Imported from libpng-0.71.tar
diff --git a/png.h b/png.h
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+++ b/png.h
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+
+/* png.h - header file for png reference library
+ libpng 1.0 beta 1 - version 0.71
+ June 26, 1995
+
+ Note: This is a beta version. It reads and writes valid files
+ on the platforms I have, but it has had limited portability
+ testing. Furthermore, you will probably have to modify the
+ includes below to get it to work on your system, and you
+ may have to supply the correct compiler flags in the makefile.
+ Read the readme.txt for more information, and how to contact
+ me if you have any problems, or if you want your compiler/
+ platform to be supported in the next official libpng release.
+
+ See readme.txt for more information
+
+ Copyright (c) 1995 Guy Eric Schalnat, Group 42, Inc.
+ Contributing Authors:
+ Guy Eric Schalnat
+
+ The PNG Reference Library is supplied "AS IS". The Contributing Authors
+ and Group 42, Inc. disclaim all warranties, expressed or implied,
+ including, without limitation, the warranties of merchantability and of
+ fitness for any purpose. The Contributing Authors and Group 42, Inc.
+ assume no liability for damages, direct or consequential, which may
+ result from the use of the PNG Reference Library.
+
+ Permission is hereby granted to use, copy, modify, and distribute this
+ source code, or portions hereof, for any purpose, without fee, subject
+ to the following restrictions:
+ 1. The origin of this source code must not be misrepresented.
+ 2. Altered versions must be plainly marked as such and must not be
+ misrepresented as being the original source.
+ 3. This Copyright notice may not be removed or altered from any source or
+ altered source distribution.
+
+ The Contributing Authors and Group 42, Inc. specifically permit, without
+ fee, and encourage the use of this source code as a component to
+ supporting the PNG file format in commercial products. If you use this
+ source code in a product, acknowledgment is not required but would be
+ appreciated.
+ */
+
+#ifndef _PNG_H
+#define _PNG_H
+
+/* This is not the place to learn how to use libpng. The file libpng.txt
+ describes how to use libpng, and the file example.c summarizes it
+ with some code to build around. This file is useful for looking
+ at the actual function definitions and structure components. */
+
+/* This file is arranged in several sections. The first section contains
+ all the definitions for libpng. The second section details the functions
+ most users will use. The third section describes the stub files that
+ users will most likely need to change. The last section contains
+ functions used internally by the code.
+
+ Any machine specific code is near the front of this file, so if you
+ are configuring libpng for a machine, you may want to read the section
+ starting here down to where it starts to typedef png_color, png_text,
+ and png_info */
+
+/* this is the size of the compression buffer, and thus the size of
+ an IDAT chunk. Make this whatever size you feel is best for your
+ machine. One of these will be allocated per png_struct. When this
+ is full, it writes the data to the disk, and does some other
+ calculations. Making this an extreamly small size will slow
+ the library down, but you may want to experiment to determine
+ where it becomes significant, if you are concerned with memory
+ usage. Note that zlib allocates at least 32Kb also. For readers,
+ this describes the size of the buffer available to read the data in.
+ Unless this gets smaller then the size of a row (compressed),
+ it should not make much difference how big this is. */
+
+#define PNG_ZBUF_SIZE 8192;
+
+/* include the compression library's header */
+#include "zlib.h"
+
+/* While libpng currently uses zlib for it's compression, it has been designed
+ to stand on it's own. Towards this end, there are two defines that are
+ used to help portability between machines. To make it simpler to
+ setup libpng on a machine, this currently uses zlib's definitions, so
+ any changes should be made in zlib. Libpng will check zlib's settings
+ and adjust it's own accordingly. */
+
+/* if you are running on a machine where you cannot allocate more then
+ 64K of memory, uncomment this. While libpng will not normally need
+ that much memory in a chunk (unless you load up a very large file),
+ zlib needs to know how big of a chunk it can use, and libpng thus
+ makes sure to check any memory allocation to verify it will fit
+ into memory.
