set_unknown_chunks() function.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1973
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1974The data from the pHYs chunk can be retrieved in several convenient
1975forms:
1976
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1977 res_x = png_get_x_pixels_per_meter(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1978 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1979
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1980 res_y = png_get_y_pixels_per_meter(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1981 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1982
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1983 res_x_and_y = png_get_pixels_per_meter(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1984 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1985
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1986 res_x = png_get_x_pixels_per_inch(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1987 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1988
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1989 res_y = png_get_y_pixels_per_inch(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1990 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1991
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1992 res_x_and_y = png_get_pixels_per_inch(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1993 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1994
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1995 aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1996 info_ptr)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1997
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1998 Each of these returns 0 [signifying "unknown"] if
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1999 the data is not present or if res_x is 0;
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2000 res_x_and_y is 0 if res_x != res_y
2001
2002 Note that because of the way the resolutions are
2003 stored internally, the inch conversions won't
2004 come out to exactly even number. For example,
2005 72 dpi is stored as 0.28346 pixels/meter, and
2006 when this is retrieved it is 71.9988 dpi, so
2007 be sure to round the returned value appropriately
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2008 if you want to display a reasonable-looking result.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2009
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2010The data from the oFFs chunk can be retrieved in several convenient
2011forms:
2012
2013 x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2014
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2015 y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2016
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2017 x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2018
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2019 y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
2020
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2021 Each of these returns 0 [signifying "unknown" if both
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2022 x and y are 0] if the data is not present or if the
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2023 chunk is present but the unit is the pixel. The
2024 remark about inexact inch conversions applies here
2025 as well, because a value in inches can't always be
2026 converted to microns and back without some loss
2027 of precision.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2028
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2029For more information, see the png_info definition in png.h and the
2030PNG specification for chunk contents. Be careful with trusting
2031rowbytes, as some of the transformations could increase the space
2032needed to hold a row (expand, filler, gray_to_rgb, etc.).
2033See png_read_update_info(), below.
2034
2035A quick word about text_ptr and num_text. PNG stores comments in
2036keyword/text pairs, one pair per chunk, with no limit on the number
2037of text chunks, and a 2^31 byte limit on their size. While there are
2038suggested keywords, there is no requirement to restrict the use to these
2039strings. It is strongly suggested that keywords and text be sensible
2040to humans (that's the point), so don't use abbreviations. Non-printing
2041symbols are not allowed. See the PNG specification for more details.
2042There is also no requirement to have text after the keyword.
2043
2044Keywords should be limited to 79 Latin-1 characters without leading or
2045trailing spaces, but non-consecutive spaces are allowed within the
2046keyword. It is possible to have the same keyword any number of times.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2047The text_ptr is an array of png_text structures, each holding a
2048pointer to a language string, a pointer to a keyword and a pointer to
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2049a text string. The text string, language code, and translated
2050keyword may be empty or NULL pointers. The keyword/text
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2051pairs are put into the array in the order that they are received.
2052However, some or all of the text chunks may be after the image, so, to
2053make sure you have read all the text chunks, don't mess with these
2054until after you read the stuff after the image. This will be
2055mentioned again below in the discussion that goes with png_read_end().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2056
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2057.SS Input transformations
2058
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2059After you've read the header information, you can set up the library
2060to handle any special transformations of the image data. The various
2061ways to transform the data will be described in the order that they
2062should occur. This is important, as some of these change the color
2063type and/or bit depth of the data, and some others only work on
2064certain color types and bit depths. Even though each transformation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2065checks to see if it has data that it can do something with, you should
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2066make sure to only enable a transformation if it will be valid for the
2067data. For example, don't swap red and blue on grayscale data.
2068
2069The colors used for the background and transparency values should be
2070supplied in the same format/depth as the current image data. They
2071are stored in the same format/depth as the image data in a bKGD or tRNS
2072chunk, so this is what libpng expects for this data. The colors are
2073transformed to keep in sync with the image data when an application
2074calls the png_read_update_info() routine (see below).
2075
2076Data will be decoded into the supplied row buffers packed into bytes
2077unless the library has been told to transform it into another format.
2078For example, 4 bit/pixel paletted or grayscale data will be returned
20792 pixels/byte with the leftmost pixel in the high-order bits of the
2080byte, unless png_set_packing() is called. 8-bit RGB data will be stored
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2081in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
2082is called to insert filler bytes, either before or after each RGB triplet.
208316-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
2084byte of the color value first, unless png_set_strip_16() is called to
Glenn Randers-Pehrson16e11662004-11-01 14:13:40 -0600[diff] [blame]2085transform it to regular RGB RGB triplets, or png_set_filler() or
2086png_set_add alpha() is called to insert filler bytes, either before or
2087after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
2088be modified with
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2089png_set_filler(), png_set_add_alpha(), or png_set_strip_16().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2090
2091The following code transforms grayscale images of less than 8 to 8 bits,
2092changes paletted images to RGB, and adds a full alpha channel if there is
2093transparency information in a tRNS chunk. This is most useful on
2094grayscale images with bit depths of 2 or 4 or if there is a multiple-image
2095viewing application that wishes to treat all images in the same way.
2096
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2097 if (color_type == PNG_COLOR_TYPE_PALETTE)
2098 png_set_palette_to_rgb(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2099
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2100 if (png_get_valid(png_ptr, info_ptr,
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2101 PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
2102
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2103 if (color_type == PNG_COLOR_TYPE_GRAY &&
2104 bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
2105
2106The first two functions are actually aliases for png_set_expand(), added
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2107in libpng version 1.0.4, with the function names expanded to improve code
2108readability. In some future version they may actually do different
2109things.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2110
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]2111As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
2112added. It expands the sample depth without changing tRNS to alpha.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]2113
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2114As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2115png_set_expand(), however, the resultant channels have 16 bits rather than 8.
2116Use this when the output color or gray channels are made linear to avoid fairly
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2117severe accuracy loss.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]2118
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2119 if (bit_depth < 16)
2120 png_set_expand_16(png_ptr);
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]2121
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2122PNG can have files with 16 bits per channel. If you only can handle
21238 bits per channel, this will strip the pixels down to 8 bit.
2124
2125 if (bit_depth == 16)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2126 png_set_strip_16(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2127
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2128If, for some reason, you don't need the alpha channel on an image,
2129and you want to remove it rather than combining it with the background
2130(but the image author certainly had in mind that you *would* combine
2131it with the background, so that's what you should probably do):
2132
2133 if (color_type & PNG_COLOR_MASK_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2134 png_set_strip_alpha(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2135
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2136See below for png_set_background(), which does the correct composition on a
2137single opaque color. This is probably what you should do in all cases rather
2138than use png_set_strip_alpha() - unless you know for sure that it is the wrong
2139thing to do.
2140
2141As of libpng version 1.5.2, almost all useful expansions are supported, the
2142major ommissions are convertion of grayscale to indexed images (which can be
2143done trivially in the application) and convertion of indexed to grayscale (which
2144can be done by a trivial manipulation of the palette.)
2145
2146In the following table, the 01 means grayscale with depth<8, 31 means
2147indexed with depth<8, other numerals represent the color type, "T" means
2148the tRNS chunk is present, A means an alpha channel is present, and O
2149means tRNS or alpha is present but all pixels in the image are opaque.
2150
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2151 FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2152 TO
2153 01 - [G] - - - - - - - - - - - - -
2154 31 [Q] Q [Q] [Q] [Q] Q Q Q Q Q Q [Q] [Q] Q Q
2155 0 1 G + . . G G G G G G B B GB GB
2156 0T lt Gt t + . Gt G G Gt G G Bt Bt GBt GBt
2157 0O lt Gt t . + Gt Gt G Gt Gt G Bt Bt GBt GBt
2158 2 C P C C C + . . C - - CB CB B B
2159 2T Ct - Ct C C t + t - - - CBt CBt Bt Bt
2160 2O Ct - Ct C C t t + - - - CBt CBt Bt Bt
2161 3 [Q] p [Q] [Q] [Q] Q Q Q + . . [Q] [Q] Q Q
2162 3T [Qt] p [Qt][Q] [Q] Qt Qt Qt t + t [Qt][Qt] Qt Qt
2163 3O [Qt] p [Qt][Q] [Q] Qt Qt Qt t t + [Qt][Qt] Qt Qt
2164 4A lA G A T T GA GT GT GA GT GT + BA G GBA
2165 4O lA GBA A T T GA GT GT GA GT GT BA + GBA G
2166 6A CA PA CA C C A T tT PA P P C CBA + BA
2167 6O CA PBA CA C C A tT T PA P P CBA C BA +
2168
2169Within the matrix,
2170 "+" identifies entries where 'from' and 'to' are the same.
2171 "-" means the transformation is not supported.
2172 "." means nothing is necessary (a tRNS chunk can just be ignored).
2173 "t" means the transformation is obtained by png_set_tRNS.
2174 "A" means the transformation is obtained by png_set_add_alpha().
2175 "X" means the transformation is obtained by png_set_expand().
2176 "1" means the transformation is obtained by
2177 png_set_expand_gray_1_2_4_to_8() (and by png_set_expand() if there
2178 is no transparency in the original or the final format).
2179 "C" means the transformation is obtained by png_set_gray_to_rgb().
2180 "G" means the transformation is obtained by png_set_rgb_to_gray() or
2181 png_set_rgb_to_Y().
2182 "P" means the transformation is obtained by
2183 png_set_expand_palette_to_rgb().
2184 "p" means the transformation is obtained by png_set_packing().
2185 "Q" means the transformation is obtained by png_set_quantize().
2186 "T" means the transformation is obtained by png_set_tRNS_to_alpha().
2187 "B" means the transformation is obtained by png_set_background(), or
2188 png_strip_alpha().
2189 "8" means the transformation is obtained by png_set_strip_16().
2190 "6" means the transformation is obtained by png_set_expand_16().
2191
2192When an entry has multiple transforms listed all are required to cause the
2193right overall transformation. When two transforms are separated by a comma
2194either will do the job. When transforms are enclosed in [] the transform should
2195do the job but this is currently unimplemented - a different format will result
2196if the suggested transformations are used.
2197
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2198In PNG files, the alpha channel in an image
2199is the level of opacity. If you need the alpha channel in an image to
2200be the level of transparency instead of opacity, you can invert the
2201alpha channel (or the tRNS chunk data) after it's read, so that 0 is
2202fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
2203images) is fully transparent, with
2204
2205 png_set_invert_alpha(png_ptr);
2206
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2207PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
2208they can, resulting in, for example, 8 pixels per byte for 1 bit
2209files. This code expands to 1 pixel per byte without changing the
2210values of the pixels:
2211
2212 if (bit_depth < 8)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2213 png_set_packing(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2214
2215PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
2216stored in a PNG image have been "scaled" or "shifted" up to the next
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2217higher possible bit depth (e.g. from 5 bits/sample in the range [0,31]
2218to 8 bits/sample in the range [0, 255]). However, it is also possible
2219to convert the PNG pixel data back to the original bit depth of the
2220image. This call reduces the pixels back down to the original bit depth:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2221
Glenn Randers-Pehrson1ea0ff32001-08-07 22:25:59 -0500[diff] [blame]2222 png_color_8p sig_bit;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2223
2224 if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2225 png_set_shift(png_ptr, sig_bit);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2226
2227PNG files store 3-color pixels in red, green, blue order. This code
2228changes the storage of the pixels to blue, green, red:
2229
2230 if (color_type == PNG_COLOR_TYPE_RGB ||
2231 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2232 png_set_bgr(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2233
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]2234PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
2235into 4 or 8 bytes for windowing systems that need them in this format:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2236
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]2237 if (color_type == PNG_COLOR_TYPE_RGB)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2238 png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2239
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]2240where "filler" is the 8 or 16-bit number to fill with, and the location is
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2241either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
2242you want the filler before the RGB or after. This transformation
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]2243does not affect images that already have full alpha channels. To add an
2244opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
2245will generate RGBA pixels.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2246
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2247Note that png_set_filler() does not change the color type. If you want
2248to do that, you can add a true alpha channel with
2249
2250 if (color_type == PNG_COLOR_TYPE_RGB ||
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2251 color_type == PNG_COLOR_TYPE_GRAY)
2252 png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2253
2254where "filler" contains the alpha value to assign to each pixel.
Glenn Randers-Pehrson16e11662004-11-01 14:13:40 -0600[diff] [blame]2255This function was added in libpng-1.2.7.
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2256
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2257If you are reading an image with an alpha channel, and you need the
2258data as ARGB instead of the normal PNG format RGBA:
2259
2260 if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2261 png_set_swap_alpha(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2262
2263For some uses, you may want a grayscale image to be represented as
2264RGB. This code will do that conversion:
2265
2266 if (color_type == PNG_COLOR_TYPE_GRAY ||
2267 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2268 png_set_gray_to_rgb(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2269
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2270Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2271with alpha.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2272
2273 if (color_type == PNG_COLOR_TYPE_RGB ||
2274 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2275 png_set_rgb_to_gray_fixed(png_ptr, error_action,
2276 int red_weight, int green_weight);
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2277
2278 error_action = 1: silently do the conversion
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2279
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2280 error_action = 2: issue a warning if the original
2281 image has any pixel where
2282 red != green or red != blue
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2283
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2284 error_action = 3: issue an error and abort the
2285 conversion if the original
2286 image has any pixel where
2287 red != green or red != blue
2288
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2289 red_weight: weight of red component times 100000
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2290
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2291 green_weight: weight of green component times 100000
2292 If either weight is negative, default
2293 weights (21268, 71514) are used.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2294
2295If you have set error_action = 1 or 2, you can
2296later check whether the image really was gray, after processing
2297the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
2298It will return a png_byte that is zero if the image was gray or
22991 if there were any non-gray pixels. bKGD and sBIT data
2300will be silently converted to grayscale, using the green channel
2301data, regardless of the error_action setting.
2302
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2303With red_weight+green_weight<=100000,
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2304the normalized graylevel is computed:
2305
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2306 int rw = red_weight * 65536;
2307 int gw = green_weight * 65536;
2308 int bw = 65536 - (rw + gw);
2309 gray = (rw*red + gw*green + bw*blue)/65536;
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2310
2311The default values approximate those recommended in the Charles
2312Poynton's Color FAQ, <http://www.inforamp.net/~poynton/>
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]2313Copyright (c) 1998-01-04 Charles Poynton <poynton at inforamp.net>
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2314
2315 Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2316
Glenn Randers-Pehrson9962b842011-01-24 00:12:14 -0600[diff] [blame]2317Libpng approximates this with integers scaled by 32768:
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2318
Glenn Randers-Pehrson9962b842011-01-24 00:12:14 -0600[diff] [blame]2319 Y = (6968 * R + 23434 * G + 2366 * B)/32768
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2320
2321The calculation is done in a linear colorspace, if the image gamma
Glenn Randers-Pehrson9962b842011-01-24 00:12:14 -0600[diff] [blame]2322can be determined.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2323
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2324If you have a grayscale and you are using png_set_expand_gray_1_2_4_to_8(),
Glenn Randers-Pehrson73d57cb2002-03-25 18:49:08 -0600[diff] [blame]2325png_set_expand(), or png_set_gray_to_rgb to change to truecolor or to
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2326a higher bit-depth, you must either supply the background color as a gray
2327value at the original file bit-depth (need_expand = 1) or else supply the
2328background color as an RGB triplet at the final, expanded bit depth
2329(need_expand = 0). Similarly, if you are reading a paletted image, you
2330must either supply the background color as a palette index (need_expand = 1)
2331or as an RGB triplet that may or may not be in the palette (need_expand = 0).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2332
2333 png_color_16 my_background;
2334 png_color_16p image_background;
2335
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2336 if (png_get_bKGD(png_ptr, info_ptr, &image_background))
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2337 png_set_background(png_ptr, image_background,
2338 PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2339 else
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2340 png_set_background(png_ptr, &my_background,
2341 PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2342
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2343The png_set_background() function tells libpng to composite images
2344with alpha or simple transparency against the supplied background
2345color. If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
2346you may use this color, or supply another color more suitable for
2347the current display (e.g., the background color from a web page). You
2348need to tell libpng whether the color is in the gamma space of the
2349display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
2350(PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
2351that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
2352know why anyone would use this, but it's here).
2353
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2354To properly display PNG images on any kind of system, the application needs
2355to know what the display gamma is. Ideally, the user will know this, and
2356the application will allow them to set it. One method of allowing the user
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]2357to set the display gamma separately for each system is to check for a
2358SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be
2359correctly set.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2360
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]2361Note that display_gamma is the overall gamma correction required to produce
2362pleasing results, which depends on the lighting conditions in the surrounding
2363environment. In a dim or brightly lit room, no compensation other than
2364the physical gamma exponent of the monitor is needed, while in a dark room
2365a slightly smaller exponent is better.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2366
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2367 double gamma, screen_gamma;
2368
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2369 if (/* We have a user-defined screen
2370 gamma value */)
2371 {
2372 screen_gamma = user_defined_screen_gamma;
2373 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2374
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2375 /* One way that applications can share the same
2376 screen gamma value */
2377 else if ((gamma_str = getenv("SCREEN_GAMMA"))
2378 != NULL)
2379 {
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2380 screen_gamma = (double)atof(gamma_str);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2381 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2382
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2383 /* If we don't have another value */
2384 else
2385 {
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2386 screen_gamma = 2.2; /* A good guess for a
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2387 PC monitor in a bright office or a dim room */
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2388
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2389 screen_gamma = 2.0; /* A good guess for a
2390 PC monitor in a dark room */
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2391
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2392 screen_gamma = 1.7 or 1.0; /* A good
2393 guess for Mac systems */
2394 }
2395
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]2396The functions png_set_gamma() and its fixed point equivalent
2397png_set_gamma_fixed() handle gamma transformations of the data.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2398Pass both the file gamma and the current screen_gamma. If the file does
2399not have a gamma value, you can pass one anyway if you have an idea what
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2400it is (usually 0.45455 is a good guess for GIF images on PCs). Note
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2401that file gammas are inverted from screen gammas. See the discussions
2402on gamma in the PNG specification for an excellent description of what
2403gamma is, and why all applications should support it. It is strongly
2404recommended that PNG viewers support gamma correction.
2405
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]2406 if (png_get_gAMA(png_ptr, info_ptr, &file_gamma))
2407 png_set_gamma(png_ptr, screen_gamma, file_gamma);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2408
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2409 else
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2410 png_set_gamma(png_ptr, screen_gamma, 0.45455);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2411
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2412If you need to reduce an RGB file to a paletted file, or if a paletted
2413file has more entries then will fit on your screen, png_set_quantize()
Glenn Randers-Pehrson862cb202010-04-16 22:12:51 -0500[diff] [blame]2414will do that. Note that this is a simple match quantization that merely
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2415finds the closest color available. This should work fairly well with
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2416optimized palettes, but fairly badly with linear color cubes. If you
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2417pass a palette that is larger then maximum_colors, the file will
2418reduce the number of colors in the palette so it will fit into
2419maximum_colors. If there is a histogram, it will use it to make
2420more intelligent choices when reducing the palette. If there is no
2421histogram, it may not do as good a job.
