|  | 
 | /* png.h - header file for PNG reference library | 
 |  * | 
 |  * libpng version 1.6.0beta07 - January 24, 2012 | 
 |  * Copyright (c) 1998-2012 Glenn Randers-Pehrson | 
 |  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) | 
 |  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) | 
 |  * | 
 |  * This code is released under the libpng license (See LICENSE, below) | 
 |  * | 
 |  * Authors and maintainers: | 
 |  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat | 
 |  *   libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger | 
 |  *   libpng versions 0.97, January 1998, through 1.6.0beta07 - January 24, 2012: Glenn | 
 |  *   See also "Contributing Authors", below. | 
 |  * | 
 |  * Note about libpng version numbers: | 
 |  * | 
 |  *   Due to various miscommunications, unforeseen code incompatibilities | 
 |  *   and occasional factors outside the authors' control, version numbering | 
 |  *   on the library has not always been consistent and straightforward. | 
 |  *   The following table summarizes matters since version 0.89c, which was | 
 |  *   the first widely used release: | 
 |  * | 
 |  *    source                 png.h  png.h  shared-lib | 
 |  *    version                string   int  version | 
 |  *    -------                ------ -----  ---------- | 
 |  *    0.89c "1.0 beta 3"     0.89      89  1.0.89 | 
 |  *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90] | 
 |  *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95] | 
 |  *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96] | 
 |  *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97] | 
 |  *    0.97c                  0.97      97  2.0.97 | 
 |  *    0.98                   0.98      98  2.0.98 | 
 |  *    0.99                   0.99      98  2.0.99 | 
 |  *    0.99a-m                0.99      99  2.0.99 | 
 |  *    1.00                   1.00     100  2.1.0 [100 should be 10000] | 
 |  *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000] | 
 |  *    1.0.1       png.h string is   10001  2.1.0 | 
 |  *    1.0.1a-e    identical to the  10002  from here on, the shared library | 
 |  *    1.0.2       source version)   10002  is 2.V where V is the source code | 
 |  *    1.0.2a-b                      10003  version, except as noted. | 
 |  *    1.0.3                         10003 | 
 |  *    1.0.3a-d                      10004 | 
 |  *    1.0.4                         10004 | 
 |  *    1.0.4a-f                      10005 | 
 |  *    1.0.5 (+ 2 patches)           10005 | 
 |  *    1.0.5a-d                      10006 | 
 |  *    1.0.5e-r                      10100 (not source compatible) | 
 |  *    1.0.5s-v                      10006 (not binary compatible) | 
 |  *    1.0.6 (+ 3 patches)           10006 (still binary incompatible) | 
 |  *    1.0.6d-f                      10007 (still binary incompatible) | 
 |  *    1.0.6g                        10007 | 
 |  *    1.0.6h                        10007  10.6h (testing xy.z so-numbering) | 
 |  *    1.0.6i                        10007  10.6i | 
 |  *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0) | 
 |  *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible) | 
 |  *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible) | 
 |  *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible) | 
 |  *    1.0.7                    1    10007  (still compatible) | 
 |  *    1.0.8beta1-4             1    10008  2.1.0.8beta1-4 | 
 |  *    1.0.8rc1                 1    10008  2.1.0.8rc1 | 
 |  *    1.0.8                    1    10008  2.1.0.8 | 
 |  *    1.0.9beta1-6             1    10009  2.1.0.9beta1-6 | 
 |  *    1.0.9rc1                 1    10009  2.1.0.9rc1 | 
 |  *    1.0.9beta7-10            1    10009  2.1.0.9beta7-10 | 
 |  *    1.0.9rc2                 1    10009  2.1.0.9rc2 | 
 |  *    1.0.9                    1    10009  2.1.0.9 | 
 |  *    1.0.10beta1              1    10010  2.1.0.10beta1 | 
 |  *    1.0.10rc1                1    10010  2.1.0.10rc1 | 
 |  *    1.0.10                   1    10010  2.1.0.10 | 
 |  *    1.0.11beta1-3            1    10011  2.1.0.11beta1-3 | 
 |  *    1.0.11rc1                1    10011  2.1.0.11rc1 | 
 |  *    1.0.11                   1    10011  2.1.0.11 | 
 |  *    1.0.12beta1-2            2    10012  2.1.0.12beta1-2 | 
 |  *    1.0.12rc1                2    10012  2.1.0.12rc1 | 
 |  *    1.0.12                   2    10012  2.1.0.12 | 
 |  *    1.1.0a-f                 -    10100  2.1.1.0a-f (branch abandoned) | 
 |  *    1.2.0beta1-2             2    10200  2.1.2.0beta1-2 | 
 |  *    1.2.0beta3-5             3    10200  3.1.2.0beta3-5 | 
 |  *    1.2.0rc1                 3    10200  3.1.2.0rc1 | 
 |  *    1.2.0                    3    10200  3.1.2.0 | 
 |  *    1.2.1beta1-4             3    10201  3.1.2.1beta1-4 | 
 |  *    1.2.1rc1-2               3    10201  3.1.2.1rc1-2 | 
 |  *    1.2.1                    3    10201  3.1.2.1 | 
 |  *    1.2.2beta1-6            12    10202  12.so.0.1.2.2beta1-6 | 
 |  *    1.0.13beta1             10    10013  10.so.0.1.0.13beta1 | 
 |  *    1.0.13rc1               10    10013  10.so.0.1.0.13rc1 | 
 |  *    1.2.2rc1                12    10202  12.so.0.1.2.2rc1 | 
 |  *    1.0.13                  10    10013  10.so.0.1.0.13 | 
 |  *    1.2.2                   12    10202  12.so.0.1.2.2 | 
 |  *    1.2.3rc1-6              12    10203  12.so.0.1.2.3rc1-6 | 
 |  *    1.2.3                   12    10203  12.so.0.1.2.3 | 
 |  *    1.2.4beta1-3            13    10204  12.so.0.1.2.4beta1-3 | 
 |  *    1.0.14rc1               13    10014  10.so.0.1.0.14rc1 | 
 |  *    1.2.4rc1                13    10204  12.so.0.1.2.4rc1 | 
 |  *    1.0.14                  10    10014  10.so.0.1.0.14 | 
 |  *    1.2.4                   13    10204  12.so.0.1.2.4 | 
 |  *    1.2.5beta1-2            13    10205  12.so.0.1.2.5beta1-2 | 
 |  *    1.0.15rc1-3             10    10015  10.so.0.1.0.15rc1-3 | 
 |  *    1.2.5rc1-3              13    10205  12.so.0.1.2.5rc1-3 | 
 |  *    1.0.15                  10    10015  10.so.0.1.0.15 | 
 |  *    1.2.5                   13    10205  12.so.0.1.2.5 | 
 |  *    1.2.6beta1-4            13    10206  12.so.0.1.2.6beta1-4 | 
 |  *    1.0.16                  10    10016  10.so.0.1.0.16 | 
 |  *    1.2.6                   13    10206  12.so.0.1.2.6 | 
 |  *    1.2.7beta1-2            13    10207  12.so.0.1.2.7beta1-2 | 
 |  *    1.0.17rc1               10    10017  12.so.0.1.0.17rc1 | 
 |  *    1.2.7rc1                13    10207  12.so.0.1.2.7rc1 | 
 |  *    1.0.17                  10    10017  12.so.0.1.0.17 | 
 |  *    1.2.7                   13    10207  12.so.0.1.2.7 | 
 |  *    1.2.8beta1-5            13    10208  12.so.0.1.2.8beta1-5 | 
 |  *    1.0.18rc1-5             10    10018  12.so.0.1.0.18rc1-5 | 
 |  *    1.2.8rc1-5              13    10208  12.so.0.1.2.8rc1-5 | 
 |  *    1.0.18                  10    10018  12.so.0.1.0.18 | 
 |  *    1.2.8                   13    10208  12.so.0.1.2.8 | 
 |  *    1.2.9beta1-3            13    10209  12.so.0.1.2.9beta1-3 | 
 |  *    1.2.9beta4-11           13    10209  12.so.0.9[.0] | 
 |  *    1.2.9rc1                13    10209  12.so.0.9[.0] | 
 |  *    1.2.9                   13    10209  12.so.0.9[.0] | 
 |  *    1.2.10beta1-7           13    10210  12.so.0.10[.0] | 
 |  *    1.2.10rc1-2             13    10210  12.so.0.10[.0] | 
 |  *    1.2.10                  13    10210  12.so.0.10[.0] | 
 |  *    1.4.0beta1-5            14    10400  14.so.0.0[.0] | 
 |  *    1.2.11beta1-4           13    10211  12.so.0.11[.0] | 
 |  *    1.4.0beta7-8            14    10400  14.so.0.0[.0] | 
 |  *    1.2.11                  13    10211  12.so.0.11[.0] | 
 |  *    1.2.12                  13    10212  12.so.0.12[.0] | 
 |  *    1.4.0beta9-14           14    10400  14.so.0.0[.0] | 
 |  *    1.2.13                  13    10213  12.so.0.13[.0] | 
 |  *    1.4.0beta15-36          14    10400  14.so.0.0[.0] | 
 |  *    1.4.0beta37-87          14    10400  14.so.14.0[.0] | 
 |  *    1.4.0rc01               14    10400  14.so.14.0[.0] | 
 |  *    1.4.0beta88-109         14    10400  14.so.14.0[.0] | 
 |  *    1.4.0rc02-08            14    10400  14.so.14.0[.0] | 
 |  *    1.4.0                   14    10400  14.so.14.0[.0] | 
 |  *    1.4.1beta01-03          14    10401  14.so.14.1[.0] | 
 |  *    1.4.1rc01               14    10401  14.so.14.1[.0] | 
 |  *    1.4.1beta04-12          14    10401  14.so.14.1[.0] | 
 |  *    1.4.1                   14    10401  14.so.14.1[.0] | 
 |  *    1.4.2                   14    10402  14.so.14.2[.0] | 
 |  *    1.4.3                   14    10403  14.so.14.3[.0] | 
 |  *    1.4.4                   14    10404  14.so.14.4[.0] | 
 |  *    1.5.0beta01-58          15    10500  15.so.15.0[.0] | 
 |  *    1.5.0rc01-07            15    10500  15.so.15.0[.0] | 
 |  *    1.5.0                   15    10500  15.so.15.0[.0] | 
 |  *    1.5.1beta01-11          15    10501  15.so.15.1[.0] | 
 |  *    1.5.1rc01-02            15    10501  15.so.15.1[.0] | 
 |  *    1.5.1                   15    10501  15.so.15.1[.0] | 
 |  *    1.5.2beta01-03          15    10502  15.so.15.2[.0] | 
 |  *    1.5.2rc01-03            15    10502  15.so.15.2[.0] | 
 |  *    1.5.2                   15    10502  15.so.15.2[.0] | 
 |  *    1.5.3beta01-10          15    10503  15.so.15.3[.0] | 
 |  *    1.5.3rc01-02            15    10503  15.so.15.3[.0] | 
 |  *    1.5.3beta11             15    10503  15.so.15.3[.0] | 
 |  *    1.5.3 [omitted] | 
 |  *    1.5.4beta01-08          15    10504  15.so.15.4[.0] | 
 |  *    1.5.4rc01               15    10504  15.so.15.4[.0] | 
 |  *    1.5.4                   15    10504  15.so.15.4[.0] | 
 |  *    1.5.5beta01-08          15    10505  15.so.15.5[.0] | 
 |  *    1.5.5rc01               15    10505  15.so.15.5[.0] | 
 |  *    1.5.5                   15    10505  15.so.15.5[.0] | 
 |  *    1.5.6beta01-07          15    10506  15.so.15.6[.0] | 
 |  *    1.5.6rc01-03            15    10506  15.so.15.6[.0] | 
 |  *    1.5.6                   15    10506  15.so.15.6[.0] | 
 |  *    1.5.7beta01-05          15    10507  15.so.15.7[.0] | 
 |  *    1.5.7rc01-03            15    10507  15.so.15.7[.0] | 
 |  *    1.5.7                   15    10507  15.so.15.7[.0] | 
 |  *    1.6.0beta01-07          16    10600  16.so.16.0[.0] | 
 |  * | 
 |  *   Henceforth the source version will match the shared-library major | 
 |  *   and minor numbers; the shared-library major version number will be | 
 |  *   used for changes in backward compatibility, as it is intended.  The | 
 |  *   PNG_LIBPNG_VER macro, which is not used within libpng but is available | 
 |  *   for applications, is an unsigned integer of the form xyyzz corresponding | 
 |  *   to the source version x.y.z (leading zeros in y and z).  Beta versions | 
 |  *   were given the previous public release number plus a letter, until | 
 |  *   version 1.0.6j; from then on they were given the upcoming public | 
 |  *   release number plus "betaNN" or "rcN". | 
 |  * | 
 |  *   Binary incompatibility exists only when applications make direct access | 
 |  *   to the info_ptr or png_ptr members through png.h, and the compiled | 
 |  *   application is loaded with a different version of the library. | 
 |  * | 
 |  *   DLLNUM will change each time there are forward or backward changes | 
 |  *   in binary compatibility (e.g., when a new feature is added). | 
 |  * | 
 |  * See libpng-manual.txt or libpng.3 for more information.  The PNG | 
 |  * specification is available as a W3C Recommendation and as an ISO | 
 |  * Specification, <http://www.w3.org/TR/2003/REC-PNG-20031110/ | 
 |  */ | 
 |  | 
 | /* | 
 |  * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE: | 
 |  * | 
 |  * If you modify libpng you may insert additional notices immediately following | 
 |  * this sentence. | 
 |  * | 
 |  * This code is released under the libpng license. | 
 |  * | 
 |  * libpng versions 1.2.6, August 15, 2004, through 1.6.0beta07, January 24, 2012, are | 
 |  * Copyright (c) 2004, 2006-2012 Glenn Randers-Pehrson, and are | 
 |  * distributed according to the same disclaimer and license as libpng-1.2.5 | 
 |  * with the following individual added to the list of Contributing Authors: | 
 |  * | 
 |  *    Cosmin Truta | 
 |  * | 
 |  * libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are | 
 |  * Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are | 
 |  * distributed according to the same disclaimer and license as libpng-1.0.6 | 
 |  * with the following individuals added to the list of Contributing Authors: | 
 |  * | 
 |  *    Simon-Pierre Cadieux | 
 |  *    Eric S. Raymond | 
 |  *    Gilles Vollant | 
 |  * | 
 |  * and with the following additions to the disclaimer: | 
 |  * | 
 |  *    There is no warranty against interference with your enjoyment of the | 
 |  *    library or against infringement.  There is no warranty that our | 
 |  *    efforts or the library will fulfill any of your particular purposes | 
 |  *    or needs.  This library is provided with all faults, and the entire | 
 |  *    risk of satisfactory quality, performance, accuracy, and effort is with | 
 |  *    the user. | 
 |  * | 
 |  * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are | 
 |  * Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson, and are | 
 |  * distributed according to the same disclaimer and license as libpng-0.96, | 
 |  * with the following individuals added to the list of Contributing Authors: | 
 |  * | 
 |  *    Tom Lane | 
 |  *    Glenn Randers-Pehrson | 
 |  *    Willem van Schaik | 
 |  * | 
 |  * libpng versions 0.89, June 1996, through 0.96, May 1997, are | 
 |  * Copyright (c) 1996, 1997 Andreas Dilger | 
 |  * Distributed according to the same disclaimer and license as libpng-0.88, | 
 |  * with the following individuals added to the list of Contributing Authors: | 
 |  * | 
 |  *    John Bowler | 
 |  *    Kevin Bracey | 
 |  *    Sam Bushell | 
 |  *    Magnus Holmgren | 
 |  *    Greg Roelofs | 
 |  *    Tom Tanner | 
 |  * | 
 |  * libpng versions 0.5, May 1995, through 0.88, January 1996, are | 
 |  * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc. | 
 |  * | 
 |  * For the purposes of this copyright and license, "Contributing Authors" | 
 |  * is defined as the following set of individuals: | 
 |  * | 
 |  *    Andreas Dilger | 
 |  *    Dave Martindale | 
 |  *    Guy Eric Schalnat | 
 |  *    Paul Schmidt | 
 |  *    Tim Wegner | 
 |  * | 
 |  * 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 direct, indirect, incidental, special, exemplary, | 
 |  * or consequential damages, which may result from the use of the PNG | 
 |  * Reference Library, even if advised of the possibility of such damage. | 
 |  * | 
 |  * 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. | 
 |  */ | 
 |  | 
 | /* | 
 |  * A "png_get_copyright" function is available, for convenient use in "about" | 
 |  * boxes and the like: | 
 |  * | 
 |  *     printf("%s", png_get_copyright(NULL)); | 
 |  * | 
 |  * Also, the PNG logo (in PNG format, of course) is supplied in the | 
 |  * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31). | 
 |  */ | 
 |  | 
 | /* | 
 |  * Libpng is OSI Certified Open Source Software.  OSI Certified is a | 
 |  * certification mark of the Open Source Initiative. | 
 |  */ | 
 |  | 
 | /* | 
 |  * The contributing authors would like to thank all those who helped | 
 |  * with testing, bug fixes, and patience.  This wouldn't have been | 
 |  * possible without all of you. | 
 |  * | 
 |  * Thanks to Frank J. T. Wojcik for helping with the documentation. | 
 |  */ | 
 |  | 
 | /* | 
 |  * Y2K compliance in libpng: | 
 |  * ========================= | 
 |  * | 
 |  *    January 24, 2012 | 
 |  * | 
 |  *    Since the PNG Development group is an ad-hoc body, we can't make | 
 |  *    an official declaration. | 
 |  * | 
 |  *    This is your unofficial assurance that libpng from version 0.71 and | 
 |  *    upward through 1.6.0beta07 are Y2K compliant.  It is my belief that | 
 |  *    earlier versions were also Y2K compliant. | 
 |  * | 
 |  *    Libpng only has two year fields.  One is a 2-byte unsigned integer | 
 |  *    that will hold years up to 65535.  The other holds the date in text | 
 |  *    format, and will hold years up to 9999. | 
 |  * | 
 |  *    The integer is | 
 |  *        "png_uint_16 year" in png_time_struct. | 
 |  * | 
 |  *    The string is | 
 |  *        "png_char time_buffer" in png_struct | 
 |  * | 
 |  *    There are seven time-related functions: | 
 |  *        png.c: png_convert_to_rfc_1123() in png.c | 
 |  *          (formerly png_convert_to_rfc_1152() in error) | 
 |  *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c | 
 |  *        png_convert_from_time_t() in pngwrite.c | 
 |  *        png_get_tIME() in pngget.c | 
 |  *        png_handle_tIME() in pngrutil.c, called in pngread.c | 
 |  *        png_set_tIME() in pngset.c | 
 |  *        png_write_tIME() in pngwutil.c, called in pngwrite.c | 
 |  * | 
 |  *    All handle dates properly in a Y2K environment.  The | 
 |  *    png_convert_from_time_t() function calls gmtime() to convert from system | 
 |  *    clock time, which returns (year - 1900), which we properly convert to | 
 |  *    the full 4-digit year.  There is a possibility that applications using | 
 |  *    libpng are not passing 4-digit years into the png_convert_to_rfc_1123() | 
 |  *    function, or that they are incorrectly passing only a 2-digit year | 
 |  *    instead of "year - 1900" into the png_convert_from_struct_tm() function, | 
 |  *    but this is not under our control.  The libpng documentation has always | 
 |  *    stated that it works with 4-digit years, and the APIs have been | 
 |  *    documented as such. | 
 |  * | 
 |  *    The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned | 
 |  *    integer to hold the year, and can hold years as large as 65535. | 
 |  * | 
 |  *    zlib, upon which libpng depends, is also Y2K compliant.  It contains | 
 |  *    no date-related code. | 
 |  * | 