+#define PNG_MAX_ALLOC_64K
+*/
+#ifdef MAXSEG_64K
+#define PNG_MAX_ALLOC_64K
+#endif
+
+/* this macro protects us against machines that don't have function
+ prototypes. If your compiler does not handle function prototypes,
+ define this macro. I've always been able to use _NO_PROTO as the
+ indicator, but you may need to drag the empty declaration out in
+ front of here, or change the ifdef to suit your own needs. */
+#ifndef PNGARG
+
+#ifdef __P
+#define PNGARG(arglist) __P(arglist)
+#else
+
+#ifdef _NO_PROTO
+#define PNGARG(arglist)
+#else
+#define PNGARG(arglist) arglist
+#endif /* _NO_PROTO */
+
+#endif /* __P(arglist) */
+
+#endif /* PNGARG */
+
+/* enough people need this for various reasons to include it here */
+#include <sys/types.h>
+/* need the time information for reading tIME chunks */
+#include <time.h>
+
+/* for FILE. If you are not using standard io, you don't need this */
+#include <stdio.h>
+
+/* include setjmp.h for error handling */
+#include <setjmp.h>
+
+/* other defines for things like memory and the like can go here. These
+ are the only files included in libpng, so if you need to change them,
+ change them here. They are only included if PNG_INTERNAL is defined. */
+#ifdef PNG_INTERNAL
+#include <stdlib.h>
+#include <ctype.h>
+#ifdef BSD
+#include <strings.h>
+#else
+#include <string.h>
+#endif
+#include <math.h>
+
+/* other defines specific to compilers can go here. Try to keep
+ them inside an appropriate ifdef/endif pair for portability */
+
+/* for some reason, Borland C++ defines memcmp, etc. in mem.h, not
+ stdlib.h like it should (I think). Or perhaps this is a C++
+ feature */
+#ifdef __TURBOC__
+#include <mem.h>
+#include "alloc.h"
+#endif
+
+#ifdef _MSC_VER
+#include <malloc.h>
+#endif
+
+/* this controls how fine the dithering gets. As this allocates
+ a largish chunk of memory (32K), those who are not as concerned
+ with dithering quality can decrease some or all of these */
+#define PNG_DITHER_RED_BITS 5
+#define PNG_DITHER_GREEN_BITS 5
+#define PNG_DITHER_BLUE_BITS 5
+
+/* this controls how fine the gamma correction becomes when you
+ are only interested in 8 bits anyway. Increasing this value
+ results in more memory being used, and more pow() functions
+ being called to fill in the gamma tables. Don't get this
+ value less then 8, and even that may not work (I haven't tested
+ it). */
+
+#define PNG_MAX_GAMMA_8 11
+
+#endif /* PNG_INTERNAL */
+
+/* some typedefs to get us started. These should be safe on most of the
+ common platforms. The typedefs should be at least as large
+ as the numbers suggest (a png_uint_32 must be at least 32 bits long),
+ but they don't have to be exactly that size. */
+
+typedef unsigned long png_uint_32;
+typedef long png_int_32;
+typedef unsigned short png_uint_16;
+typedef short png_int_16;
+typedef unsigned char png_byte;
+
+/* this is usually size_t. it is typedef'ed just in case you need it to
+ change (I'm not sure if you will or not, so I thought I'd be safe) */
+typedef size_t png_size_t;
+
+/* three color definitions. The order of the red, green, and blue, (and the
+ exact size) is not important, although the size of the fields need to
+ be png_byte or png_uint_16 (as defined below). While png_color_8 and
+ png_color_16 have more fields then they need, they are never used in
+ arrays, so the size isn't that important. I thought about using
+ unions, but it looked too clumsy, so I left it. If you're using C++,
+ you can union red, index, and gray, if you want. */
+typedef struct png_color_struct
+{
+ png_byte red;
+ png_byte green;
+ png_byte blue;
+} png_color;
+
+typedef struct png_color_16_struct
+{
+ png_byte index; /* used for palette files */
+ png_uint_16 red; /* for use in red green blue files */
+ png_uint_16 green;
+ png_uint_16 blue;
+ png_uint_16 gray; /* for use in grayscale files */
+} png_color_16;
+
+typedef struct png_color_8_struct
+{
+ png_byte red; /* for use in red green blue files */
+ png_byte green;
+ png_byte blue;
+ png_byte gray; /* for use in grayscale files */
+ png_byte alpha; /* for alpha channel files */
+} png_color_8;
+
+/* png_text holds the text in a png file, and whether they are compressed
+ or not. If compression is -1, the text is not compressed. */
+typedef struct png_text_struct
+{
+ int compression; /* compression value, -1 if uncompressed */
+ char *key; /* keyword */
+ char *text; /* comment */
+ png_uint_32 text_length; /* length of text field */
+} png_text;
+
+/* png_time is a way to hold the time in an machine independent way.
+ Two conversions are provided, both from time_t and struct tm. There
+ is no portable way to convert to either of these structures, as far
+ as I know. If you know of a portable way, send it to me. */
+typedef struct png_time_struct
+{
+ png_uint_16 year; /* full year, as in, 1995 */
+ png_byte month; /* month of year, 1 - 12 */
+ png_byte day; /* day of month, 1 - 31 */
+ png_byte hour; /* hour of day, 0 - 23 */
+ png_byte minute; /* minute of hour, 0 - 59 */
+ png_byte second; /* second of minute, 0 - 60 (for leap seconds) */
+} png_time;
+
+/* png_info is a structure that holds the information in a png file.
+ If you are reading the file, This structure will tell you what is
+ in the png file. If you are writing the file, fill in the information
+ you want to put into the png file, then call png_write_info().