2422
2423 if (color_type & PNG_COLOR_MASK_COLOR)
2424 {
2425 if (png_get_valid(png_ptr, info_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2426 PNG_INFO_PLTE))
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2427 {
2428 png_uint_16p histogram = NULL;
2429
2430 png_get_hIST(png_ptr, info_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2431 &histogram);
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2432 png_set_quantize(png_ptr, palette, num_palette,
2433 max_screen_colors, histogram, 1);
2434 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2435
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2436 else
2437 {
2438 png_color std_color_cube[MAX_SCREEN_COLORS] =
2439 { ... colors ... };
2440
2441 png_set_quantize(png_ptr, std_color_cube,
2442 MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
2443 NULL,0);
2444 }
2445 }
2446
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2447PNG files describe monochrome as black being zero and white being one.
2448The following code will reverse this (make black be one and white be
2449zero):
2450
Glenn Randers-Pehrson1ea0ff32001-08-07 22:25:59 -0500[diff] [blame]2451 if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
2452 png_set_invert_mono(png_ptr);
2453
2454This function can also be used to invert grayscale and gray-alpha images:
2455
2456 if (color_type == PNG_COLOR_TYPE_GRAY ||
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2457 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2458 png_set_invert_mono(png_ptr);
2459
2460PNG files store 16 bit pixels in network byte order (big-endian,
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2461ie. most significant bits first). This code changes the storage to the
2462other way (little-endian, i.e. least significant bits first, the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2463way PCs store them):
2464
2465 if (bit_depth == 16)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2466 png_set_swap(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2467
2468If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
2469need to change the order the pixels are packed into bytes, you can use:
2470
2471 if (bit_depth < 8)
2472 png_set_packswap(png_ptr);
2473
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2474Finally, you can write your own transformation function if none of
2475the existing ones meets your needs. This is done by setting a callback
2476with
2477
2478 png_set_read_user_transform_fn(png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2479 read_transform_fn);
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2480
2481You must supply the function
2482
Glenn Randers-Pehrson93215672011-02-13 19:42:19 -0600[diff] [blame]2483 void read_transform_fn(png_structp png_ptr, png_row_infop
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2484 row_info, png_bytep data)
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2485
2486See pngtest.c for a working example. Your function will be called
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]2487after all of the other transformations have been processed. Take care with
2488interlaced images if you do the interlace yourself - the width of the row is the
2489width in 'row_info', not the overall image width.
2490
2491If supported libpng provides two information routines that you can use to find
2492where you are in processing the image:
2493
2494 png_get_current_pass_number(png_structp png_ptr);
2495 png_get_current_row_number(png_structp png_ptr);
2496
2497Don't try using these outside a transform callback - firstly they are only
2498supported if user transforms are supported, secondly they may well return
2499unexpected results unless the row is actually being processed at the moment they
2500are called.
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2501
John Bowlercd113452011-02-16 06:15:13 -0600[diff] [blame]2502With interlaced
2503images the value returned is the row in the input sub-image image. Use
2504PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
2505find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
2506
2507The discussion of interlace handling above contains more information on how to
2508use these values.
2509
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2510You can also set up a pointer to a user structure for use by your
2511callback function, and you can inform libpng that your transform
2512function will change the number of channels or bit depth with the
2513function
2514
2515 png_set_user_transform_info(png_ptr, user_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2516 user_depth, user_channels);
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2517
2518The user's application, not libpng, is responsible for allocating and
2519freeing any memory required for the user structure.
2520
2521You can retrieve the pointer via the function
2522png_get_user_transform_ptr(). For example:
2523
2524 voidp read_user_transform_ptr =
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2525 png_get_user_transform_ptr(png_ptr);
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2526
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2527The last thing to handle is interlacing; this is covered in detail below,
2528but you must call the function here if you want libpng to handle expansion
2529of the interlaced image.
2530
2531 number_of_passes = png_set_interlace_handling(png_ptr);
2532
2533After setting the transformations, libpng can update your png_info
2534structure to reflect any transformations you've requested with this
2535call. This is most useful to update the info structure's rowbytes
2536field so you can use it to allocate your image memory. This function
2537will also update your palette with the correct screen_gamma and
2538background if these have been given with the calls above.
2539
2540 png_read_update_info(png_ptr, info_ptr);
2541
2542After you call png_read_update_info(), you can allocate any
2543memory you need to hold the image. The row data is simply
2544raw byte data for all forms of images. As the actual allocation
2545varies among applications, no example will be given. If you
2546are allocating one large chunk, you will need to build an
2547array of pointers to each row, as it will be needed for some
2548of the functions below.
2549
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2550Remember: Before you call png_read_update_info(), the png_get_
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]2551functions return the values corresponding to the original PNG image.
2552After you call png_read_update_info the values refer to the image
2553that libpng will output. Consequently you must call all the png_set_
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2554functions before you call png_read_update_info(). This is particularly
2555important for png_set_interlace_handling() - if you are going to call
2556png_read_update_info() you must call png_set_interlace_handling() before
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]2557it unless you want to receive interlaced output.
2558
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2559.SS Reading image data
2560
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2561After you've allocated memory, you can read the image data.
2562The simplest way to do this is in one function call. If you are
2563allocating enough memory to hold the whole image, you can just
2564call png_read_image() and libpng will read in all the image data
2565and put it in the memory area supplied. You will need to pass in
2566an array of pointers to each row.
2567
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]2568This function automatically handles interlacing, so you don't
2569need to call png_set_interlace_handling() (unless you call
2570png_read_update_info()) or call this function multiple times, or any
2571of that other stuff necessary with png_read_rows().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2572
2573 png_read_image(png_ptr, row_pointers);
2574
2575where row_pointers is:
2576
2577 png_bytep row_pointers[height];
2578
2579You can point to void or char or whatever you use for pixels.
2580
2581If you don't want to read in the whole image at once, you can
2582use png_read_rows() instead. If there is no interlacing (check
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2583interlace_type == PNG_INTERLACE_NONE), this is simple:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2584
2585 png_read_rows(png_ptr, row_pointers, NULL,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2586 number_of_rows);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2587
2588where row_pointers is the same as in the png_read_image() call.
2589
2590If you are doing this just one row at a time, you can do this with
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2591a single row_pointer instead of an array of row_pointers:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2592
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2593 png_bytep row_pointer = row;
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2594 png_read_row(png_ptr, row_pointer, NULL);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2595
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2596If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
2597get somewhat harder. The only current (PNG Specification version 1.2)
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2598interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7);
2599a somewhat complicated 2D interlace scheme, known as Adam7, that
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2600breaks down an image into seven smaller images of varying size, based
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2601on an 8x8 grid. This number is defined (from libpng 1.5) as
2602PNG_INTERLACE_ADAM7_PASSES in png.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2603
2604libpng can fill out those images or it can give them to you "as is".
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2605It is almost always better to have libpng handle the interlacing for you.
2606If you want the images filled out, there are two ways to do that. The one
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2607mentioned in the PNG specification is to expand each pixel to cover
2608those pixels that have not been read yet (the "rectangle" method).
2609This results in a blocky image for the first pass, which gradually
2610smooths out as more pixels are read. The other method is the "sparkle"
2611method, where pixels are drawn only in their final locations, with the
2612rest of the image remaining whatever colors they were initialized to
2613before the start of the read. The first method usually looks better,
2614but tends to be slower, as there are more pixels to put in the rows.
2615
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2616If, as is likely, you want libpng to expand the images, call this before
2617calling png_start_read_image() or png_read_update_info():
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2618
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2619 if (interlace_type == PNG_INTERLACE_ADAM7)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2620 number_of_passes
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2621 = png_set_interlace_handling(png_ptr);
2622
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2623This will return the number of passes needed. Currently, this is seven,
2624but may change if another interlace type is added. This function can be
2625called even if the file is not interlaced, where it will return one pass.
2626You then need to read the whole image 'number_of_passes' times. Each time
2627will distribute the pixels from the current pass to the correct place in
2628the output image, so you need to supply the same rows to png_read_rows in
2629each pass.
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]2630
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2631If you are not going to display the image after each pass, but are
2632going to wait until the entire image is read in, use the sparkle
2633effect. This effect is faster and the end result of either method
2634is exactly the same. If you are planning on displaying the image
2635after each pass, the "rectangle" effect is generally considered the
2636better looking one.
2637
2638If you only want the "sparkle" effect, just call png_read_rows() as
2639normal, with the third parameter NULL. Make sure you make pass over
2640the image number_of_passes times, and you don't change the data in the
2641rows between calls. You can change the locations of the data, just
2642not the data. Each pass only writes the pixels appropriate for that
2643pass, and assumes the data from previous passes is still valid.
2644
2645 png_read_rows(png_ptr, row_pointers, NULL,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2646 number_of_rows);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2647
2648If you only want the first effect (the rectangles), do the same as
2649before except pass the row buffer in the third parameter, and leave
2650the second parameter NULL.
2651
2652 png_read_rows(png_ptr, NULL, row_pointers,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2653 number_of_rows);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2654
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2655If you don't want libpng to handle the interlacing details, just call
2656png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
2657Each of the images is a valid image by itself, however you will almost
2658certainly need to distribute the pixels from each sub-image to the
2659correct place. This is where everything gets very tricky.
2660
2661If you want to retrieve the separate images you must pass the correct
2662number of rows to each successive call of png_read_rows(). The calculation
2663gets pretty complicated for small images, where some sub-images may
2664not even exist because either their width or height ends up zero.
2665libpng provides two macros to help you in 1.5 and later versions:
2666
2667 png_uint_32 width = PNG_PASS_COLS(image_width, pass_number);
2668 png_uint_32 height = PNG_PASS_ROWS(image_height, pass_number);
2669
2670Respectively these tell you the width and height of the sub-image
2671corresponding to the numbered pass. 'pass' is in in the range 0 to 6 -
2672this can be confusing because the specification refers to the same passes
2673as 1 to 7! Be careful, you must check both the width and height before
2674calling png_read_rows() and not call it for that pass if either is zero.
2675
2676You can, of course, read each sub-image row by row. If you want to
2677produce optimal code to make a pixel-by-pixel transformation of an
2678interlaced image this is the best approach; read each row of each pass,
2679transform it, and write it out to a new interlaced image.
2680
2681If you want to de-interlace the image yourself libpng provides further
2682macros to help that tell you where to place the pixels in the output image.
2683Because the interlacing scheme is rectangular - sub-image pixels are always
2684arranged on a rectangular grid - all you need to know for each pass is the
2685starting column and row in the output image of the first pixel plus the
2686spacing between each pixel. As of libpng 1.5 there are four macros to
2687retrieve this information:
2688
2689 png_uint_32 x = PNG_PASS_START_COL(pass);
2690 png_uint_32 y = PNG_PASS_START_ROW(pass);
2691 png_uint_32 xStep = 1U << PNG_PASS_COL_SHIFT(pass);
2692 png_uint_32 yStep = 1U << PNG_PASS_ROW_SHIFT(pass);
2693
2694These allow you to write the obvious loop:
2695
2696 png_uint_32 input_y = 0;
2697 png_uint_32 output_y = PNG_PASS_START_ROW(pass);
2698
2699 while (output_y < output_image_height)
2700 {
2701 png_uint_32 input_x = 0;
2702 png_uint_32 output_x = PNG_PASS_START_COL(pass);
2703
2704 while (output_x < output_image_width)
2705 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2706 image[output_y][output_x] =
2707 subimage[pass][input_y][input_x++];
2708
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2709 output_x += xStep;
2710 }
2711
2712 ++input_y;
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2713 output_y += yStep;
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2714 }
2715
2716Notice that the steps between successive output rows and columns are
2717returned as shifts. This is possible because the pixels in the subimages
2718are always a power of 2 apart - 1, 2, 4 or 8 pixels - in the original
2719image. In practice you may need to directly calculate the output coordinate
2720given an input coordinate. libpng provides two further macros for this
2721purpose:
2722
2723 png_uint_32 output_x = PNG_COL_FROM_PASS_COL(input_x, pass);
2724 png_uint_32 output_y = PNG_ROW_FROM_PASS_ROW(input_y, pass);
2725
2726Finally a pair of macros are provided to tell you if a particular image
2727row or column appears in a given pass:
2728
2729 int col_in_pass = PNG_COL_IN_INTERLACE_PASS(output_x, pass);
2730 int row_in_pass = PNG_ROW_IN_INTERLACE_PASS(output_y, pass);
2731
2732Bear in mind that you will probably also need to check the width and height
2733of the pass in addition to the above to be sure the pass even exists!
2734
2735With any luck you are convinced by now that you don't want to do your own
2736interlace handling. In reality normally the only good reason for doing this
2737is if you are processing PNG files on a pixel-by-pixel basis and don't want
2738to load the whole file into memory when it is interlaced.
2739
2740libpng includes a test program, pngvalid, that illustrates reading and
2741writing of interlaced images. If you can't get interlacing to work in your
2742code and don't want to leave it to libpng (the recommended approach) see
2743how pngvalid.c does it.
2744
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2745.SS Finishing a sequential read
2746
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]2747After you are finished reading the image through the
2748low-level interface, you can finish reading the file. If you are
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2749interested in comments or time, which may be stored either before or
2750after the image data, you should pass the separate png_info struct if
2751you want to keep the comments from before and after the image
2752separate. If you are not interested, you can pass NULL.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2753
2754 png_read_end(png_ptr, end_info);
2755
2756When you are done, you can free all memory allocated by libpng like this:
2757
2758 png_destroy_read_struct(&png_ptr, &info_ptr,
2759 &end_info);
2760
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2761It is also possible to individually free the info_ptr members that
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2762point to libpng-allocated storage with the following function:
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2763
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2764 png_free_data(png_ptr, info_ptr, mask, seq)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2765
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2766 mask - identifies data to be freed, a mask
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2767 containing the bitwise OR of one or
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2768 more of
2769 PNG_FREE_PLTE, PNG_FREE_TRNS,
2770 PNG_FREE_HIST, PNG_FREE_ICCP,
2771 PNG_FREE_PCAL, PNG_FREE_ROWS,
2772 PNG_FREE_SCAL, PNG_FREE_SPLT,
2773 PNG_FREE_TEXT, PNG_FREE_UNKN,
2774 or simply PNG_FREE_ALL
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2775
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2776 seq - sequence number of item to be freed
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2777 (-1 for all items)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2778
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2779This function may be safely called when the relevant storage has
Glenn Randers-Pehrson68ea2432000-04-01 21:10:05 -0600[diff] [blame]2780already been freed, or has not yet been allocated, or was allocated
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2781by the user and not by libpng, and will in those cases do nothing.
2782The "seq" parameter is ignored if only one item of the selected data
2783type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
2784are allowed for the data type identified in the mask, such as text or
2785sPLT, only the n'th item in the structure is freed, where n is "seq".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2786
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2787The default behavior is only to free data that was allocated internally
2788by libpng. This can be changed, so that libpng will not free the data,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2789or so that it will free data that was allocated by the user with png_malloc()
2790or png_zalloc() and passed in via a png_set_*() function, with
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2791
2792 png_data_freer(png_ptr, info_ptr, freer, mask)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2793
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2794 freer - one of
2795 PNG_DESTROY_WILL_FREE_DATA
2796 PNG_SET_WILL_FREE_DATA
2797 PNG_USER_WILL_FREE_DATA
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2798
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2799 mask - which data elements are affected
2800 same choices as in png_free_data()
2801
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2802This function only affects data that has already been allocated.
2803You can call this function after reading the PNG data but before calling
2804any png_set_*() functions, to control whether the user or the png_set_*()
2805function is responsible for freeing any existing data that might be present,
2806and again after the png_set_*() functions to control whether the user
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2807or png_destroy_*() is supposed to free the data. When the user assumes
2808responsibility for libpng-allocated data, the application must use
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2809png_free() to free it, and when the user transfers responsibility to libpng
2810for data that the user has allocated, the user must have used png_malloc()
Glenn Randers-Pehrsonb1828932001-06-23 08:03:17 -0500[diff] [blame]2811or png_zalloc() to allocate it.
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2812
2813If you allocated your row_pointers in a single block, as suggested above in
2814the description of the high level read interface, you must not transfer
2815responsibility for freeing it to the png_set_rows or png_read_destroy function,
2816because they would also try to free the individual row_pointers[i].
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2817
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2818If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
2819separately, do not transfer responsibility for freeing text_ptr to libpng,
2820because when libpng fills a png_text structure it combines these members with
2821the key member, and png_free_data() will free only text_ptr.key. Similarly,
2822if you transfer responsibility for free'ing text_ptr from libpng to your
2823application, your application must not separately free those members.
2824
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2825The png_free_data() function will turn off the "valid" flag for anything
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2826it frees. If you need to turn the flag off for a chunk that was freed by
2827your application instead of by libpng, you can use
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2828
2829 png_set_invalid(png_ptr, info_ptr, mask);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2830
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2831 mask - identifies the chunks to be made invalid,
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2832 containing the bitwise OR of one or
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]2833 more of
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2834 PNG_INFO_gAMA, PNG_INFO_sBIT,
2835 PNG_INFO_cHRM, PNG_INFO_PLTE,
2836 PNG_INFO_tRNS, PNG_INFO_bKGD,
2837 PNG_INFO_hIST, PNG_INFO_pHYs,
2838 PNG_INFO_oFFs, PNG_INFO_tIME,
2839 PNG_INFO_pCAL, PNG_INFO_sRGB,
2840 PNG_INFO_iCCP, PNG_INFO_sPLT,
2841 PNG_INFO_sCAL, PNG_INFO_IDAT
2842
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2843For a more compact example of reading a PNG image, see the file example.c.
2844
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2845.SS Reading PNG files progressively
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2846
2847The progressive reader is slightly different then the non-progressive
2848reader. Instead of calling png_read_info(), png_read_rows(), and
2849png_read_end(), you make one call to png_process_data(), which calls
2850callbacks when it has the info, a row, or the end of the image. You
2851set up these callbacks with png_set_progressive_read_fn(). You don't
2852have to worry about the input/output functions of libpng, as you are
2853giving the library the data directly in png_process_data(). I will
2854assume that you have read the section on reading PNG files above,
2855so I will only highlight the differences (although I will show
2856all of the code).