 |  *       Glenn Randers-Pehrson | 
 |  *       libpng maintainer | 
 |  *       PNG Development Group | 
 |  */ | 
 |  | 
 | #ifndef PNG_H | 
 | #define PNG_H | 
 |  | 
 | /* This is not the place to learn how to use libpng. The file libpng-manual.txt | 
 |  * describes how to use libpng, and the file example.c summarizes it | 
 |  * with some code on which to build.  This file is useful for looking | 
 |  * at the actual function definitions and structure components. | 
 |  * | 
 |  * If you just need to read a PNG file and don't want to read the documentation | 
 |  * skip to the end of this file and read the section entitled 'simplified API'. | 
 |  */ | 
 |  | 
 | /* Version information for png.h - this should match the version in png.c */ | 
 | #define PNG_LIBPNG_VER_STRING "1.6.0beta07" | 
 | #define PNG_HEADER_VERSION_STRING \ | 
 |      " libpng version 1.6.0beta07 - January 24, 2012\n" | 
 |  | 
 | #define PNG_LIBPNG_VER_SONUM   16 | 
 | #define PNG_LIBPNG_VER_DLLNUM  16 | 
 |  | 
 | /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */ | 
 | #define PNG_LIBPNG_VER_MAJOR   1 | 
 | #define PNG_LIBPNG_VER_MINOR   6 | 
 | #define PNG_LIBPNG_VER_RELEASE 0 | 
 |  | 
 | /* This should match the numeric part of the final component of | 
 |  * PNG_LIBPNG_VER_STRING, omitting any leading zero: | 
 |  */ | 
 |  | 
 | #define PNG_LIBPNG_VER_BUILD  07 | 
 |  | 
 | /* Release Status */ | 
 | #define PNG_LIBPNG_BUILD_ALPHA    1 | 
 | #define PNG_LIBPNG_BUILD_BETA     2 | 
 | #define PNG_LIBPNG_BUILD_RC       3 | 
 | #define PNG_LIBPNG_BUILD_STABLE   4 | 
 | #define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7 | 
 |  | 
 | /* Release-Specific Flags */ | 
 | #define PNG_LIBPNG_BUILD_PATCH    8 /* Can be OR'ed with | 
 |                                        PNG_LIBPNG_BUILD_STABLE only */ | 
 | #define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with | 
 |                                        PNG_LIBPNG_BUILD_SPECIAL */ | 
 | #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with | 
 |                                        PNG_LIBPNG_BUILD_PRIVATE */ | 
 |  | 
 | #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_BETA | 
 |  | 
 | /* Careful here.  At one time, Guy wanted to use 082, but that would be octal. | 
 |  * We must not include leading zeros. | 
 |  * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only | 
 |  * version 1.0.0 was mis-numbered 100 instead of 10000).  From | 
 |  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release | 
 |  */ | 
 | #define PNG_LIBPNG_VER 10600 /* 1.6.0 */ | 
 |  | 
 | /* Library configuration: these options cannot be changed after | 
 |  * the library has been built. | 
 |  */ | 
 | #ifndef PNGLCONF_H | 
 |     /* If pnglibconf.h is missing, you can | 
 |      * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h | 
 |      */ | 
 | #   include "pnglibconf.h" | 
 | #endif | 
 |  | 
 | #ifndef PNG_VERSION_INFO_ONLY | 
 |    /* Machine specific configuration. */ | 
 | #  include "pngconf.h" | 
 | #endif | 
 |  | 
 | /* | 
 |  * Added at libpng-1.2.8 | 
 |  * | 
 |  * Ref MSDN: Private as priority over Special | 
 |  * VS_FF_PRIVATEBUILD File *was not* built using standard release | 
 |  * procedures. If this value is given, the StringFileInfo block must | 
 |  * contain a PrivateBuild string. | 
 |  * | 
 |  * VS_FF_SPECIALBUILD File *was* built by the original company using | 
 |  * standard release procedures but is a variation of the standard | 
 |  * file of the same version number. If this value is given, the | 
 |  * StringFileInfo block must contain a SpecialBuild string. | 
 |  */ | 
 |  | 
 | #ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */ | 
 | #  define PNG_LIBPNG_BUILD_TYPE \ | 
 |        (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE) | 
 | #else | 
 | #  ifdef PNG_LIBPNG_SPECIALBUILD | 
 | #    define PNG_LIBPNG_BUILD_TYPE \ | 
 |          (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL) | 
 | #  else | 
 | #    define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE) | 
 | #  endif | 
 | #endif | 
 |  | 
 | #ifndef PNG_VERSION_INFO_ONLY | 
 |  | 
 | /* Inhibit C++ name-mangling for libpng functions but not for system calls. */ | 
 | #ifdef __cplusplus | 
 | extern "C" { | 
 | #endif /* __cplusplus */ | 
 |  | 
 | /* Version information for C files, stored in png.c.  This had better match | 
 |  * the version above. | 
 |  */ | 
 | #define png_libpng_ver png_get_header_ver(NULL) | 
 |  | 
 | /* This file is arranged in several sections: | 
 |  * | 
 |  * 1. Any configuration options that can be specified by for the application | 
 |  *    code when it is built.  (Build time configuration is in pnglibconf.h) | 
 |  * 2. Type definitions (base types are defined in pngconf.h), structure | 
 |  *    definitions. | 
 |  * 3. Exported library functions. | 
 |  * 4. Simplified API. | 
 |  * | 
 |  * The library source code has additional files (principally pngpriv.h) that | 
 |  * allow configuration of the library. | 
 |  */ | 
 | /* Section 1: run time configuration | 
 |  * See pnglibconf.h for build time configuration | 
 |  * | 
 |  * Run time configuration allows the application to choose between | 
 |  * implementations of certain arithmetic APIs.  The default is set | 
 |  * at build time and recorded in pnglibconf.h, but it is safe to | 
 |  * override these (and only these) settings.  Note that this won't | 
 |  * change what the library does, only application code, and the | 
 |  * settings can (and probably should) be made on a per-file basis | 
 |  * by setting the #defines before including png.h | 
 |  * | 
 |  * Use macros to read integers from PNG data or use the exported | 
 |  * functions? | 
 |  *   PNG_USE_READ_MACROS: use the macros (see below)  Note that | 
 |  *     the macros evaluate their argument multiple times. | 
 |  *   PNG_NO_USE_READ_MACROS: call the relevant library function. | 
 |  * | 
 |  * Use the alternative algorithm for compositing alpha samples that | 
 |  * does not use division? | 
 |  *   PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division' | 
 |  *      algorithm. | 
 |  *   PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm. | 
 |  * | 
 |  * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is | 
 |  * false? | 
 |  *   PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error | 
 |  *      APIs to png_warning. | 
 |  * Otherwise the calls are mapped to png_error. | 
 |  */ | 
 |  | 
 | /* Section 2: type definitions, including structures and compile time | 
 |  * constants. | 
 |  * See pngconf.h for base types that vary by machine/system | 
 |  */ | 
 |  | 
 | /* This triggers a compiler error in png.c, if png.c and png.h | 
 |  * do not agree upon the version number. | 
 |  */ | 
 | typedef char* png_libpng_version_1_6_0beta07; | 
 |  | 
 | /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info. | 
 |  * | 
 |  * png_struct is the cache of information used while reading or writing a single | 
 |  * PNG file.  One of these is always required, although the simplified API | 
 |  * (below) hides the creation and destruction of it. | 
 |  */ | 
 | typedef struct png_struct_def png_struct; | 
 | typedef const png_struct * png_const_structp; | 
 | typedef png_struct * png_structp; | 
 | typedef png_struct * * png_structpp; | 
 |  | 
 | /* png_info contains information read from or to be written to a PNG file.  One | 
 |  * or more of these must exist while reading or creating a PNG file.  The | 
 |  * information is not used by libpng during read but is used to control what | 
 |  * gets written when a PNG file is created.  "png_get_" function calls read | 
 |  * information during read and "png_set_" functions calls write information | 
 |  * when creating a PNG. | 
 |  * been moved into a separate header file that is not accessible to | 
 |  * applications.  Read libpng-manual.txt or libpng.3 for more info. | 
 |  */ | 
 | typedef struct png_info_def png_info; | 
 | typedef png_info * png_infop; | 
 | typedef const png_info * png_const_infop; | 
 | typedef png_info * * png_infopp; | 
 |  | 
 | /* Types with names ending 'p' are pointer types.  The corresponding types with | 
 |  * names ending 'rp' are identical pointer types except that the pointer is | 
 |  * marked 'restrict', which means that it is the only pointer to the object | 
 |  * passed to the function.  Applications should not use the 'restrict' types; | 
 |  * it is always valid to pass 'p' to a pointer with a function argument of the | 
 |  * corresponding 'rp' type.  Different compilers have different rules with | 
 |  * regard to type matching in the presence of 'restrict'.  For backward | 
 |  * compatibility libpng callbacks never have 'restrict' in their parameters and, | 
 |  * consequentially, writing portable application code is extremely difficult if | 
 |  * an attempt is made to use 'restrict'. | 
 |  */ | 
 | typedef png_struct * PNG_RESTRICT png_structrp; | 
 | typedef const png_struct * PNG_RESTRICT png_const_structrp; | 
 | typedef png_info * PNG_RESTRICT png_inforp; | 
 | typedef const png_info * PNG_RESTRICT png_const_inforp; | 
 |  | 
 | /* 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). | 
 |  */ | 
 | typedef struct png_color_struct | 
 | { | 
 |    png_byte red; | 
 |    png_byte green; | 
 |    png_byte blue; | 
 | } png_color; | 
 | typedef png_color * png_colorp; | 
 | typedef const png_color * png_const_colorp; | 
 | typedef png_color * * png_colorpp; | 
 |  | 
 | 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 png_color_16 * png_color_16p; | 
 | typedef const png_color_16 * png_const_color_16p; | 
 | typedef png_color_16 * * png_color_16pp; | 
 |  | 
 | 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; | 
 | typedef png_color_8 * png_color_8p; | 
 | typedef const png_color_8 * png_const_color_8p; | 
 | typedef png_color_8 * * png_color_8pp; | 
 |  | 
 | /* | 
 |  * The following two structures are used for the in-core representation | 
 |  * of sPLT chunks. | 
 |  */ | 
 | typedef struct png_sPLT_entry_struct | 
 | { | 
 |    png_uint_16 red; | 
 |    png_uint_16 green; | 
 |    png_uint_16 blue; | 
 |    png_uint_16 alpha; | 
 |    png_uint_16 frequency; | 
 | } png_sPLT_entry; | 
 | typedef png_sPLT_entry * png_sPLT_entryp; | 
 | typedef const png_sPLT_entry * png_const_sPLT_entryp; | 
 | typedef png_sPLT_entry * * png_sPLT_entrypp; | 
 |  | 
 | /*  When the depth of the sPLT palette is 8 bits, the color and alpha samples | 
 |  *  occupy the LSB of their respective members, and the MSB of each member | 
 |  *  is zero-filled.  The frequency member always occupies the full 16 bits. | 
 |  */ | 
 |  | 
 | typedef struct png_sPLT_struct | 
 | { | 
 |    png_charp name;           /* palette name */ | 
 |    png_byte depth;           /* depth of palette samples */ | 
 |    png_sPLT_entryp entries;  /* palette entries */ | 
 |    png_int_32 nentries;      /* number of palette entries */ | 
 | } png_sPLT_t; | 
 | typedef png_sPLT_t * png_sPLT_tp; | 
 | typedef const png_sPLT_t * png_const_sPLT_tp; | 
 | typedef png_sPLT_t * * png_sPLT_tpp; | 
 |  | 
 | #ifdef PNG_TEXT_SUPPORTED | 
 | /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file, | 
 |  * and whether that contents is compressed or not.  The "key" field | 
 |  * points to a regular zero-terminated C string.  The "text" fields can be a | 
 |  * regular C string, an empty string, or a NULL pointer. | 
 |  * However, the structure returned by png_get_text() will always contain | 
 |  * the "text" field as a regular zero-terminated C string (possibly | 
 |  * empty), never a NULL pointer, so it can be safely used in printf() and | 
 |  * other string-handling functions.  Note that the "itxt_length", "lang", and | 
 |  * "lang_key" members of the structure only exist when the library is built | 
 |  * with iTXt chunk support.  Prior to libpng-1.4.0 the library was built by | 
 |  * default without iTXt support. Also note that when iTXt *is* supported, | 
 |  * the "lang" and "lang_key" fields contain NULL pointers when the | 
 |  * "compression" field contains * PNG_TEXT_COMPRESSION_NONE or | 
 |  * PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the | 
 |  * same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag" | 
 |  * which is always 0 or 1, or its "compression method" which is always 0. | 
 |  */ | 
 | typedef struct png_text_struct | 
 | { | 
 |    int  compression;       /* compression value: | 
 |                              -1: tEXt, none | 
 |                               0: zTXt, deflate | 
 |                               1: iTXt, none | 
 |                               2: iTXt, deflate  */ | 
 |    png_charp key;          /* keyword, 1-79 character description of "text" */ | 
 |    png_charp text;         /* comment, may be an empty string (ie "") | 
 |                               or a NULL pointer */ | 
 |    png_size_t text_length; /* length of the text string */ | 
 |    png_size_t itxt_length; /* length of the itxt string */ | 
 |    png_charp lang;         /* language code, 0-79 characters | 
 |                               or a NULL pointer */ | 
 |    png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more | 
 |                               chars or a NULL pointer */ | 
 | } png_text; | 
 | typedef png_text * png_textp; | 
 | typedef const png_text * png_const_textp; | 
 | typedef png_text * * png_textpp; | 
 | #endif | 
 |  | 
 | /* Supported compression types for text in PNG files (tEXt, and zTXt). | 
 |  * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */ | 
 | #define PNG_TEXT_COMPRESSION_NONE_WR -3 | 
 | #define PNG_TEXT_COMPRESSION_zTXt_WR -2 | 
 | #define PNG_TEXT_COMPRESSION_NONE    -1 | 
 | #define PNG_TEXT_COMPRESSION_zTXt     0 | 
 | #define PNG_ITXT_COMPRESSION_NONE     1 | 
 | #define PNG_ITXT_COMPRESSION_zTXt     2 | 
 | #define PNG_TEXT_COMPRESSION_LAST     3  /* Not a valid value */ | 
 |  | 
 | /* 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.  As a side | 
 |  * note - PNG has always been Year 2000 compliant! | 
 |  */ | 
 | 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; | 
 | typedef png_time * png_timep; | 
 | typedef const png_time * png_const_timep; | 
 | typedef png_time * * png_timepp; | 
 |  | 
 | #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \ | 
 |     defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED) | 
 | /* png_unknown_chunk is a structure to hold queued chunks for which there is | 
 |  * no specific support.  The idea is that we can use this to queue | 
 |  * up private chunks for output even though the library doesn't actually | 
 |  * know about their semantics. | 
 |  */ | 
 | typedef struct png_unknown_chunk_t | 
 | { | 
 |     png_byte name[5]; | 
 |     png_byte *data; | 
 |     png_size_t size; | 
 |  | 
 |     /* libpng-using applications should NOT directly modify this byte. */ | 
 |     png_byte location; /* mode of operation at read time */ | 
 | } | 
 | png_unknown_chunk; | 
 |  | 
 | typedef png_unknown_chunk * png_unknown_chunkp; | 
 | typedef const png_unknown_chunk * png_const_unknown_chunkp; | 
 | typedef png_unknown_chunk * * png_unknown_chunkpp; | 
 | #endif | 
 |  | 
 | /* Values for the unknown chunk location byte */ | 
 |  | 
 | #define PNG_HAVE_IHDR  0x01 | 
 | #define PNG_HAVE_PLTE  0x02 | 
 | #define PNG_AFTER_IDAT 0x08 | 
 |  | 
 | /* Maximum positive integer used in PNG is (2^31)-1 */ | 
 | #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL) | 
 | #define PNG_UINT_32_MAX ((png_uint_32)(-1)) | 
 | #define PNG_SIZE_MAX ((png_size_t)(-1)) | 
 |  | 
 | /* These are constants for fixed point values encoded in the | 
 |  * PNG specification manner (x100000) | 
 |  */ | 
 | #define PNG_FP_1    100000 | 
 | #define PNG_FP_HALF  50000 | 
 | #define PNG_FP_MAX  ((png_fixed_point)0x7fffffffL) | 
 | #define PNG_FP_MIN  (-PNG_FP_MAX) | 
 |  | 
 | /* 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_GRAY 0 | 
 | #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_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA) | 
 | #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA) | 
 | /* aliases */ | 
 | #define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA | 
 | #define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA | 
 |  | 
 | /* This is for compression type. PNG 1.0-1.2 only define the single type. */ | 
 | #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */ | 
 | #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE | 
 |  | 
 | /* This is for filter type. PNG 1.0-1.2 only define the single type. */ | 
 | #define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */ | 
 | #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */ | 
 | #define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE | 
 |  | 
 | /* These are for the interlacing type.  These values should NOT be changed. */ | 
 | #define PNG_INTERLACE_NONE        0 /* Non-interlaced image */ | 
 | #define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */ | 
 | #define PNG_INTERLACE_LAST        2 /* Not a valid value */ | 
 |  | 
 | /* These are for the oFFs chunk.  These values should NOT be changed. */ | 
 | #define PNG_OFFSET_PIXEL          0 /* Offset in pixels */ | 
 | #define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */ | 
 | #define PNG_OFFSET_LAST           2 /* Not a valid value */ | 
 |  | 
 | /* These are for the pCAL chunk.  These values should NOT be changed. */ | 
 | #define PNG_EQUATION_LINEAR       0 /* Linear transformation */ | 
 | #define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */ | 
 | #define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */ | 
 | #define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */ | 
 | #define PNG_EQUATION_LAST         4 /* Not a valid value */ | 
 |  | 
 | /* These are for the sCAL chunk.  These values should NOT be changed. */ | 
 | #define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */ | 
 | #define PNG_SCALE_METER           1 /* meters per pixel */ | 
 | #define PNG_SCALE_RADIAN          2 /* radians per pixel */ | 
