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  1.  
  2. /* png.h - header file for PNG reference library
  3.  *
  4.  * libpng version 1.6.5 - September 14, 2013
  5.  * Copyright (c) 1998-2013 Glenn Randers-Pehrson
  6.  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  7.  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  8.  *
  9.  * This code is released under the libpng license (See LICENSE, below)
  10.  *
  11.  * Authors and maintainers:
  12.  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  13.  *   libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
  14.  *   libpng versions 0.97, January 1998, through 1.6.5 - September 14, 2013: Glenn
  15.  *   See also "Contributing Authors", below.
  16.  *
  17.  * Note about libpng version numbers:
  18.  *
  19.  *   Due to various miscommunications, unforeseen code incompatibilities
  20.  *   and occasional factors outside the authors' control, version numbering
  21.  *   on the library has not always been consistent and straightforward.
  22.  *   The following table summarizes matters since version 0.89c, which was
  23.  *   the first widely used release:
  24.  *
  25.  *    source                 png.h  png.h  shared-lib
  26.  *    version                string   int  version
  27.  *    -------                ------ -----  ----------
  28.  *    0.89c "1.0 beta 3"     0.89      89  1.0.89
  29.  *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
  30.  *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
  31.  *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
  32.  *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
  33.  *    0.97c                  0.97      97  2.0.97
  34.  *    0.98                   0.98      98  2.0.98
  35.  *    0.99                   0.99      98  2.0.99
  36.  *    0.99a-m                0.99      99  2.0.99
  37.  *    1.00                   1.00     100  2.1.0 [100 should be 10000]
  38.  *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
  39.  *    1.0.1       png.h string is   10001  2.1.0
  40.  *    1.0.1a-e    identical to the  10002  from here on, the shared library
  41.  *    1.0.2       source version)   10002  is 2.V where V is the source code
  42.  *    1.0.2a-b                      10003  version, except as noted.
  43.  *    1.0.3                         10003
  44.  *    1.0.3a-d                      10004
  45.  *    1.0.4                         10004
  46.  *    1.0.4a-f                      10005
  47.  *    1.0.5 (+ 2 patches)           10005
  48.  *    1.0.5a-d                      10006
  49.  *    1.0.5e-r                      10100 (not source compatible)
  50.  *    1.0.5s-v                      10006 (not binary compatible)
  51.  *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)
  52.  *    1.0.6d-f                      10007 (still binary incompatible)
  53.  *    1.0.6g                        10007
  54.  *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)
  55.  *    1.0.6i                        10007  10.6i
  56.  *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
  57.  *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
  58.  *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
  59.  *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
  60.  *    1.0.7                    1    10007  (still compatible)
  61.  *    1.0.8beta1-4             1    10008  2.1.0.8beta1-4
  62.  *    1.0.8rc1                 1    10008  2.1.0.8rc1
  63.  *    1.0.8                    1    10008  2.1.0.8