2857
2858png_structp png_ptr;
2859png_infop info_ptr;
2860
2861 /* An example code fragment of how you would
2862 initialize the progressive reader in your
2863 application. */
2864 int
2865 initialize_png_reader()
2866 {
2867 png_ptr = png_create_read_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2868 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2869 user_error_fn, user_warning_fn);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2870
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2871 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2872 return (ERROR);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2873
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2874 info_ptr = png_create_info_struct(png_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2875
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2876 if (!info_ptr)
2877 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2878 png_destroy_read_struct(&png_ptr,
2879 (png_infopp)NULL, (png_infopp)NULL);
2880 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2881 }
2882
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2883 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2884 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2885 png_destroy_read_struct(&png_ptr, &info_ptr,
2886 (png_infopp)NULL);
2887 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2888 }
2889
2890 /* This one's new. You can provide functions
2891 to be called when the header info is valid,
2892 when each row is completed, and when the image
2893 is finished. If you aren't using all functions,
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2894 you can specify NULL parameters. Even when all
2895 three functions are NULL, you need to call
2896 png_set_progressive_read_fn(). You can use
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2897 any struct as the user_ptr (cast to a void pointer
2898 for the function call), and retrieve the pointer
2899 from inside the callbacks using the function
2900
2901 png_get_progressive_ptr(png_ptr);
2902
2903 which will return a void pointer, which you have
2904 to cast appropriately.
2905 */
2906 png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
2907 info_callback, row_callback, end_callback);
2908
2909 return 0;
2910 }
2911
2912 /* A code fragment that you call as you receive blocks
2913 of data */
2914 int
2915 process_data(png_bytep buffer, png_uint_32 length)
2916 {
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2917 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2918 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2919 png_destroy_read_struct(&png_ptr, &info_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2920 (png_infopp)NULL);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2921 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2922 }
2923
2924 /* This one's new also. Simply give it a chunk
2925 of data from the file stream (in order, of
2926 course). On machines with segmented memory
2927 models machines, don't give it any more than
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2928 64K. The library seems to run fine with sizes
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2929 of 4K. Although you can give it much less if
2930 necessary (I assume you can give it chunks of
2931 1 byte, I haven't tried less then 256 bytes
2932 yet). When this function returns, you may
2933 want to display any rows that were generated
2934 in the row callback if you don't already do
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2935 so there.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2936 */
2937 png_process_data(png_ptr, info_ptr, buffer, length);
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]2938
2939 /* At this point you can call png_process_data_skip if
2940 you want to handle data the library will skip yourself;
2941 it simply returns the number of bytes to skip (and stops
2942 libpng skipping that number of bytes on the next
2943 png_process_data call).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2944 return 0;
2945 }
2946
2947 /* This function is called (as set by
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2948 png_set_progressive_read_fn() above) when enough data
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2949 has been supplied so all of the header has been
2950 read.
2951 */
2952 void
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2953 info_callback(png_structp png_ptr, png_infop info)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2954 {
2955 /* Do any setup here, including setting any of
2956 the transformations mentioned in the Reading
2957 PNG files section. For now, you _must_ call
2958 either png_start_read_image() or
2959 png_read_update_info() after all the
2960 transformations are set (even if you don't set
2961 any). You may start getting rows before
2962 png_process_data() returns, so this is your
2963 last chance to prepare for that.
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2964
2965 This is where you turn on interlace handling,
2966 assuming you don't want to do it yourself.
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]2967
2968 If you need to you can stop the processing of
2969 your original input data at this point by calling
2970 png_process_data_pause. This returns the number
2971 of unprocessed bytes from the last png_process_data
2972 call - it is up to you to ensure that the next call
2973 sees these bytes again. If you don't want to bother
2974 with this you can get libpng to cache the unread
2975 bytes by setting the 'save' parameter (see png.h) but
2976 then libpng will have to copy the data internally.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2977 */
2978 }
2979
2980 /* This function is called when each row of image
2981 data is complete */
2982 void
2983 row_callback(png_structp png_ptr, png_bytep new_row,
Glenn Randers-Pehrsone68f5a32001-05-14 09:20:53 -0500[diff] [blame]2984 png_uint_32 row_num, int pass)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2985 {
2986 /* If the image is interlaced, and you turned
2987 on the interlace handler, this function will
2988 be called for every row in every pass. Some
2989 of these rows will not be changed from the
2990 previous pass. When the row is not changed,
2991 the new_row variable will be NULL. The rows
2992 and passes are called in order, so you don't
2993 really need the row_num and pass, but I'm
2994 supplying them because it may make your life
2995 easier.
2996
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2997 If you did not turn on interlace handling then
2998 the callback is called for each row of each
2999 sub-image when the image is interlaced. In this
3000 case 'row_num' is the row in the sub-image, not
3001 the row in the output image as it is in all other
3002 cases.
3003
3004 For the non-NULL rows of interlaced images when
3005 you have switched on libpng interlace handling,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3006 you must call png_progressive_combine_row()
3007 passing in the row and the old row. You can
3008 call this function for NULL rows (it will just
3009 return) and for non-interlaced images (it just
3010 does the memcpy for you) if it will make the
3011 code easier. Thus, you can just do this for
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3012 all cases if you switch on interlace handling;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3013 */
3014
3015 png_progressive_combine_row(png_ptr, old_row,
3016 new_row);
3017
3018 /* where old_row is what was displayed for
Glenn Randers-Pehrson345bc271998-06-14 14:43:31 -0500[diff] [blame]3019 previously for the row. Note that the first
3020 pass (pass == 0, really) will completely cover
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3021 the old row, so the rows do not have to be
3022 initialized. After the first pass (and only
3023 for interlaced images), you will have to pass
3024 the current row, and the function will combine
3025 the old row and the new row.
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]3026
3027 You can also call png_process_data_pause in this
3028 callback - see above.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3029 */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3030 }
3031
3032 void
3033 end_callback(png_structp png_ptr, png_infop info)
3034 {
3035 /* This function is called after the whole image
3036 has been read, including any chunks after the
3037 image (up to and including the IEND). You
3038 will usually have the same info chunk as you
3039 had in the header, although some data may have
3040 been added to the comments and time fields.
3041
3042 Most people won't do much here, perhaps setting
3043 a flag that marks the image as finished.
3044 */
3045 }
3046
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3047
3048
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3049.SH IV. Writing
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3050
3051Much of this is very similar to reading. However, everything of
3052importance is repeated here, so you won't have to constantly look
3053back up in the reading section to understand writing.
3054
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3055.SS Setup
3056
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3057You will want to do the I/O initialization before you get into libpng,
3058so if it doesn't work, you don't have anything to undo. If you are not
3059using the standard I/O functions, you will need to replace them with
3060custom writing functions. See the discussion under Customizing libpng.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3061
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3062 FILE *fp = fopen(file_name, "wb");
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3063
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3064 if (!fp)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]3065 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3066
3067Next, png_struct and png_info need to be allocated and initialized.
3068As these can be both relatively large, you may not want to store these
3069on the stack, unless you have stack space to spare. Of course, you
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3070will want to check if they return NULL. If you are also reading,
3071you won't want to name your read structure and your write structure
3072both "png_ptr"; you can call them anything you like, such as
3073"read_ptr" and "write_ptr". Look at pngtest.c, for example.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3074
3075 png_structp png_ptr = png_create_write_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]3076 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3077 user_error_fn, user_warning_fn);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3078
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3079 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]3080 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3081
3082 png_infop info_ptr = png_create_info_struct(png_ptr);
3083 if (!info_ptr)
3084 {
3085 png_destroy_write_struct(&png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3086 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]3087 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3088 }
3089
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3090If you want to use your own memory allocation routines,
3091define PNG_USER_MEM_SUPPORTED and use
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3092png_create_write_struct_2() instead of png_create_write_struct():
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3093
3094 png_structp png_ptr = png_create_write_struct_2
3095 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
3096 user_error_fn, user_warning_fn, (png_voidp)
3097 user_mem_ptr, user_malloc_fn, user_free_fn);
3098
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3099After you have these structures, you will need to set up the
3100error handling. When libpng encounters an error, it expects to
3101longjmp() back to your routine. Therefore, you will need to call
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3102setjmp() and pass the png_jmpbuf(png_ptr). If you
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3103write the file from different routines, you will need to update
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3104the png_jmpbuf(png_ptr) every time you enter a new routine that will
3105call a png_*() function. See your documentation of setjmp/longjmp
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3106for your compiler for more information on setjmp/longjmp. See
3107the discussion on libpng error handling in the Customizing Libpng
3108section below for more information on the libpng error handling.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3109
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3110 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3111 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3112 png_destroy_write_struct(&png_ptr, &info_ptr);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]3113 fclose(fp);
3114 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3115 }
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3116 ...
3117 return;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3118
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3119If you would rather avoid the complexity of setjmp/longjmp issues,
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]3120you can compile libpng with PNG_NO_SETJMP, in which case
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3121errors will result in a call to PNG_ABORT() which defaults to abort().
3122
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]3123You can #define PNG_ABORT() to a function that does something
3124more useful than abort(), as long as your function does not
3125return.
3126
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3127Now you need to set up the output code. The default for libpng is to
3128use the C function fwrite(). If you use this, you will need to pass a
3129valid FILE * in the function png_init_io(). Be sure that the file is
3130opened in binary mode. Again, if you wish to handle writing data in
3131another way, see the discussion on libpng I/O handling in the Customizing
3132Libpng section below.
3133
3134 png_init_io(png_ptr, fp);
3135
Glenn Randers-Pehrsond60b8fa2006-04-20 21:31:14 -0500[diff] [blame]3136If you are embedding your PNG into a datastream such as MNG, and don't
3137want libpng to write the 8-byte signature, or if you have already
3138written the signature in your application, use
3139
3140 png_set_sig_bytes(png_ptr, 8);
3141
3142to inform libpng that it should not write a signature.
3143
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3144.SS Write callbacks
3145
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3146At this point, you can set up a callback function that will be
3147called after each row has been written, which you can use to control
3148a progress meter or the like. It's demonstrated in pngtest.c.
3149You must supply a function
3150
Glenn Randers-Pehrson81ce8892011-01-24 08:04:37 -0600[diff] [blame]3151 void write_row_callback(png_structp png_ptr, png_uint_32 row,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3152 int pass);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3153 {
3154 /* put your code here */
3155 }
3156
3157(You can give it another name that you like instead of "write_row_callback")
3158
3159To inform libpng about your function, use
3160
3161 png_set_write_status_fn(png_ptr, write_row_callback);
3162
John Bowler59010e52011-02-16 06:16:31 -0600[diff] [blame]3163When this function is called the row has already been completely processed and
3164it has also been written out. The 'row' and 'pass' refer to the next row to be
3165handled. For the
3166non-interlaced case the row that was just handled is simply one less than the
3167passed in row number, and pass will always be 0. For the interlaced case the
3168same applies unless the row value is 0, in which case the row just handled was
3169the last one from one of the preceding passes. Because interlacing may skip a
3170pass you cannot be sure that the preceding pass is just 'pass-1', if you really
3171need to know what the last pass is record (row,pass) from the callback and use
3172the last recorded value each time.
3173
3174As with the user transform you can find the output row using the
3175PNG_ROW_FROM_PASS_ROW macro.
3176
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3177You now have the option of modifying how the compression library will
3178run. The following functions are mainly for testing, but may be useful
3179in some cases, like if you need to write PNG files extremely fast and
3180are willing to give up some compression, or if you want to get the
3181maximum possible compression at the expense of slower writing. If you
3182have no special needs in this area, let the library do what it wants by
3183not calling this function at all, as it has been tuned to deliver a good
3184speed/compression ratio. The second parameter to png_set_filter() is
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3185the filter method, for which the only valid values are 0 (as of the
3186July 1999 PNG specification, version 1.2) or 64 (if you are writing
3187a PNG datastream that is to be embedded in a MNG datastream). The third
3188parameter is a flag that indicates which filter type(s) are to be tested
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3189for each scanline. See the PNG specification for details on the specific
3190filter types.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3191
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3192
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3193 /* turn on or off filtering, and/or choose
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3194 specific filters. You can use either a single
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3195 PNG_FILTER_VALUE_NAME or the bitwise OR of one
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3196 or more PNG_FILTER_NAME masks.
3197 */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3198 png_set_filter(png_ptr, 0,
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3199 PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
3200 PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
3201 PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3202 PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG |
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3203 PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
3204 PNG_ALL_FILTERS);
3205
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3206If an application wants to start and stop using particular filters during
3207compression, it should start out with all of the filters (to ensure that
3208the previous row of pixels will be stored in case it's needed later),
3209and then add and remove them after the start of compression.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3210
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3211If you are writing a PNG datastream that is to be embedded in a MNG
3212datastream, the second parameter can be either 0 or 64.
3213
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3214The png_set_compression_*() functions interface to the zlib compression
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3215library, and should mostly be ignored unless you really know what you are
3216doing. The only generally useful call is png_set_compression_level()
3217which changes how much time zlib spends on trying to compress the image
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3218data. See the Compression Library (zlib.h and algorithm.txt, distributed
3219with zlib) for details on the compression levels.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3220
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]3221 #include zlib.h
3222
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3223 /* set the zlib compression level */
3224 png_set_compression_level(png_ptr,
3225 Z_BEST_COMPRESSION);
3226
3227 /* set other zlib parameters */
3228 png_set_compression_mem_level(png_ptr, 8);
3229 png_set_compression_strategy(png_ptr,
3230 Z_DEFAULT_STRATEGY);
3231 png_set_compression_window_bits(png_ptr, 15);
3232 png_set_compression_method(png_ptr, 8);
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3233 png_set_compression_buffer_size(png_ptr, 8192)
3234
3235extern PNG_EXPORT(void,png_set_zbuf_size)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3236
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3237.SS Setting the contents of info for output
3238
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3239You now need to fill in the png_info structure with all the data you
3240wish to write before the actual image. Note that the only thing you
3241are allowed to write after the image is the text chunks and the time
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3242chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3243the latest PNG specification for more information on that. If you
3244wish to write them before the image, fill them in now, and flag that
3245data as being valid. If you want to wait until after the data, don't
3246fill them until png_write_end(). For all the fields in png_info and
3247their data types, see png.h. For explanations of what the fields
3248contain, see the PNG specification.
3249
3250Some of the more important parts of the png_info are:
3251
3252 png_set_IHDR(png_ptr, info_ptr, width, height,
3253 bit_depth, color_type, interlace_type,
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3254 compression_type, filter_method)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3255
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3256 width - holds the width of the image
3257 in pixels (up to 2^31).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3258
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3259 height - holds the height of the image
3260 in pixels (up to 2^31).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3261
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3262 bit_depth - holds the bit depth of one of the
3263 image channels.
3264 (valid values are 1, 2, 4, 8, 16
3265 and depend also on the
3266 color_type. See also significant
3267 bits (sBIT) below).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3268
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3269 color_type - describes which color/alpha
3270 channels are present.
3271 PNG_COLOR_TYPE_GRAY
3272 (bit depths 1, 2, 4, 8, 16)
3273 PNG_COLOR_TYPE_GRAY_ALPHA
3274 (bit depths 8, 16)
3275 PNG_COLOR_TYPE_PALETTE
3276 (bit depths 1, 2, 4, 8)
3277 PNG_COLOR_TYPE_RGB
3278 (bit_depths 8, 16)
3279 PNG_COLOR_TYPE_RGB_ALPHA
3280 (bit_depths 8, 16)
3281
3282 PNG_COLOR_MASK_PALETTE
3283 PNG_COLOR_MASK_COLOR
3284 PNG_COLOR_MASK_ALPHA
3285
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3286 interlace_type - PNG_INTERLACE_NONE or
3287 PNG_INTERLACE_ADAM7
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3288
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3289 compression_type - (must be
3290 PNG_COMPRESSION_TYPE_DEFAULT)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3291
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3292 filter_method - (must be PNG_FILTER_TYPE_DEFAULT
3293 or, if you are writing a PNG to
3294 be embedded in a MNG datastream,
3295 can also be
3296 PNG_INTRAPIXEL_DIFFERENCING)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3297
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3298If you call png_set_IHDR(), the call must appear before any of the
Glenn Randers-Pehrsond60c8862009-06-15 21:56:14 -0500[diff] [blame]3299other png_set_*() functions, because they might require access to some of
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3300the IHDR settings. The remaining png_set_*() functions can be called
3301in any order.
3302
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame]3303If you wish, you can reset the compression_type, interlace_type, or
3304filter_method later by calling png_set_IHDR() again; if you do this, the
3305width, height, bit_depth, and color_type must be the same in each call.
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]3306
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3307 png_set_PLTE(png_ptr, info_ptr, palette,
3308 num_palette);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3309
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3310 palette - the palette for the file
3311 (array of png_color)
3312 num_palette - number of entries in the palette
3313
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]3314 png_set_gAMA(png_ptr, info_ptr, file_gamma);
3315 png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3316
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]3317 file_gamma - the gamma at which the image was
3318 created (PNG_INFO_gAMA)
3319
3320 int_file_gamma - 100,000 times the gamma at which
3321 the image was created
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3322
3323 png_set_sRGB(png_ptr, info_ptr, srgb_intent);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3324
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3325 srgb_intent - the rendering intent
3326 (PNG_INFO_sRGB) The presence of
3327 the sRGB chunk means that the pixel
3328 data is in the sRGB color space.
3329 This chunk also implies specific
3330 values of gAMA and cHRM. Rendering
3331 intent is the CSS-1 property that
3332 has been defined by the International
3333 Color Consortium
3334 (http://www.color.org).
3335 It can be one of
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]3336 PNG_sRGB_INTENT_SATURATION,
3337 PNG_sRGB_INTENT_PERCEPTUAL,
3338 PNG_sRGB_INTENT_ABSOLUTE, or
3339 PNG_sRGB_INTENT_RELATIVE.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3340
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3341
3342 png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
3343 srgb_intent);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3344
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3345 srgb_intent - the rendering intent
3346 (PNG_INFO_sRGB) The presence of the
3347 sRGB chunk means that the pixel
3348 data is in the sRGB color space.
3349 This function also causes gAMA and
3350 cHRM chunks with the specific values
3351 that are consistent with sRGB to be
3352 written.