 | #define PNG_SCALE_LAST            3 /* Not a valid value */ | 
 |  | 
 | /* These are for the pHYs chunk.  These values should NOT be changed. */ | 
 | #define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */ | 
 | #define PNG_RESOLUTION_METER      1 /* pixels/meter */ | 
 | #define PNG_RESOLUTION_LAST       2 /* Not a valid value */ | 
 |  | 
 | /* These are for the sRGB chunk.  These values should NOT be changed. */ | 
 | #define PNG_sRGB_INTENT_PERCEPTUAL 0 | 
 | #define PNG_sRGB_INTENT_RELATIVE   1 | 
 | #define PNG_sRGB_INTENT_SATURATION 2 | 
 | #define PNG_sRGB_INTENT_ABSOLUTE   3 | 
 | #define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */ | 
 |  | 
 | /* This is for text chunks */ | 
 | #define PNG_KEYWORD_MAX_LENGTH     79 | 
 |  | 
 | /* Maximum number of entries in PLTE/sPLT/tRNS arrays */ | 
 | #define PNG_MAX_PALETTE_LENGTH    256 | 
 |  | 
 | /* These determine if an ancillary chunk's data has been successfully read | 
 |  * from the PNG header, or if the application has filled in the corresponding | 
 |  * data in the info_struct to be written into the output file.  The values | 
 |  * of the PNG_INFO_<chunk> defines should NOT be changed. | 
 |  */ | 
 | #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 | 
 | #define PNG_INFO_pCAL 0x0400 | 
 | #define PNG_INFO_sRGB 0x0800   /* GR-P, 0.96a */ | 
 | #define PNG_INFO_iCCP 0x1000   /* ESR, 1.0.6 */ | 
 | #define PNG_INFO_sPLT 0x2000   /* ESR, 1.0.6 */ | 
 | #define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */ | 
 | #define PNG_INFO_IDAT 0x8000   /* ESR, 1.0.6 */ | 
 |  | 
 | /* 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 purposes. | 
 |  */ | 
 | typedef struct png_row_info_struct | 
 | { | 
 |    png_uint_32 width;    /* width of row */ | 
 |    png_size_t 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; | 
 |  | 
 | typedef png_row_info * png_row_infop; | 
 | typedef png_row_info * * png_row_infopp; | 
 |  | 
 | /* These are the function types for the I/O functions and for the functions | 
 |  * that allow the user to override the default I/O functions with his or her | 
 |  * own.  The png_error_ptr type should match that of user-supplied warning | 
 |  * and error functions, while the png_rw_ptr type should match that of the | 
 |  * user read/write data functions.  Note that the 'write' function must not | 
 |  * modify the buffer it is passed. The 'read' function, on the other hand, is | 
 |  * expected to return the read data in the buffer. | 
 |  */ | 
 | typedef PNG_CALLBACK(void, *png_error_ptr, (png_structp, png_const_charp)); | 
 | typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, png_size_t)); | 
 | typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp)); | 
 | typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32, | 
 |     int)); | 
 | typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32, | 
 |     int)); | 
 |  | 
 | #ifdef PNG_PROGRESSIVE_READ_SUPPORTED | 
 | typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop)); | 
 | typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop)); | 
 |  | 
 | /* The following callback receives png_uint_32 row_number, int pass for the | 
 |  * png_bytep data of the row.  When transforming an interlaced image the | 
 |  * row number is the row number within the sub-image of the interlace pass, so | 
 |  * the value will increase to the height of the sub-image (not the full image) | 
 |  * then reset to 0 for the next pass. | 
 |  * | 
 |  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to | 
 |  * find the output pixel (x,y) given an interlaced sub-image pixel | 
 |  * (row,col,pass).  (See below for these macros.) | 
 |  */ | 
 | typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp, png_bytep, | 
 |     png_uint_32, int)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \ | 
 |     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) | 
 | typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop, | 
 |     png_bytep)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_USER_CHUNKS_SUPPORTED | 
 | typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp, | 
 |     png_unknown_chunkp)); | 
 | #endif | 
 | #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED | 
 | typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_SETJMP_SUPPORTED | 
 | /* This must match the function definition in <setjmp.h>, and the application | 
 |  * must include this before png.h to obtain the definition of jmp_buf.  The | 
 |  * function is required to be PNG_NORETURN, but this is not checked.  If the | 
 |  * function does return the application will crash via an abort() or similar | 
 |  * system level call. | 
 |  * | 
 |  * If you get a warning here while building the library you may need to make | 
 |  * changes to ensure that pnglibconf.h records the calling convention used by | 
 |  * your compiler.  This may be very difficult - try using a different compiler | 
 |  * to build the library! | 
 |  */ | 
 | PNG_FUNCTION(void, (PNGCAPI *png_longjmp_ptr), PNGARG((jmp_buf, int)), typedef); | 
 | #endif | 
 |  | 
 | /* Transform masks for the high-level interface */ | 
 | #define PNG_TRANSFORM_IDENTITY       0x0000    /* read and write */ | 
 | #define PNG_TRANSFORM_STRIP_16       0x0001    /* read only */ | 
 | #define PNG_TRANSFORM_STRIP_ALPHA    0x0002    /* read only */ | 
 | #define PNG_TRANSFORM_PACKING        0x0004    /* read and write */ | 
 | #define PNG_TRANSFORM_PACKSWAP       0x0008    /* read and write */ | 
 | #define PNG_TRANSFORM_EXPAND         0x0010    /* read only */ | 
 | #define PNG_TRANSFORM_INVERT_MONO    0x0020    /* read and write */ | 
 | #define PNG_TRANSFORM_SHIFT          0x0040    /* read and write */ | 
 | #define PNG_TRANSFORM_BGR            0x0080    /* read and write */ | 
 | #define PNG_TRANSFORM_SWAP_ALPHA     0x0100    /* read and write */ | 
 | #define PNG_TRANSFORM_SWAP_ENDIAN    0x0200    /* read and write */ | 
 | #define PNG_TRANSFORM_INVERT_ALPHA   0x0400    /* read and write */ | 
 | #define PNG_TRANSFORM_STRIP_FILLER   0x0800    /* write only */ | 
 | /* Added to libpng-1.2.34 */ | 
 | #define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER | 
 | #define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */ | 
 | /* Added to libpng-1.4.0 */ | 
 | #define PNG_TRANSFORM_GRAY_TO_RGB   0x2000      /* read only */ | 
 | /* Added to libpng-1.5.4 */ | 
 | #define PNG_TRANSFORM_EXPAND_16     0x4000      /* read only */ | 
 | #define PNG_TRANSFORM_SCALE_16      0x8000      /* read only */ | 
 |  | 
 | /* Flags for MNG supported features */ | 
 | #define PNG_FLAG_MNG_EMPTY_PLTE     0x01 | 
 | #define PNG_FLAG_MNG_FILTER_64      0x04 | 
 | #define PNG_ALL_MNG_FEATURES        0x05 | 
 |  | 
 | /* NOTE: prior to 1.5 these functions had no 'API' style declaration, | 
 |  * this allowed the zlib default functions to be used on Windows | 
 |  * platforms.  In 1.5 the zlib default malloc (which just calls malloc and | 
 |  * ignores the first argument) should be completely compatible with the | 
 |  * following. | 
 |  */ | 
 | typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp, | 
 |     png_alloc_size_t)); | 
 | typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp)); | 
 |  | 
 | /* Section 3: exported functions | 
 |  * Here are the function definitions most commonly used.  This is not | 
 |  * the place to find out how to use libpng.  See libpng-manual.txt for the | 
 |  * full explanation, see example.c for the summary.  This just provides | 
 |  * a simple one line description of the use of each function. | 
 |  * | 
 |  * The PNG_EXPORT() and PNG_EXPORTA() macros used below are defined in | 
 |  * pngconf.h and in the *.dfn files in the scripts directory. | 
 |  * | 
 |  *   PNG_EXPORT(ordinal, type, name, (args)); | 
 |  * | 
 |  *       ordinal:    ordinal that is used while building | 
 |  *                   *.def files. The ordinal value is only | 
 |  *                   relevant when preprocessing png.h with | 
 |  *                   the *.dfn files for building symbol table | 
 |  *                   entries, and are removed by pngconf.h. | 
 |  *       type:       return type of the function | 
 |  *       name:       function name | 
 |  *       args:       function arguments, with types | 
 |  * | 
 |  * When we wish to append attributes to a function prototype we use | 
 |  * the PNG_EXPORTA() macro instead. | 
 |  * | 
 |  *   PNG_EXPORTA(ordinal, type, name, (args), attributes); | 
 |  * | 
 |  *       ordinal, type, name, and args: same as in PNG_EXPORT(). | 
 |  *       attributes: function attributes | 
 |  */ | 
 |  | 
 | /* Returns the version number of the library */ | 
 | PNG_EXPORT(1, png_uint_32, png_access_version_number, (void)); | 
 |  | 
 | /* Tell lib we have already handled the first <num_bytes> magic bytes. | 
 |  * Handling more than 8 bytes from the beginning of the file is an error. | 
 |  */ | 
 | PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes)); | 
 |  | 
 | /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a | 
 |  * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG | 
 |  * signature, and non-zero otherwise.  Having num_to_check == 0 or | 
 |  * start > 7 will always fail (ie return non-zero). | 
 |  */ | 
 | PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, png_size_t start, | 
 |     png_size_t num_to_check)); | 
 |  | 
 | /* Simple signature checking function.  This is the same as calling | 
 |  * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n). | 
 |  */ | 
 | #define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n)) | 
 |  | 
 | /* Allocate and initialize png_ptr struct for reading, and any other memory. */ | 
 | PNG_EXPORTA(4, png_structp, png_create_read_struct, | 
 |     (png_const_charp user_png_ver, png_voidp error_ptr, | 
 |     png_error_ptr error_fn, png_error_ptr warn_fn), | 
 |     PNG_ALLOCATED); | 
 |  | 
 | /* Allocate and initialize png_ptr struct for writing, and any other memory */ | 
 | PNG_EXPORTA(5, png_structp, png_create_write_struct, | 
 |     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, | 
 |     png_error_ptr warn_fn), | 
 |     PNG_ALLOCATED); | 
 |  | 
 | PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size, | 
 |     (png_const_structrp png_ptr)); | 
 |  | 
 | PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr, | 
 |     png_size_t size)); | 
 |  | 
 | /* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp | 
 |  * match up. | 
 |  */ | 
 | #ifdef PNG_SETJMP_SUPPORTED | 
 | /* This function returns the jmp_buf built in to *png_ptr.  It must be | 
 |  * supplied with an appropriate 'longjmp' function to use on that jmp_buf | 
 |  * unless the default error function is overridden in which case NULL is | 
 |  * acceptable.  The size of the jmp_buf is checked against the actual size | 
 |  * allocated by the library - the call will return NULL on a mismatch | 
 |  * indicating an ABI mismatch. | 
 |  */ | 
 | PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structrp png_ptr, | 
 |     png_longjmp_ptr longjmp_fn, size_t jmp_buf_size)); | 
 | #  define png_jmpbuf(png_ptr) \ | 
 |       (*png_set_longjmp_fn((png_ptr), longjmp, sizeof (jmp_buf))) | 
 | #else | 
 | #  define png_jmpbuf(png_ptr) \ | 
 |       (LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP) | 
 | #endif | 
 | /* This function should be used by libpng applications in place of | 
 |  * longjmp(png_ptr->jmpbuf, val).  If longjmp_fn() has been set, it | 
 |  * will use it; otherwise it will call PNG_ABORT().  This function was | 
 |  * added in libpng-1.5.0. | 
 |  */ | 
 | PNG_EXPORTA(9, void, png_longjmp, (png_const_structrp png_ptr, int val), | 
 |     PNG_NORETURN); | 
 |  | 
 | #ifdef PNG_READ_SUPPORTED | 
 | /* Reset the compression stream */ | 
 | PNG_EXPORT(10, int, png_reset_zstream, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */ | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 | PNG_EXPORTA(11, png_structp, png_create_read_struct_2, | 
 |     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, | 
 |     png_error_ptr warn_fn, | 
 |     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn), | 
 |     PNG_ALLOCATED); | 
 | PNG_EXPORTA(12, png_structp, png_create_write_struct_2, | 
 |     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, | 
 |     png_error_ptr warn_fn, | 
 |     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn), | 
 |     PNG_ALLOCATED); | 
 | #endif | 
 |  | 
 | /* Write the PNG file signature. */ | 
 | PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr)); | 
 |  | 
 | /* Write a PNG chunk - size, type, (optional) data, CRC. */ | 
 | PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep | 
 |     chunk_name, png_const_bytep data, png_size_t length)); | 
 |  | 
 | /* Write the start of a PNG chunk - length and chunk name. */ | 
 | PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr, | 
 |     png_const_bytep chunk_name, png_uint_32 length)); | 
 |  | 
 | /* Write the data of a PNG chunk started with png_write_chunk_start(). */ | 
 | PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr, | 
 |     png_const_bytep data, png_size_t length)); | 
 |  | 
 | /* Finish a chunk started with png_write_chunk_start() (includes CRC). */ | 
 | PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr)); | 
 |  | 
 | /* Allocate and initialize the info structure */ | 
 | PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr), | 
 |     PNG_ALLOCATED); | 
 |  | 
 | /* DEPRECATED: this function allowed init structures to be created using the | 
 |  * default allocation method (typically malloc).  Use is deprecated in 1.6.0 and | 
 |  * the API will be removed in the future. | 
 |  */ | 
 | PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr, | 
 |     png_size_t png_info_struct_size), PNG_DEPRECATED); | 
 |  | 
 | /* Writes all the PNG information before the image. */ | 
 | PNG_EXPORT(20, void, png_write_info_before_PLTE, | 
 |     (png_structrp png_ptr, png_inforp info_ptr)); | 
 | PNG_EXPORT(21, void, png_write_info, | 
 |     (png_structrp png_ptr, png_inforp info_ptr)); | 
 |  | 
 | #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | 
 | /* Read the information before the actual image data. */ | 
 | PNG_EXPORT(22, void, png_read_info, | 
 |     (png_structrp png_ptr, png_inforp info_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_TIME_RFC1123_SUPPORTED | 
 |    /* Convert to a US string format: there is no localization support in this | 
 |     * routine.  The original implementation used a 29 character buffer in | 
 |     * png_struct, this will be removed in future versions. | 
 |     */ | 
 | #if PNG_LIBPNG_VER < 10700 | 
 | PNG_EXPORTA(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr, | 
 |     png_const_timep ptime),PNG_DEPRECATED); | 
 | #endif | 
 | PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29], | 
 |     png_const_timep ptime)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_CONVERT_tIME_SUPPORTED | 
 | /* Convert from a struct tm to png_time */ | 
 | PNG_EXPORT(24, void, png_convert_from_struct_tm, (png_timep ptime, | 
 |     const struct tm * ttime)); | 
 |  | 
 | /* Convert from time_t to png_time.  Uses gmtime() */ | 
 | PNG_EXPORT(25, void, png_convert_from_time_t, (png_timep ptime, time_t ttime)); | 
 | #endif /* PNG_CONVERT_tIME_SUPPORTED */ | 
 |  | 
 | #ifdef PNG_READ_EXPAND_SUPPORTED | 
 | /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */ | 
 | PNG_EXPORT(26, void, png_set_expand, (png_structrp png_ptr)); | 
 | PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structrp png_ptr)); | 
 | PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structrp png_ptr)); | 
 | PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_EXPAND_16_SUPPORTED | 
 | /* Expand to 16-bit channels, forces conversion of palette to RGB and expansion | 
 |  * of a tRNS chunk if present. | 
 |  */ | 
 | PNG_EXPORT(221, void, png_set_expand_16, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED) | 
 | /* Use blue, green, red order for pixels. */ | 
 | PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED | 
 | /* Expand the grayscale to 24-bit RGB if necessary. */ | 
 | PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED | 
 | /* Reduce RGB to grayscale. */ | 
 | #define PNG_ERROR_ACTION_NONE  1 | 
 | #define PNG_ERROR_ACTION_WARN  2 | 
 | #define PNG_ERROR_ACTION_ERROR 3 | 
 | #define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/ | 
 |  | 
 | PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structrp png_ptr, | 
 |     int error_action, double red, double green)); | 
 | PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structrp png_ptr, | 
 |     int error_action, png_fixed_point red, png_fixed_point green)); | 
 |  | 
 | PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp | 
 |     png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED | 
 | PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth, | 
 |     png_colorp palette)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_ALPHA_MODE_SUPPORTED | 
 | /* How the alpha channel is interpreted - this affects how the color channels of | 
 |  * a PNG file are returned when an alpha channel, or tRNS chunk in a palette | 
 |  * file, is present. | 
 |  * | 
 |  * This has no effect on the way pixels are written into a PNG output | 
 |  * datastream. The color samples in a PNG datastream are never premultiplied | 
 |  * with the alpha samples. | 
 |  * | 
 |  * The default is to return data according to the PNG specification: the alpha | 
 |  * channel is a linear measure of the contribution of the pixel to the | 
 |  * corresponding composited pixel.  The gamma encoded color channels must be | 
 |  * scaled according to the contribution and to do this it is necessary to undo | 
 |  * the encoding, scale the color values, perform the composition and reencode | 
 |  * the values.  This is the 'PNG' mode. | 
 |  * | 
 |  * The alternative is to 'associate' the alpha with the color information by | 
 |  * storing color channel values that have been scaled by the alpha.  The | 