  64.  *    1.0.9beta1-6             1    10009  2.1.0.9beta1-6
  65.  *    1.0.9rc1                 1    10009  2.1.0.9rc1
  66.  *    1.0.9beta7-10            1    10009  2.1.0.9beta7-10
  67.  *    1.0.9rc2                 1    10009  2.1.0.9rc2
  68.  *    1.0.9                    1    10009  2.1.0.9
  69.  *    1.0.10beta1              1    10010  2.1.0.10beta1
  70.  *    1.0.10rc1                1    10010  2.1.0.10rc1
  71.  *    1.0.10                   1    10010  2.1.0.10
  72.  *    1.0.11beta1-3            1    10011  2.1.0.11beta1-3
  73.  *    1.0.11rc1                1    10011  2.1.0.11rc1
  74.  *    1.0.11                   1    10011  2.1.0.11
  75.  *    1.0.12beta1-2            2    10012  2.1.0.12beta1-2
  76.  *    1.0.12rc1                2    10012  2.1.0.12rc1
  77.  *    1.0.12                   2    10012  2.1.0.12
  78.  *    1.1.0a-f                 -    10100  2.1.1.0a-f (branch abandoned)
  79.  *    1.2.0beta1-2             2    10200  2.1.2.0beta1-2
  80.  *    1.2.0beta3-5             3    10200  3.1.2.0beta3-5
  81.  *    1.2.0rc1                 3    10200  3.1.2.0rc1
  82.  *    1.2.0                    3    10200  3.1.2.0
  83.  *    1.2.1beta1-4             3    10201  3.1.2.1beta1-4
  84.  *    1.2.1rc1-2               3    10201  3.1.2.1rc1-2
  85.  *    1.2.1                    3    10201  3.1.2.1
  86.  *    1.2.2beta1-6            12    10202  12.so.0.1.2.2beta1-6
  87.  *    1.0.13beta1             10    10013  10.so.0.1.0.13beta1
  88.  *    1.0.13rc1               10    10013  10.so.0.1.0.13rc1
  89.  *    1.2.2rc1                12    10202  12.so.0.1.2.2rc1
  90.  *    1.0.13                  10    10013  10.so.0.1.0.13
  91.  *    1.2.2                   12    10202  12.so.0.1.2.2
  92.  *    1.2.3rc1-6              12    10203  12.so.0.1.2.3rc1-6
  93.  *    1.2.3                   12    10203  12.so.0.1.2.3
  94.  *    1.2.4beta1-3            13    10204  12.so.0.1.2.4beta1-3
  95.  *    1.0.14rc1               13    10014  10.so.0.1.0.14rc1
  96.  *    1.2.4rc1                13    10204  12.so.0.1.2.4rc1
  97.  *    1.0.14                  10    10014  10.so.0.1.0.14
  98.  *    1.2.4                   13    10204  12.so.0.1.2.4
  99.  *    1.2.5beta1-2            13    10205  12.so.0.1.2.5beta1-2
  100.  *    1.0.15rc1-3             10    10015  10.so.0.1.0.15rc1-3
  101.  *    1.2.5rc1-3              13    10205  12.so.0.1.2.5rc1-3
  102.  *    1.0.15                  10    10015  10.so.0.1.0.15
  103.  *    1.2.5                   13    10205  12.so.0.1.2.5
  104.  *    1.2.6beta1-4            13    10206  12.so.0.1.2.6beta1-4
  105.  *    1.0.16                  10    10016  10.so.0.1.0.16
  106.  *    1.2.6                   13    10206  12.so.0.1.2.6
  107.  *    1.2.7beta1-2            13    10207  12.so.0.1.2.7beta1-2
  108.  *    1.0.17rc1               10    10017  12.so.0.1.0.17rc1
  109.  *    1.2.7rc1                13    10207  12.so.0.1.2.7rc1
  110.  *    1.0.17                  10    10017  12.so.0.1.0.17
  111.  *    1.2.7                   13    10207  12.so.0.1.2.7
  112.  *    1.2.8beta1-5            13    10208  12.so.0.1.2.8beta1-5
  113.  *    1.0.18rc1-5             10    10018  12.so.0.1.0.18rc1-5
  114.  *    1.2.8rc1-5              13    10208  12.so.0.1.2.8rc1-5
  115.  *    1.0.18                  10    10018  12.so.0.1.0.18
  116.  *    1.2.8                   13    10208  12.so.0.1.2.8
  117.  *    1.2.9beta1-3            13    10209  12.so.0.1.2.9beta1-3
  118.  *    1.2.9beta4-11           13    10209  12.so.0.9[.0]