3353
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3354 png_set_iCCP(png_ptr, info_ptr, name, compression_type,
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3355 profile, proflen);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3356
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3357 name - The profile name.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3358
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3359 compression_type - The compression type; always
3360 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
3361 You may give NULL to this argument to
3362 ignore it.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3363
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3364 profile - International Color Consortium color
3365 profile data. May contain NULs.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3366
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3367 proflen - length of profile data in bytes.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3368
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3369 png_set_sBIT(png_ptr, info_ptr, sig_bit);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3370
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3371 sig_bit - the number of significant bits for
3372 (PNG_INFO_sBIT) each of the gray, red,
3373 green, and blue channels, whichever are
3374 appropriate for the given color type
3375 (png_color_16)
3376
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]3377 png_set_tRNS(png_ptr, info_ptr, trans_alpha,
3378 num_trans, trans_color);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3379
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]3380 trans_alpha - array of alpha (transparency)
3381 entries for palette (PNG_INFO_tRNS)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3382
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame]3383 trans_color - graylevel or color sample values
3384 (in order red, green, blue) of the
3385 single transparent color for
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]3386 non-paletted images (PNG_INFO_tRNS)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3387
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3388 num_trans - number of transparent entries
3389 (PNG_INFO_tRNS)
3390
3391 png_set_hIST(png_ptr, info_ptr, hist);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3392
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3393 hist - histogram of palette (array of
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]3394 png_uint_16) (PNG_INFO_hIST)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3395
3396 png_set_tIME(png_ptr, info_ptr, mod_time);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3397
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3398 mod_time - time image was last modified
3399 (PNG_VALID_tIME)
3400
3401 png_set_bKGD(png_ptr, info_ptr, background);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3402
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3403 background - background color (PNG_VALID_bKGD)
3404
3405 png_set_text(png_ptr, info_ptr, text_ptr, num_text);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3406
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3407 text_ptr - array of png_text holding image
3408 comments
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3409
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3410 text_ptr[i].compression - type of compression used
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3411 on "text" PNG_TEXT_COMPRESSION_NONE
3412 PNG_TEXT_COMPRESSION_zTXt
3413 PNG_ITXT_COMPRESSION_NONE
3414 PNG_ITXT_COMPRESSION_zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3415 text_ptr[i].key - keyword for comment. Must contain
3416 1-79 characters.
3417 text_ptr[i].text - text comments for current
3418 keyword. Can be NULL or empty.
3419 text_ptr[i].text_length - length of text string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3420 after decompression, 0 for iTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3421 text_ptr[i].itxt_length - length of itxt string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3422 after decompression, 0 for tEXt/zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3423 text_ptr[i].lang - language of comment (NULL or
3424 empty for unknown).
3425 text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
3426 or empty for unknown).
Glenn Randers-Pehrson8f5846f2009-10-31 21:31:08 -0500[diff] [blame]3427 Note that the itxt_length, lang, and lang_key
3428 members of the text_ptr structure only exist
3429 when the library is built with iTXt chunk support.
3430
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3431 num_text - number of comments
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3432
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3433 png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
3434 num_spalettes);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3435
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3436 palette_ptr - array of png_sPLT_struct structures
3437 to be added to the list of palettes
3438 in the info structure.
3439 num_spalettes - number of palette structures to be
3440 added.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3441
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3442 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
3443 unit_type);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3444
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3445 offset_x - positive offset from the left
3446 edge of the screen
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3447
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3448 offset_y - positive offset from the top
3449 edge of the screen
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3450
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3451 unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
3452
3453 png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
3454 unit_type);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3455
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3456 res_x - pixels/unit physical resolution
3457 in x direction
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3458
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3459 res_y - pixels/unit physical resolution
3460 in y direction
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3461
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3462 unit_type - PNG_RESOLUTION_UNKNOWN,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3463 PNG_RESOLUTION_METER
3464
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3465 png_set_sCAL(png_ptr, info_ptr, unit, width, height)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3466
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3467 unit - physical scale units (an integer)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3468
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3469 width - width of a pixel in physical scale units
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3470
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3471 height - height of a pixel in physical scale units
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3472 (width and height are doubles)
3473
3474 png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3475
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3476 unit - physical scale units (an integer)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3477
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3478 width - width of a pixel in physical scale units
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3479
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3480 height - height of a pixel in physical scale units
3481 (width and height are strings like "2.54")
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3482
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3483 png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
3484 num_unknowns)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3485
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3486 unknowns - array of png_unknown_chunk
3487 structures holding unknown chunks
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3488 unknowns[i].name - name of unknown chunk
3489 unknowns[i].data - data of unknown chunk
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3490 unknowns[i].size - size of unknown chunk's data
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3491 unknowns[i].location - position to write chunk in file
3492 0: do not write chunk
3493 PNG_HAVE_IHDR: before PLTE
3494 PNG_HAVE_PLTE: before IDAT
3495 PNG_AFTER_IDAT: after IDAT
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3496
3497The "location" member is set automatically according to
3498what part of the output file has already been written.
3499You can change its value after calling png_set_unknown_chunks()
3500as demonstrated in pngtest.c. Within each of the "locations",
3501the chunks are sequenced according to their position in the
3502structure (that is, the value of "i", which is the order in which
3503the chunk was either read from the input file or defined with
3504png_set_unknown_chunks).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3505
3506A quick word about text and num_text. text is an array of png_text
3507structures. num_text is the number of valid structures in the array.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3508Each png_text structure holds a language code, a keyword, a text value,
3509and a compression type.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3510
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3511The compression types have the same valid numbers as the compression
3512types of the image data. Currently, the only valid number is zero.
3513However, you can store text either compressed or uncompressed, unlike
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3514images, which always have to be compressed. So if you don't want the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3515text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3516Because tEXt and zTXt chunks don't have a language field, if you
3517specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
3518any language code or translated keyword will not be written out.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3519
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3520Until text gets around 1000 bytes, it is not worth compressing it.
3521After the text has been written out to the file, the compression type
3522is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
3523so that it isn't written out again at the end (in case you are calling
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3524png_write_end() with the same struct).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3525
3526The keywords that are given in the PNG Specification are:
3527
3528 Title Short (one line) title or
3529 caption for image
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3530
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3531 Author Name of image's creator
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3532
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3533 Description Description of image (possibly long)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3534
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3535 Copyright Copyright notice
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3536
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3537 Creation Time Time of original image creation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3538 (usually RFC 1123 format, see below)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3539
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3540 Software Software used to create the image
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3541
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3542 Disclaimer Legal disclaimer
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3543
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3544 Warning Warning of nature of content
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3545
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3546 Source Device used to create the image
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3547
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3548 Comment Miscellaneous comment; conversion
3549 from other image format
3550
3551The keyword-text pairs work like this. Keywords should be short
3552simple descriptions of what the comment is about. Some typical
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3553keywords are found in the PNG specification, as is some recommendations
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3554on keywords. You can repeat keywords in a file. You can even write
3555some text before the image and some after. For example, you may want
3556to put a description of the image before the image, but leave the
3557disclaimer until after, so viewers working over modem connections
3558don't have to wait for the disclaimer to go over the modem before
3559they start seeing the image. Finally, keywords should be full
3560words, not abbreviations. Keywords and text are in the ISO 8859-1
3561(Latin-1) character set (a superset of regular ASCII) and can not
3562contain NUL characters, and should not contain control or other
3563unprintable characters. To make the comments widely readable, stick
3564with basic ASCII, and avoid machine specific character set extensions
3565like the IBM-PC character set. The keyword must be present, but
3566you can leave off the text string on non-compressed pairs.
3567Compressed pairs must have a text string, as only the text string
3568is compressed anyway, so the compression would be meaningless.
3569
3570PNG supports modification time via the png_time structure. Two
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3571conversion routines are provided, png_convert_from_time_t() for
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3572time_t and png_convert_from_struct_tm() for struct tm. The
3573time_t routine uses gmtime(). You don't have to use either of
3574these, but if you wish to fill in the png_time structure directly,
3575you should provide the time in universal time (GMT) if possible
3576instead of your local time. Note that the year number is the full
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3577year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3578that months start with 1.
3579
3580If you want to store the time of the original image creation, you should
3581use a plain tEXt chunk with the "Creation Time" keyword. This is
3582necessary because the "creation time" of a PNG image is somewhat vague,
3583depending on whether you mean the PNG file, the time the image was
3584created in a non-PNG format, a still photo from which the image was
3585scanned, or possibly the subject matter itself. In order to facilitate
3586machine-readable dates, it is recommended that the "Creation Time"
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3587tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3588although this isn't a requirement. Unlike the tIME chunk, the
3589"Creation Time" tEXt chunk is not expected to be automatically changed
3590by the software. To facilitate the use of RFC 1123 dates, a function
3591png_convert_to_rfc1123(png_timep) is provided to convert from PNG
3592time to an RFC 1123 format string.
3593
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3594.SS Writing unknown chunks
3595
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3596You can use the png_set_unknown_chunks function to queue up chunks
3597for writing. You give it a chunk name, raw data, and a size; that's
3598all there is to it. The chunks will be written by the next following
3599png_write_info_before_PLTE, png_write_info, or png_write_end function.
3600Any chunks previously read into the info structure's unknown-chunk
3601list will also be written out in a sequence that satisfies the PNG
3602specification's ordering rules.
3603
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3604.SS The high-level write interface
3605
3606At this point there are two ways to proceed; through the high-level
3607write interface, or through a sequence of low-level write operations.
3608You can use the high-level interface if your image data is present
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3609in the info structure. All defined output
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3610transformations are permitted, enabled by the following masks.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3611
3612 PNG_TRANSFORM_IDENTITY No transformation
3613 PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3614 PNG_TRANSFORM_PACKSWAP Change order of packed
3615 pixels to LSB first
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3616 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3617 PNG_TRANSFORM_SHIFT Normalize pixels to the
3618 sBIT depth
3619 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
3620 to BGRA
3621 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
3622 to AG
3623 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
3624 to transparency
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3625 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
Glenn Randers-Pehrson1eb14e92008-12-10 07:14:45 -0600[diff] [blame]3626 PNG_TRANSFORM_STRIP_FILLER Strip out filler
3627 bytes (deprecated).
3628 PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading
3629 filler bytes
3630 PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing
3631 filler bytes
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3632
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3633If you have valid image data in the info structure (you can use
3634png_set_rows() to put image data in the info structure), simply do this:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3635
3636 png_write_png(png_ptr, info_ptr, png_transforms, NULL)
3637
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3638where png_transforms is an integer containing the bitwise OR of some set of
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3639transformation flags. This call is equivalent to png_write_info(),
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3640followed the set of transformations indicated by the transform mask,
3641then png_write_image(), and finally png_write_end().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3642
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3643(The final parameter of this call is not yet used. Someday it might point
3644to transformation parameters required by some future output transform.)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3645
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]3646You must use png_transforms and not call any png_set_transform() functions
3647when you use png_write_png().
3648
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3649.SS The low-level write interface
3650
3651If you are going the low-level route instead, you are now ready to
3652write all the file information up to the actual image data. You do
3653this with a call to png_write_info().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3654
3655 png_write_info(png_ptr, info_ptr);
3656
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3657Note that there is one transformation you may need to do before
3658png_write_info(). In PNG files, the alpha channel in an image is the
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3659level of opacity. If your data is supplied as a level of transparency,
3660you can invert the alpha channel before you write it, so that 0 is
3661fully transparent and 255 (in 8-bit or paletted images) or 65535
3662(in 16-bit images) is fully opaque, with
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3663
3664 png_set_invert_alpha(png_ptr);
3665
3666This must appear before png_write_info() instead of later with the
3667other transformations because in the case of paletted images the tRNS
3668chunk data has to be inverted before the tRNS chunk is written. If
3669your image is not a paletted image, the tRNS data (which in such cases
3670represents a single color to be rendered as transparent) won't need to
3671be changed, and you can safely do this transformation after your
3672png_write_info() call.
3673
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]3674If you need to write a private chunk that you want to appear before
3675the PLTE chunk when PLTE is present, you can write the PNG info in
3676two steps, and insert code to write your own chunk between them:
3677
3678 png_write_info_before_PLTE(png_ptr, info_ptr);
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3679 png_set_unknown_chunks(png_ptr, info_ptr, ...);
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]3680 png_write_info(png_ptr, info_ptr);
3681
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3682After you've written the file information, you can set up the library
3683to handle any special transformations of the image data. The various
3684ways to transform the data will be described in the order that they
3685should occur. This is important, as some of these change the color
3686type and/or bit depth of the data, and some others only work on
3687certain color types and bit depths. Even though each transformation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3688checks to see if it has data that it can do something with, you should
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3689make sure to only enable a transformation if it will be valid for the
3690data. For example, don't swap red and blue on grayscale data.
3691
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3692PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
Glenn Randers-Pehrson68ea2432000-04-01 21:10:05 -0600[diff] [blame]3693the library to strip input data that has 4 or 8 bytes per pixel down
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3694to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
3695bytes per pixel).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3696
3697 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
3698
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3699where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3700PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
3701is stored XRGB or RGBX.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3702
3703PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
3704they can, resulting in, for example, 8 pixels per byte for 1 bit files.
3705If the data is supplied at 1 pixel per byte, use this code, which will
3706correctly pack the pixels into a single byte:
3707
3708 png_set_packing(png_ptr);
3709
3710PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
3711data is of another bit depth, you can write an sBIT chunk into the
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3712file so that decoders can recover the original data if desired.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3713
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3714 /* Set the true bit depth of the image data */
3715 if (color_type & PNG_COLOR_MASK_COLOR)
3716 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3717 sig_bit.red = true_bit_depth;
3718 sig_bit.green = true_bit_depth;
3719 sig_bit.blue = true_bit_depth;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3720 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3721
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3722 else
3723 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3724 sig_bit.gray = true_bit_depth;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3725 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3726
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3727 if (color_type & PNG_COLOR_MASK_ALPHA)
3728 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3729 sig_bit.alpha = true_bit_depth;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3730 }
3731
3732 png_set_sBIT(png_ptr, info_ptr, &sig_bit);
3733
3734If the data is stored in the row buffer in a bit depth other than
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3735one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3736this will scale the values to appear to be the correct bit depth as
3737is required by PNG.
3738
3739 png_set_shift(png_ptr, &sig_bit);
3740
3741PNG files store 16 bit pixels in network byte order (big-endian,
3742ie. most significant bits first). This code would be used if they are
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3743supplied the other way (little-endian, i.e. least significant bits
3744first, the way PCs store them):
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3745
3746 if (bit_depth > 8)
3747 png_set_swap(png_ptr);
3748
3749If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
3750need to change the order the pixels are packed into bytes, you can use:
3751
3752 if (bit_depth < 8)
3753 png_set_packswap(png_ptr);
3754
3755PNG files store 3 color pixels in red, green, blue order. This code
3756would be used if they are supplied as blue, green, red:
3757
3758 png_set_bgr(png_ptr);
3759
3760PNG files describe monochrome as black being zero and white being
3761one. This code would be used if the pixels are supplied with this reversed
3762(black being one and white being zero):
3763
3764 png_set_invert_mono(png_ptr);
3765
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3766Finally, you can write your own transformation function if none of
3767the existing ones meets your needs. This is done by setting a callback
3768with
3769
3770 png_set_write_user_transform_fn(png_ptr,
3771 write_transform_fn);
3772
3773You must supply the function
3774
Glenn Randers-Pehrson93215672011-02-13 19:42:19 -0600[diff] [blame]3775 void write_transform_fn(png_structp png_ptr, png_row_infop
3776 row_info, png_bytep data)
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3777
3778See pngtest.c for a working example. Your function will be called
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]3779before any of the other transformations are processed. If supported
3780libpng also supplies an information routine that may be called from
3781your callback:
3782
3783 png_get_current_row_number(png_ptr);
John Bowlercd113452011-02-16 06:15:13 -0600[diff] [blame]3784 png_get_current_pass_number(png_ptr);
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]3785
John Bowlercd113452011-02-16 06:15:13 -0600[diff] [blame]3786This returns the current row passed to the transform. With interlaced
3787images the value returned is the row in the input sub-image image. Use
3788PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
3789find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
3790
3791The discussion of interlace handling above contains more information on how to
3792use these values.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3793
3794You can also set up a pointer to a user structure for use by your
3795callback function.
3796
3797 png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
3798
3799The user_channels and user_depth parameters of this function are ignored
3800when writing; you can set them to zero as shown.
3801
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3802You can retrieve the pointer via the function png_get_user_transform_ptr().
3803For example:
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3804
3805 voidp write_user_transform_ptr =
3806 png_get_user_transform_ptr(png_ptr);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3807
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3808It is possible to have libpng flush any pending output, either manually,
3809or automatically after a certain number of lines have been written. To
3810flush the output stream a single time call:
3811
3812 png_write_flush(png_ptr);
3813
3814and to have libpng flush the output stream periodically after a certain
3815number of scanlines have been written, call:
3816
3817 png_set_flush(png_ptr, nrows);
3818
3819Note that the distance between rows is from the last time png_write_flush()
3820was called, or the first row of the image if it has never been called.
3821So if you write 50 lines, and then png_set_flush 25, it will flush the
3822output on the next scanline, and every 25 lines thereafter, unless
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3823png_write_flush() is called before 25 more lines have been written.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3824If nrows is too small (less than about 10 lines for a 640 pixel wide
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3825RGB image) the image compression may decrease noticeably (although this
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3826may be acceptable for real-time applications). Infrequent flushing will
3827only degrade the compression performance by a few percent over images
3828that do not use flushing.
3829
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3830.SS Writing the image data
3831
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3832That's it for the transformations. Now you can write the image data.
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3833The simplest way to do this is in one function call. If you have the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3834whole image in memory, you can just call png_write_image() and libpng
3835will write the image. You will need to pass in an array of pointers to
3836each row. This function automatically handles interlacing, so you don't
3837need to call png_set_interlace_handling() or call this function multiple
3838times, or any of that other stuff necessary with png_write_rows().
3839
3840 png_write_image(png_ptr, row_pointers);
3841
3842where row_pointers is:
3843
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3844 png_byte *row_pointers[height];
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3845
3846You can point to void or char or whatever you use for pixels.
3847
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3848If you don't want to write the whole image at once, you can
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3849use png_write_rows() instead. If the file is not interlaced,
3850this is simple:
3851
3852 png_write_rows(png_ptr, row_pointers,
3853 number_of_rows);
3854
3855row_pointers is the same as in the png_write_image() call.
3856
3857If you are just writing one row at a time, you can do this with
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3858a single row_pointer instead of an array of row_pointers:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3859
3860 png_bytep row_pointer = row;
3861
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3862 png_write_row(png_ptr, row_pointer);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3863
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3864When the file is interlaced, things can get a good deal more complicated.
3865The only currently (as of the PNG Specification version 1.2, dated July
38661999) defined interlacing scheme for PNG files is the "Adam7" interlace
3867scheme, that breaks down an image into seven smaller images of varying
3868size. libpng will build these images for you, or you can do them
3869yourself. If you want to build them yourself, see the PNG specification
3870for details of which pixels to write when.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3871
3872If you don't want libpng to handle the interlacing details, just
3873use png_set_interlace_handling() and call png_write_rows() the
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3874correct number of times to write all the sub-images
3875(png_set_interlace_handling() returns the number of sub-images.)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3876
3877If you want libpng to build the sub-images, call this before you start
3878writing any rows:
3879
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3880 number_of_passes = png_set_interlace_handling(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3881
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3882This will return the number of passes needed. Currently, this is seven,
3883but may change if another interlace type is added.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3884
3885Then write the complete image number_of_passes times.