+ The names chosen should be very close to the PNG
+ specification, so consult that document for information
+ about the meaning of each field. */
+typedef struct png_info_struct
+{
+ /* the following are necessary for every png file */
+ png_uint_32 width; /* with of file */
+ png_uint_32 height; /* height of file */
+ png_byte bit_depth; /* 1, 2, 4, 8, or 16 */
+ png_byte color_type; /* use the PNG_COLOR_TYPE_ defines */
+ png_byte compression_type; /* must be 0 */
+ png_byte filter_type; /* must be 0 */
+ png_byte interlace_type; /* 0 for non-interlaced, 1 for interlaced */
+ png_uint_32 valid; /* the PNG_INFO_ defines, OR'd together */
+ /* the following is informational only on read, and not used on
+ writes */
+ png_byte channels; /* number of channels of data per pixel */
+ png_byte pixel_depth; /* number of bits per pixel */
+ png_uint_32 rowbytes; /* bytes needed for untransformed row */
+ /* the rest are optional. If you are reading, check the valid
+ field to see if the information in these are valid. If you
+ are writing, set the valid field to those chunks you want
+ written, and initialize the appropriate fields below */
+ float gamma; /* gamma value of file, if gAMA chunk is valid */
+ png_color_8 sig_bit; /* significant bits */
+ float x_white; /* cHRM chunk values */
+ float y_white;
+ float x_red;
+ float y_red;
+ float x_green;
+ float y_green;
+ float x_blue;
+ float y_blue;
+ png_color *palette; /* palette of file */
+ png_uint_16 num_palette; /* number of values in palette */
+ png_byte *trans; /* tRNS values for palette image */
+ png_uint_16 num_trans; /* number of trans values */
+ png_color_16 trans_values; /* tRNS values for non-palette image */
+ png_color_16 background; /* background color of image */
+ png_uint_16 *hist; /* histogram of palette usage */
+ png_uint_32 x_pixels_per_unit; /* x resolution */
+ png_uint_32 y_pixels_per_unit; /* y resolution */
+ png_byte phys_unit_type; /* resolution type */
+ png_uint_32 x_offset; /* x offset on page */
+ png_uint_32 y_offset; /* y offset on page */
+ png_byte offset_unit_type; /* offset units type */
+ png_time mod_time; /* modification time */
+ int num_text; /* number of comments */
+ int max_text; /* size of text array */
+ png_text *text; /* array of comments */
+} png_info;
+
+#define PNG_RESOLUTION_UNKNOWN 0
+#define PNG_RESOLUTION_METER 1
+
+#define PNG_OFFSET_PIXEL 0
+#define PNG_OFFSET_MICROMETER 1
+
+/* these describe the color_type field in png_info */
+
+/* color type masks */
+#define PNG_COLOR_MASK_PALETTE 1
+#define PNG_COLOR_MASK_COLOR 2
+#define PNG_COLOR_MASK_ALPHA 4
+
+/* color types. Note that not all combinations are legal */
+#define PNG_COLOR_TYPE_PALETTE \
+ (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
+#define PNG_COLOR_TYPE_RGB (PNG_COLOR_MASK_COLOR)
+#define PNG_COLOR_TYPE_GRAY 0
+#define PNG_COLOR_TYPE_RGB_ALPHA \
+ (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
+#define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
+
+/* These determine if a chunks information is present in a read operation, or
+ if the chunk should be written in a write operation. */
+#define PNG_INFO_gAMA 0x0001
+#define PNG_INFO_sBIT 0x0002
+#define PNG_INFO_cHRM 0x0004
+#define PNG_INFO_PLTE 0x0008
+#define PNG_INFO_tRNS 0x0010
+#define PNG_INFO_bKGD 0x0020
+#define PNG_INFO_hIST 0x0040
+#define PNG_INFO_pHYs 0x0080
+#define PNG_INFO_oFFs 0x0100
+#define PNG_INFO_tIME 0x0200
+
+/* this is used for the transformation routines, as some of them
+ change these values for the row. It also should enable using
+ the routines for other uses. */
+typedef struct png_row_info_struct
+{
+ png_uint_32 width; /* width of row */
+ png_uint_32 rowbytes; /* number of bytes in row */
+ png_byte color_type; /* color type of row */
+ png_byte bit_depth; /* bit depth of row */
+ png_byte channels; /* number of channels (1, 2, 3, or 4) */
+ png_byte pixel_depth; /* bits per pixel (depth * channels) */
+} png_row_info;
+
+/* The structure that holds the information to read and write png files.
+ The only people who need to care about what is inside of this are the
+ people who will be modifying the library for their own special needs.