  119.  *    1.2.9rc1                13    10209  12.so.0.9[.0]
  120.  *    1.2.9                   13    10209  12.so.0.9[.0]
  121.  *    1.2.10beta1-7           13    10210  12.so.0.10[.0]
  122.  *    1.2.10rc1-2             13    10210  12.so.0.10[.0]
  123.  *    1.2.10                  13    10210  12.so.0.10[.0]
  124.  *    1.4.0beta1-5            14    10400  14.so.0.0[.0]
  125.  *    1.2.11beta1-4           13    10211  12.so.0.11[.0]
  126.  *    1.4.0beta7-8            14    10400  14.so.0.0[.0]
  127.  *    1.2.11                  13    10211  12.so.0.11[.0]
  128.  *    1.2.12                  13    10212  12.so.0.12[.0]
  129.  *    1.4.0beta9-14           14    10400  14.so.0.0[.0]
  130.  *    1.2.13                  13    10213  12.so.0.13[.0]
  131.  *    1.4.0beta15-36          14    10400  14.so.0.0[.0]
  132.  *    1.4.0beta37-87          14    10400  14.so.14.0[.0]
  133.  *    1.4.0rc01               14    10400  14.so.14.0[.0]
  134.  *    1.4.0beta88-109         14    10400  14.so.14.0[.0]
  135.  *    1.4.0rc02-08            14    10400  14.so.14.0[.0]
  136.  *    1.4.0                   14    10400  14.so.14.0[.0]
  137.  *    1.4.1beta01-03          14    10401  14.so.14.1[.0]
  138.  *    1.4.1rc01               14    10401  14.so.14.1[.0]
  139.  *    1.4.1beta04-12          14    10401  14.so.14.1[.0]
  140.  *    1.4.1                   14    10401  14.so.14.1[.0]
  141.  *    1.4.2                   14    10402  14.so.14.2[.0]
  142.  *    1.4.3                   14    10403  14.so.14.3[.0]
  143.  *    1.4.4                   14    10404  14.so.14.4[.0]
  144.  *    1.5.0beta01-58          15    10500  15.so.15.0[.0]
  145.  *    1.5.0rc01-07            15    10500  15.so.15.0[.0]
  146.  *    1.5.0                   15    10500  15.so.15.0[.0]
  147.  *    1.5.1beta01-11          15    10501  15.so.15.1[.0]
  148.  *    1.5.1rc01-02            15    10501  15.so.15.1[.0]
  149.  *    1.5.1                   15    10501  15.so.15.1[.0]
  150.  *    1.5.2beta01-03          15    10502  15.so.15.2[.0]
  151.  *    1.5.2rc01-03            15    10502  15.so.15.2[.0]
  152.  *    1.5.2                   15    10502  15.so.15.2[.0]
  153.  *    1.5.3beta01-10          15    10503  15.so.15.3[.0]
  154.  *    1.5.3rc01-02            15    10503  15.so.15.3[.0]
  155.  *    1.5.3beta11             15    10503  15.so.15.3[.0]
  156.  *    1.5.3 [omitted]
  157.  *    1.5.4beta01-08          15    10504  15.so.15.4[.0]
  158.  *    1.5.4rc01               15    10504  15.so.15.4[.0]
  159.  *    1.5.4                   15    10504  15.so.15.4[.0]
  160.  *    1.5.5beta01-08          15    10505  15.so.15.5[.0]
  161.  *    1.5.5rc01               15    10505  15.so.15.5[.0]
  162.  *    1.5.5                   15    10505  15.so.15.5[.0]
  163.  *    1.5.6beta01-07          15    10506  15.so.15.6[.0]
  164.  *    1.5.6rc01-03            15    10506  15.so.15.6[.0]
  165.  *    1.5.6                   15    10506  15.so.15.6[.0]
  166.  *    1.5.7beta01-05          15    10507  15.so.15.7[.0]
  167.  *    1.5.7rc01-03            15    10507  15.so.15.7[.0]
  168.  *    1.5.7                   15    10507  15.so.15.7[.0]
  169.  *    1.6.0beta01-40          16    10600  16.so.16.0[.0]
  170.  *    1.6.0rc01-08            16    10600  16.so.16.0[.0]
  171.  *    1.6.0                   16    10600  16.so.16.0[.0]
  172.  *    1.6.1beta01-09          16    10601  16.so.16.1[.0]
  173.  *    1.6.1rc01               16    10601  16.so.16.1[.0]
  174.  *    1.6.1                   16    10601  16.so.16.1[.0]