 |  * advantage is that the color channels can be resampled (the image can be | 
 |  * scaled) in this form.  The disadvantage is that normal practice is to store | 
 |  * linear, not (gamma) encoded, values and this requires 16-bit channels for | 
 |  * still images rather than the 8-bit channels that are just about sufficient if | 
 |  * gamma encoding is used.  In addition all non-transparent pixel values, | 
 |  * including completely opaque ones, must be gamma encoded to produce the final | 
 |  * image.  This is the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' mode (the | 
 |  * latter being the two common names for associated alpha color channels.) | 
 |  * | 
 |  * Since it is not necessary to perform arithmetic on opaque color values so | 
 |  * long as they are not to be resampled and are in the final color space it is | 
 |  * possible to optimize the handling of alpha by storing the opaque pixels in | 
 |  * the PNG format (adjusted for the output color space) while storing partially | 
 |  * opaque pixels in the standard, linear, format.  The accuracy required for | 
 |  * standard alpha composition is relatively low, because the pixels are | 
 |  * isolated, therefore typically the accuracy loss in storing 8-bit linear | 
 |  * values is acceptable.  (This is not true if the alpha channel is used to | 
 |  * simulate transparency over large areas - use 16 bits or the PNG mode in | 
 |  * this case!)  This is the 'OPTIMIZED' mode.  For this mode a pixel is | 
 |  * treated as opaque only if the alpha value is equal to the maximum value. | 
 |  * | 
 |  * The final choice is to gamma encode the alpha channel as well.  This is | 
 |  * broken because, in practice, no implementation that uses this choice | 
 |  * correctly undoes the encoding before handling alpha composition.  Use this | 
 |  * choice only if other serious errors in the software or hardware you use | 
 |  * mandate it; the typical serious error is for dark halos to appear around | 
 |  * opaque areas of the composited PNG image because of arithmetic overflow. | 
 |  * | 
 |  * The API function png_set_alpha_mode specifies which of these choices to use | 
 |  * with an enumerated 'mode' value and the gamma of the required output: | 
 |  */ | 
 | #define PNG_ALPHA_PNG           0 /* according to the PNG standard */ | 
 | #define PNG_ALPHA_STANDARD      1 /* according to Porter/Duff */ | 
 | #define PNG_ALPHA_ASSOCIATED    1 /* as above; this is the normal practice */ | 
 | #define PNG_ALPHA_PREMULTIPLIED 1 /* as above */ | 
 | #define PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */ | 
 | #define PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */ | 
 |  | 
 | PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structrp png_ptr, int mode, | 
 |     double output_gamma)); | 
 | PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr, | 
 |     int mode, png_fixed_point output_gamma)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED) | 
 | /* The output_gamma value is a screen gamma in libpng terminology: it expresses | 
 |  * how to decode the output values, not how they are encoded.  The values used | 
 |  * correspond to the normal numbers used to describe the overall gamma of a | 
 |  * computer display system; for example 2.2 for an sRGB conformant system.  The | 
 |  * values are scaled by 100000 in the _fixed version of the API (so 220000 for | 
 |  * sRGB.) | 
 |  * | 
 |  * The inverse of the value is always used to provide a default for the PNG file | 
 |  * encoding if it has no gAMA chunk and if png_set_gamma() has not been called | 
 |  * to override the PNG gamma information. | 
 |  * | 
 |  * When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode | 
 |  * opaque pixels however pixels with lower alpha values are not encoded, | 
 |  * regardless of the output gamma setting. | 
 |  * | 
 |  * When the standard Porter Duff handling is requested with mode 1 the output | 
 |  * encoding is set to be linear and the output_gamma value is only relevant | 
 |  * as a default for input data that has no gamma information.  The linear output | 
 |  * encoding will be overridden if png_set_gamma() is called - the results may be | 
 |  * highly unexpected! | 
 |  * | 
 |  * The following numbers are derived from the sRGB standard and the research | 
 |  * behind it.  sRGB is defined to be approximated by a PNG gAMA chunk value of | 
 |  * 0.45455 (1/2.2) for PNG.  The value implicitly includes any viewing | 
 |  * correction required to take account of any differences in the color | 
 |  * environment of the original scene and the intended display environment; the | 
 |  * value expresses how to *decode* the image for display, not how the original | 
 |  * data was *encoded*. | 
 |  * | 
 |  * sRGB provides a peg for the PNG standard by defining a viewing environment. | 
 |  * sRGB itself, and earlier TV standards, actually use a more complex transform | 
 |  * (a linear portion then a gamma 2.4 power law) than PNG can express.  (PNG is | 
 |  * limited to simple power laws.)  By saying that an image for direct display on | 
 |  * an sRGB conformant system should be stored with a gAMA chunk value of 45455 | 
 |  * (11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification | 
 |  * makes it possible to derive values for other display systems and | 
 |  * environments. | 
 |  * | 
 |  * The Mac value is deduced from the sRGB based on an assumption that the actual | 
 |  * extra viewing correction used in early Mac display systems was implemented as | 
 |  * a power 1.45 lookup table. | 
 |  * | 
 |  * Any system where a programmable lookup table is used or where the behavior of | 
 |  * the final display device characteristics can be changed requires system | 
 |  * specific code to obtain the current characteristic.  However this can be | 
 |  * difficult and most PNG gamma correction only requires an approximate value. | 
 |  * | 
 |  * By default, if png_set_alpha_mode() is not called, libpng assumes that all | 
 |  * values are unencoded, linear, values and that the output device also has a | 
 |  * linear characteristic.  This is only very rarely correct - it is invariably | 
 |  * better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the | 
 |  * default if you don't know what the right answer is! | 
 |  * | 
 |  * The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS | 
 |  * 10.6) which used a correction table to implement a somewhat lower gamma on an | 
 |  * otherwise sRGB system. | 
 |  * | 
 |  * Both these values are reserved (not simple gamma values) in order to allow | 
 |  * more precise correction internally in the future. | 
 |  * | 
 |  * NOTE: the following values can be passed to either the fixed or floating | 
 |  * point APIs, but the floating point API will also accept floating point | 
 |  * values. | 
 |  */ | 
 | #define PNG_DEFAULT_sRGB -1       /* sRGB gamma and color space */ | 
 | #define PNG_GAMMA_MAC_18 -2       /* Old Mac '1.8' gamma and color space */ | 
 | #define PNG_GAMMA_sRGB   220000   /* Television standards--matches sRGB gamma */ | 
 | #define PNG_GAMMA_LINEAR PNG_FP_1 /* Linear */ | 
 | #endif | 
 |  | 
 | /* The following are examples of calls to png_set_alpha_mode to achieve the | 
 |  * required overall gamma correction and, where necessary, alpha | 
 |  * premultiplication. | 
 |  * | 
 |  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB); | 
 |  *    This is the default libpng handling of the alpha channel - it is not | 
 |  *    pre-multiplied into the color components.  In addition the call states | 
 |  *    that the output is for a sRGB system and causes all PNG files without gAMA | 
 |  *    chunks to be assumed to be encoded using sRGB. | 
 |  * | 
 |  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC); | 
 |  *    In this case the output is assumed to be something like an sRGB conformant | 
 |  *    display preceeded by a power-law lookup table of power 1.45.  This is how | 
 |  *    early Mac systems behaved. | 
 |  * | 
 |  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR); | 
 |  *    This is the classic Jim Blinn approach and will work in academic | 
 |  *    environments where everything is done by the book.  It has the shortcoming | 
 |  *    of assuming that input PNG data with no gamma information is linear - this | 
 |  *    is unlikely to be correct unless the PNG files where generated locally. | 
 |  *    Most of the time the output precision will be so low as to show | 
 |  *    significant banding in dark areas of the image. | 
 |  * | 
 |  * png_set_expand_16(pp); | 
 |  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB); | 
 |  *    This is a somewhat more realistic Jim Blinn inspired approach.  PNG files | 
 |  *    are assumed to have the sRGB encoding if not marked with a gamma value and | 
 |  *    the output is always 16 bits per component.  This permits accurate scaling | 
 |  *    and processing of the data.  If you know that your input PNG files were | 
 |  *    generated locally you might need to replace PNG_DEFAULT_sRGB with the | 
 |  *    correct value for your system. | 
 |  * | 
 |  * png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB); | 
 |  *    If you just need to composite the PNG image onto an existing background | 
 |  *    and if you control the code that does this you can use the optimization | 
 |  *    setting.  In this case you just copy completely opaque pixels to the | 
 |  *    output.  For pixels that are not completely transparent (you just skip | 
 |  *    those) you do the composition math using png_composite or png_composite_16 | 
 |  *    below then encode the resultant 8-bit or 16-bit values to match the output | 
 |  *    encoding. | 
 |  * | 
 |  * Other cases | 
 |  *    If neither the PNG nor the standard linear encoding work for you because | 
 |  *    of the software or hardware you use then you have a big problem.  The PNG | 
 |  *    case will probably result in halos around the image.  The linear encoding | 
 |  *    will probably result in a washed out, too bright, image (it's actually too | 
 |  *    contrasty.)  Try the ALPHA_OPTIMIZED mode above - this will probably | 
 |  *    substantially reduce the halos.  Alternatively try: | 
 |  * | 
 |  * png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB); | 
 |  *    This option will also reduce the halos, but there will be slight dark | 
 |  *    halos round the opaque parts of the image where the background is light. | 
 |  *    In the OPTIMIZED mode the halos will be light halos where the background | 
 |  *    is dark.  Take your pick - the halos are unavoidable unless you can get | 
 |  *    your hardware/software fixed!  (The OPTIMIZED approach is slightly | 
 |  *    faster.) | 
 |  * | 
 |  * When the default gamma of PNG files doesn't match the output gamma. | 
 |  *    If you have PNG files with no gamma information png_set_alpha_mode allows | 
 |  *    you to provide a default gamma, but it also sets the ouput gamma to the | 
 |  *    matching value.  If you know your PNG files have a gamma that doesn't | 
 |  *    match the output you can take advantage of the fact that | 
 |  *    png_set_alpha_mode always sets the output gamma but only sets the PNG | 
 |  *    default if it is not already set: | 
 |  * | 
 |  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB); | 
 |  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC); | 
 |  *    The first call sets both the default and the output gamma values, the | 
 |  *    second call overrides the output gamma without changing the default.  This | 
 |  *    is easier than achieving the same effect with png_set_gamma.  You must use | 
 |  *    PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will | 
 |  *    fire if more than one call to png_set_alpha_mode and png_set_background is | 
 |  *    made in the same read operation, however multiple calls with PNG_ALPHA_PNG | 
 |  *    are ignored. | 
 |  */ | 
 |  | 
 | #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED | 
 | PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \ | 
 |     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED) | 
 | PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \ | 
 |     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED) | 
 | PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED) | 
 | /* Add a filler byte to 8-bit Gray or 24-bit RGB images. */ | 
 | PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler, | 
 |     int flags)); | 
 | /* The values of the PNG_FILLER_ defines should NOT be changed */ | 
 | #  define PNG_FILLER_BEFORE 0 | 
 | #  define PNG_FILLER_AFTER 1 | 
 | /* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */ | 
 | PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr, | 
 |     png_uint_32 filler, int flags)); | 
 | #endif /* PNG_READ_FILLER_SUPPORTED || PNG_WRITE_FILLER_SUPPORTED */ | 
 |  | 
 | #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED) | 
 | /* Swap bytes in 16-bit depth files. */ | 
 | PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED) | 
 | /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */ | 
 | PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \ | 
 |     defined(PNG_WRITE_PACKSWAP_SUPPORTED) | 
 | /* Swap packing order of pixels in bytes. */ | 
 | PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED) | 
 | /* Converts files to legal bit depths. */ | 
 | PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p | 
 |     true_bits)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_INTERLACING_SUPPORTED) || \ | 
 |     defined(PNG_WRITE_INTERLACING_SUPPORTED) | 
 | /* Have the code handle the interlacing.  Returns the number of passes. | 
 |  * MUST be called before png_read_update_info or png_start_read_image, | 
 |  * otherwise it will not have the desired effect.  Note that it is still | 
 |  * necessary to call png_read_row or png_read_rows png_get_image_height | 
 |  * times for each pass. | 
 | */ | 
 | PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED) | 
 | /* Invert monochrome files */ | 
 | PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_BACKGROUND_SUPPORTED | 
 | /* Handle alpha and tRNS by replacing with a background color.  Prior to | 
 |  * libpng-1.5.4 this API must not be called before the PNG file header has been | 
 |  * read.  Doing so will result in unexpected behavior and possible warnings or | 
 |  * errors if the PNG file contains a bKGD chunk. | 
 |  */ | 
 | PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr, | 
 |     png_const_color_16p background_color, int background_gamma_code, | 
 |     int need_expand, double background_gamma)); | 
 | PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr, | 
 |     png_const_color_16p background_color, int background_gamma_code, | 
 |     int need_expand, png_fixed_point background_gamma)); | 
 | #endif | 
 | #ifdef PNG_READ_BACKGROUND_SUPPORTED | 
 | #  define PNG_BACKGROUND_GAMMA_UNKNOWN 0 | 
 | #  define PNG_BACKGROUND_GAMMA_SCREEN  1 | 
 | #  define PNG_BACKGROUND_GAMMA_FILE    2 | 
 | #  define PNG_BACKGROUND_GAMMA_UNIQUE  3 | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED | 
 | /* Scale a 16-bit depth file down to 8-bit, accurately. */ | 
 | PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED | 
 | #define PNG_READ_16_TO_8 SUPPORTED /* Name prior to 1.5.4 */ | 
 | /* Strip the second byte of information from a 16-bit depth file. */ | 
 | PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_QUANTIZE_SUPPORTED | 
 | /* Turn on quantizing, and reduce the palette to the number of colors | 
 |  * available. | 
 |  */ | 
 | PNG_EXPORT(49, void, png_set_quantize, (png_structrp png_ptr, png_colorp palette, | 
 |     int num_palette, int maximum_colors, png_const_uint_16p histogram, | 
 |     int full_quantize)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_GAMMA_SUPPORTED | 
 | /* The threshold on gamma processing is configurable but hard-wired into the | 
 |  * library.  The following is the floating point variant. | 
 |  */ | 
 | #define PNG_GAMMA_THRESHOLD (PNG_GAMMA_THRESHOLD_FIXED*.00001) | 
 |  | 
 | /* Handle gamma correction. Screen_gamma=(display_exponent). | 
 |  * NOTE: this API simply sets the screen and file gamma values. It will | 
 |  * therefore override the value for gamma in a PNG file if it is called after | 
 |  * the file header has been read - use with care  - call before reading the PNG | 
 |  * file for best results! | 
 |  * | 
 |  * These routines accept the same gamma values as png_set_alpha_mode (described | 
 |  * above).  The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either | 
 |  * API (floating point or fixed.)  Notice, however, that the 'file_gamma' value | 
 |  * is the inverse of a 'screen gamma' value. | 
 |  */ | 
 | PNG_FP_EXPORT(50, void, png_set_gamma, (png_structrp png_ptr, | 
 |     double screen_gamma, double override_file_gamma)); | 
 | PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structrp png_ptr, | 
 |     png_fixed_point screen_gamma, png_fixed_point override_file_gamma)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_WRITE_FLUSH_SUPPORTED | 
 | /* Set how many lines between output flushes - 0 for no flushing */ | 
 | PNG_EXPORT(51, void, png_set_flush, (png_structrp png_ptr, int nrows)); | 
 | /* Flush the current PNG output buffer */ | 
 | PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | /* Optional update palette with requested transformations */ | 
 | PNG_EXPORT(53, void, png_start_read_image, (png_structrp png_ptr)); | 
 |  | 
 | /* Optional call to update the users info structure */ | 
 | PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr, | 
 |     png_inforp info_ptr)); | 
 |  | 
 | #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | 
 | /* Read one or more rows of image data. */ | 
 | PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row, | 
 |     png_bytepp display_row, png_uint_32 num_rows)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | 
 | /* Read a row of data. */ | 
 | PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row, | 