+ */
+typedef struct png_struct_def
+{
+ jmp_buf jmpbuf; /* used in png_error */
+ png_byte mode; /* used to determine where we are in the png file */
+ png_byte color_type; /* color type of file */
+ png_byte bit_depth; /* bit depth of file */
+ png_byte interlaced; /* interlace type of file */
+ png_byte compession; /* compression type of file */
+ png_byte filter; /* filter type */
+ png_byte channels; /* number of channels in file */
+ png_byte pixel_depth; /* number of bits per pixel */
+ png_byte usr_bit_depth; /* bit depth of users row */
+ png_byte usr_channels; /* channels at start of write */
+ png_byte gamma_shift; /* amount of shift for 16 bit gammas */
+ png_byte pass; /* current pass (0 - 6) */
+ png_byte row_init; /* 1 if png_read_start_row() has been called */
+ png_byte background_gamma_type;
+ png_byte background_expand;
+ png_byte zlib_finished;
+ png_byte user_palette;
+ png_uint_16 num_palette; /* number of entries in palette */
+ png_uint_16 num_trans; /* number of transparency values */
+ png_uint_32 transformations; /* which transformations to perform */
+ png_uint_32 crc; /* current crc value */
+ png_uint_32 width; /* width of file */
+ png_uint_32 height; /* height of file */
+ png_uint_32 num_rows; /* number of rows in current pass */
+ png_uint_32 rowbytes; /* size of row in bytes */
+ png_uint_32 usr_width; /* width of row at start of write */
+ png_uint_32 iwidth; /* interlaced width */
+ png_uint_32 irowbytes; /* interlaced rowbytes */
+ png_uint_32 row_number; /* current row in pass */
+ png_uint_32 idat_size; /* current idat size for read */
+ png_uint_32 zbuf_size; /* size of zbuf */
+ png_color *palette; /* files palette */
+ png_byte *palette_lookup; /* lookup table for dithering */
+ png_byte *gamma_table; /* gamma table for 8 bit depth files */
+ png_byte *gamma_from_1; /* converts from 1.0 to screen */
+ png_byte *gamma_to_1; /* converts from file to 1.0 */
+ png_byte *trans; /* transparency values for paletted files */
+ png_byte *dither_index; /* index translation for palette files */
+ png_uint_16 **gamma_16_table; /* gamma table for 16 bit depth files */
+ png_uint_16 **gamma_16_from_1; /* converts from 1.0 to screen */
+ png_uint_16 **gamma_16_to_1; /* converts from file to 1.0 */
+ png_uint_16 *hist; /* histogram */
+ png_byte *zbuf; /* buffer for zlib */
+ png_byte *row_buf; /* row buffer */
+ png_byte *prev_row; /* previous row */
+ png_byte *save_row; /* place to save row before filtering */
+ z_stream *zstream; /* pointer to decompression structure (below) */
+ float gamma; /* file gamma value */
+ float display_gamma; /* display gamma value */
+ float background_gamma;
+ png_color_8 shift; /* shift for significant bit tranformation */
+ png_color_8 sig_bit; /* significant bits in file */
+ png_color_16 trans_values; /* transparency values for non-paletted files */
+ png_color_16 background; /* background color, gamma corrected for screen */
+ png_color_16 background_1; /* background normalized to gamma 1.0 */
+ png_row_info row_info; /* used for transformation routines */
+ z_stream zstream_struct; /* decompression structure */
+ FILE *fp; /* used for png_read and png_write */
+} png_struct;
+
+
+/* Here are the function definitions most commonly used. This is not
+ the place to find out how to use libpng. See libpng.txt for the
+ full explanation, see example.c for the summary. This just provides
+ a simple one line of the use of each function. */
+
+/* check the first 1 - 8 bytes to see if it is a png file */
+extern int png_check_sig PNGARG((png_byte *sig, int num));
+
+/* initialize png structure for reading, and allocate any memory needed */
+extern void png_read_init PNGARG((png_struct *png_ptr));
+
+/* initialize png structure for writing, and allocate any memory needed */
+extern void png_write_init PNGARG((png_struct *png_ptr));
+
+/* initialize the info structure */
+extern void png_info_init PNGARG((png_info *info));
+
+/* Writes all the png information before the image. */
+extern void png_write_info PNGARG((png_struct *png_ptr, png_info *info));
+
+/* read the information before the actual image data. */
+extern void png_read_info PNGARG((png_struct *png_ptr, png_info *info));
+
+/* convert from a struct tm to png_time */
+extern void png_convert_from_struct_tm PNGARG((png_time *ptime,
+ struct tm *ttime));
+
+/* convert from time_t to png_time. Uses gmtime() */
+extern void png_convert_from_time_t PNGARG((png_time *ptime, time_t ttime));
+
+/* Expand the data to 24 bit RGB, or 8 bit Grayscale,
+ with alpha if necessary. */
+extern void png_set_expand PNGARG((png_struct *png_ptr));
+
+/* Use blue, green, red order for pixels. */
+extern void png_set_bgr PNGARG((png_struct *png_ptr));
+
+/* Add a filler byte to rgb images after the colors. */
+extern void png_set_rgbx PNGARG((png_struct *png_ptr));