  175.  *    1.6.2beta01             16    10602  16.so.16.2[.0]
  176.  *    1.6.2rc01-06            16    10602  16.so.16.2[.0]
  177.  *    1.6.2                   16    10602  16.so.16.2[.0]
  178.  *    1.6.3beta01-11          16    10603  16.so.16.3[.0]
  179.  *    1.6.3rc01               16    10603  16.so.16.3[.0]
  180.  *    1.6.3                   16    10603  16.so.16.3[.0]
  181.  *    1.6.4beta01-02          16    10604  16.so.16.4[.0]
  182.  *    1.6.4rc01               16    10604  16.so.16.4[.0]
  183.  *    1.6.4                   16    10604  16.so.16.4[.0]
  184.  *    1.6.5                   16    10605  16.so.16.5[.0]
  185.  *
  186.  *   Henceforth the source version will match the shared-library major
  187.  *   and minor numbers; the shared-library major version number will be
  188.  *   used for changes in backward compatibility, as it is intended.  The
  189.  *   PNG_LIBPNG_VER macro, which is not used within libpng but is available
  190.  *   for applications, is an unsigned integer of the form xyyzz corresponding
  191.  *   to the source version x.y.z (leading zeros in y and z).  Beta versions
  192.  *   were given the previous public release number plus a letter, until
  193.  *   version 1.0.6j; from then on they were given the upcoming public
  194.  *   release number plus "betaNN" or "rcNN".
  195.  *
  196.  *   Binary incompatibility exists only when applications make direct access
  197.  *   to the info_ptr or png_ptr members through png.h, and the compiled
  198.  *   application is loaded with a different version of the library.
  199.  *
  200.  *   DLLNUM will change each time there are forward or backward changes
  201.  *   in binary compatibility (e.g., when a new feature is added).
  202.  *
  203.  * See libpng-manual.txt or libpng.3 for more information.  The PNG
  204.  * specification is available as a W3C Recommendation and as an ISO
  205.  * Specification, <http://www.w3.org/TR/2003/REC-PNG-20031110/
  206.  */
  207.  
  208. /*
  209.  * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
  210.  *
  211.  * If you modify libpng you may insert additional notices immediately following
  212.  * this sentence.
  213.  *
  214.  * This code is released under the libpng license.
  215.  *
  216.  * libpng versions 1.2.6, August 15, 2004, through 1.6.5, September 14, 2013, are
  217.  * Copyright (c) 2004, 2006-2013 Glenn Randers-Pehrson, and are
  218.  * distributed according to the same disclaimer and license as libpng-1.2.5
  219.  * with the following individual added to the list of Contributing Authors:
  220.  *
  221.  *    Cosmin Truta
  222.  *
  223.  * libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are
  224.  * Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
  225.  * distributed according to the same disclaimer and license as libpng-1.0.6
  226.  * with the following individuals added to the list of Contributing Authors:
  227.  *
  228.  *    Simon-Pierre Cadieux
  229.  *    Eric S. Raymond
  230.  *    Gilles Vollant
  231.  *
  232.  * and with the following additions to the disclaimer:
  233.  *
  234.  *    There is no warranty against interference with your enjoyment of the
  235.  *    library or against infringement.  There is no warranty that our
  236.  *    efforts or the library will fulfill any of your particular purposes
  237.  *    or needs.  This library is provided with all faults, and the entire
  238.  *    risk of satisfactory quality, performance, accuracy, and effort is with
  239.  *    the user.