 |     png_bytep display_row)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | 
 | /* Read the whole image into memory at once. */ | 
 | PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image)); | 
 | #endif | 
 |  | 
 | /* Write a row of image data */ | 
 | PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr, png_const_bytep row)); | 
 |  | 
 | /* Write a few rows of image data: (*row) is not written; however, the type | 
 |  * is declared as writeable to maintain compatibility with previous versions | 
 |  * of libpng and to allow the 'display_row' array from read_rows to be passed | 
 |  * unchanged to write_rows. | 
 |  */ | 
 | PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row, | 
 |     png_uint_32 num_rows)); | 
 |  | 
 | /* Write the image data */ | 
 | PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image)); | 
 |  | 
 | /* Write the end of the PNG file. */ | 
 | PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr, png_inforp info_ptr)); | 
 |  | 
 | #ifdef PNG_SEQUENTIAL_READ_SUPPORTED | 
 | /* Read the end of the PNG file. */ | 
 | PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr)); | 
 | #endif | 
 |  | 
 | /* Free any memory associated with the png_info_struct */ | 
 | PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr, | 
 |     png_infopp info_ptr_ptr)); | 
 |  | 
 | /* Free any memory associated with the png_struct and the png_info_structs */ | 
 | PNG_EXPORT(64, void, png_destroy_read_struct, (png_structpp png_ptr_ptr, | 
 |     png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr)); | 
 |  | 
 | /* Free any memory associated with the png_struct and the png_info_structs */ | 
 | PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr, | 
 |     png_infopp info_ptr_ptr)); | 
 |  | 
 | /* Set the libpng method of handling chunk CRC errors */ | 
 | PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action, | 
 |     int ancil_action)); | 
 |  | 
 | /* Values for png_set_crc_action() say how to handle CRC errors in | 
 |  * ancillary and critical chunks, and whether to use the data contained | 
 |  * therein.  Note that it is impossible to "discard" data in a critical | 
 |  * chunk.  For versions prior to 0.90, the action was always error/quit, | 
 |  * whereas in version 0.90 and later, the action for CRC errors in ancillary | 
 |  * chunks is warn/discard.  These values should NOT be changed. | 
 |  * | 
 |  *      value                       action:critical     action:ancillary | 
 |  */ | 
 | #define PNG_CRC_DEFAULT       0  /* error/quit          warn/discard data */ | 
 | #define PNG_CRC_ERROR_QUIT    1  /* error/quit          error/quit        */ | 
 | #define PNG_CRC_WARN_DISCARD  2  /* (INVALID)           warn/discard data */ | 
 | #define PNG_CRC_WARN_USE      3  /* warn/use data       warn/use data     */ | 
 | #define PNG_CRC_QUIET_USE     4  /* quiet/use data      quiet/use data    */ | 
 | #define PNG_CRC_NO_CHANGE     5  /* use current value   use current value */ | 
 |  | 
 | /* These functions give the user control over the scan-line filtering in | 
 |  * libpng and the compression methods used by zlib.  These functions are | 
 |  * mainly useful for testing, as the defaults should work with most users. | 
 |  * Those users who are tight on memory or want faster performance at the | 
 |  * expense of compression can modify them.  See the compression library | 
 |  * header file (zlib.h) for an explination of the compression functions. | 
 |  */ | 
 |  | 
 | /* Set the filtering method(s) used by libpng.  Currently, the only valid | 
 |  * value for "method" is 0. | 
 |  */ | 
 | PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method, | 
 |     int filters)); | 
 |  | 
 | /* Flags for png_set_filter() to say which filters to use.  The flags | 
 |  * are chosen so that they don't conflict with real filter types | 
 |  * below, in case they are supplied instead of the #defined constants. | 
 |  * These values should NOT be changed. | 
 |  */ | 
 | #define PNG_NO_FILTERS     0x00 | 
 | #define PNG_FILTER_NONE    0x08 | 
 | #define PNG_FILTER_SUB     0x10 | 
 | #define PNG_FILTER_UP      0x20 | 
 | #define PNG_FILTER_AVG     0x40 | 
 | #define PNG_FILTER_PAETH   0x80 | 
 | #define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \ | 
 |                          PNG_FILTER_AVG | PNG_FILTER_PAETH) | 
 |  | 
 | /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now. | 
 |  * These defines should NOT be changed. | 
 |  */ | 
 | #define PNG_FILTER_VALUE_NONE  0 | 
 | #define PNG_FILTER_VALUE_SUB   1 | 
 | #define PNG_FILTER_VALUE_UP    2 | 
 | #define PNG_FILTER_VALUE_AVG   3 | 
 | #define PNG_FILTER_VALUE_PAETH 4 | 
 | #define PNG_FILTER_VALUE_LAST  5 | 
 |  | 
 | #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* EXPERIMENTAL */ | 
 | /* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_ | 
 |  * defines, either the default (minimum-sum-of-absolute-differences), or | 
 |  * the experimental method (weighted-minimum-sum-of-absolute-differences). | 
 |  * | 
 |  * Weights are factors >= 1.0, indicating how important it is to keep the | 
 |  * filter type consistent between rows.  Larger numbers mean the current | 
 |  * filter is that many times as likely to be the same as the "num_weights" | 
 |  * previous filters.  This is cumulative for each previous row with a weight. | 
 |  * There needs to be "num_weights" values in "filter_weights", or it can be | 
 |  * NULL if the weights aren't being specified.  Weights have no influence on | 
 |  * the selection of the first row filter.  Well chosen weights can (in theory) | 
 |  * improve the compression for a given image. | 
 |  * | 
 |  * Costs are factors >= 1.0 indicating the relative decoding costs of a | 
 |  * filter type.  Higher costs indicate more decoding expense, and are | 
 |  * therefore less likely to be selected over a filter with lower computational | 
 |  * costs.  There needs to be a value in "filter_costs" for each valid filter | 
 |  * type (given by PNG_FILTER_VALUE_LAST), or it can be NULL if you aren't | 
 |  * setting the costs.  Costs try to improve the speed of decompression without | 
 |  * unduly increasing the compressed image size. | 
 |  * | 
 |  * A negative weight or cost indicates the default value is to be used, and | 
 |  * values in the range [0.0, 1.0) indicate the value is to remain unchanged. | 
 |  * The default values for both weights and costs are currently 1.0, but may | 
 |  * change if good general weighting/cost heuristics can be found.  If both | 
 |  * the weights and costs are set to 1.0, this degenerates the WEIGHTED method | 
 |  * to the UNWEIGHTED method, but with added encoding time/computation. | 
 |  */ | 
 | PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr, | 
 |     int heuristic_method, int num_weights, png_const_doublep filter_weights, | 
 |     png_const_doublep filter_costs)); | 
 | PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed, | 
 |     (png_structrp png_ptr, int heuristic_method, int num_weights, | 
 |     png_const_fixed_point_p filter_weights, | 
 |     png_const_fixed_point_p filter_costs)); | 
 | #endif /*  PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */ | 
 |  | 
 | /* Heuristic used for row filter selection.  These defines should NOT be | 
 |  * changed. | 
 |  */ | 
 | #define PNG_FILTER_HEURISTIC_DEFAULT    0  /* Currently "UNWEIGHTED" */ | 
 | #define PNG_FILTER_HEURISTIC_UNWEIGHTED 1  /* Used by libpng < 0.95 */ | 
 | #define PNG_FILTER_HEURISTIC_WEIGHTED   2  /* Experimental feature */ | 
 | #define PNG_FILTER_HEURISTIC_LAST       3  /* Not a valid value */ | 
 |  | 
 | #ifdef PNG_WRITE_SUPPORTED | 
 | /* Set the library compression level.  Currently, valid values range from | 
 |  * 0 - 9, corresponding directly to the zlib compression levels 0 - 9 | 
 |  * (0 - no compression, 9 - "maximal" compression).  Note that tests have | 
 |  * shown that zlib compression levels 3-6 usually perform as well as level 9 | 
 |  * for PNG images, and do considerably fewer caclulations.  In the future, | 
 |  * these values may not correspond directly to the zlib compression levels. | 
 |  */ | 
 | PNG_EXPORT(69, void, png_set_compression_level, (png_structrp png_ptr, | 
 |     int level)); | 
 |  | 
 | PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structrp png_ptr, | 
 |     int mem_level)); | 
 |  | 
 | PNG_EXPORT(71, void, png_set_compression_strategy, (png_structrp png_ptr, | 
 |     int strategy)); | 
 |  | 
 | /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a | 
 |  * smaller value of window_bits if it can do so safely. | 
 |  */ | 
 | PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr, | 
 |     int window_bits)); | 
 |  | 
 | PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr, | 
 |     int method)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED | 
 | /* Also set zlib parameters for compressing non-IDAT chunks */ | 
 | PNG_EXPORT(222, void, png_set_text_compression_level, (png_structrp png_ptr, | 
 |     int level)); | 
 |  | 
 | PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structrp png_ptr, | 
 |     int mem_level)); | 
 |  | 
 | PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structrp png_ptr, | 
 |     int strategy)); | 
 |  | 
 | /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a | 
 |  * smaller value of window_bits if it can do so safely. | 
 |  */ | 
 | PNG_EXPORT(225, void, png_set_text_compression_window_bits, | 
 |     (png_structrp png_ptr, int window_bits)); | 
 |  | 
 | PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr, | 
 |     int method)); | 
 | #endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */ | 
 |  | 
 | /* These next functions are called for input/output, memory, and error | 
 |  * handling.  They are in the file pngrio.c, pngwio.c, and pngerror.c, | 
 |  * and call standard C I/O routines such as fread(), fwrite(), and | 
 |  * fprintf().  These functions can be made to use other I/O routines | 
 |  * at run time for those applications that need to handle I/O in a | 
 |  * different manner by calling png_set_???_fn().  See libpng-manual.txt for | 
 |  * more information. | 
 |  */ | 
 |  | 
 | #ifdef PNG_STDIO_SUPPORTED | 
 | /* Initialize the input/output for the PNG file to the default functions. */ | 
 | PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp)); | 
 | #endif | 
 |  | 
 | /* Replace the (error and abort), and warning functions with user | 
 |  * supplied functions.  If no messages are to be printed you must still | 
 |  * write and use replacement functions. The replacement error_fn should | 
 |  * still do a longjmp to the last setjmp location if you are using this | 
 |  * method of error handling.  If error_fn or warning_fn is NULL, the | 
 |  * default function will be used. | 
 |  */ | 
 |  | 
 | PNG_EXPORT(75, void, png_set_error_fn, (png_structrp png_ptr, | 
 |     png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn)); | 
 |  | 
 | /* Return the user pointer associated with the error functions */ | 
 | PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structrp png_ptr)); | 
 |  | 
 | /* Replace the default data output functions with a user supplied one(s). | 
 |  * If buffered output is not used, then output_flush_fn can be set to NULL. | 
 |  * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time | 
 |  * output_flush_fn will be ignored (and thus can be NULL). | 
 |  * It is probably a mistake to use NULL for output_flush_fn if | 
 |  * write_data_fn is not also NULL unless you have built libpng with | 
 |  * PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's | 
 |  * default flush function, which uses the standard *FILE structure, will | 
 |  * be used. | 
 |  */ | 
 | PNG_EXPORT(77, void, png_set_write_fn, (png_structrp png_ptr, png_voidp io_ptr, | 
 |     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn)); | 
 |  | 
 | /* Replace the default data input function with a user supplied one. */ | 
 | PNG_EXPORT(78, void, png_set_read_fn, (png_structrp png_ptr, png_voidp io_ptr, | 
 |     png_rw_ptr read_data_fn)); | 
 |  | 
 | /* Return the user pointer associated with the I/O functions */ | 
 | PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_const_structrp png_ptr)); | 
 |  | 
 | PNG_EXPORT(80, void, png_set_read_status_fn, (png_structrp png_ptr, | 
 |     png_read_status_ptr read_row_fn)); | 
 |  | 
 | PNG_EXPORT(81, void, png_set_write_status_fn, (png_structrp png_ptr, | 
 |     png_write_status_ptr write_row_fn)); | 
 |  | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 | /* Replace the default memory allocation functions with user supplied one(s). */ | 
 | PNG_EXPORT(82, void, png_set_mem_fn, (png_structrp png_ptr, png_voidp mem_ptr, | 
 |     png_malloc_ptr malloc_fn, png_free_ptr free_fn)); | 
 | /* Return the user pointer associated with the memory functions */ | 
 | PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED | 
 | PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr, | 
 |     png_user_transform_ptr read_user_transform_fn)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED | 
 | PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr, | 
 |     png_user_transform_ptr write_user_transform_fn)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED | 
 | PNG_EXPORT(86, void, png_set_user_transform_info, (png_structrp png_ptr, | 
 |     png_voidp user_transform_ptr, int user_transform_depth, | 
 |     int user_transform_channels)); | 
 | /* Return the user pointer associated with the user transform functions */ | 
 | PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr, | 
 |     (png_const_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED | 
 | /* Return information about the row currently being processed.  Note that these | 
 |  * APIs do not fail but will return unexpected results if called outside a user | 
 |  * transform callback.  Also note that when transforming an interlaced image the | 
 |  * row number is the row number within the sub-image of the interlace pass, so | 
 |  * the value will increase to the height of the sub-image (not the full image) | 
 |  * then reset to 0 for the next pass. | 
 |  * | 
 |  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to | 
 |  * find the output pixel (x,y) given an interlaced sub-image pixel | 
 |  * (row,col,pass).  (See below for these macros.) | 
 |  */ | 
 | PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structrp)); | 
 | PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_USER_CHUNKS_SUPPORTED | 
 | PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr, | 
 |     png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn)); | 
 | PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_PROGRESSIVE_READ_SUPPORTED | 
 | /* Sets the function callbacks for the push reader, and a pointer to a | 
 |  * user-defined structure available to the callback functions. | 
 |  */ | 
 | PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structrp png_ptr, | 
 |     png_voidp progressive_ptr, png_progressive_info_ptr info_fn, | 
 |     png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn)); | 
 |  | 
 | /* Returns the user pointer associated with the push read functions */ | 
 | PNG_EXPORT(91, png_voidp, png_get_progressive_ptr, (png_const_structrp png_ptr)); | 
 |  | 
 | /* Function to be called when data becomes available */ | 
 | PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr, png_inforp info_ptr, | 
 |     png_bytep buffer, png_size_t buffer_size)); | 
 |  | 
 | /* A function which may be called *only* within png_process_data to stop the | 
 |  * processing of any more data.  The function returns the number of bytes | 
 |  * remaining, excluding any that libpng has cached internally.  A subsequent | 
 |  * call to png_process_data must supply these bytes again.  If the argument | 
 |  * 'save' is set to true the routine will first save all the pending data and | 
 |  * will always return 0. | 
 |  */ | 
 | PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save)); | 
 |  | 
 | /* A function which may be called *only* outside (after) a call to | 
 |  * png_process_data.  It returns the number of bytes of data to skip in the | 
 |  * input.  Normally it will return 0, but if it returns a non-zero value the | 
 |  * application must skip than number of bytes of input data and pass the | 
 |  * following data to the next call to png_process_data. | 
 |  */ | 
 | PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structrp)); | 
 |  | 
 | #ifdef PNG_READ_INTERLACING_SUPPORTED | 
 | /* Function that combines rows.  'new_row' is a flag that should come from | 
 |  * the callback and be non-NULL if anything needs to be done; the library | 
 |  * stores its own version of the new data internally and ignores the passed | 
 |  * in value. | 
 |  */ | 
 | PNG_EXPORT(93, void, png_progressive_combine_row, (png_const_structrp png_ptr, | 
 |     png_bytep old_row, png_const_bytep new_row)); | 
 | #endif /* PNG_READ_INTERLACING_SUPPORTED */ | 
 | #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */ | 
 |  | 
 | PNG_EXPORTA(94, png_voidp, png_malloc, (png_const_structrp png_ptr, | 
 |     png_alloc_size_t size), PNG_ALLOCATED); | 
 | /* Added at libpng version 1.4.0 */ | 
 | PNG_EXPORTA(95, png_voidp, png_calloc, (png_const_structrp png_ptr, | 
 |     png_alloc_size_t size), PNG_ALLOCATED); | 
 |  | 
 | /* Added at libpng version 1.2.4 */ | 
 | PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_const_structrp png_ptr, | 
 |     png_alloc_size_t size), PNG_ALLOCATED); | 
 |  | 
 | /* Frees a pointer allocated by png_malloc() */ | 
 | PNG_EXPORT(97, void, png_free, (png_const_structrp png_ptr, png_voidp ptr)); | 
 |  | 
 | /* Free data that was allocated internally */ | 
 | PNG_EXPORT(98, void, png_free_data, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_uint_32 free_me, int num)); | 
 |  | 
 | /* Reassign responsibility for freeing existing data, whether allocated | 
 |  * by libpng or by the application; this works on the png_info structure passed | 
 |  * in, it does not change the state for other png_info structures. | 