+
+/* Add a filler byte to rgb images before the colors. */
+extern void png_set_xrgb PNGARG((png_struct *png_ptr));
+
+/* Swap bytes in 16 bit depth files. */
+extern void png_set_swap PNGARG((png_struct *png_ptr));
+
+/* Use 1 byte per pixel in 1, 2, or 4 bit depth files. */
+extern void png_set_packing PNGARG((png_struct *png_ptr));
+
+/* Converts files to legal bit depths. */
+extern void png_set_shift PNGARG((png_struct *png_ptr,
+ png_color_8 *true_bits));
+
+/* Have the code handle the interlacing. Returns the number of passes. */
+extern int png_set_interlace_handling PNGARG((png_struct *png_ptr));
+
+/* Invert monocrome files */
+extern void png_set_invert_mono PNGARG((png_struct *png_ptr));
+
+/* Handle alpha and tRNS by replacing with a background color. */
+#define PNG_BACKGROUND_GAMMA_SCREEN 0
+#define PNG_BACKGROUND_GAMMA_FILE 1
+#define PNG_BACKGROUND_GAMMA_UNIQUE 2
+#define PNG_BACKGROUND_GAMMA_UNKNOWN 3
+extern void png_set_background PNGARG((png_struct *png_ptr,
+ png_color_16 *background_color, int background_gamma_code,
+ int need_expand, float background_gamma));
+
+/* strip the second byte of information from a 16 bit depth file. */
+extern void png_set_strip_16 PNGARG((png_struct *png_ptr));
+
+/* convert a grayscale file into rgb. */
+extern void png_set_gray_to_rgb PNGARG((png_struct *png_ptr));
+
+/* Turn on dithering, and reduce the palette to the number of colors available. */
+extern void png_set_dither PNGARG((png_struct *png_ptr, png_color *palette,
+ int num_palette, int maximum_colors, png_uint_16 *histogram, int full_dither));
+
+/* Handle gamma correction. */
+extern void png_set_gamma PNGARG((png_struct *png_ptr, float screen_gamma,
+ float default_file_gamma));
+
+/* optional update palette with requested transformations */
+void png_start_read_image PNGARG((png_struct *png_ptr));
+
+/* read a one or more rows of image data.*/
+extern void png_read_rows PNGARG((png_struct *png_ptr,
+ png_byte **row,
+ png_byte **display_row, png_uint_32 num_rows));
+
+/* read a row of data.*/
+extern void png_read_row PNGARG((png_struct *png_ptr,
+ png_byte *row,
+ png_byte *display_row));
+
+/* read the whole image into memory at once. */
+extern void png_read_image PNGARG((png_struct *png_ptr,
+ png_byte **image));
+
+/* write a row of image data */
+extern void png_write_row PNGARG((png_struct *png_ptr,
+ png_byte *row));
+
+/* write a few rows of image data */
+extern void png_write_rows PNGARG((png_struct *png_ptr,
+ png_byte **row,
+ png_uint_32 num_rows));
+
+/* write the image data */
+extern void png_write_image PNGARG((png_struct *png_ptr, png_byte **image));
+
+/* writes the end of the png file. */
+extern void png_write_end PNGARG((png_struct *png_ptr, png_info *info));
+
+/* read the end of the png file. */
+extern void png_read_end PNGARG((png_struct *png_ptr, png_info *info));
+
+/* free all memory used by the read */
+extern void png_read_destroy PNGARG((png_struct *png_ptr, png_info *info,
+ png_info *end_info));
+
+/* free any memory used in png struct */
+extern void png_write_destroy PNGARG((png_struct *png_ptr));
+
+
+/* These next functions are stubs of typical c functions for input/output,
+ memory, and error handling. They are in the file pngstub.c, and are
+ set up to be easily modified for users that need to. See the file
+ pngstub.c for more information */
+
+/* Write the data to whatever output you are using. */
+extern void png_write_data PNGARG((png_struct *png_ptr, png_byte *data,
+ png_uint_32 length));
+
+/* Read data from whatever input you are using */
+extern void png_read_data PNGARG((png_struct *png_ptr, png_byte *data,
+ png_uint_32 length));
+
+/* Initialize the input/output for the png file. */
+extern void png_init_io PNGARG((png_struct *png_ptr, FILE *fp));
+
+/* Allocate memory in larger chunks. */
+extern void *png_large_malloc PNGARG((png_struct *png_ptr, png_uint_32 size));
+
+/* free's a pointer allocated by png_large_malloc() */
+extern void png_large_free PNGARG((png_struct *png_ptr, void *ptr));
+
+/* Allocate memory. */
+extern void *png_malloc PNGARG((png_struct *png_ptr, png_uint_32 size));
+
+/* Reallocate memory. */
+extern void *png_realloc PNGARG((png_struct *png_ptr, void *ptr,
+ png_uint_32 size));
+
+/* free's a pointer allocated by png_malloc() */
+extern void png_free PNGARG((png_struct *png_ptr, void *ptr));
+
+/* Fatal error in libpng - can't continue */
+extern void png_error PNGARG((png_struct *png_ptr, char *error));
+
+/* Non-fatal error in libpng. Can continue, but may have a problem. */
+extern void png_warning PNGARG((png_struct *png_ptr, char *message));
+
+
+/* These next functions are used internally in the code. If you use
+ them, make sure you read and understand the png spec. More information
+ about them can be found in the files where the functions are.