  240.  *
  241.  * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
  242.  * Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson, and are
  243.  * distributed according to the same disclaimer and license as libpng-0.96,
  244.  * with the following individuals added to the list of Contributing Authors:
  245.  *
  246.  *    Tom Lane
  247.  *    Glenn Randers-Pehrson
  248.  *    Willem van Schaik
  249.  *
  250.  * libpng versions 0.89, June 1996, through 0.96, May 1997, are
  251.  * Copyright (c) 1996, 1997 Andreas Dilger
  252.  * Distributed according to the same disclaimer and license as libpng-0.88,
  253.  * with the following individuals added to the list of Contributing Authors:
  254.  *
  255.  *    John Bowler
  256.  *    Kevin Bracey
  257.  *    Sam Bushell
  258.  *    Magnus Holmgren
  259.  *    Greg Roelofs
  260.  *    Tom Tanner
  261.  *
  262.  * libpng versions 0.5, May 1995, through 0.88, January 1996, are
  263.  * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
  264.  *
  265.  * For the purposes of this copyright and license, "Contributing Authors"
  266.  * is defined as the following set of individuals:
  267.  *
  268.  *    Andreas Dilger
  269.  *    Dave Martindale
  270.  *    Guy Eric Schalnat
  271.  *    Paul Schmidt
  272.  *    Tim Wegner
  273.  *
  274.  * The PNG Reference Library is supplied "AS IS".  The Contributing Authors
  275.  * and Group 42, Inc. disclaim all warranties, expressed or implied,
  276.  * including, without limitation, the warranties of merchantability and of
  277.  * fitness for any purpose.  The Contributing Authors and Group 42, Inc.
  278.  * assume no liability for direct, indirect, incidental, special, exemplary,
  279.  * or consequential damages, which may result from the use of the PNG
  280.  * Reference Library, even if advised of the possibility of such damage.
  281.  *
  282.  * Permission is hereby granted to use, copy, modify, and distribute this
  283.  * source code, or portions hereof, for any purpose, without fee, subject
  284.  * to the following restrictions:
  285.  *
  286.  *   1. The origin of this source code must not be misrepresented.
  287.  *
  288.  *   2. Altered versions must be plainly marked as such and must not
  289.  *      be misrepresented as being the original source.
  290.  *
  291.  *   3. This Copyright notice may not be removed or altered from
  292.  *      any source or altered source distribution.
  293.  *
  294.  * The Contributing Authors and Group 42, Inc. specifically permit, without
  295.  * fee, and encourage the use of this source code as a component to
  296.  * supporting the PNG file format in commercial products.  If you use this
  297.  * source code in a product, acknowledgment is not required but would be
  298.  * appreciated.
  299.  */
  300.  
  301. /*
  302.  * A "png_get_copyright" function is available, for convenient use in "about"
  303.  * boxes and the like:
  304.  *
  305.  *     printf("%s", png_get_copyright(NULL));
  306.  *
  307.  * Also, the PNG logo (in PNG format, of course) is supplied in the
  308.  * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
  309.  */
  310.  
  311. /*
  312.  * Libpng is OSI Certified Open Source Software.  OSI Certified is a
  313.  * certification mark of the Open Source Initiative.
  314.  */
  315.  
  316. /*
  317.  * The contributing authors would like to thank all those who helped
  318.  * with testing, bug fixes, and patience.  This wouldn't have been
  319.  * possible without all of you.
  320.  *
  321.  * Thanks to Frank J. T. Wojcik for helping with the documentation.
  322.  */
  323.  
  324. /*
  325.  * Y2K compliance in libpng:
  326.  * =========================
  327.  *
  328.  *    September 14, 2013
  329.  *
  330.  *    Since the PNG Development group is an ad-hoc body, we can't make
  331.  *    an official declaration.
  332.  *
  333.  *    This is your unofficial assurance that libpng from version 0.71 and
  334.  *    upward through 1.6.5 are Y2K compliant.  It is my belief that
  335.  *    earlier versions were also Y2K compliant.
  336.  *
  337.  *    Libpng only has two year fields.  One is a 2-byte unsigned integer
  338.  *    that will hold years up to 65535.  The other, which is deprecated,
  339.  *    holds the date in text format, and will hold years up to 9999.