 |  */ | 
 | PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, int freer, png_uint_32 mask)); | 
 |  | 
 | /* Assignments for png_data_freer */ | 
 | #define PNG_DESTROY_WILL_FREE_DATA 1 | 
 | #define PNG_SET_WILL_FREE_DATA 1 | 
 | #define PNG_USER_WILL_FREE_DATA 2 | 
 | /* Flags for png_ptr->free_me and info_ptr->free_me */ | 
 | #define PNG_FREE_HIST 0x0008 | 
 | #define PNG_FREE_ICCP 0x0010 | 
 | #define PNG_FREE_SPLT 0x0020 | 
 | #define PNG_FREE_ROWS 0x0040 | 
 | #define PNG_FREE_PCAL 0x0080 | 
 | #define PNG_FREE_SCAL 0x0100 | 
 | #define PNG_FREE_UNKN 0x0200 | 
 | #define PNG_FREE_LIST 0x0400 | 
 | #define PNG_FREE_PLTE 0x1000 | 
 | #define PNG_FREE_TRNS 0x2000 | 
 | #define PNG_FREE_TEXT 0x4000 | 
 | #define PNG_FREE_ALL  0x7fff | 
 | #define PNG_FREE_MUL  0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */ | 
 |  | 
 | #ifdef PNG_USER_MEM_SUPPORTED | 
 | PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr, | 
 |     png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED); | 
 | PNG_EXPORTA(101, void, png_free_default, (png_const_structrp png_ptr, | 
 |     png_voidp ptr), PNG_DEPRECATED); | 
 | #endif | 
 |  | 
 | #ifdef PNG_ERROR_TEXT_SUPPORTED | 
 | /* Fatal error in PNG image of libpng - can't continue */ | 
 | PNG_EXPORTA(102, void, png_error, (png_const_structrp png_ptr, | 
 |     png_const_charp error_message), PNG_NORETURN); | 
 |  | 
 | /* The same, but the chunk name is prepended to the error string. */ | 
 | PNG_EXPORTA(103, void, png_chunk_error, (png_const_structrp png_ptr, | 
 |     png_const_charp error_message), PNG_NORETURN); | 
 |  | 
 | #else | 
 | /* Fatal error in PNG image of libpng - can't continue */ | 
 | PNG_EXPORTA(104, void, png_err, (png_const_structrp png_ptr), PNG_NORETURN); | 
 | #endif | 
 |  | 
 | #ifdef PNG_WARNINGS_SUPPORTED | 
 | /* Non-fatal error in libpng.  Can continue, but may have a problem. */ | 
 | PNG_EXPORT(105, void, png_warning, (png_const_structrp png_ptr, | 
 |     png_const_charp warning_message)); | 
 |  | 
 | /* Non-fatal error in libpng, chunk name is prepended to message. */ | 
 | PNG_EXPORT(106, void, png_chunk_warning, (png_const_structrp png_ptr, | 
 |     png_const_charp warning_message)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_BENIGN_ERRORS_SUPPORTED | 
 | /* Benign error in libpng.  Can continue, but may have a problem. | 
 |  * User can choose whether to handle as a fatal error or as a warning. */ | 
 | #  undef png_benign_error | 
 | PNG_EXPORT(107, void, png_benign_error, (png_const_structrp png_ptr, | 
 |     png_const_charp warning_message)); | 
 |  | 
 | /* Same, chunk name is prepended to message. */ | 
 | #  undef png_chunk_benign_error | 
 | PNG_EXPORT(108, void, png_chunk_benign_error, (png_const_structrp png_ptr, | 
 |     png_const_charp warning_message)); | 
 |  | 
 | PNG_EXPORT(109, void, png_set_benign_errors, | 
 |     (png_structrp png_ptr, int allowed)); | 
 | #else | 
 | #  ifdef PNG_ALLOW_BENIGN_ERRORS | 
 | #    define png_benign_error png_warning | 
 | #    define png_chunk_benign_error png_chunk_warning | 
 | #  else | 
 | #    define png_benign_error png_error | 
 | #    define png_chunk_benign_error png_chunk_error | 
 | #  endif | 
 | #endif | 
 |  | 
 | /* The png_set_<chunk> functions are for storing values in the png_info_struct. | 
 |  * Similarly, the png_get_<chunk> calls are used to read values from the | 
 |  * png_info_struct, either storing the parameters in the passed variables, or | 
 |  * setting pointers into the png_info_struct where the data is stored.  The | 
 |  * png_get_<chunk> functions return a non-zero value if the data was available | 
 |  * in info_ptr, or return zero and do not change any of the parameters if the | 
 |  * data was not available. | 
 |  * | 
 |  * These functions should be used instead of directly accessing png_info | 
 |  * to avoid problems with future changes in the size and internal layout of | 
 |  * png_info_struct. | 
 |  */ | 
 | /* Returns "flag" if chunk data is valid in info_ptr. */ | 
 | PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_uint_32 flag)); | 
 |  | 
 | /* Returns number of bytes needed to hold a transformed row. */ | 
 | PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | #ifdef PNG_INFO_IMAGE_SUPPORTED | 
 | /* Returns row_pointers, which is an array of pointers to scanlines that was | 
 |  * returned from png_read_png(). | 
 |  */ | 
 | PNG_EXPORT(112, png_bytepp, png_get_rows, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | /* Set row_pointers, which is an array of pointers to scanlines for use | 
 |  * by png_write_png(). | 
 |  */ | 
 | PNG_EXPORT(113, void, png_set_rows, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_bytepp row_pointers)); | 
 | #endif | 
 |  | 
 | /* Returns number of color channels in image. */ | 
 | PNG_EXPORT(114, png_byte, png_get_channels, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | #ifdef PNG_EASY_ACCESS_SUPPORTED | 
 | /* Returns image width in pixels. */ | 
 | PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | /* Returns image height in pixels. */ | 
 | PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | /* Returns image bit_depth. */ | 
 | PNG_EXPORT(117, png_byte, png_get_bit_depth, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | /* Returns image color_type. */ | 
 | PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | /* Returns image filter_type. */ | 
 | PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | /* Returns image interlace_type. */ | 
 | PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | /* Returns image compression_type. */ | 
 | PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | /* Returns image resolution in pixels per meter, from pHYs chunk data. */ | 
 | PNG_EXPORT(122, png_uint_32, png_get_pixels_per_meter, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 | PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 | PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 |  | 
 | /* Returns pixel aspect ratio, computed from pHYs chunk data.  */ | 
 | PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 | PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 |  | 
 | /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */ | 
 | PNG_EXPORT(126, png_int_32, png_get_x_offset_pixels, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 | PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 | PNG_EXPORT(128, png_int_32, png_get_x_offset_microns, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 | PNG_EXPORT(129, png_int_32, png_get_y_offset_microns, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 |  | 
 | #endif /* PNG_EASY_ACCESS_SUPPORTED */ | 
 |  | 
 | /* Returns pointer to signature string read from PNG header */ | 
 | PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 |  | 
 | #ifdef PNG_bKGD_SUPPORTED | 
 | PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_color_16p *background)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_bKGD_SUPPORTED | 
 | PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_color_16p background)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_cHRM_SUPPORTED | 
 | PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr, | 
 |    png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x, | 
 |     double *red_y, double *green_x, double *green_y, double *blue_x, | 
 |     double *blue_y)); | 
 | PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z, | 
 |     double *green_X, double *green_Y, double *green_Z, double *blue_X, | 
 |     double *blue_Y, double *blue_Z)); | 
 | #ifdef PNG_FIXED_POINT_SUPPORTED /* Otherwise not implemented */ | 
 | PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr, | 
 |     png_fixed_point *int_white_x, png_fixed_point *int_white_y, | 
 |     png_fixed_point *int_red_x, png_fixed_point *int_red_y, | 
 |     png_fixed_point *int_green_x, png_fixed_point *int_green_y, | 
 |     png_fixed_point *int_blue_x, png_fixed_point *int_blue_y)); | 
 | #endif | 
 | PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr, | 
 |     png_fixed_point *int_red_X, png_fixed_point *int_red_Y, | 
 |     png_fixed_point *int_red_Z, png_fixed_point *int_green_X, | 
 |     png_fixed_point *int_green_Y, png_fixed_point *int_green_Z, | 
 |     png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y, | 
 |     png_fixed_point *int_blue_Z)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_cHRM_SUPPORTED | 
 | PNG_FP_EXPORT(135, void, png_set_cHRM, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, | 
 |     double white_x, double white_y, double red_x, double red_y, double green_x, | 
 |     double green_y, double blue_x, double blue_y)); | 
 | PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, double red_X, double red_Y, double red_Z, | 
 |     double green_X, double green_Y, double green_Z, double blue_X, | 
 |     double blue_Y, double blue_Z)); | 
 | PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_fixed_point int_white_x, | 
 |     png_fixed_point int_white_y, png_fixed_point int_red_x, | 
 |     png_fixed_point int_red_y, png_fixed_point int_green_x, | 
 |     png_fixed_point int_green_y, png_fixed_point int_blue_x, | 
 |     png_fixed_point int_blue_y)); | 
 | PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y, | 
 |     png_fixed_point int_red_Z, png_fixed_point int_green_X, | 
 |     png_fixed_point int_green_Y, png_fixed_point int_green_Z, | 
 |     png_fixed_point int_blue_X, png_fixed_point int_blue_Y, | 
 |     png_fixed_point int_blue_Z)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_gAMA_SUPPORTED | 
 | PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, double *file_gamma)); | 
 | PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr, | 
 |     png_fixed_point *int_file_gamma)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_gAMA_SUPPORTED | 
 | PNG_FP_EXPORT(139, void, png_set_gAMA, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, double file_gamma)); | 
 | PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_fixed_point int_file_gamma)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_hIST_SUPPORTED | 
 | PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_uint_16p *hist)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_hIST_SUPPORTED | 
 | PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_uint_16p hist)); | 
 | #endif | 
 |  | 
 | PNG_EXPORT(143, png_uint_32, png_get_IHDR, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height, | 
 |     int *bit_depth, int *color_type, int *interlace_method, | 
 |     int *compression_method, int *filter_method)); | 
 |  | 
 | PNG_EXPORT(144, void, png_set_IHDR, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth, | 
 |     int color_type, int interlace_method, int compression_method, | 
 |     int filter_method)); | 
 |  | 
 | #ifdef PNG_oFFs_SUPPORTED | 
 | PNG_EXPORT(145, png_uint_32, png_get_oFFs, (png_const_structrp png_ptr, | 
 |    png_const_inforp info_ptr, png_int_32 *offset_x, png_int_32 *offset_y, | 
 |    int *unit_type)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_oFFs_SUPPORTED | 
 | PNG_EXPORT(146, void, png_set_oFFs, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_int_32 offset_x, png_int_32 offset_y, | 
 |     int unit_type)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_pCAL_SUPPORTED | 
 | PNG_EXPORT(147, png_uint_32, png_get_pCAL, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_charp *purpose, png_int_32 *X0, | 
 |     png_int_32 *X1, int *type, int *nparams, png_charp *units, | 
 |     png_charpp *params)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_pCAL_SUPPORTED | 
 | PNG_EXPORT(148, void, png_set_pCAL, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_charp purpose, png_int_32 X0, png_int_32 X1, | 
 |     int type, int nparams, png_const_charp units, png_charpp params)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_pHYs_SUPPORTED | 
 | PNG_EXPORT(149, png_uint_32, png_get_pHYs, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y, | 
 |     int *unit_type)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_pHYs_SUPPORTED | 
 | PNG_EXPORT(150, void, png_set_pHYs, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type)); | 
 | #endif | 
 |  | 
 | PNG_EXPORT(151, png_uint_32, png_get_PLTE, (png_const_structrp png_ptr, | 
 |    png_const_inforp info_ptr, png_colorp *palette, int *num_palette)); | 
 |  | 
 | PNG_EXPORT(152, void, png_set_PLTE, (png_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_colorp palette, int num_palette)); | 
 |  | 
 | #ifdef PNG_sBIT_SUPPORTED | 
 | PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_color_8p *sig_bit)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_sBIT_SUPPORTED | 
 | PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_color_8p sig_bit)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_sRGB_SUPPORTED | 
 | PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, int *file_srgb_intent)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_sRGB_SUPPORTED | 
 | PNG_EXPORT(156, void, png_set_sRGB, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, int srgb_intent)); | 
 | PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, int srgb_intent)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_iCCP_SUPPORTED | 
 | PNG_EXPORT(158, png_uint_32, png_get_iCCP, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_charpp name, int *compression_type, | 
 |     png_bytepp profile, png_uint_32 *proflen)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_iCCP_SUPPORTED | 
 | PNG_EXPORT(159, void, png_set_iCCP, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_charp name, int compression_type, | 
 |     png_const_bytep profile, png_uint_32 proflen)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_sPLT_SUPPORTED | 
 | PNG_EXPORT(160, png_uint_32, png_get_sPLT, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_sPLT_tpp entries)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_sPLT_SUPPORTED | 
 | PNG_EXPORT(161, void, png_set_sPLT, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_sPLT_tp entries, int nentries)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_TEXT_SUPPORTED | 
 | /* png_get_text also returns the number of text chunks in *num_text */ | 
 | PNG_EXPORT(162, png_uint_32, png_get_text, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_textp *text_ptr, int *num_text)); | 
 | #endif | 
 |  | 
 | /* Note while png_set_text() will accept a structure whose text, | 
 |  * language, and  translated keywords are NULL pointers, the structure | 
 |  * returned by png_get_text will always contain regular | 
 |  * zero-terminated C strings.  They might be empty strings but | 
 |  * they will never be NULL pointers. | 
 |  */ | 
 |  | 
 | #ifdef PNG_TEXT_SUPPORTED | 
 | PNG_EXPORT(163, void, png_set_text, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_textp text_ptr, int num_text)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_tIME_SUPPORTED | 
 | PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_timep *mod_time)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_tIME_SUPPORTED | 
 | PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_timep mod_time)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_tRNS_SUPPORTED | 
 | PNG_EXPORT(166, png_uint_32, png_get_tRNS, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans, | 
 |     png_color_16p *trans_color)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_tRNS_SUPPORTED | 
 | PNG_EXPORT(167, void, png_set_tRNS, (png_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_bytep trans_alpha, int num_trans, | 
 |     png_const_color_16p trans_color)); | 
 | #endif | 
 |  | 
 | #ifdef PNG_sCAL_SUPPORTED | 
 | PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, int *unit, double *width, double *height)); | 
 | #if (defined PNG_FLOATING_ARITHMETIC_SUPPORTED) || \ | 
 |    (defined PNG_FLOATING_POINT_SUPPORTED) | 
 | /* NOTE: this API is currently implemented using floating point arithmetic, | 
 |  * consequently it can only be used on systems with floating point support. | 
 |  * In any case the range of values supported by png_fixed_point is small and it | 
 |  * is highly recommended that png_get_sCAL_s be used instead. | 
 |  */ | 
 | PNG_FIXED_EXPORT(214, png_uint_32, png_get_sCAL_fixed, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit, | 
 |     png_fixed_point *width, png_fixed_point *height)); | 
 | #endif | 
 | PNG_EXPORT(169, png_uint_32, png_get_sCAL_s, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit, | 
 |     png_charpp swidth, png_charpp sheight)); | 
 |  | 
 | PNG_FP_EXPORT(170, void, png_set_sCAL, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, int unit, double width, double height)); | 
 | PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_const_structrp png_ptr, | 
 |    png_inforp info_ptr, int unit, png_fixed_point width, | 
 |    png_fixed_point height)); | 
 | PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, int unit, | 
 |     png_const_charp swidth, png_const_charp sheight)); | 
 | #endif /* PNG_sCAL_SUPPORTED */ | 
 |  | 
 | #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED | 
 | /* Provide a list of chunks and how they are to be handled, if the built-in | 
 |    handling or default unknown chunk handling is not desired.  Any chunks not | 
 |    listed will be handled in the default manner.  The IHDR and IEND chunks | 
 |    must not be listed.  Because this turns off the default handling for chunks | 
 |    that would otherwise be recognized the behavior of libpng transformations may | 
 |    well become incorrect! | 
 |       keep = 0: PNG_HANDLE_CHUNK_AS_DEFAULT: follow default behavior | 
 |            = 1: PNG_HANDLE_CHUNK_NEVER:      do not keep | 
 |            = 2: PNG_HANDLE_CHUNK_IF_SAFE:    keep only if safe-to-copy | 
 |            = 3: PNG_HANDLE_CHUNK_ALWAYS:     keep even if unsafe-to-copy | 
 | */ | 
 | PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr, | 
 |     int keep, png_const_bytep chunk_list, int num_chunks)); | 
 |  | 
 | /* The handling code is returned; the result is therefore true (non-zero) if | 