+ Feel free to move any of these outside the PNG_INTERNAL define if
+ you just need a few of them, but if you need access to more, you should
+ define PNG_INTERNAL inside your code, so everyone who includes png.h
+ won't get yet another definition the compiler has to deal with. */
+
+#ifdef PNG_INTERNAL
+
+/* various modes of operation. Note that after an init, mode is set to
+ zero automatically */
+#define PNG_BEFORE_IHDR 0
+#define PNG_HAVE_IHDR 1
+#define PNG_HAVE_PLTE 2
+#define PNG_HAVE_IDAT 3
+#define PNG_AT_LAST_IDAT 4
+#define PNG_AFTER_IDAT 5
+#define PNG_AFTER_IEND 6
+
+/* defines for the transformations the png library does on the image data */
+#define PNG_BGR 0x0001
+#define PNG_INTERLACE 0x0002
+#define PNG_PACK 0x0004
+#define PNG_SHIFT 0x0008
+#define PNG_SWAP_BYTES 0x0010
+#define PNG_INVERT_MONO 0x0020
+#define PNG_DITHER 0x0040
+#define PNG_BACKGROUND 0x0080
+#define PNG_XRGB 0x0100
+#define PNG_16_TO_8 0x0200
+#define PNG_RGBA 0x0400
+#define PNG_EXPAND 0x0800
+#define PNG_GAMMA 0x1000
+#define PNG_GRAY_TO_RGB 0x2000
+
+/* save typing and make code easier to understand */
+#define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
+ abs((int)((c1).green) - (int)((c2).green)) + \
+ abs((int)((c1).blue) - (int)((c2).blue)))
+
+/* variables defined in png.c - only it needs to define PNG_NO_EXTERN */
+#ifndef PNG_NO_EXTERN
+/* place to hold the signiture string for a png file. */
+extern png_byte png_sig[];
+
+/* constant strings for known chunk types. If you need to add a chunk,
+ add a string holding the name here. See png.c for more details */
+extern png_byte png_IHDR[];
+extern png_byte png_IDAT[];
+extern png_byte png_IEND[];
+extern png_byte png_PLTE[];
+extern png_byte png_gAMA[];
+extern png_byte png_sBIT[];
+extern png_byte png_cHRM[];
+extern png_byte png_tRNS[];
+extern png_byte png_bKGD[];
+extern png_byte png_hIST[];
+extern png_byte png_tEXt[];
+extern png_byte png_zTXt[];
+extern png_byte png_pHYs[];
+extern png_byte png_oFFs[];
+extern png_byte png_tIME[];
+/* Structures to facilitate easy interlacing. See png.c for more details */
+extern int png_pass_start[];
+extern int png_pass_inc[];
+extern int png_pass_ystart[];
+extern int png_pass_yinc[];
+/* these are not currently used. If you need them, see png.c
+extern int png_pass_width[];
+extern int png_pass_height[];
+*/
+extern int png_pass_mask[];
+extern int png_pass_dsp_mask[];
+
+#endif /* PNG_NO_EXTERN */
+
+/* Function to allocate memory for zlib. */
+extern voidp png_zalloc PNGARG((voidp png_ptr, uInt items, uInt size));
+
+/* function to free memory for zlib */
+extern void png_zfree PNGARG((voidp png_ptr, voidp ptr));
+
+/* reset the crc variable */
+extern void png_reset_crc PNGARG((png_struct *png_ptr));
+
+/* calculate the crc over a section of data. Note that while we
+ are passing in a 32 bit value for length, on 16 bit machines, you
+ would need to use huge pointers to access all that data. See the
+ code in png.c for more information. */
+extern void png_calculate_crc PNGARG((png_struct *png_ptr, png_byte *ptr,
+ png_uint_32 length));
+
+/* place a 32 bit number into a buffer in png byte order. We work
+ with unsigned numbers for convenience, you may have to cast
+ signed numbers (if you use any, most png data is unsigned). */
+extern void png_save_uint_32 PNGARG((png_byte *buf, png_uint_32 i));
+
+/* place a 16 bit number into a buffer in png byte order */
+extern void png_save_uint_16 PNGARG((png_byte *buf, png_uint_16 i));
+
+/* write a 32 bit number */
+extern void png_write_uint_32 PNGARG((png_struct *png_ptr, png_uint_32 i));
+
+/* write a 16 bit number */
+extern void png_write_uint_16 PNGARG((png_struct *png_ptr, png_uint_16 i));
+
+/* Write a png chunk. */
+extern void png_write_chunk PNGARG((png_struct *png_ptr, png_byte *type,
+ png_byte *data, png_uint_32 length));
+
+/* Write the start of a png chunk. */
+extern void png_write_chunk_start PNGARG((png_struct *png_ptr, png_byte *type,
+ png_uint_32 total_length));
+
+/* write the data of a png chunk started with png_write_chunk_start(). */
+extern void png_write_chunk_data PNGARG((png_struct *png_ptr, png_byte *data,
+ png_uint_32 length));
+
+/* finish a chunk started with png_write_chunk_start() */
+extern void png_write_chunk_end PNGARG((png_struct *png_ptr));
+
+/* simple function to write the signiture */