3886
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3887 png_write_rows(png_ptr, row_pointers, number_of_rows);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3888
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3889Think carefully before you write an interlaced image. Typically code that
3890reads such images reads all the image data into memory, uncompressed, before
3891doing any processing. Only code that can display an image on the fly can
3892take advantage of the interlacing and even then the image has to be exactly
3893the correct size for the output device, because scaling an image requires
3894adjacent pixels and these are not available until all the passes have been
3895read.
3896
3897If you do write an interlaced image you will hardly ever need to handle
3898the interlacing yourself. Call png_set_interlace_handling() and use the
3899approach described above.
3900
3901The only time it is conceivable that you will really need to write an
3902interlaced image pass-by-pass is when you have read one pass by pass and
3903made some pixel-by-pixel transformation to it, as described in the read
3904code above. In this case use the PNG_PASS_ROWS and PNG_PASS_COLS macros
3905to determine the size of each sub-image in turn and simply write the rows
3906you obtained from the read code.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3907
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3908.SS Finishing a sequential write
3909
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3910After you are finished writing the image, you should finish writing
3911the file. If you are interested in writing comments or time, you should
3912pass an appropriately filled png_info pointer. If you are not interested,
3913you can pass NULL.
3914
3915 png_write_end(png_ptr, info_ptr);
3916
3917When you are done, you can free all memory used by libpng like this:
3918
3919 png_destroy_write_struct(&png_ptr, &info_ptr);
3920
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3921It is also possible to individually free the info_ptr members that
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]3922point to libpng-allocated storage with the following function:
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3923
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3924 png_free_data(png_ptr, info_ptr, mask, seq)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3925
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3926 mask - identifies data to be freed, a mask
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3927 containing the bitwise OR of one or
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3928 more of
3929 PNG_FREE_PLTE, PNG_FREE_TRNS,
3930 PNG_FREE_HIST, PNG_FREE_ICCP,
3931 PNG_FREE_PCAL, PNG_FREE_ROWS,
3932 PNG_FREE_SCAL, PNG_FREE_SPLT,
3933 PNG_FREE_TEXT, PNG_FREE_UNKN,
3934 or simply PNG_FREE_ALL
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3935
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3936 seq - sequence number of item to be freed
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3937 (-1 for all items)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3938
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]3939This function may be safely called when the relevant storage has
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3940already been freed, or has not yet been allocated, or was allocated
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3941by the user and not by libpng, and will in those cases do nothing.
3942The "seq" parameter is ignored if only one item of the selected data
3943type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
3944are allowed for the data type identified in the mask, such as text or
3945sPLT, only the n'th item in the structure is freed, where n is "seq".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3946
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3947If you allocated data such as a palette that you passed in to libpng
3948with png_set_*, you must not free it until just before the call to
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3949png_destroy_write_struct().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3950
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3951The default behavior is only to free data that was allocated internally
3952by libpng. This can be changed, so that libpng will not free the data,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3953or so that it will free data that was allocated by the user with png_malloc()
3954or png_zalloc() and passed in via a png_set_*() function, with
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3955
3956 png_data_freer(png_ptr, info_ptr, freer, mask)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3957
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3958 freer - one of
3959 PNG_DESTROY_WILL_FREE_DATA
3960 PNG_SET_WILL_FREE_DATA
3961 PNG_USER_WILL_FREE_DATA
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3962
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3963 mask - which data elements are affected
3964 same choices as in png_free_data()
3965
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3966For example, to transfer responsibility for some data from a read structure
3967to a write structure, you could use
3968
3969 png_data_freer(read_ptr, read_info_ptr,
3970 PNG_USER_WILL_FREE_DATA,
3971 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3972
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3973 png_data_freer(write_ptr, write_info_ptr,
3974 PNG_DESTROY_WILL_FREE_DATA,
3975 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
3976
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3977thereby briefly reassigning responsibility for freeing to the user but
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3978immediately afterwards reassigning it once more to the write_destroy
3979function. Having done this, it would then be safe to destroy the read
3980structure and continue to use the PLTE, tRNS, and hIST data in the write
3981structure.
3982
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3983This function only affects data that has already been allocated.
3984You can call this function before calling after the png_set_*() functions
3985to control whether the user or png_destroy_*() is supposed to free the data.
3986When the user assumes responsibility for libpng-allocated data, the
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3987application must use
3988png_free() to free it, and when the user transfers responsibility to libpng
3989for data that the user has allocated, the user must have used png_malloc()
3990or png_zalloc() to allocate it.
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3991
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3992If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
3993separately, do not transfer responsibility for freeing text_ptr to libpng,
3994because when libpng fills a png_text structure it combines these members with
3995the key member, and png_free_data() will free only text_ptr.key. Similarly,
3996if you transfer responsibility for free'ing text_ptr from libpng to your
3997application, your application must not separately free those members.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3998For a more compact example of writing a PNG image, see the file example.c.
3999
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4000.SH V. Modifying/Customizing libpng:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4001
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4002There are two issues here. The first is changing how libpng does
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4003standard things like memory allocation, input/output, and error handling.
4004The second deals with more complicated things like adding new chunks,
4005adding new transformations, and generally changing how libpng works.
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]4006Both of those are compile-time issues; that is, they are generally
4007determined at the time the code is written, and there is rarely a need
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4008to provide the user with a means of changing them.
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]4009
4010Memory allocation, input/output, and error handling
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4011
4012All of the memory allocation, input/output, and error handling in libpng
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]4013goes through callbacks that are user-settable. The default routines are
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4014in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]4015these functions, call the appropriate png_set_*_fn() function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4016
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4017Memory allocation is done through the functions png_malloc(), png_calloc(),
4018and png_free(). These currently just call the standard C functions.
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]4019png_calloc() calls png_malloc() and then clears the newly
4020allocated memory to zero. There is limited support for certain systems
4021with segmented memory architectures and the types of pointers declared by
4022png.h match this; you will have to use appropriate pointers in your
4023application. Since it is
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4024unlikely that the method of handling memory allocation on a platform
4025will change between applications, these functions must be modified in
4026the library at compile time. If you prefer to use a different method
4027of allocating and freeing data, you can use png_create_read_struct_2() or
4028png_create_write_struct_2() to register your own functions as described
4029above. These functions also provide a void pointer that can be retrieved
4030via
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4031
4032 mem_ptr=png_get_mem_ptr(png_ptr);
4033
4034Your replacement memory functions must have prototypes as follows:
4035
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4036 png_voidp malloc_fn(png_structp png_ptr,
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4037 png_alloc_size_t size);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4038
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4039 void free_fn(png_structp png_ptr, png_voidp ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4040
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4041Your malloc_fn() must return NULL in case of failure. The png_malloc()
4042function will normally call png_error() if it receives a NULL from the
4043system memory allocator or from your replacement malloc_fn().
Glenn Randers-Pehrson82ae3832001-04-20 10:32:10 -0500[diff] [blame]4044
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4045Your free_fn() will never be called with a NULL ptr, since libpng's
4046png_free() checks for NULL before calling free_fn().
4047
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4048Input/Output in libpng is done through png_read() and png_write(),
4049which currently just call fread() and fwrite(). The FILE * is stored in
4050png_struct and is initialized via png_init_io(). If you wish to change
4051the method of I/O, the library supplies callbacks that you can set
4052through the function png_set_read_fn() and png_set_write_fn() at run
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4053time, instead of calling the png_init_io() function. These functions
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4054also provide a void pointer that can be retrieved via the function
4055png_get_io_ptr(). For example:
4056
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]4057 png_set_read_fn(png_structp read_ptr,
4058 voidp read_io_ptr, png_rw_ptr read_data_fn)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4059
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]4060 png_set_write_fn(png_structp write_ptr,
4061 voidp write_io_ptr, png_rw_ptr write_data_fn,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4062 png_flush_ptr output_flush_fn);
4063
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]4064 voidp read_io_ptr = png_get_io_ptr(read_ptr);
4065 voidp write_io_ptr = png_get_io_ptr(write_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4066
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4067The replacement I/O functions must have prototypes as follows:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4068
4069 void user_read_data(png_structp png_ptr,
Glenn Randers-Pehrson837a3d12002-05-10 20:19:58 -0500[diff] [blame]4070 png_bytep data, png_size_t length);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4071
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4072 void user_write_data(png_structp png_ptr,
Glenn Randers-Pehrson837a3d12002-05-10 20:19:58 -0500[diff] [blame]4073 png_bytep data, png_size_t length);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4074
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4075 void user_flush_data(png_structp png_ptr);
4076
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]4077The user_read_data() function is responsible for detecting and
4078handling end-of-data errors.
4079
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4080Supplying NULL for the read, write, or flush functions sets them back
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4081to using the default C stream functions, which expect the io_ptr to
4082point to a standard *FILE structure. It is probably a mistake
4083to use NULL for one of write_data_fn and output_flush_fn but not both
4084of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined.
4085It is an error to read from a write stream, and vice versa.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4086
4087Error handling in libpng is done through png_error() and png_warning().
4088Errors handled through png_error() are fatal, meaning that png_error()
4089should never return to its caller. Currently, this is handled via
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4090setjmp() and longjmp() (unless you have compiled libpng with
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]4091PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()),
Glenn Randers-Pehrson60988072010-04-13 22:11:06 -0500[diff] [blame]4092but you could change this to do things like exit() if you should wish,
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]4093as long as your function does not return.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4094
4095On non-fatal errors, png_warning() is called
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4096to print a warning message, and then control returns to the calling code.
4097By default png_error() and png_warning() print a message on stderr via
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]4098fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
4099(because you don't want the messages) or PNG_NO_STDIO defined (because
4100fprintf() isn't available). If you wish to change the behavior of the error
4101functions, you will need to set up your own message callbacks. These
4102functions are normally supplied at the time that the png_struct is created.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4103It is also possible to redirect errors and warnings to your own replacement
4104functions after png_create_*_struct() has been called by calling:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4105
4106 png_set_error_fn(png_structp png_ptr,
4107 png_voidp error_ptr, png_error_ptr error_fn,
4108 png_error_ptr warning_fn);
4109
4110 png_voidp error_ptr = png_get_error_ptr(png_ptr);
4111
4112If NULL is supplied for either error_fn or warning_fn, then the libpng
4113default function will be used, calling fprintf() and/or longjmp() if a
4114problem is encountered. The replacement error functions should have
4115parameters as follows:
4116
4117 void user_error_fn(png_structp png_ptr,
4118 png_const_charp error_msg);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4119
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4120 void user_warning_fn(png_structp png_ptr,
4121 png_const_charp warning_msg);
4122
4123The motivation behind using setjmp() and longjmp() is the C++ throw and
4124catch exception handling methods. This makes the code much easier to write,
4125as there is no need to check every return code of every function call.
4126However, there are some uncertainties about the status of local variables
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4127after a longjmp, so the user may want to be careful about doing anything
4128after setjmp returns non-zero besides returning itself. Consult your
4129compiler documentation for more details. For an alternative approach, you
4130may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4131
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4132.SS Custom chunks
4133
4134If you need to read or write custom chunks, you may need to get deeper
4135into the libpng code. The library now has mechanisms for storing
4136and writing chunks of unknown type; you can even declare callbacks
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]4137for custom chunks. However, this may not be good enough if the
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4138library code itself needs to know about interactions between your
4139chunk and existing `intrinsic' chunks.
4140
4141If you need to write a new intrinsic chunk, first read the PNG
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4142specification. Acquire a first level of understanding of how it works.
4143Pay particular attention to the sections that describe chunk names,
4144and look at how other chunks were designed, so you can do things
4145similarly. Second, check out the sections of libpng that read and
4146write chunks. Try to find a chunk that is similar to yours and use
4147it as a template. More details can be found in the comments inside
4148the code. It is best to handle unknown chunks in a generic method,
4149via callback functions, instead of by modifying libpng functions.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4150
4151If you wish to write your own transformation for the data, look through
4152the part of the code that does the transformations, and check out some of
4153the simpler ones to get an idea of how they work. Try to find a similar
4154transformation to the one you want to add and copy off of it. More details
4155can be found in the comments inside the code itself.
4156
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4157.SS Configuring for 16 bit platforms
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4158
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4159You will want to look into zconf.h to tell zlib (and thus libpng) that
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4160it cannot allocate more then 64K at a time. Even if you can, the memory
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4161won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4162
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4163.SS Configuring for DOS
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4164
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4165For DOS users who only have access to the lower 640K, you will
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4166have to limit zlib's memory usage via a png_set_compression_mem_level()
4167call. See zlib.h or zconf.h in the zlib library for more information.
4168
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4169.SS Configuring for Medium Model
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4170
4171Libpng's support for medium model has been tested on most of the popular
4172compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
4173defined, and FAR gets defined to far in pngconf.h, and you should be
4174all set. Everything in the library (except for zlib's structure) is
4175expecting far data. You must use the typedefs with the p or pp on
4176the end for pointers (or at least look at them and be careful). Make
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4177note that the rows of data are defined as png_bytepp, which is an
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4178unsigned char far * far *.
4179
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4180.SS Configuring for gui/windowing platforms:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4181
4182You will need to write new error and warning functions that use the GUI
4183interface, as described previously, and set them to be the error and
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]4184warning functions at the time that png_create_*_struct() is called,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4185in order to have them available during the structure initialization.
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4186They can be changed later via png_set_error_fn(). On some compilers,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4187you may also have to change the memory allocators (png_malloc, etc.).
4188
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4189.SS Configuring for compiler xxx:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4190
Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]4191All includes for libpng are in pngconf.h. If you need to add, change
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4192or delete an include, this is the place to do it.
4193The includes that are not needed outside libpng are placed in pngpriv.h,
4194which is only used by the routines inside libpng itself.
4195The files in libpng proper only include pngpriv.h and png.h, which
4196in turn includes pngconf.h.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4197
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4198.SS Configuring zlib:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4199
4200There are special functions to configure the compression. Perhaps the
4201most useful one changes the compression level, which currently uses
4202input compression values in the range 0 - 9. The library normally
4203uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
4204have shown that for a large majority of images, compression values in
4205the range 3-6 compress nearly as well as higher levels, and do so much
4206faster. For online applications it may be desirable to have maximum speed
4207(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
4208specify no compression (Z_NO_COMPRESSION = 0), but this would create
4209files larger than just storing the raw bitmap. You can specify the
4210compression level by calling:
4211
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]4212 #include zlib.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4213 png_set_compression_level(png_ptr, level);
4214
4215Another useful one is to reduce the memory level used by the library.
4216The memory level defaults to 8, but it can be lowered if you are
4217short on memory (running DOS, for example, where you only have 640K).
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4218Note that the memory level does have an effect on compression; among
4219other things, lower levels will result in sections of incompressible
4220data being emitted in smaller stored blocks, with a correspondingly
4221larger relative overhead of up to 15% in the worst case.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4222
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]4223 #include zlib.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4224 png_set_compression_mem_level(png_ptr, level);
4225
4226The other functions are for configuring zlib. They are not recommended
4227for normal use and may result in writing an invalid PNG file. See
4228zlib.h for more information on what these mean.
4229
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]4230 #include zlib.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4231 png_set_compression_strategy(png_ptr,
4232 strategy);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4233
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4234 png_set_compression_window_bits(png_ptr,
4235 window_bits);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4236
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4237 png_set_compression_method(png_ptr, method);
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4238 png_set_compression_buffer_size(png_ptr, size);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4239
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4240.SS Controlling row filtering
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4241
4242If you want to control whether libpng uses filtering or not, which
4243filters are used, and how it goes about picking row filters, you
4244can call one of these functions. The selection and configuration
4245of row filters can have a significant impact on the size and
4246encoding speed and a somewhat lesser impact on the decoding speed
4247of an image. Filtering is enabled by default for RGB and grayscale
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4248images (with and without alpha), but not for paletted images nor
4249for any images with bit depths less than 8 bits/pixel.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4250
4251The 'method' parameter sets the main filtering method, which is
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4252currently only '0' in the PNG 1.2 specification. The 'filters'
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4253parameter sets which filter(s), if any, should be used for each
4254scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
4255to turn filtering on and off, respectively.
4256
4257Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
4258PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4259ORed together with '|' to specify one or more filters to use.
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4260These filters are described in more detail in the PNG specification.
4261If you intend to change the filter type during the course of writing
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4262the image, you should start with flags set for all of the filters
4263you intend to use so that libpng can initialize its internal
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4264structures appropriately for all of the filter types. (Note that this
4265means the first row must always be adaptively filtered, because libpng
4266currently does not allocate the filter buffers until png_write_row()
4267is called for the first time.)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4268
4269 filters = PNG_FILTER_NONE | PNG_FILTER_SUB
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4270 PNG_FILTER_UP | PNG_FILTER_AVG |
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4271 PNG_FILTER_PAETH | PNG_ALL_FILTERS;
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4272
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4273 png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
4274 filters);
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4275 The second parameter can also be
4276 PNG_INTRAPIXEL_DIFFERENCING if you are
4277 writing a PNG to be embedded in a MNG
4278 datastream. This parameter must be the
4279 same as the value of filter_method used
4280 in png_set_IHDR().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4281
4282It is also possible to influence how libpng chooses from among the
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4283available filters. This is done in one or both of two ways - by
4284telling it how important it is to keep the same filter for successive
4285rows, and by telling it the relative computational costs of the filters.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4286
4287 double weights[3] = {1.5, 1.3, 1.1},
4288 costs[PNG_FILTER_VALUE_LAST] =
4289 {1.0, 1.3, 1.3, 1.5, 1.7};
4290
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4291 png_set_filter_heuristics(png_ptr,
4292 PNG_FILTER_HEURISTIC_WEIGHTED, 3,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4293 weights, costs);
4294
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4295The weights are multiplying factors that indicate to libpng that the
4296row filter should be the same for successive rows unless another row filter
4297is that many times better than the previous filter. In the above example,
4298if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4299"sum of absolute differences" 1.5 x 1.3 times higher than other filters
4300and still be chosen, while the NONE filter could have a sum 1.1 times
4301higher than other filters and still be chosen. Unspecified weights are
4302taken to be 1.0, and the specified weights should probably be declining
4303like those above in order to emphasize recent filters over older filters.
4304
4305The filter costs specify for each filter type a relative decoding cost
4306to be considered when selecting row filters. This means that filters
4307with higher costs are less likely to be chosen over filters with lower
4308costs, unless their "sum of absolute differences" is that much smaller.