  340.  *
  341.  *    The integer is
  342.  *        "png_uint_16 year" in png_time_struct.
  343.  *
  344.  *    The string is
  345.  *        "char time_buffer[29]" in png_struct.  This is no longer used
  346.  *    in libpng-1.6.x and will be removed from libpng-1.7.0.
  347.  *
  348.  *    There are seven time-related functions:
  349.  *        png.c: png_convert_to_rfc_1123_buffer() in png.c
  350.  *          (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
  351.  *          png_convert_to_rfc_1152() in error prior to libpng-0.98)
  352.  *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
  353.  *        png_convert_from_time_t() in pngwrite.c
  354.  *        png_get_tIME() in pngget.c
  355.  *        png_handle_tIME() in pngrutil.c, called in pngread.c
  356.  *        png_set_tIME() in pngset.c
  357.  *        png_write_tIME() in pngwutil.c, called in pngwrite.c
  358.  *
  359.  *    All handle dates properly in a Y2K environment.  The
  360.  *    png_convert_from_time_t() function calls gmtime() to convert from system
  361.  *    clock time, which returns (year - 1900), which we properly convert to
  362.  *    the full 4-digit year.  There is a possibility that libpng applications
  363.  *    are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
  364.  *    function, or that they are incorrectly passing only a 2-digit year
  365.  *    instead of "year - 1900" into the png_convert_from_struct_tm() function,
  366.  *    but this is not under our control.  The libpng documentation has always
  367.  *    stated that it works with 4-digit years, and the APIs have been
  368.  *    documented as such.
  369.  *
  370.  *    The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
  371.  *    integer to hold the year, and can hold years as large as 65535.
  372.  *
  373.  *    zlib, upon which libpng depends, is also Y2K compliant.  It contains
  374.  *    no date-related code.
  375.  *
  376.  *       Glenn Randers-Pehrson
  377.  *       libpng maintainer
  378.  *       PNG Development Group
  379.  */
  380.  
  381. #ifndef PNG_H
  382. #define PNG_H
  383.  
  384. /* This is not the place to learn how to use libpng. The file libpng-manual.txt
  385.  * describes how to use libpng, and the file example.c summarizes it
  386.  * with some code on which to build.  This file is useful for looking
  387.  * at the actual function definitions and structure components.
  388.  *
  389.  * If you just need to read a PNG file and don't want to read the documentation
  390.  * skip to the end of this file and read the section entitled 'simplified API'.
  391.  */
  392.  
  393. /* Version information for png.h - this should match the version in png.c */
  394. #define PNG_LIBPNG_VER_STRING "1.6.5"
  395. #define PNG_HEADER_VERSION_STRING \
  396.      " libpng version 1.6.5 - September 14, 2013\n"
  397.  
  398. #define PNG_LIBPNG_VER_SONUM   16
  399. #define PNG_LIBPNG_VER_DLLNUM  16
  400.  
  401. /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
  402. #define PNG_LIBPNG_VER_MAJOR   1
  403. #define PNG_LIBPNG_VER_MINOR   6
  404. #define PNG_LIBPNG_VER_RELEASE 5
  405.  
  406. /* This should match the numeric part of the final component of
  407.  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
  408.  */
  409.  
  410. #define PNG_LIBPNG_VER_BUILD  0
  411.  
  412. /* Release Status */
  413. #define PNG_LIBPNG_BUILD_ALPHA    1
  414. #define PNG_LIBPNG_BUILD_BETA     2
  415. #define PNG_LIBPNG_BUILD_RC       3
  416. #define PNG_LIBPNG_BUILD_STABLE   4
  417. #define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7
  418.  
  419. /* Release-Specific Flags */
  420. #define PNG_LIBPNG_BUILD_PATCH    8 /* Can be OR'ed with
  421.                                        PNG_LIBPNG_BUILD_STABLE only */
  422. #define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with
  423.                                        PNG_LIBPNG_BUILD_SPECIAL */
  424. #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
  425.                                        PNG_LIBPNG_BUILD_PRIVATE */
  426.  