 |  * special handling is required, false for the default handling. | 
 |  */ | 
 | PNG_EXPORT(173, int, png_handle_as_unknown, (png_structrp png_ptr, | 
 |     png_const_bytep chunk_name)); | 
 | #endif | 
 | #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED | 
 | PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, png_const_unknown_chunkp unknowns, | 
 |     int num_unknowns)); | 
 | PNG_EXPORT(175, void, png_set_unknown_chunk_location, | 
 |     (png_const_structrp png_ptr, png_inforp info_ptr, int chunk, int location)); | 
 | PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_unknown_chunkpp entries)); | 
 | #endif | 
 |  | 
 | /* Png_free_data() will turn off the "valid" flag for anything it frees. | 
 |  * If you need to turn it off for a chunk that your application has freed, | 
 |  * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK); | 
 |  */ | 
 | PNG_EXPORT(177, void, png_set_invalid, (png_const_structrp png_ptr, | 
 |     png_inforp info_ptr, int mask)); | 
 |   | 
 | #ifdef PNG_INFO_IMAGE_SUPPORTED | 
 | /* The "params" pointer is currently not used and is for future expansion. */ | 
 | PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr, | 
 |     int transforms, png_voidp params)); | 
 | PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr, | 
 |     int transforms, png_voidp params)); | 
 | #endif | 
 |  | 
 | PNG_EXPORT(180, png_const_charp, png_get_copyright, | 
 |     (png_const_structrp png_ptr)); | 
 | PNG_EXPORT(181, png_const_charp, png_get_header_ver, | 
 |     (png_const_structrp png_ptr)); | 
 | PNG_EXPORT(182, png_const_charp, png_get_header_version, | 
 |     (png_const_structrp png_ptr)); | 
 | PNG_EXPORT(183, png_const_charp, png_get_libpng_ver, | 
 |     (png_const_structrp png_ptr)); | 
 |  | 
 | #ifdef PNG_MNG_FEATURES_SUPPORTED | 
 | PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr, | 
 |     png_uint_32 mng_features_permitted)); | 
 | #endif | 
 |  | 
 | /* For use in png_set_keep_unknown, added to version 1.2.6 */ | 
 | #define PNG_HANDLE_CHUNK_AS_DEFAULT   0 | 
 | #define PNG_HANDLE_CHUNK_NEVER        1 | 
 | #define PNG_HANDLE_CHUNK_IF_SAFE      2 | 
 | #define PNG_HANDLE_CHUNK_ALWAYS       3 | 
 |  | 
 | /* Strip the prepended error numbers ("#nnn ") from error and warning | 
 |  * messages before passing them to the error or warning handler. | 
 |  */ | 
 | #ifdef PNG_ERROR_NUMBERS_SUPPORTED | 
 | PNG_EXPORT(185, void, png_set_strip_error_numbers, (png_structrp png_ptr, | 
 |     png_uint_32 strip_mode)); | 
 | #endif | 
 |  | 
 | /* Added in libpng-1.2.6 */ | 
 | #ifdef PNG_SET_USER_LIMITS_SUPPORTED | 
 | PNG_EXPORT(186, void, png_set_user_limits, (png_structrp png_ptr, | 
 |     png_uint_32 user_width_max, png_uint_32 user_height_max)); | 
 | PNG_EXPORT(187, png_uint_32, png_get_user_width_max, | 
 |     (png_const_structrp png_ptr)); | 
 | PNG_EXPORT(188, png_uint_32, png_get_user_height_max, | 
 |     (png_const_structrp png_ptr)); | 
 | /* Added in libpng-1.4.0 */ | 
 | PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structrp png_ptr, | 
 |     png_uint_32 user_chunk_cache_max)); | 
 | PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max, | 
 |     (png_const_structrp png_ptr)); | 
 | /* Added in libpng-1.4.1 */ | 
 | PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structrp png_ptr, | 
 |     png_alloc_size_t user_chunk_cache_max)); | 
 | PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max, | 
 |     (png_const_structrp png_ptr)); | 
 | #endif | 
 |  | 
 | #if defined(PNG_INCH_CONVERSIONS_SUPPORTED) | 
 | PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 |  | 
 | PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 |  | 
 | PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 |  | 
 | PNG_FP_EXPORT(196, float, png_get_x_offset_inches, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 | #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */ | 
 | PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 | #endif | 
 |  | 
 | PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr)); | 
 | #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */ | 
 | PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed, | 
 |     (png_const_structrp png_ptr, png_const_inforp info_ptr)); | 
 | #endif | 
 |  | 
 | #  ifdef PNG_pHYs_SUPPORTED | 
 | PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structrp png_ptr, | 
 |     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y, | 
 |     int *unit_type)); | 
 | #  endif /* PNG_pHYs_SUPPORTED */ | 
 | #endif  /* PNG_INCH_CONVERSIONS_SUPPORTED */ | 
 |  | 
 | /* Added in libpng-1.4.0 */ | 
 | #ifdef PNG_IO_STATE_SUPPORTED | 
 | PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_const_structrp png_ptr)); | 
 |  | 
 | /* Removed from libpng 1.6; use png_get_io_chunk_type. */ | 
 | PNG_REMOVED(200, png_const_bytep, png_get_io_chunk_name, (png_structrp png_ptr), | 
 |     PNG_DEPRECATED) | 
 |  | 
 | PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type, | 
 |     (png_const_structrp png_ptr)); | 
 |  | 
 | /* The flags returned by png_get_io_state() are the following: */ | 
 | #  define PNG_IO_NONE        0x0000   /* no I/O at this moment */ | 
 | #  define PNG_IO_READING     0x0001   /* currently reading */ | 
 | #  define PNG_IO_WRITING     0x0002   /* currently writing */ | 
 | #  define PNG_IO_SIGNATURE   0x0010   /* currently at the file signature */ | 
 | #  define PNG_IO_CHUNK_HDR   0x0020   /* currently at the chunk header */ | 
 | #  define PNG_IO_CHUNK_DATA  0x0040   /* currently at the chunk data */ | 
 | #  define PNG_IO_CHUNK_CRC   0x0080   /* currently at the chunk crc */ | 
 | #  define PNG_IO_MASK_OP     0x000f   /* current operation: reading/writing */ | 
 | #  define PNG_IO_MASK_LOC    0x00f0   /* current location: sig/hdr/data/crc */ | 
 | #endif /* ?PNG_IO_STATE_SUPPORTED */ | 
 |  | 
 | /* Interlace support.  The following macros are always defined so that if | 
 |  * libpng interlace handling is turned off the macros may be used to handle | 
 |  * interlaced images within the application. | 
 |  */ | 
 | #define PNG_INTERLACE_ADAM7_PASSES 7 | 
 |  | 
 | /* Two macros to return the first row and first column of the original, | 
 |  * full, image which appears in a given pass.  'pass' is in the range 0 | 
 |  * to 6 and the result is in the range 0 to 7. | 
 |  */ | 
 | #define PNG_PASS_START_ROW(pass) (((1&~(pass))<<(3-((pass)>>1)))&7) | 
 | #define PNG_PASS_START_COL(pass) (((1& (pass))<<(3-(((pass)+1)>>1)))&7) | 
 |  | 
 | /* A macro to return the offset between pixels in the output row for a pair of | 
 |  * pixels in the input - effectively the inverse of the 'COL_SHIFT' macro that | 
 |  * follows.  Note that ROW_OFFSET is the offset from one row to the next whereas | 
 |  * COL_OFFSET is from one column to the next, within a row. | 
 |  */ | 
 | #define PNG_PASS_ROW_OFFSET(pass) ((pass)>2?(8>>(((pass)-1)>>1)):8) | 
 | #define PNG_PASS_COL_OFFSET(pass) (1<<((7-(pass))>>1)) | 
 |  | 
 | /* Two macros to help evaluate the number of rows or columns in each | 
 |  * pass.  This is expressed as a shift - effectively log2 of the number or | 
 |  * rows or columns in each 8x8 tile of the original image. | 
 |  */ | 
 | #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3) | 
 | #define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3) | 
 |  | 
 | /* Hence two macros to determine the number of rows or columns in a given | 
 |  * pass of an image given its height or width.  In fact these macros may | 
 |  * return non-zero even though the sub-image is empty, because the other | 
 |  * dimension may be empty for a small image. | 
 |  */ | 
 | #define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\ | 
 |    -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass)) | 
 | #define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\ | 
 |    -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass)) | 
 |  | 
 | /* For the reader row callbacks (both progressive and sequential) it is | 
 |  * necessary to find the row in the output image given a row in an interlaced | 
 |  * image, so two more macros: | 
 |  */ | 
 | #define PNG_ROW_FROM_PASS_ROW(yIn, pass) \ | 
 |    (((yIn)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass)) | 
 | #define PNG_COL_FROM_PASS_COL(xIn, pass) \ | 
 |    (((xIn)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass)) | 
 |  | 
 | /* Two macros which return a boolean (0 or 1) saying whether the given row | 
 |  * or column is in a particular pass.  These use a common utility macro that | 
 |  * returns a mask for a given pass - the offset 'off' selects the row or | 
 |  * column version.  The mask has the appropriate bit set for each column in | 
 |  * the tile. | 
 |  */ | 
 | #define PNG_PASS_MASK(pass,off) ( \ | 
 |    ((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \ | 
 |    ((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0)) | 
 |  | 
 | #define PNG_ROW_IN_INTERLACE_PASS(y, pass) \ | 
 |    ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1) | 
 | #define PNG_COL_IN_INTERLACE_PASS(x, pass) \ | 
 |    ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1) | 
 |  | 
 | #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED | 
 | /* With these routines we avoid an integer divide, which will be slower on | 
 |  * most machines.  However, it does take more operations than the corresponding | 
 |  * divide method, so it may be slower on a few RISC systems.  There are two | 
 |  * shifts (by 8 or 16 bits) and an addition, versus a single integer divide. | 
 |  * | 
 |  * Note that the rounding factors are NOT supposed to be the same!  128 and | 
 |  * 32768 are correct for the NODIV code; 127 and 32767 are correct for the | 
 |  * standard method. | 
 |  * | 
 |  * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ] | 
 |  */ | 
 |  | 
 |  /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */ | 
 |  | 
 | #  define png_composite(composite, fg, alpha, bg)         \ | 
 |      { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \ | 
 |            * (png_uint_16)(alpha)                         \ | 
 |            + (png_uint_16)(bg)*(png_uint_16)(255          \ | 
 |            - (png_uint_16)(alpha)) + 128);                \ | 
 |        (composite) = (png_byte)((temp + (temp >> 8)) >> 8); } | 
 |  | 
 | #  define png_composite_16(composite, fg, alpha, bg)       \ | 
 |      { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg)  \ | 
 |            * (png_uint_32)(alpha)                          \ | 
 |            + (png_uint_32)(bg)*(65535                      \ | 
 |            - (png_uint_32)(alpha)) + 32768);               \ | 
 |        (composite) = (png_uint_16)((temp + (temp >> 16)) >> 16); } | 
 |  | 
 | #else  /* Standard method using integer division */ | 
 |  | 
 | #  define png_composite(composite, fg, alpha, bg)                          \ | 
 |      (composite) = (png_byte)(((png_uint_16)(fg) * (png_uint_16)(alpha) +  \ | 
 |      (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) +       \ | 
 |      127) / 255) | 
 |  | 
 | #  define png_composite_16(composite, fg, alpha, bg)                         \ | 
 |      (composite) = (png_uint_16)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \ | 
 |      (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) +         \ | 
 |      32767) / 65535) | 
 | #endif /* PNG_READ_COMPOSITE_NODIV_SUPPORTED */ | 
 |  | 
 | #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED | 
 | PNG_EXPORT(201, png_uint_32, png_get_uint_32, (png_const_bytep buf)); | 
 | PNG_EXPORT(202, png_uint_16, png_get_uint_16, (png_const_bytep buf)); | 
 | PNG_EXPORT(203, png_int_32, png_get_int_32, (png_const_bytep buf)); | 
 | #endif | 
 |  | 
 | PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_const_structrp png_ptr, | 
 |     png_const_bytep buf)); | 
 | /* No png_get_int_16 -- may be added if there's a real need for it. */ | 
 |  | 
 | /* Place a 32-bit number into a buffer in PNG byte order (big-endian). */ | 
 | #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED | 
 | PNG_EXPORT(205, void, png_save_uint_32, (png_bytep buf, png_uint_32 i)); | 
 | #endif | 
 | #ifdef PNG_SAVE_INT_32_SUPPORTED | 
 | PNG_EXPORT(206, void, png_save_int_32, (png_bytep buf, png_int_32 i)); | 
 | #endif | 
 |  | 
 | /* Place a 16-bit number into a buffer in PNG byte order. | 
 |  * The parameter is declared unsigned int, not png_uint_16, | 
 |  * just to avoid potential problems on pre-ANSI C compilers. | 
 |  */ | 
 | #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED | 
 | PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i)); | 
 | /* No png_save_int_16 -- may be added if there's a real need for it. */ | 
 | #endif | 
 |  | 
 | #ifdef PNG_USE_READ_MACROS | 
 | /* Inline macros to do direct reads of bytes from the input buffer. | 
 |  * The png_get_int_32() routine assumes we are using two's complement | 
 |  * format for negative values, which is almost certainly true. | 
 |  */ | 
 | #  define png_get_uint_32(buf) \ | 
 |      (((png_uint_32)(*(buf)) << 24) + \ | 
 |       ((png_uint_32)(*((buf) + 1)) << 16) + \ | 
 |       ((png_uint_32)(*((buf) + 2)) << 8) + \ | 
 |       ((png_uint_32)(*((buf) + 3)))) | 
 |  | 
 |    /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the | 
 |     * function) incorrectly returned a value of type png_uint_32. | 
 |     */ | 
 | #  define png_get_uint_16(buf) \ | 
 |      ((png_uint_16) \ | 
 |       (((unsigned int)(*(buf)) << 8) + \ | 
 |        ((unsigned int)(*((buf) + 1))))) | 
 |  | 
 | #  define png_get_int_32(buf) \ | 
 |      ((png_int_32)((*(buf) & 0x80) \ | 
 |       ? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffffL) + 1)) \ | 
 |       : (png_int_32)png_get_uint_32(buf))) | 
 | #endif | 
 |  | 
 | /******************************************************************************* | 
 |  *  SIMPLIFIED API | 
 |  ******************************************************************************* | 
 |  * | 
 |  * Please read the documentation in libpng-manual.txt (TODO: write said | 
 |  * documentation) if you don't understand what follows. | 
 |  * | 
 |  * The simplified API hides the details of both libpng and the PNG file format | 
 |  * itself.  It allows PNG files to be read into a very limited number of | 
 |  * in-memory bitmap formats or to be written from the same formats.  If these | 
 |  * formats do not accomodate your needs then you can, and should, use the more | 
 |  * sophisticated APIs above - these support a wide variety of in-memory formats | 
 |  * and a wide variety of sophisticated transformations to those formats as well | 
 |  * as a wide variety of APIs to manipulate ancilliary information. | 
 |  * | 
 |  * To read a PNG file using the simplified API: | 
 |  * | 
 |  * 1) Declare a 'png_image' structure (see below) on the stack and set the | 
 |  *    version field to PNG_IMAGE_VERSION. | 
 |  * 2) Call the appropriate png_image_begin_read... function. | 
 |  * 3) Set the png_image 'format' member to the required sample format. | 
 |  * 4) Allocate a buffer for the image and, if required, the color-map. | 
 |  * 5) Call png_image_finish_read to read the image and, if required, the | 
 |  *    color-map into your buffers. | 
 |  * | 
 |  * There are no restrictions on the format of the PNG input itself; all valid | 
 |  * color types, bit depths, and interlace methods are acceptable, and the | 
 |  * input image is transformed as necessary to the requested in-memory format | 
 |  * during the png_image_finish_read() step.  The only caveat is that if you | 
 |  * request a color-mapped image from a PNG that is full-color or makes | 
 |  * complex use of an alpha channel the transformation is extremely lossy and the | 
 |  * result may look terrible. | 
 |  * | 
 |  * To write a PNG file using the simplified API: | 
 |  * | 
 |  * 1) Declare a 'png_image' structure on the stack and memset() it to all zero. | 
 |  * 2) Initialize the members of the structure that describe the image, setting | 
 |  *    the 'format' member to the format of the image samples. | 
 |  * 3) Call the appropriate png_image_write... function with a pointer to the | 
 |  *    image and, if necessary, the color-map to write the PNG data. | 
 |  * | 
 |  * png_image is a structure that describes the in-memory format of an image | 
 |  * when it is being read or defines the in-memory format of an image that you | 
 |  * need to write: | 
 |  */ | 
 | #define PNG_IMAGE_VERSION 1 | 
 |  | 
 | typedef struct png_control *png_controlp; | 
 | typedef struct | 
 | { | 
 |    png_controlp opaque;    /* Initialize to NULL, free with png_image_free */ | 
 |    png_uint_32  version;   /* Set to PNG_IMAGE_VERSION */ | 
 |    png_uint_32  width;     /* Image width in pixels (columns) */ | 
 |    png_uint_32  height;    /* Image height in pixels (rows) */ | 
 |    png_uint_32  format;    /* Image format as defined below */ | 
 |    png_uint_32  flags;     /* A bit mask containing informational flags */ | 
 |    png_uint_32  colormap_entries; | 
 |                            /* Number of entries in the color-map */ | 
 |  | 
 |    /* In the event of an error or warning the following field will be set to a | 
 |     * non-zero value and the 'message' field will contain a '\0' terminated | 
 |     * string with the libpng error or warning message.  If both warnings and | 
 |     * an error were encountered, only the error is recorded.  If there | 
 |     * are multiple warnings, only the first one is recorded. | 
 |     * | 
 |     * The upper 30 bits of this value are reserved, the low two bits contain | 
 |     * a value as follows: | 
 |     */ | 
 | #  define PNG_IMAGE_WARNING 1 | 
 | #  define PNG_IMAGE_ERROR 2 | 
 |    /* | 
 |     * The result is a two bit code such that a value more than 1 indicates | 
 |     * a failure in the API just called: | 
 |     * | 
 |     *    0 - no warning or error | 
 |     *    1 - warning | 
 |     *    2 - error | 
 |     *    3 - error preceded by warning | 
 |     */ | 