+extern void png_write_sig PNGARG((png_struct *png_ptr));
+
+/* write various chunks */
+
+/* Write the IHDR chunk, and update the png_struct with the necessary
+ information. */
+extern void png_write_IHDR PNGARG((png_struct *png_ptr, png_uint_32 width,
+ png_uint_32 height,
+ int bit_depth, int color_type, int compression_type, int filter_type,
+ int interlace_type));
+
+extern void png_write_PLTE PNGARG((png_struct *png_ptr, png_color *palette,
+ int number));
+
+extern void png_write_IDAT PNGARG((png_struct *png_ptr, png_byte *data,
+ png_uint_32 length));
+
+extern void png_write_IEND PNGARG((png_struct *png_ptr));
+
+extern void png_write_gAMA PNGARG((png_struct *png_ptr, float gamma));
+
+extern void png_write_sBIT PNGARG((png_struct *png_ptr, png_color_8 *sbit,
+ int color_type));
+
+extern void png_write_cHRM PNGARG((png_struct *png_ptr,
+ float white_x, float white_y,
+ float red_x, float red_y, float green_x, float green_y,
+ float blue_x, float blue_y));
+
+extern void png_write_tRNS PNGARG((png_struct *png_ptr, png_byte *trans,
+ png_color_16 *values, int number, int color_type));
+
+extern void png_write_bKGD PNGARG((png_struct *png_ptr, png_color_16 *values,
+ int color_type));
+
+extern void png_write_hIST PNGARG((png_struct *png_ptr, png_uint_16 *hist,
+ int number));
+
+extern void png_write_tEXt PNGARG((png_struct *png_ptr, char *key,
+ char *text, png_uint_32 text_len));
+
+extern void png_write_zTXt PNGARG((png_struct *png_ptr, char *key,
+ char *text, png_uint_32 text_len, int compression));
+
+extern void png_write_pHYs PNGARG((png_struct *png_ptr,
+ png_uint_32 x_pixels_per_unit,
+ png_uint_32 y_pixels_per_unit,
+ int unit_type));
+
+extern void png_write_oFFs PNGARG((png_struct *png_ptr,
+ png_uint_32 x_offset,
+ png_uint_32 y_offset,
+ int unit_type));
+
+extern void png_write_tIME PNGARG((png_struct *png_ptr, png_time *mod_time));
+
+/* Internal use only. Called when finished processing a row of data */
+extern void png_write_finish_row PNGARG((png_struct *png_ptr));
+
+/* Internal use only. Called before first row of data */
+extern void png_write_start_row PNGARG((png_struct *png_ptr));
+
+/* callbacks for png chunks */
+extern void png_read_IHDR PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 width, png_uint_32 height, int bit_depth,
+ int color_type, int compression_type, int filter_type,
+ int interlace_type));
+extern void png_read_PLTE PNGARG((png_struct *png_ptr, png_info *info,
+ png_color *palette, int num));
+extern void png_read_gAMA PNGARG((png_struct *png_ptr, png_info *info,
+ float gamma));
+extern void png_read_sBIT PNGARG((png_struct *png_ptr, png_info *info,
+ png_color_8 *sig_bit));
+extern void png_read_cHRM PNGARG((png_struct *png_ptr, png_info *info,
+ float white_x, float white_y, float red_x, float red_y,
+ float green_x, float green_y, float blue_x, float blue_y));
+extern void png_read_tRNS PNGARG((png_struct *png_ptr, png_info *info,
+ png_byte *trans, int num_trans, png_color_16 *trans_values));
+extern void png_read_bKGD PNGARG((png_struct *png_ptr, png_info *info,
+ png_color_16 *background));
+extern void png_read_hIST PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_16 *hist));
+extern void png_read_pHYs PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 res_x, png_uint_32 res_y, int unit_type));
+extern void png_read_oFFs PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 offset_x, png_uint_32 offset_y, int unit_type));
+extern void png_read_tIME PNGARG((png_struct *png_ptr, png_info *info,
+ png_time *mod_time));
+extern void png_read_tEXt PNGARG((png_struct *png_ptr, png_info *info,
+ char *key, char *text, png_uint_32 text_len));
+extern void png_read_zTXt PNGARG((png_struct *png_ptr, png_info *info,
+ char *key, char *text, png_uint_32 text_len, int compression));
+
+void
+png_build_gamma_table PNGARG((png_struct *png_ptr));
+
+/* combine a row of data, dealing with alpha, etc. if requested */
+extern void png_combine_row PNGARG((png_struct *png_ptr, png_byte *row,
+ int mask));
+/* expand an interlaced row */
+extern void png_do_read_interlace PNGARG((png_row_info *row_info,
+ png_byte *row, int pass));
+/* grab pixels out of a row for an interlaced pass */
+extern void png_do_write_interlace PNGARG((png_row_info *row_info,
+ png_byte *row, int pass));
+
+/* unfilter a row */