4309The costs do not necessarily reflect the exact computational speeds of
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4310the various filters, since this would unduly influence the final image
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4311size.
4312
4313Note that the numbers above were invented purely for this example and
4314are given only to help explain the function usage. Little testing has
4315been done to find optimum values for either the costs or the weights.
4316
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4317.SS Removing unwanted object code
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4318
4319There are a bunch of #define's in pngconf.h that control what parts of
4320libpng are compiled. All the defines end in _SUPPORTED. If you are
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]4321never going to use a capability, you can change the #define to #undef
4322before recompiling libpng and save yourself code and data space, or
4323you can turn off individual capabilities with defines that begin with
4324PNG_NO_.
4325
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4326In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
4327
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]4328You can also turn all of the transforms and ancillary chunk capabilities
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4329off en masse with compiler directives that define
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]4330PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
4331or all four,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4332along with directives to turn on any of the capabilities that you do
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4333want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the extra
4334transformations but still leave the library fully capable of reading
4335and writing PNG files with all known public chunks. Use of the
4336PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
4337that is incapable of reading or writing ancillary chunks. If you are
4338not using the progressive reading capability, you can turn that off
4339with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
4340capability, which you'll still have).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4341
4342All the reading and writing specific code are in separate files, so the
4343linker should only grab the files it needs. However, if you want to
4344make sure, or if you are building a stand alone library, all the
4345reading files start with pngr and all the writing files start with
4346pngw. The files that don't match either (like png.c, pngtrans.c, etc.)
4347are used for both reading and writing, and always need to be included.
4348The progressive reader is in pngpread.c
4349
4350If you are creating or distributing a dynamically linked library (a .so
4351or DLL file), you should not remove or disable any parts of the library,
4352as this will cause applications linked with different versions of the
4353library to fail if they call functions not available in your library.
4354The size of the library itself should not be an issue, because only
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4355those sections that are actually used will be loaded into memory.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4356
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4357.SS Requesting debug printout
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4358
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4359The macro definition PNG_DEBUG can be used to request debugging
4360printout. Set it to an integer value in the range 0 to 3. Higher
4361numbers result in increasing amounts of debugging information. The
4362information is printed to the "stderr" file, unless another file
4363name is specified in the PNG_DEBUG_FILE macro definition.
4364
4365When PNG_DEBUG > 0, the following functions (macros) become available:
4366
4367 png_debug(level, message)
4368 png_debug1(level, message, p1)
4369 png_debug2(level, message, p1, p2)
4370
4371in which "level" is compared to PNG_DEBUG to decide whether to print
4372the message, "message" is the formatted string to be printed,
4373and p1 and p2 are parameters that are to be embedded in the string
4374according to printf-style formatting directives. For example,
4375
4376 png_debug1(2, "foo=%d\n", foo);
4377
4378is expanded to
4379
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4380 if (PNG_DEBUG > 2)
4381 fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4382
4383When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
4384can still use PNG_DEBUG to control your own debugging:
4385
4386 #ifdef PNG_DEBUG
4387 fprintf(stderr, ...
4388 #endif
4389
4390When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
4391having level = 0 will be printed. There aren't any such statements in
4392this version of libpng, but if you insert some they will be printed.
4393
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]4394.SH VI. MNG support
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]4395
4396The MNG specification (available at http://www.libpng.org/pub/mng) allows
4397certain extensions to PNG for PNG images that are embedded in MNG datastreams.
4398Libpng can support some of these extensions. To enable them, use the
4399png_permit_mng_features() function:
4400
4401 feature_set = png_permit_mng_features(png_ptr, mask)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4402
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]4403 mask is a png_uint_32 containing the bitwise OR of the
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]4404 features you want to enable. These include
4405 PNG_FLAG_MNG_EMPTY_PLTE
4406 PNG_FLAG_MNG_FILTER_64
4407 PNG_ALL_MNG_FEATURES
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4408
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]4409 feature_set is a png_uint_32 that is the bitwise AND of
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]4410 your mask with the set of MNG features that is
4411 supported by the version of libpng that you are using.
4412
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]4413It is an error to use this function when reading or writing a standalone
4414PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
Glenn Randers-Pehrsonf05f8032000-12-23 14:27:39 -0600[diff] [blame]4415in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
4416and the MHDR and MEND chunks. Libpng does not provide support for these
4417or any other MNG chunks; your application must provide its own support for
4418them. You may wish to consider using libmng (available at
4419http://www.libmng.com) instead.
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]4420
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4421.SH VII. Changes to Libpng from version 0.88
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4422
4423It should be noted that versions of libpng later than 0.96 are not
4424distributed by the original libpng author, Guy Schalnat, nor by
4425Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
4426distributed versions 0.89 through 0.96, but rather by another member
4427of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
4428still alive and well, but they have moved on to other things.
4429
4430The old libpng functions png_read_init(), png_write_init(),
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]4431png_info_init(), png_read_destroy(), and png_write_destroy() have been
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]4432moved to PNG_INTERNAL in version 0.95 to discourage their use. These
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4433functions will be removed from libpng version 1.4.0.
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]4434
4435The preferred method of creating and initializing the libpng structures is
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4436via the png_create_read_struct(), png_create_write_struct(), and
4437png_create_info_struct() because they isolate the size of the structures
4438from the application, allow version error checking, and also allow the
4439use of custom error handling routines during the initialization, which
4440the old functions do not. The functions png_read_destroy() and
4441png_write_destroy() do not actually free the memory that libpng
4442allocated for these structs, but just reset the data structures, so they
4443can be used instead of png_destroy_read_struct() and
4444png_destroy_write_struct() if you feel there is too much system overhead
4445allocating and freeing the png_struct for each image read.
4446
4447Setting the error callbacks via png_set_message_fn() before
4448png_read_init() as was suggested in libpng-0.88 is no longer supported
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4449because this caused applications that do not use custom error functions
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4450to fail if the png_ptr was not initialized to zero. It is still possible
4451to set the error callbacks AFTER png_read_init(), or to change them with
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]4452png_set_error_fn(), which is essentially the same function, but with a new
4453name to force compilation errors with applications that try to use the old
4454method.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4455
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]4456Starting with version 1.0.7, you can find out which version of the library
4457you are using at run-time:
4458
4459 png_uint_32 libpng_vn = png_access_version_number();
4460
4461The number libpng_vn is constructed from the major version, minor
4462version with leading zero, and release number with leading zero,
4463(e.g., libpng_vn for version 1.0.7 is 10007).
4464
4465You can also check which version of png.h you used when compiling your
4466application:
4467
4468 png_uint_32 application_vn = PNG_LIBPNG_VER;
4469
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4470.SH VIII. Changes to Libpng from version 1.0.x to 1.2.x
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4471
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4472Support for user memory management was enabled by default. To
4473accomplish this, the functions png_create_read_struct_2(),
4474png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(),
4475png_malloc_default(), and png_free_default() were added.
4476
Glenn Randers-Pehrsond6ea40a2009-11-02 07:32:00 -0600[diff] [blame]4477Support for the iTXt chunk has been enabled by default as of
4478version 1.2.41.
4479
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4480Support for certain MNG features was enabled.
4481
4482Support for numbered error messages was added. However, we never got
4483around to actually numbering the error messages. The function
4484png_set_strip_error_numbers() was added (Note: the prototype for this
4485function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE
4486builds of libpng-1.2.15. It was restored in libpng-1.2.36).
4487
4488The png_malloc_warn() function was added at libpng-1.2.3. This issues
4489a png_warning and returns NULL instead of aborting when it fails to
4490acquire the requested memory allocation.
4491
4492Support for setting user limits on image width and height was enabled
4493by default. The functions png_set_user_limits(), png_get_user_width_max(),
4494and png_get_user_height_max() were added at libpng-1.2.6.
4495
4496The png_set_add_alpha() function was added at libpng-1.2.7.
4497
4498The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9.
4499Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the
4500tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is
4501deprecated.
4502
4503A number of macro definitions in support of runtime selection of
4504assembler code features (especially Intel MMX code support) were
4505added at libpng-1.2.0:
4506
4507 PNG_ASM_FLAG_MMX_SUPPORT_COMPILED
4508 PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
4509 PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
4510 PNG_ASM_FLAG_MMX_READ_INTERLACE
4511 PNG_ASM_FLAG_MMX_READ_FILTER_SUB
4512 PNG_ASM_FLAG_MMX_READ_FILTER_UP
4513 PNG_ASM_FLAG_MMX_READ_FILTER_AVG
4514 PNG_ASM_FLAG_MMX_READ_FILTER_PAETH
4515 PNG_ASM_FLAGS_INITIALIZED
4516 PNG_MMX_READ_FLAGS
4517 PNG_MMX_FLAGS
4518 PNG_MMX_WRITE_FLAGS
4519 PNG_MMX_FLAGS
4520
4521We added the following functions in support of runtime
4522selection of assembler code features:
4523
4524 png_get_mmx_flagmask()
4525 png_set_mmx_thresholds()
4526 png_get_asm_flags()
4527 png_get_mmx_bitdepth_threshold()
4528 png_get_mmx_rowbytes_threshold()
4529 png_set_asm_flags()
4530
4531We replaced all of these functions with simple stubs in libpng-1.2.20,
4532when the Intel assembler code was removed due to a licensing issue.
4533
Glenn Randers-Pehrson3d893a02009-08-31 13:32:46 -0500[diff] [blame]4534These macros are deprecated:
4535
4536 PNG_READ_TRANSFORMS_NOT_SUPPORTED
4537 PNG_PROGRESSIVE_READ_NOT_SUPPORTED
4538 PNG_NO_SEQUENTIAL_READ_SUPPORTED
4539 PNG_WRITE_TRANSFORMS_NOT_SUPPORTED
4540 PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
4541 PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
4542
4543They have been replaced, respectively, by:
4544
4545 PNG_NO_READ_TRANSFORMS
4546 PNG_NO_PROGRESSIVE_READ
4547 PNG_NO_SEQUENTIAL_READ
4548 PNG_NO_WRITE_TRANSFORMS
4549 PNG_NO_READ_ANCILLARY_CHUNKS
4550 PNG_NO_WRITE_ANCILLARY_CHUNKS
4551
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4552PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been
4553deprecated since libpng-1.0.16 and libpng-1.2.6.
4554
4555The function
4556 png_check_sig(sig, num)
4557was replaced with
4558 !png_sig_cmp(sig, 0, num)
4559It has been deprecated since libpng-0.90.
4560
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4561The function
4562 png_set_gray_1_2_4_to_8()
4563which also expands tRNS to alpha was replaced with
4564 png_set_expand_gray_1_2_4_to_8()
4565which does not. It has been deprecated since libpng-1.0.18 and 1.2.9.
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4566
Glenn Randers-Pehrsond740c842009-11-04 19:01:54 -0600[diff] [blame]4567.SH IX. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
4568
4569Private libpng prototypes and macro definitions were moved from
4570png.h and pngconf.h into a new pngpriv.h header file.
4571
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4572Functions png_set_benign_errors(), png_benign_error(), and
4573png_chunk_benign_error() were added.
4574
4575Support for setting the maximum amount of memory that the application
4576will allocate for reading chunks was added, as a security measure.
4577The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
4578were added to the library.
4579
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4580We implemented support for I/O states by adding png_ptr member io_state
4581and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4582
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]4583We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level
4584input transforms.
4585
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]4586Checking for and reporting of errors in the IHDR chunk is more thorough.
4587
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4588Support for global arrays was removed, to improve thread safety.
4589
4590Some obsolete/deprecated macros and functions have been removed.
4591
4592Typecasted NULL definitions such as
4593 #define png_voidp_NULL (png_voidp)NULL
4594were eliminated. If you used these in your application, just use
4595NULL instead.
4596
4597The png_struct and info_struct members "trans" and "trans_values" were
4598changed to "trans_alpha" and "trans_color", respectively.
4599
4600The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4601were removed.
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4602
4603The PNG_1_0_X and PNG_1_2_X macros were eliminated.
4604
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]4605The PNG_LEGACY_SUPPORTED macro was eliminated.
4606
4607Many WIN32_WCE #ifdefs were removed.
4608
4609The functions png_read_init(info_ptr), png_write_init(info_ptr),
4610png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
4611have been removed. They have been deprecated since libpng-0.95.
4612
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4613The png_permit_empty_plte() was removed. It has been deprecated
4614since libpng-1.0.9. Use png_permit_mng_features() instead.
4615
4616We removed the obsolete stub functions png_get_mmx_flagmask(),
4617png_set_mmx_thresholds(), png_get_asm_flags(),
4618png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
4619png_set_asm_flags(), and png_mmx_supported()
4620
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4621We removed the obsolete png_check_sig(), png_memcpy_check(), and
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]4622png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(),
4623and memset(), respectively.
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4624
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4625The function png_set_gray_1_2_4_to_8() was removed. It has been
4626deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
4627png_set_expand_gray_1_2_4_to_8() because the former function also
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]4628expanded any tRNS chunk to an alpha channel.
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4629
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4630Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32
4631were added and are used by default instead of the corresponding
4632functions. Unfortunately,
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]4633from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4634function) incorrectly returned a value of type png_uint_32.
4635
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4636We changed the prototype for png_malloc() from
4637 png_malloc(png_structp png_ptr, png_uint_32 size)
4638to
4639 png_malloc(png_structp png_ptr, png_alloc_size_t size)
4640
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4641This also applies to the prototype for the user replacement malloc_fn().
4642
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4643The png_calloc() function was added and is used in place of
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]4644of "png_malloc(); memset();" except in the case in png_read_png()
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4645where the array consists of pointers; in this case a "for" loop is used
4646after the png_malloc() to set the pointers to NULL, to give robust.
4647behavior in case the application runs out of memory part-way through
4648the process.
4649
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4650We changed the prototypes of png_get_compression_buffer_size() and
4651png_set_compression_buffer_size() to work with png_size_t instead of
4652png_uint_32.
4653
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4654Support for numbered error messages was removed by default, since we
4655never got around to actually numbering the error messages. The function
4656png_set_strip_error_numbers() was removed from the library by default.
4657
4658The png_zalloc() and png_zfree() functions are no longer exported.
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4659The png_zalloc() function no longer zeroes out the memory that it
4660allocates.
4661
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]4662Support for dithering was disabled by default in libpng-1.4.0, because
4663been well tested and doesn't actually "dither". The code was not
4664removed, however, and could be enabled by building libpng with
4665PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support
4666was reenabled, but the function was renamed png_set_quantize() to
4667reflect more accurately what it actually does. At the same time,
4668the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4669PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED
4670was renamed to PNG_READ_QUANTIZE_SUPPORTED.
Glenn Randers-Pehrson60988072010-04-13 22:11:06 -0500[diff] [blame]4671
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4672We removed the trailing '.' from the warning and error messages.
4673
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4674.SH X. Changes to Libpng from version 1.4.x to 1.5.x
4675
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]4676From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4677function) incorrectly returned a value of type png_uint_32.
4678
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4679A. Changes that affect users of libpng
4680
4681There are no substantial API changes between the non-deprecated parts of
4682the 1.4.5 API and the 1.5.0 API, however the ability to directly access
4683the main libpng control structures, png_struct and png_info, deprecated
4684in earlier versions of libpng, has been completely removed from
4685libpng 1.5.
4686
Glenn Randers-Pehrson00879b12011-01-15 19:25:34 -0600[diff] [blame]4687We no longer include zlib.h in png.h. Applications that need access
4688to information in zlib.h will need to add the '#include "zlib.h"'
4689directive. It does not matter whether it is placed prior to or after
4690the '"#include png.h"' directive.
4691
4692We moved the png_strcpy(), png_strncpy(), png_strlen(), png_memcpy(),
4693png_memcmp(), png_sprintf, and png_memcpy() macros into a private
4694header file (pngpriv.h) that is not accessible to applications.
4695
Glenn Randers-Pehrson9d23b402011-01-08 10:42:01 -0600[diff] [blame]4696In png_get_iCCP, the type of "profile" was changed from png_charpp
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4697to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
Glenn Randers-Pehrson9d23b402011-01-08 10:42:01 -0600[diff] [blame]4698
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4699There are changes of form in png.h, including new and changed macros to
4700declare
Glenn Randers-Pehrsonf5ea1b72011-01-06 06:42:51 -0600[diff] [blame]4701parts of the API. Some API functions with arguments that are pointers to
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4702data not modified within the function have been corrected to declare
4703these arguments with PNG_CONST.
4704
4705Much of the internal use of C macros to control the library build has also
4706changed and some of this is visible in the exported header files, in
4707particular the use of macros to control data and API elements visible
4708during application compilation may require significant revision to
4709application code. (It is extremely rare for an application to do this.)
4710
4711Any program that compiled against libpng 1.4 and did not use deprecated
4712features or access internal library structures should compile and work
Glenn Randers-Pehrsond08b6bd2011-02-19 15:50:17 -0600[diff] [blame]4713against libpng 1.5, except for the change in the prototype for
4714png_get_iCCP() and png_set_iCCP() API functions mentioned above.
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4715
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]4716libpng 1.5.0 adds PNG_ PASS macros to help in the reading and writing of
4717interlaced images. The macros return the number of rows and columns in
4718each pass and information that can be used to de-interlace and (if
4719absolutely necessary) interlace an image.
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4720
4721libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls
Glenn Randers-Pehrsond08b6bd2011-02-19 15:50:17 -0600[diff] [blame]4722the application-provided png_longjmp_ptr on the internal, but application
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4723initialized, jmpbuf. It is provided as a convenience to avoid the need
4724to use the png_jmpbuf macro, which had the unnecessary side effect of
4725resetting the internal png_longjmp_ptr value.
4726
4727libpng 1.5.0 includes a complete fixed point API. By default this is
4728present along with the corresponding floating point API. In general the
4729fixed point API is faster and smaller than the floating point one because
4730the PNG file format used fixed point, not floating point. This applies
4731even if the library uses floating point in internal calculations. A new
4732macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library
4733uses floating point arithmetic (the default) or fixed point arithmetic
4734internally for performance critical calculations such as gamma correction.
Glenn Randers-Pehrson00879b12011-01-15 19:25:34 -0600[diff] [blame]4735In some cases, the gamma calculations may produce slightly different
4736results. This has changed the results in png_rgb_to_gray and in alpha
4737composition (png_set_background for example). This applies even if the
4738original image was already linear (gamma == 1.0) and, therefore, it is
4739not necessary to linearize the image. This is because libpng has *not*
4740been changed to optimize that case correctly, yet.