 | #  define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1) | 
 |  | 
 |    png_uint_32  warning_or_error; | 
 |  | 
 |    char         message[64]; | 
 | } png_image, *png_imagep; | 
 |  | 
 | /* The samples of the image have one to four channels whose components have | 
 |  * original values in the range 0 to 1.0: | 
 |  * | 
 |  * 1: A single gray or luminance channel (G). | 
 |  * 2: A gray/luminance channel and an alpha channel (GA). | 
 |  * 3: Three red, green, blue color channels (RGB). | 
 |  * 4: Three color channels and an alpha channel (RGBA). | 
 |  * | 
 |  * The components are encoded in one of two ways: | 
 |  * | 
 |  * a) As a small integer, value 0..255, contained in a single byte.  For the | 
 |  * alpha channel the original value is simply value/255.  For the color or | 
 |  * luminance channels the value is encoded according to the sRGB specification | 
 |  * and matches the 8-bit format expected by typical display devices. | 
 |  * | 
 |  *    The color/gray channels are not scaled (pre-multiplied) by the alpha | 
 |  * channel and are suitable for passing to color management software. | 
 |  * | 
 |  * b) As a value in the range 0..65535, contained in a 2-byte integer.  All | 
 |  * channels can be converted to the original value by dividing by 65535; all | 
 |  * channels are linear.  Color channels use the RGB encoding (RGB end-points) of | 
 |  * the sRGB specification.  This encoding is identified by the | 
 |  * PNG_FORMAT_FLAG_LINEAR flag below. | 
 |  * | 
 |  *    When an alpha channel is present it is expected to denote pixel coverage | 
 |  * of the color or luminance channels and is returned as an associated alpha | 
 |  * channel: the color/gray channels are scaled (pre-multiplied) by the alpha | 
 |  * value. | 
 |  * | 
 |  * The samples are either contained directly in the image data, between 1 and 8 | 
 |  * bytes per pixel according to the encoding, or are held in a color-map indexed | 
 |  * by bytes in the image data.  In the case of a color-map the color-map entries | 
 |  * are individual samples, encoded as above, and the image data has one byte per | 
 |  * pixel to select the relevant sample from the color-map. | 
 |  */ | 
 |  | 
 | /* PNG_FORMAT_* | 
 |  * | 
 |  * #defines to be used in png_image::format.  Each #define identifies a | 
 |  * particular layout of sample data and, if present, alpha values.  There are | 
 |  * separate defines for each of the two component encodings. | 
 |  * | 
 |  * A format is built up using single bit flag values.  All combinations are | 
 |  * valid.  Formats can be built up from the flag values or you can use one of | 
 |  * the predefined values below.  When testing formats always use the FORMAT_FLAG | 
 |  * macros to test for individual features - future versions of the library may | 
 |  * add new flags. | 
 |  * | 
 |  * When reading or writing color-mapped images the format should be set to the | 
 |  * format of the entries in the color-map then png_image_{read,write}_colormap | 
 |  * called to read or write the color-map and set the format correctly for the | 
 |  * image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly! | 
 |  * | 
 |  * NOTE: libpng can be built with particular features disabled, if you see | 
 |  * compiler errors because the definition of one of the following flags has been | 
 |  * compiled out it is because libpng does not have the required support.  It is | 
 |  * possible, however, for the libpng configuration to enable the format on just | 
 |  * read or just write; in that case you may see an error at run time.  You can | 
 |  * guard against this by checking for the definition of the appropriate | 
 |  * "_SUPPORTED" macro, one of: | 
 |  * | 
 |  *    PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED | 
 |  */ | 
 | #define PNG_FORMAT_FLAG_ALPHA    0x01U /* format with an alpha channel */ | 
 | #define PNG_FORMAT_FLAG_COLOR    0x02U /* color format: otherwise grayscale */ | 
 | #define PNG_FORMAT_FLAG_LINEAR   0x04U /* 2 byte channels else 1 byte */ | 
 | #define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */ | 
 |  | 
 | #ifdef PNG_FORMAT_BGR_SUPPORTED | 
 | #  define PNG_FORMAT_FLAG_BGR    0x10U /* BGR colors, else order is RGB */ | 
 | #endif | 
 |  | 
 | #ifdef PNG_FORMAT_AFIRST_SUPPORTED | 
 | #  define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */ | 
 | #endif | 
 |  | 
 | /* Commonly used formats have predefined macros. | 
 |  * | 
 |  * First the single byte (sRGB) formats: | 
 |  */ | 
 | #define PNG_FORMAT_GRAY 0 | 
 | #define PNG_FORMAT_GA   PNG_FORMAT_FLAG_ALPHA | 
 | #define PNG_FORMAT_AG   (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST) | 
 | #define PNG_FORMAT_RGB  PNG_FORMAT_FLAG_COLOR | 
 | #define PNG_FORMAT_BGR  (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR) | 
 | #define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA) | 
 | #define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST) | 
 | #define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA) | 
 | #define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST) | 
 |  | 
 | /* Then the linear 2-byte formats.  When naming these "Y" is used to | 
 |  * indicate a luminance (gray) channel. | 
 |  */ | 
 | #define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR | 
 | #define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA) | 
 | #define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR) | 
 | #define PNG_FORMAT_LINEAR_RGB_ALPHA \ | 
 |    (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA) | 
 |  | 
 | /* With color-mapped formats the image data is one byte for each pixel, the byte | 
 |  * is an index into the color-map which is formatted as above.  To obtain a | 
 |  * color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP | 
 |  * to one of the above definitions, or you can use one of the definitions below. | 
 |  */ | 
 | #define PNG_FORMAT_RGB_COLORMAP  (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP) | 
 | #define PNG_FORMAT_BGR_COLORMAP  (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP) | 
 | #define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP) | 
 | #define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP) | 
 | #define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP) | 
 | #define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP) | 
 |  | 
 | /* PNG_IMAGE macros | 
 |  * | 
 |  * These are convenience macros to derive information from a png_image | 
 |  * structure.  The PNG_IMAGE_SAMPLE_ macros return values appropriate to the | 
 |  * actual image sample values - either the entries in the color-map or the | 
 |  * pixels in the image.  The PNG_IMAGE_PIXEL_ macros return corresponding values | 
 |  * for the pixels and will always return 1 for color-mapped formats.  The | 
 |  * remaining macros return information about the rows in the image and the | 
 |  * complete image. | 
 |  * | 
 |  * NOTE: All the macros that take a png_image::format parameter are compile time | 
 |  * constants if the format parameter is, itself, a constant.  Therefore these | 
 |  * macros can be used in array declarations and case labels where required. | 
 |  * Similarly the macros are also pre-processor constants (sizeof is not used) so | 
 |  * they can be used in #if tests. | 
 |  * | 
 |  * First the information about the samples. | 
 |  */ | 
 | #define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\ | 
 |    (((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1) | 
 |    /* Return the total number of channels in a given format: 1..4 */ | 
 |  | 
 | #define PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)\ | 
 |    ((((fmt) & PNG_FORMAT_FLAG_LINEAR) >> 2)+1) | 
 |    /* Return the size in bytes of a single component of a pixel or color-map | 
 |     * entry (as appropriate) in the image: 1 or 2. | 
 |     */ | 
 |  | 
 | #define PNG_IMAGE_SAMPLE_SIZE(fmt)\ | 
 |    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)) | 
 |    /* This is the size of the sample data for one sample.  If the image is | 
 |     * color-mapped it is the size of one color-map entry (and image pixels are | 
 |     * one byte in size), otherwise it is the size of one image pixel. | 
 |     */ | 
 |  | 
 | #define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\ | 
 |    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256) | 
 |    /* The maximum size of the color-map required by the format expressed in a | 
 |     * count of components.  This can be used to compile-time allocate a | 
 |     * color-map: | 
 |     * | 
 |     * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)]; | 
 |     * | 
 |     * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)]; | 
 |     * | 
 |     * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the | 
 |     * information from one of the png_image_begin_read_ APIs and dynamically | 
 |     * allocate the required memory. | 
 |     */ | 
 |  | 
 | /* Corresponding information about the pixels */ | 
 | #define PNG_IMAGE_PIXEL_(test,fmt)\ | 
 |    (((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt)) | 
 |  | 
 | #define PNG_IMAGE_PIXEL_CHANNELS(fmt)\ | 
 |    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt) | 
 |    /* The number of separate channels (components) in a pixel; 1 for a | 
 |     * color-mapped image. | 
 |     */ | 
 |  | 
 | #define PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\ | 
 |    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_COMPONENT_SIZE,fmt) | 
 |    /* The size, in bytes, of each component in a pixel; 1 for a color-mapped | 
 |     * image. | 
 |     */ | 
 |  | 
 | #define PNG_IMAGE_PIXEL_SIZE(fmt) PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_SIZE,fmt) | 
 |    /* The size, in bytes, of a complete pixel; 1 for a color-mapped image. */ | 
 |  | 
 | /* Information about the whole row, or whole image */ | 
 | #define PNG_IMAGE_ROW_STRIDE(image)\ | 
 |    (PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width) | 
 |    /* Return the total number of components in a single row of the image; this | 
 |     * is the minimum 'row stride', the minimum count of components between each | 
 |     * row.  For a color-mapped image this is the minimum number of bytes in a | 
 |     * row. | 
 |     */ | 
 |  | 
 | #define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\ | 
 |    (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride)) | 
 |    /* Return the size, in bytes, of an image buffer given a png_image and a row | 
 |     * stride - the number of components to leave space for in each row. | 
 |     */ | 
 |  | 
 | #define PNG_IMAGE_SIZE(image)\ | 
 |    PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image)) | 
 |    /* Return the size, in bytes, of the image in memory given just a png_image; | 
 |     * the row stride is the minimum stride required for the image. | 
 |     */ | 
 |  | 
 | #define PNG_IMAGE_COLORMAP_SIZE(image)\ | 
 |    (PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries) | 
 |    /* Return the size, in bytes, of the color-map of this image.  If the image | 
 |     * format is not a color-map format this will return a size sufficient for | 
 |     * 256 entries in the given format; check PNG_IMAGE_FORMAT_FLAG_COLORMAP if | 
 |     * you don't want to allocate a color-map in this case. | 
 |     */ | 
 |  | 
 | /* PNG_IMAGE_FLAG_* | 
 |  * | 
 |  * Flags containing additional information about the image are held in the | 
 |  * 'flags' field of png_image. | 
 |  */ | 
 | #define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01 | 
 |    /* This indicates the the RGB values of the in-memory bitmap do not | 
 |     * correspond to the red, green and blue end-points defined by sRGB. | 
 |     */ | 
 |  | 
 | #ifdef PNG_SIMPLIFIED_READ_SUPPORTED | 
 | /* READ APIs | 
 |  * --------- | 
 |  * | 
 |  * The png_image passed to the read APIs must have been initialized by setting | 
 |  * the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.) | 
 |  */ | 
 | #ifdef PNG_STDIO_SUPPORTED | 
 | PNG_EXPORT(234, int, png_image_begin_read_from_file, (png_imagep image, | 
 |    const char *file_name)); | 
 |    /* The named file is opened for read and the image header is filled in | 
 |     * from the PNG header in the file. | 
 |     */ | 
 |  | 
 | PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image, | 
 |    FILE* file)); | 
 |    /* The PNG header is read from the stdio FILE object. */ | 
 | #endif /* PNG_STDIO_SUPPORTED */ | 
 |  | 
 | PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image, | 
 |    png_const_voidp memory, png_size_t size)); | 
 |    /* The PNG header is read from the given memory buffer. */ | 
 |  | 
 | PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image, | 
 |    png_colorp background, void *buffer, png_int_32 row_stride, | 
 |    void *colormap)); | 
 |    /* Finish reading the image into the supplied buffer and clean up the | 
 |     * png_image structure. | 
 |     * | 
 |     * row_stride is the step, in byte or 2-byte units as appropriate, | 
 |     * between adjacent rows.  A positive stride indicates that the top-most row | 
 |     * is first in the buffer - the normal top-down arrangement.  A negative | 
 |     * stride indicates that the bottom-most row is first in the buffer. | 
 |     * | 
 |     * background need only be supplied if an alpha channel must be removed from | 
 |     * a png_byte format and the removal is to be done by compositing on a solid | 
 |     * color; otherwise it may be NULL and any composition will be done directly | 
 |     * onto the buffer.  The value is an sRGB color to use for the background, | 
 |     * for grayscale output the green channel is used. | 
 |     * | 
 |     * background must be supplied when an alpha channel must be removed from a | 
 |     * single byte color-mapped output format, in other words if: | 
 |     * | 
 |     * 1) The original format from png_image_begin_read_from_* had | 
 |     *    PNG_FORMAT_FLAG_ALPHA set. | 
 |     * 2) The format set by the application does not. | 
 |     * 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and | 
 |     *    PNG_FORMAT_FLAG_LINEAR *not* set. | 
 |     * | 
 |     * For linear output removing the alpha channel is always done by compositing | 
 |     * on black and background is ignored.: | 
 |     * | 
 |     * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set.  It must | 
 |     * be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE. | 
 |     * image->colormap_entries will be updated to the actual number of entries | 
 |     * written to the colormap; this may be less than the original value. | 
 |     */ | 
 |  | 
 | PNG_EXPORT(238, void, png_image_free, (png_imagep image)); | 
 |    /* Free any data allocated by libpng in image->opaque, setting the pointer to | 
 |     * NULL.  May be called at any time after the structure is initialized. | 
 |     */ | 
 | #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */ | 
 |  | 
 | #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED | 
 | /* WRITE APIS | 
 |  * ---------- | 
 |  * For write you must initialize a png_image structure to describe the image to | 
 |  * be written.  To do this use memset to set the whole structure to 0 then | 
 |  * initialize fields describing your image. | 
 |  * | 
 |  * version: must be set to PNG_IMAGE_VERSION | 
 |  * opaque: must be initialized to NULL | 
 |  * width: image width in pixels | 
 |  * height: image height in rows | 
 |  * format: the format of the data (image and color-map) you wish to write | 
 |  * flags: set to 0 unless one of the defined flags applies; set | 
 |  *    PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB | 
 |  *    values do not correspond to the colors in sRGB. | 
 |  * colormap_entries: set to the number of entries in the color-map (0 to 256) | 
 |  */ | 
 | PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image, | 
 |    const char *file, int convert_to_8bit, const void *buffer, | 
 |    png_int_32 row_stride, const void *colormap)); | 
 |    /* Write the image to the named file. */ | 
 |  | 
 | PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file, | 
 |    int convert_to_8_bit, const void *buffer, png_int_32 row_stride, | 
 |    const void *colormap)); | 
 |    /* Write the image to the given (FILE*). */ | 
 |  | 
 | /* With both write APIs if image is in one of the linear formats with 16-bit | 
 |  * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG | 
 |  * gamma encoded according to the sRGB specification, otherwise a 16-bit linear | 
 |  * encoded PNG file is written. | 
 |  * | 
 |  * With color-mapped data formats the colormap parameter point to a color-map | 
 |  * with at least image->colormap_entries encoded in the specified format.  If | 
 |  * the format is linear the written PNG color-map will be converted to sRGB | 
 |  * regardless of the convert_to_8_bit flag. | 
 |  * | 
 |  * With all APIs row_stride is handled as in the read APIs - it is the spacing | 
 |  * from one row to the next in component sized units (1 or 2 bytes) and if | 
 |  * negative indicates a bottom-up row layout in the buffer. | 
 |  * | 
 |  * Note that the write API does not support interlacing or sub-8-bit pixels. | 
 |  */ | 
 | #endif /* PNG_SIMPLIFIED_WRITE_SUPPORTED */ | 
 | /******************************************************************************* | 
 |  *  END OF SIMPLIFIED API | 
 |  ******************************************************************************/ | 
 |  | 
 | /* Maintainer: Put new public prototypes here ^, in libpng.3, and project | 
 |  * defs | 
 |  */ | 
 |  | 
 | /* The last ordinal number (this is the *last* one already used; the next | 
 |  * one to use is one more than this.)  Maintainer, remember to add an entry to | 
 |  * scripts/symbols.def as well. | 
 |  */ | 
 | #ifdef PNG_EXPORT_LAST_ORDINAL | 
 |   PNG_EXPORT_LAST_ORDINAL(241); | 
 | #endif | 
 |  | 
 | #ifdef __cplusplus | 
 | } | 
 | #endif | 
 |  | 
 | #endif /* PNG_VERSION_INFO_ONLY */ | 
 | /* Do not put anything past this line */ | 
 | #endif /* PNG_H */ |