+extern void png_read_filter_row PNGARG((png_row_info *row_info,
+ png_byte *row, png_byte *prev_row, int filter));
+/* filter a row, and place the correct filter byte in the row */
+extern void png_write_filter_row PNGARG((png_row_info *row_info,
+ png_byte *row, png_byte *prev_row));
+/* finish a row while reading, dealing with interlacing passes, etc. */
+extern void png_read_finish_row PNGARG((png_struct *png_ptr));
+/* initialize the row buffers, etc. */
+extern void png_read_start_row PNGARG((png_struct *png_ptr));
+
+/* these are the functions that do the transformations */
+extern void png_do_read_rgbx PNGARG((png_row_info *row_info,
+ png_byte *row));
+extern void png_do_write_rgbx PNGARG((png_row_info *row_info,
+ png_byte *row));
+extern void png_do_read_xrgb PNGARG((png_row_info *row_info,
+ png_byte *row));
+extern void png_do_write_xrgb PNGARG((png_row_info *row_info,
+ png_byte *row));
+extern void png_do_swap PNGARG((png_row_info *row_info, png_byte *row));
+extern void png_do_unpack PNGARG((png_row_info *row_info, png_byte *row));
+extern void png_do_unshift PNGARG((png_row_info *row_info, png_byte *row,
+ png_color_8 *sig_bits));
+extern void png_do_invert PNGARG((png_row_info *row_info, png_byte *row));
+extern void png_do_gray_to_rgb PNGARG((png_row_info *row_info,
+ png_byte *row));
+extern void png_do_chop PNGARG((png_row_info *row_info, png_byte *row));
+extern void png_do_dither PNGARG((png_row_info *row_info,
+ png_byte *row, png_byte *palette_lookup, png_byte *dither_lookup));
+extern void png_do_bgr PNGARG((png_row_info *row_info, png_byte *row));
+extern void png_do_pack PNGARG((png_row_info *row_info,
+ png_byte *row, png_byte bit_depth));
+extern void png_do_shift PNGARG((png_row_info *row_info, png_byte *row,
+ png_color_8 *bit_depth));
+extern void png_do_background PNGARG((png_row_info *row_info, png_byte *row,
+ png_color_16 *trans_values, png_color_16 *background,
+ png_color_16 *background_1,
+ png_byte *gamma_table, png_byte *gamma_from_1, png_byte *gamma_to_1,
+ png_uint_16 **gamma_16, png_uint_16 **gamma_16_from_1,
+ png_uint_16 **gamma_16_to_1, int gamma_shift));
+extern void png_do_gamma PNGARG((png_row_info *row_info, png_byte *row,
+ png_byte *gamma_table, png_uint_16 **gamma_16_table,
+ int gamma_shift));
+extern void png_do_expand_palette PNGARG((png_row_info *row_info,
+ png_byte *row, png_color *palette, png_byte *trans, int num_trans));
+extern void png_do_expand PNGARG((png_row_info *row_info,
+ png_byte *row, png_color_16 *trans_value));
+
+/* unpack 16 and 32 bit values from a string */
+extern png_uint_32 png_get_uint_32 PNGARG((png_byte *buf));
+extern png_uint_16 png_get_uint_16 PNGARG((png_byte *buf));
+
+/* read bytes into buf, and update png_ptr->crc */
+extern void png_crc_read PNGARG((png_struct *png_ptr, png_byte *buf,
+ png_uint_32 length));
+/* skip length bytes, and update png_ptr->crc */
+extern void png_crc_skip PNGARG((png_struct *png_ptr, png_uint_32 length));
+
+/* the following decodes the appropriate chunks, and does error correction,
+ then calls the appropriate callback for the chunk if it is valid */
+
+/* decode the IHDR chunk */
+extern void png_handle_IHDR PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_PLTE PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_gAMA PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_sBIT PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_cHRM PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_tRNS PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_bKGD PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_hIST PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_pHYs PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_oFFs PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_tIME PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_tEXt PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+extern void png_handle_zTXt PNGARG((png_struct *png_ptr, png_info *info,
+ png_uint_32 length));
+
+/* handle the transformations for reading and writing */
+extern void png_do_read_transformations PNGARG((png_struct *png_ptr));
+extern void png_do_write_transformations PNGARG((png_struct *png_ptr));
+
+extern void png_init_read_transformations PNGARG((png_struct *png_ptr));
+
+
+#endif /* PNG_INTERNAL */
+
+/* do not put anything past this line */
+#endif /* _PNG_H */