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4741
4742Fixed point support for the sCAL chunk comes with an important caveat;
4743the sCAL specification uses a decimal encoding of floating point values
4744and the accuracy of PNG fixed point values is insufficient for
4745representation of these values. Consequently a "string" API
4746(png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
4747arbitrary sCAL chunks in the absence of either the floating point API or
4748internal floating point calculations.
4749
4750Applications no longer need to include the optional distribution header
4751file pngusr.h or define the corresponding macros during application
4752build in order to see the correct variant of the libpng API. From 1.5.0
4753application code can check for the corresponding _SUPPORTED macro:
4754
4755#ifdef PNG_INCH_CONVERSIONS_SUPPORTED
4756 /* code that uses the inch conversion APIs. */
4757#endif
4758
4759This macro will only be defined if the inch conversion functions have been
4760compiled into libpng. The full set of macros, and whether or not support
4761has been compiled in, are available in the header file pnglibconf.h.
4762This header file is specific to the libpng build. Notice that prior to
47631.5.0 the _SUPPORTED macros would always have the default definition unless
4764reset by pngusr.h or by explicit settings on the compiler command line.
4765These settings may produce compiler warnings or errors in 1.5.0 because
4766of macro redefinition.
4767
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]4768From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4769function) incorrectly returned a value of type png_uint_32. libpng 1.5.0
4770is consistent with the implementation in 1.4.5 and 1.2.x (where the macro
4771did not exist.)
4772
4773Applications can now choose whether to use these macros or to call the
4774corresponding function by defining PNG_USE_READ_MACROS or
4775PNG_NO_USE_READ_MACROS before including png.h. Notice that this is
4776only supported from 1.5.0 -defining PNG_NO_USE_READ_MACROS prior to 1.5.0
4777 will lead to a link failure.
Glenn Randers-Pehrson59fa3e92011-01-06 07:07:06 -0600[diff] [blame]4778
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4779B. Changes to the build and configuration of libpng
4780
4781Details of internal changes to the library code can be found in the CHANGES
4782file. These will be of no concern to the vast majority of library users or
4783builders, however the few who configure libpng to a non-default feature
4784set may need to change how this is done.
4785
4786There should be no need for library builders to alter build scripts if
4787these use the distributed build support - configure or the makefiles -
4788however users of the makefiles may care to update their build scripts
4789to build pnglibconf.h where the corresponding makefile does not do so.
4790
4791Building libpng with a non-default configuration has changed completely.
4792The old method using pngusr.h should still work correctly even though the
4793way pngusr.h is used in the build has been changed, however library
4794builders will probably want to examine the changes to take advantage of
4795new capabilities and to simplify their build system.
4796
4797B.1 Specific changes to library configuration capabilities
4798
4799The library now supports a complete fixed point implementation and can
4800thus be used on systems which have no floating point support or very
4801limited or slow support. Previously gamma correction, an essential part
4802of complete PNG support, required reasonably fast floating point.
4803
4804As part of this the choice of internal implementation has been made
4805independent of the choice of fixed versus floating point APIs and all the
4806missing fixed point APIs have been implemented.
4807
4808The exact mechanism used to control attributes of API functions has
4809changed. A single set of operating system independent macro definitions
4810is used and operating system specific directives are defined in
4811pnglibconf.h
4812
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4813As part of this the mechanism used to choose procedure call standards on
4814those systems that allow a choice has been changed. At present this only
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4815affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
4816running on Intel processors. As before PNGAPI is defined where required
4817to control the exported API functions; however, two new macros, PNGCBAPI
4818and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
4819(PNGCAPI) for functions that must match a C library prototype (currently
4820only png_longjmp_ptr, which must match the C longjmp function.) The new
4821approach is documented in pngconf.h
4822
4823Despite these changes libpng 1.5.0 only supports the native C function
4824calling standard on those platforms tested so far (__cdecl on Microsoft
4825Windows). This is because the support requirements for alternative
4826calling conventions seem to no longer exist. Developers who find it
4827necessary to set PNG_API_RULE to 1 should advise the mailing list
4828(png-mng-implement) of this and library builders who use Openwatcom and
4829therefore set PNG_API_RULE to 2 should also contact the mailing list.
4830
4831A new test program, pngvalid, is provided in addition to pngtest.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4832pngvalid validates the arithmetic accuracy of the gamma correction
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4833calculations and includes a number of validations of the file format.
4834A subset of the full range of tests is run when "make check" is done
4835(in the 'configure' build.) pngvalid also allows total allocated memory
4836usage to be evaluated and performs additional memory overwrite validation.
4837
4838Many changes to individual feature macros have been made. The following
4839are the changes most likely to be noticed by library builders who
4840configure libpng:
4841
48421) All feature macros now have consistent naming:
4843
4844#define PNG_NO_feature turns the feature off
4845#define PNG_feature_SUPPORTED turns the feature on
4846
4847pnglibconf.h contains one line for each feature macro which is either:
4848
4849#define PNG_feature_SUPPORTED
4850
4851if the feature is supported or:
4852
4853/*#undef PNG_feature_SUPPORTED*/
4854
4855if it is not. Library code consistently checks for the 'SUPPORTED' macro.
4856It does not, and should not, check for the 'NO' macro which will not
4857normally be defined even if the feature is not supported.
4858
4859Compatibility with the old names is provided as follows:
4860
4861PNG_INCH_CONVERSIONS turns on PNG_INCH_CONVERSIONS_SUPPORTED
4862
4863And the following definitions disable the corresponding feature:
4864
4865PNG_SETJMP_NOT_SUPPORTED disables SETJMP
4866PNG_READ_TRANSFORMS_NOT_SUPPORTED disables READ_TRANSFORMS
4867PNG_NO_READ_COMPOSITED_NODIV disables READ_COMPOSITE_NODIV
4868PNG_WRITE_TRANSFORMS_NOT_SUPPORTED disables WRITE_TRANSFORMS
4869PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED disables READ_ANCILLARY_CHUNKS
4870PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED disables WRITE_ANCILLARY_CHUNKS
4871
4872Library builders should remove use of the above, inconsistent, names.
4873
48742) Warning and error message formatting was previously conditional on
4875the STDIO feature. The library has been changed to use the
4876CONSOLE_IO feature instead. This means that if CONSOLE_IO is disabled
4877the library no longer uses the printf(3) functions, even though the
4878default read/write implementations use (FILE) style stdio.h functions.
4879
48803) Three feature macros now control the fixed/floating point decisions:
4881
4882PNG_FLOATING_POINT_SUPPORTED enables the floating point APIs
4883
4884PNG_FIXED_POINT_SUPPORTED enables the fixed point APIs; however, in
4885practice these are normally required internally anyway (because the PNG
4886file format is fixed point), therefore in most cases PNG_NO_FIXED_POINT
4887merely stops the function from being exported.
4888
4889PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating
4890point implementation or the fixed point one. Typically the fixed point
4891implementation is larger and slower than the floating point implementation
4892on a system that supports floating point, however it may be faster on a
4893system which lacks floating point hardware and therefore uses a software
4894emulation.
4895
48964) Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the
4897functions to read and write ints to be disabled independently of
4898PNG_USE_READ_MACROS, which allows libpng to be built with the functions
4899even though the default is to use the macros - this allows applications
4900to choose at app buildtime whether or not to use macros (previously
4901impossible because the functions weren't in the default build.)
4902
4903B.2 Changes to the configuration mechanism
4904
4905Prior to libpng-1.5.0 library builders who needed to configure libpng
4906had either to modify the exported pngconf.h header file to add system
4907specific configuration or had to write feature selection macros into
4908pngusr.h and cause this to be included into pngconf.h by defining
4909PNG_USER_CONFIG. The latter mechanism had the disadvantage that an
4910application built without PNG_USER_CONFIG defined would see the
4911unmodified, default, libpng API and thus would probably fail to link.
4912
4913These mechanisms still work in the configure build and in any makefile
4914build that builds pnglibconf.h although the feature selection macros
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4915have changed somewhat as described above. In 1.5.0, however, pngusr.h is
4916processed only once, when the exported header file pnglibconf.h is built.
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4917pngconf.h no longer includes pngusr.h, therefore it is ignored after the
4918build of pnglibconf.h and it is never included in an application build.
4919
4920The rarely used alternative of adding a list of feature macros to the
4921CFLAGS setting in the build also still works, however the macros will be
4922copied to pnglibconf.h and this may produce macro redefinition warnings
4923when the individual C files are compiled.
4924
4925All configuration now only works if pnglibconf.h is built from
4926scripts/pnglibconf.dfa. This requires the program awk. Brian Kernighan
4927(the original author of awk) maintains C source code of that awk and this
4928and all known later implementations (often called by subtly different
4929names - nawk and gawk for example) are adequate to build pnglibconf.h.
4930The Sun Microsystems (now Oracle) program 'awk' is an earlier version
4931and does not work, this may also apply to other systems that have a
4932functioning awk called 'nawk'.
4933
4934Configuration options are now documented in scripts/pnglibconf.dfa. This
4935file also includes dependency information that ensures a configuration is
4936consistent; that is, if a feature is switched off dependent features are
4937also removed. As a recommended alternative to using feature macros in
4938pngusr.h a system builder may also define equivalent options in pngusr.dfa
4939(or, indeed, any file) and add that to the configuration by setting
4940DFA_XTRA to the file name. The makefiles in contrib/pngminim illustrate
4941how to do this, and a case where pngusr.h is still required.
4942
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4943.SH XI. Detecting libpng
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]4944
4945The png_get_io_ptr() function has been present since libpng-0.88, has never
4946changed, and is unaffected by conditional compilation macros. It is the
4947best choice for use in configure scripts for detecting the presence of any
Glenn Randers-Pehrson99708d52009-06-29 17:30:00 -0500[diff] [blame]4948libpng version since 0.88. In an autoconf "configure.in" you could use
4949
4950 AC_CHECK_LIB(png, png_get_io_ptr, ...
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]4951
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4952.SH XII. Source code repository
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4953
4954Since about February 2009, version 1.2.34, libpng has been under "git" source
4955control. The git repository was built from old libpng-x.y.z.tar.gz files
4956going back to version 0.70. You can access the git repository (read only)
4957at
4958
4959 git://libpng.git.sourceforge.net/gitroot/libpng
4960
4961or you can browse it via "gitweb" at
4962
4963 http://libpng.git.sourceforge.net/git/gitweb.cgi?p=libpng
4964
4965Patches can be sent to glennrp at users.sourceforge.net or to
4966png-mng-implement at lists.sourceforge.net or you can upload them to
4967the libpng bug tracker at
4968
4969 http://libpng.sourceforge.net
4970
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4971We also accept patches built from the tar or zip distributions, and
4972simple verbal discriptions of bug fixes, reported either to the
4973SourceForge bug tracker or to the png-mng-implement at lists.sf.net
4974mailing list.
4975
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4976.SH XIII. Coding style
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4977
4978Our coding style is similar to the "Allman" style, with curly
4979braces on separate lines:
4980
4981 if (condition)
4982 {
4983 action;
4984 }
4985
4986 else if (another condition)
4987 {
4988 another action;
4989 }
4990
4991The braces can be omitted from simple one-line actions:
4992
4993 if (condition)
4994 return (0);
4995
4996We use 3-space indentation, except for continued statements which
4997are usually indented the same as the first line of the statement
4998plus four more spaces.
4999
Glenn Randers-Pehrson5ade7ed2009-09-30 15:11:49 -0500[diff] [blame]5000For macro definitions we use 2-space indentation, always leaving the "#"
5001in the first column.
5002
5003 #ifndef PNG_NO_FEATURE
5004 # ifndef PNG_FEATURE_SUPPORTED
5005 # define PNG_FEATURE_SUPPORTED
5006 # endif
5007 #endif
5008
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5009Comments appear with the leading "/*" at the same indentation as
5010the statement that follows the comment:
5011
5012 /* Single-line comment */
5013 statement;
5014
Glenn Randers-Pehrsone4c706a2010-03-06 14:51:54 -0600[diff] [blame]5015 /* This is a multiple-line
5016 * comment.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5017 */
5018 statement;
5019
Glenn Randers-Pehrsone4c706a2010-03-06 14:51:54 -0600[diff] [blame]5020Very short comments can be placed after the end of the statement
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5021to which they pertain:
5022
5023 statement; /* comment */
5024
5025We don't use C++ style ("//") comments. We have, however,
5026used them in the past in some now-abandoned MMX assembler
5027code.
5028
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame]5029Functions and their curly braces are not indented, and
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5030exported functions are marked with PNGAPI:
5031
5032 /* This is a public function that is visible to
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]5033 * application programmers. It does thus-and-so.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5034 */
5035 void PNGAPI
5036 png_exported_function(png_ptr, png_info, foo)
5037 {
5038 body;
5039 }
5040
Glenn Randers-Pehrson416976f2009-07-27 22:16:09 -0500[diff] [blame]5041The prototypes for all exported functions appear in png.h,
5042above the comment that says
5043
5044 /* Maintainer: Put new public prototypes here ... */
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5045
5046We mark all non-exported functions with "/* PRIVATE */"":
5047
5048 void /* PRIVATE */
5049 png_non_exported_function(png_ptr, png_info, foo)
5050 {
5051 body;
5052 }
5053
Glenn Randers-Pehrson416976f2009-07-27 22:16:09 -0500[diff] [blame]5054The prototypes for non-exported functions (except for those in
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]5055pngtest) appear in
5056pngpriv.h
Glenn Randers-Pehrson416976f2009-07-27 22:16:09 -0500[diff] [blame]5057above the comment that says
5058
5059 /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5060
Glenn Randers-Pehrsoncbbe9a52011-01-29 16:12:11 -0600[diff] [blame]5061To avoid polluting the global namespace, the names of all exported
5062functions and variables begin with "png_", and all publicly visible C
5063preprocessor macros begin with "PNG_". We request that applications that
5064use libpng *not* begin any of their own symbols with either of these strings.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5065
5066We put a space after each comma and after each semicolon
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]5067in "for" statements, and we put spaces before and after each
Glenn Randers-Pehrsone4c706a2010-03-06 14:51:54 -0600[diff] [blame]5068C binary operator and after "for" or "while", and before
5069"?". We don't put a space between a typecast and the expression
5070being cast, nor do we put one between a function name and the
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5071left parenthesis that follows it:
5072
5073 for (i = 2; i > 0; --i)
Glenn Randers-Pehrson67f3b482009-09-23 11:36:28 -0500[diff] [blame]5074 y[i] = a(x) + (int)b;
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5075
Glenn Randers-Pehrsond60c8862009-06-15 21:56:14 -0500[diff] [blame]5076We prefer #ifdef and #ifndef to #if defined() and if !defined()
5077when there is only one macro being tested.
5078
Glenn Randers-Pehrson67f3b482009-09-23 11:36:28 -0500[diff] [blame]5079We do not use the TAB character for indentation in the C sources.
5080
Glenn Randers-Pehrson62ca98e2009-12-20 15:14:57 -0600[diff] [blame]5081Lines do not exceed 80 characters.
5082
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]5083Other rules can be inferred by inspecting the libpng source.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5084
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]5085.SH XIV. Y2K Compliance in libpng
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5086
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]5087March 3, 2011
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5088
5089Since the PNG Development group is an ad-hoc body, we can't make
5090an official declaration.
5091
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5092This is your unofficial assurance that libpng from version 0.71 and
Glenn Randers-Pehrson7c969f32011-02-19 15:58:03 -0600[diff] [blame]5093upward through 1.5.2beta03 are Y2K compliant. It is my belief that earlier
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5094versions were also Y2K compliant.
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5095
5096Libpng only has three year fields. One is a 2-byte unsigned integer that
5097will hold years up to 65535. The other two hold the date in text
5098format, and will hold years up to 9999.
5099
5100The integer is
5101 "png_uint_16 year" in png_time_struct.
5102
5103The strings are
5104 "png_charp time_buffer" in png_struct and
5105 "near_time_buffer", which is a local character string in png.c.
5106
5107There are seven time-related functions:
5108
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]5109 png_convert_to_rfc_1123() in png.c
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5110 (formerly png_convert_to_rfc_1152() in error)
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5111 png_convert_from_struct_tm() in pngwrite.c, called
5112 in pngwrite.c
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5113 png_convert_from_time_t() in pngwrite.c
5114 png_get_tIME() in pngget.c
5115 png_handle_tIME() in pngrutil.c, called in pngread.c
5116 png_set_tIME() in pngset.c
5117 png_write_tIME() in pngwutil.c, called in pngwrite.c
5118
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]5119All appear to handle dates properly in a Y2K environment. The
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5120png_convert_from_time_t() function calls gmtime() to convert from system
5121clock time, which returns (year - 1900), which we properly convert to
5122the full 4-digit year. There is a possibility that applications using
5123libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5124function, or that they are incorrectly passing only a 2-digit year
5125instead of "year - 1900" into the png_convert_from_struct_tm() function,
5126but this is not under our control. The libpng documentation has always
5127stated that it works with 4-digit years, and the APIs have been
5128documented as such.
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5129
5130The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
5131integer to hold the year, and can hold years as large as 65535.
5132
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5133zlib, upon which libpng depends, is also Y2K compliant. It contains
5134no date-related code.
5135
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5136
5137 Glenn Randers-Pehrson
5138 libpng maintainer
5139 PNG Development Group
5140
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5141.SH NOTE
5142
5143Note about libpng version numbers:
5144
5145Due to various miscommunications, unforeseen code incompatibilities
5146and occasional factors outside the authors' control, version numbering
5147on the library has not always been consistent and straightforward.
5148The following table summarizes matters since version 0.89c, which was
5149the first widely used release:
5150
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5151 source png.h png.h shared-lib
5152 version string int version
5153 ------- ------ ----- ----------
5154 0.89c ("beta 3") 0.89 89 1.0.89
5155 0.90 ("beta 4") 0.90 90 0.90
5156 0.95 ("beta 5") 0.95 95 0.95
5157 0.96 ("beta 6") 0.96 96 0.96
5158 0.97b ("beta 7") 1.00.97 97 1.0.1
5159 0.97c 0.97 97 2.0.97
5160 0.98 0.98 98 2.0.98
5161 0.99 0.99 98 2.0.99
5162 0.99a-m 0.99 99 2.0.99
5163 1.00 1.00 100 2.1.0
5164 1.0.0 1.0.0 100 2.1.0
5165 1.0.0 (from here on, the 100 2.1.0
5166 1.0.1 png.h string is 10001 2.1.0
5167 1.0.1a-e identical to the 10002 from here on, the
5168 1.0.2 source version) 10002 shared library is 2.V
5169 1.0.2a-b 10003 where V is the source
5170 1.0.1 10001 code version except as
5171 1.0.1a-e 10002 2.1.0.1a-e noted.
5172 1.0.2 10002 2.1.0.2
5173 1.0.2a-b 10003 2.1.0.2a-b
5174 1.0.3 10003 2.1.0.3
5175 1.0.3a-d 10004 2.1.0.3a-d
5176 1.0.4 10004 2.1.0.4
5177 1.0.4a-f 10005 2.1.0.4a-f
5178 1.0.5 (+ 2 patches) 10005 2.1.0.5
5179 1.0.5a-d 10006 2.1.0.5a-d
5180 1.0.5e-r 10100 2.1.0.5e-r
5181 1.0.5s-v 10006 2.1.0.5s-v
5182 1.0.6 (+ 3 patches) 10006 2.1.0.6
5183 1.0.6d-g 10007 2.1.0.6d-g
5184 1.0.6h 10007 10.6h
5185 1.0.6i 10007 10.6i
5186 1.0.6j 10007 2.1.0.6j
Glenn Randers-Pehrson25467032011-01-28 11:58:40 -0600[diff] [blame]5187 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5188 1.0.7beta15-18 1 10007 2.1.0.7beta15-18
5189 1.0.7rc1-2 1 10007 2.1.0.7rc1-2
5190 1.0.7 1 10007 2.1.0.7
5191 1.0.8beta1-4 1 10008 2.1.0.8beta1-4
5192 1.0.8rc1 1 10008 2.1.0.8rc1
5193 1.0.8 1 10008 2.1.0.8
5194 1.0.9beta1-6 1 10009 2.1.0.9beta1-6
5195 1.0.9rc1 1 10009 2.1.0.9rc1
5196 1.0.9beta7-10 1 10009 2.1.0.9beta7-10
5197 1.0.9rc2 1 10009 2.1.0.9rc2
5198 1.0.9 1 10009 2.1.0.9
Glenn Randers-Pehrsone1644472001-03-23 05:06:56 -0600[diff] [blame]5199 1.0.10beta1 1 10010 2.1.0.10beta1
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5200 1.0.10rc1 1 10010 2.1.0.10rc1
Glenn Randers-Pehrson13cfbac2001-03-30 06:42:28 -0600[diff] [blame]5201 1.0.10 1 10010 2.1.0.10
Glenn Randers-Pehrsone1eff582001-04-14 20:15:41 -0500[diff] [blame]5202 1.0.11beta1-3 1 10011 2.1.0.11beta1-3
Glenn Randers-Pehrson82ae3832001-04-20 10:32:10 -0500[diff] [blame]5203 1.0.11rc1 1 10011 2.1.0.11rc1
Glenn Randers-Pehrson32835392001-04-27 08:29:32 -0500[diff] [blame]5204 1.0.11 1 10011 2.1.0.11
Glenn Randers-Pehrsonb1828932001-06-23 08:03:17 -0500[diff] [blame]5205 1.0.12beta1-2 2 10012 2.1.0.12beta1-2
5206 1.0.12rc1 2 10012 2.1.0.12rc1
5207 1.0.12 2 10012 2.1.0.12
5208 1.1.0a-f - 10100 2.1.1.0a-f abandoned
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]5209 1.2.0beta1-2 2 10200 2.1.2.0beta1-2
Glenn Randers-Pehrson5a0be342001-10-18 20:55:13 -0500[diff] [blame]5210 1.2.0beta3-5 3 10200 3.1.2.0beta3-5
5211 1.2.0rc1 3 10200 3.1.2.0rc1
5212 1.2.0 3 10200 3.1.2.0
Glenn Randers-Pehrson5cded0b2001-11-07 07:10:08 -0600[diff] [blame]5213 1.2.1beta-4 3 10201 3.1.2.1beta1-4
Glenn Randers-Pehrsondb3b88d2001-12-04 06:30:43 -0600[diff] [blame]5214 1.2.1rc1-2 3 10201 3.1.2.1rc1-2
5215 1.2.1 3 10201 3.1.2.1
Glenn Randers-Pehrson25228ab2002-03-31 07:33:55 -0600[diff] [blame]5216 1.2.2beta1-6 12 10202 12.so.0.1.2.2beta1-6
Glenn Randers-Pehrsonfcbd7872002-04-07 16:35:38 -0500[diff] [blame]5217 1.0.13beta1 10 10013 10.so.0.1.0.13beta1
5218 1.0.13rc1 10 10013 10.so.0.1.0.13rc1
5219 1.2.2rc1 12 10202 12.so.0.1.2.2rc1
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]5220 1.0.13 10 10013 10.so.0.1.0.13
5221 1.2.2 12 10202 12.so.0.1.2.2
Glenn Randers-Pehrson22f28962002-05-13 18:17:09 -0500[diff] [blame]5222 1.2.3rc1-6 12 10203 12.so.0.1.2.3rc1-6
5223 1.2.3 12 10203 12.so.0.1.2.3
Glenn Randers-Pehrsond020e9d2002-06-28 09:34:00 -0500[diff] [blame]5224 1.2.4beta1-3 13 10204 12.so.0.1.2.4beta1-3
Glenn Randers-Pehrson2ae022d2002-07-01 22:23:46 -0500[diff] [blame]5225 1.2.4rc1 13 10204 12.so.0.1.2.4rc1
Glenn Randers-Pehrson484a8a12002-07-07 19:15:20 -0500[diff] [blame]5226 1.0.14 10 10014 10.so.0.1.0.14
5227 1.2.4 13 10204 12.so.0.1.2.4
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]5228 1.2.5beta1-2 13 10205 12.so.0.1.2.5beta1-2
5229 1.0.15rc1 10 10015 10.so.0.1.0.15rc1
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]5230 1.0.15 10 10015 10.so.0.1.0.15
5231 1.2.5 13 10205 12.so.0.1.2.5
5232 1.2.6beta1-4 13 10206 12.so.0.1.2.6beta1-4
Glenn Randers-Pehrson37f116a2004-08-15 07:15:39 -0500[diff] [blame]5233 1.2.6rc1-5 13 10206 12.so.0.1.2.6rc1-5
5234 1.0.16 10 10016 10.so.0.1.0.16
5235 1.2.6 13 10206 12.so.0.1.2.6
Glenn Randers-Pehrson67864af2004-08-28 23:30:07 -0500[diff] [blame]5236 1.2.7beta1-2 13 10207 12.so.0.1.2.7beta1-2
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]5237 1.0.17rc1 10 10017 12.so.0.1.0.17rc1
5238 1.2.7rc1 13 10207 12.so.0.1.2.7rc1
Glenn Randers-Pehrson250dfe12004-09-11 21:19:54 -0500[diff] [blame]5239 1.0.17 10 10017 12.so.0.1.0.17
5240 1.2.7 13 10207 12.so.0.1.2.7
Glenn Randers-Pehrson40936072004-11-20 11:18:40 -0600[diff] [blame]5241 1.2.8beta1-5 13 10208 12.so.0.1.2.8beta1-5
Glenn Randers-Pehrson584b96e2004-11-29 15:08:00 -0600[diff] [blame]5242 1.0.18rc1-5 10 10018 12.so.0.1.0.18rc1-5
5243 1.2.8rc1-5 13 10208 12.so.0.1.2.8rc1-5
Glenn Randers-Pehrson917648e2004-12-02 18:14:51 -0600[diff] [blame]5244 1.0.18 10 10018 12.so.0.1.0.18
5245 1.2.8 13 10208 12.so.0.1.2.8
Glenn Randers-Pehrsone6474622006-03-04 16:50:47 -0600[diff] [blame]5246 1.2.9beta1-3 13 10209 12.so.0.1.2.9beta1-3
Glenn Randers-Pehrson4deeb792006-03-22 16:21:59 -0600[diff] [blame]5247 1.2.9beta4-11 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrson3a512032006-03-31 05:29:33 -0600[diff] [blame]5248 1.2.9rc1 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrsona7d0c942006-04-14 06:22:52 -0500[diff] [blame]5249 1.2.9 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrsond60b8fa2006-04-20 21:31:14 -0500[diff] [blame]5250 1.2.10beta1-7 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson17218292006-04-20 07:20:46 -0500[diff] [blame]5251 1.2.10rc1-2 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson86dc9812006-05-10 07:27:44 -0500[diff] [blame]5252 1.2.10 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]5253 1.4.0beta1-6 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrsond60c8862009-06-15 21:56:14 -0500[diff] [blame]5254 1.2.11beta1-4 13 10210 12.so.0.11[.0]
Glenn Randers-Pehrson3424ee72006-07-12 13:33:47 -0500[diff] [blame]5255 1.4.0beta7-8 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrson701dbaa2006-11-17 09:36:54 -0600[diff] [blame]5256 1.2.11 13 10211 12.so.0.11[.0]
5257 1.2.12 13 10212 12.so.0.12[.0]
5258 1.4.0beta9-14 14 10400 14.so.0.0[.0]
5259 1.2.13 13 10213 12.so.0.13[.0]
Glenn Randers-Pehrson97a9b482008-10-25 20:03:28 -0500[diff] [blame]5260 1.4.0beta15-36 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrsonfa028102009-10-10 06:15:21 -0500[diff] [blame]5261 1.4.0beta37-87 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrson733da8c2009-10-30 00:00:15 -0500[diff] [blame]5262 1.4.0rc01 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrson62ca98e2009-12-20 15:14:57 -0600[diff] [blame]5263 1.4.0beta88-109 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrson67a83db2010-01-01 18:26:18 -0600[diff] [blame]5264 1.4.0rc02-08 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrsondbcfb712009-12-25 14:24:18 -0600[diff] [blame]5265 1.4.0 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]5266 1.4.1beta01-03 14 10401 14.so.14.1[.0]
5267 1.4.1rc01 14 10401 14.so.14.1[.0]
Glenn Randers-Pehrson7a5be532010-02-14 07:16:19 -0600[diff] [blame]5268 1.4.1beta04-12 14 10401 14.so.14.1[.0]
Glenn Randers-Pehrsonaaf377c2010-03-08 11:20:30 -0600[diff] [blame]5269 1.4.1 14 10401 14.so.14.1[.0]
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame]5270 1.4.2 14 10402 14.so.14.2[.0]
5271 1.4.3 14 10403 14.so.14.3[.0]
Glenn Randers-Pehrson2776d5e2010-11-21 15:18:02 -0600[diff] [blame]5272 1.4.4 14 10404 14.so.14.4[.0]
Glenn Randers-Pehrsonfd20a5a2010-12-27 08:53:08 -0600[diff] [blame]5273 1.5.0beta01-58 15 10500 15.so.15.0[.0]
Glenn Randers-Pehrson64b863c2011-01-04 09:57:06 -0600[diff] [blame]5274 1.5.0rc01-07 15 10500 15.so.15.0[.0]
Glenn Randers-Pehrsonf5ea1b72011-01-06 06:42:51 -0600[diff] [blame]5275 1.5.0 15 10500 15.so.15.0[.0]
Glenn Randers-Pehrsonef123cc2011-01-28 15:20:34 -0600[diff] [blame]5276 1.5.1beta01-11 15 10501 15.so.15.1[.0]
Glenn Randers-Pehrson3d3aae12011-02-02 22:58:27 -0600[diff] [blame]5277 1.5.1rc01-02 15 10501 15.so.15.1[.0]
5278 1.5.1 15 10501 15.so.15.1[.0]
Glenn Randers-Pehrson7c969f32011-02-19 15:58:03 -0600[diff] [blame]5279 1.5.2beta01-03 15 10502 15.so.15.2[.0]
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5280
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5281Henceforth the source version will match the shared-library minor
5282and patch numbers; the shared-library major version number will be
5283used for changes in backward compatibility, as it is intended. The
5284PNG_PNGLIB_VER macro, which is not used within libpng but is available
5285for applications, is an unsigned integer of the form xyyzz corresponding
5286to the source version x.y.z (leading zeros in y and z). Beta versions
Glenn Randers-Pehrsone1644472001-03-23 05:06:56 -0600[diff] [blame]5287were given the previous public release number plus a letter, until
5288version 1.0.6j; from then on they were given the upcoming public
5289release number plus "betaNN" or "rcN".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]5290
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5291.SH "SEE ALSO"
Glenn Randers-Pehrson4e763f12010-03-03 10:45:50 -0600[diff] [blame]5292.BR "png"(5), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
Glenn Randers-Pehrson7fb32a82010-03-03 09:47:49 -0600[diff] [blame]5293
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]5294.LP
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5295.IR libpng :
5296.IP
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]5297http://libpng.sourceforge.net (follow the [DOWNLOAD] link)
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]5298http://www.libpng.org/pub/png
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5299
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]5300.LP
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5301.IR zlib :
5302.IP
5303(generally) at the same location as
5304.I libpng
5305or at
5306.br
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]5307ftp://ftp.info-zip.org/pub/infozip/zlib
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5308
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]5309.LP
5310.IR PNG specification: RFC 2083
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5311.IP
5312(generally) at the same location as
5313.I libpng
5314or at
5315.br
5316ftp://ds.internic.net/rfc/rfc2083.txt
5317.br
5318or (as a W3C Recommendation) at
5319.br
5320http://www.w3.org/TR/REC-png.html
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5321
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]5322.LP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5323In the case of any inconsistency between the PNG specification
5324and this library, the specification takes precedence.
5325
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5326.SH AUTHORS
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5327This man page: Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]5328<glennrp at users.sourceforge.net>
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5329
5330The contributing authors would like to thank all those who helped
5331with testing, bug fixes, and patience. This wouldn't have been
5332possible without all of you.
5333
5334Thanks to Frank J. T. Wojcik for helping with the documentation.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]5335
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]5336Libpng version 1.5.2beta03 - March 3, 2011:
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5337Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]5338Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5339
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5340Supported by the PNG development group
5341.br
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]5342png-mng-implement at lists.sf.net
5343(subscription required; visit
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]5344png-mng-implement at lists.sourceforge.net (subscription required; visit
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]5345https://lists.sourceforge.net/lists/listinfo/png-mng-implement
5346to subscribe).
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5347
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5348.SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5349
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]5350(This copy of the libpng notices is provided for your convenience. In case of
5351any discrepancy between this copy and the notices in the file png.h that is
5352included in the libpng distribution, the latter shall prevail.)
5353
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5354If you modify libpng you may insert additional notices immediately following
5355this sentence.
5356
Glenn Randers-Pehrsonbfbf8652009-06-26 21:46:52 -0500[diff] [blame]5357This code is released under the libpng license.
Glenn Randers-Pehrson037023b2009-06-24 10:27:36 -0500[diff] [blame]5358
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]5359libpng versions 1.2.6, August 15, 2004, through 1.5.2beta03, March 3, 2011, are
Glenn Randers-Pehrsona7dbcba2007-05-15 16:16:34 -0500[diff] [blame]5360Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]5361distributed according to the same disclaimer and license as libpng-1.2.5
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]5362with the following individual added to the list of Contributing Authors
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]5363
5364 Cosmin Truta
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]5365
5366libpng versions 1.0.7, July 1, 2000, through 1.2.5 - October 3, 2002, are
Glenn Randers-Pehrsonc6de22d2002-02-23 18:55:25 -0600[diff] [blame]5367Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
Glenn Randers-Pehrson32fc5ce2000-07-24 06:34:14 -0500[diff] [blame]5368distributed according to the same disclaimer and license as libpng-1.0.6
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5369with the following individuals added to the list of Contributing Authors
5370
5371 Simon-Pierre Cadieux
5372 Eric S. Raymond
5373 Gilles Vollant
5374
5375and with the following additions to the disclaimer:
5376
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5377 There is no warranty against interference with your
5378 enjoyment of the library or against infringement.
5379 There is no warranty that our efforts or the library
5380 will fulfill any of your particular purposes or needs.
5381 This library is provided with all faults, and the entire
5382 risk of satisfactory quality, performance, accuracy, and
5383 effort is with the user.
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5384
5385libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
5386Copyright (c) 1998, 1999 Glenn Randers-Pehrson
5387Distributed according to the same disclaimer and license as libpng-0.96,
5388with the following individuals added to the list of Contributing Authors:
5389
5390 Tom Lane
5391 Glenn Randers-Pehrson
5392 Willem van Schaik
5393
5394libpng versions 0.89, June 1996, through 0.96, May 1997, are
Glenn Randers-Pehrson54a066a1999-09-19 06:04:18 -0500[diff] [blame]5395Copyright (c) 1996, 1997 Andreas Dilger
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5396Distributed according to the same disclaimer and license as libpng-0.88,
5397with the following individuals added to the list of Contributing Authors:
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5398
5399 John Bowler
5400 Kevin Bracey
5401 Sam Bushell
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5402 Magnus Holmgren
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5403 Greg Roelofs
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5404 Tom Tanner
5405
5406libpng versions 0.5, May 1995, through 0.88, January 1996, are
5407Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
5408
5409For the purposes of this copyright and license, "Contributing Authors"
5410is defined as the following set of individuals:
5411
5412 Andreas Dilger
5413 Dave Martindale
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5414 Guy Eric Schalnat
5415 Paul Schmidt
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5416 Tim Wegner
Glenn Randers-Pehrsonc9442291999-01-06 21:50:16 -0600[diff] [blame]5417
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5418The PNG Reference Library is supplied "AS IS". The Contributing Authors
5419and Group 42, Inc. disclaim all warranties, expressed or implied,
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5420including, without limitation, the warranties of merchantability and of
5421fitness for any purpose. The Contributing Authors and Group 42, Inc.
5422assume no liability for direct, indirect, incidental, special, exemplary,
5423or consequential damages, which may result from the use of the PNG
5424Reference Library, even if advised of the possibility of such damage.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5425
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5426Permission is hereby granted to use, copy, modify, and distribute this
5427source code, or portions hereof, for any purpose, without fee, subject
5428to the following restrictions:
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5429
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]54301. The origin of this source code must not be misrepresented.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5431
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]54322. Altered versions must be plainly marked as such and
5433 must not be misrepresented as being the original source.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5434
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]54353. This Copyright notice may not be removed or altered from
5436 any source or altered source distribution.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5437
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5438The Contributing Authors and Group 42, Inc. specifically permit, without
5439fee, and encourage the use of this source code as a component to
5440supporting the PNG file format in commercial products. If you use this
5441source code in a product, acknowledgment is not required but would be
5442appreciated.
5443
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5444
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5445A "png_get_copyright" function is available, for convenient use in "about"
5446boxes and the like:
5447
5448 printf("%s",png_get_copyright(NULL));
5449
5450Also, the PNG logo (in PNG format, of course) is supplied in the
Glenn Randers-Pehrsona4d54bd2000-07-14 08:15:12 -0500[diff] [blame]5451files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5452
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5453Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5454certification mark of the Open Source Initiative.
5455
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5456Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]5457glennrp at users.sourceforge.net
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame^]5458March 3, 2011
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5459
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5460.\" end of man page
5461