  427. #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
  428.  
  429. /* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
  430.  * We must not include leading zeros.
  431.  * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
  432.  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
  433.  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
  434.  */
  435. #define PNG_LIBPNG_VER 10605 /* 1.6.5 */
  436.  
  437. /* Library configuration: these options cannot be changed after
  438.  * the library has been built.
  439.  */
  440. #ifndef PNGLCONF_H
  441.     /* If pnglibconf.h is missing, you can
  442.      * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
  443.      */
  444. #   include "pnglibconf.h"
  445. #endif
  446.  
  447. #ifndef PNG_VERSION_INFO_ONLY
  448.    /* Machine specific configuration. */
  449. #  include "pngconf.h"
  450. #endif
  451.  
  452. /*
  453.  * Added at libpng-1.2.8
  454.  *
  455.  * Ref MSDN: Private as priority over Special
  456.  * VS_FF_PRIVATEBUILD File *was not* built using standard release
  457.  * procedures. If this value is given, the StringFileInfo block must
  458.  * contain a PrivateBuild string.
  459.  *
  460.  * VS_FF_SPECIALBUILD File *was* built by the original company using
  461.  * standard release procedures but is a variation of the standard
  462.  * file of the same version number. If this value is given, the
  463.  * StringFileInfo block must contain a SpecialBuild string.
  464.  */
  465.  
  466. #ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */
  467. #  define PNG_LIBPNG_BUILD_TYPE \
  468.        (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
  469. #else
  470. #  ifdef PNG_LIBPNG_SPECIALBUILD
  471. #    define PNG_LIBPNG_BUILD_TYPE \
  472.          (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
  473. #  else
  474. #    define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)
  475. #  endif
  476. #endif
  477.  
  478. #ifndef PNG_VERSION_INFO_ONLY
  479.  
  480. /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
  481. #ifdef __cplusplus
  482. extern "C" {
  483. #endif /* __cplusplus */
  484.  
  485. /* Version information for C files, stored in png.c.  This had better match
  486.  * the version above.
  487.  */
  488. #define png_libpng_ver png_get_header_ver(NULL)
  489.  
  490. /* This file is arranged in several sections:
  491.  *
  492.  * 1. Any configuration options that can be specified by for the application
  493.  *    code when it is built.  (Build time configuration is in pnglibconf.h)
  494.  * 2. Type definitions (base types are defined in pngconf.h), structure
  495.  *    definitions.
  496.  * 3. Exported library functions.
  497.  * 4. Simplified API.
  498.  *
  499.  * The library source code has additional files (principally pngpriv.h) that
  500.  * allow configuration of the library.
  501.  */
  502. /* Section 1: run time configuration
  503.  * See pnglibconf.h for build time configuration
  504.  *
  505.  * Run time configuration allows the application to choose between
  506.  * implementations of certain arithmetic APIs.  The default is set
  507.  * at build time and recorded in pnglibconf.h, but it is safe to
  508.  * override these (and only these) settings.  Note that this won't
  509.  * change what the library does, only application code, and the
  510.  * settings can (and probably should) be made on a per-file basis
  511.  * by setting the #defines before including png.h
  512.  *
  513.  * Use macros to read integers from PNG data or use the exported
  514.  * functions?
  515.  *   PNG_USE_READ_MACROS: use the macros (see below)  Note that
  516.  *     the macros evaluate their argument multiple times.
  517.  *   PNG_NO_USE_READ_MACROS: call the relevant library function.
  518.  *
  519.  * Use the alternative algorithm for compositing alpha samples that
  520.  * does not use division?
  521.  *   PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division'
  522.  *      algorithm.
  523.  *   PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm.
  524.  *
  525.  * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is
  526.  * false?
  527.  *   PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error
  528.  *      APIs to png_warning.
  529.  * Otherwise the calls are mapped to png_error.
  530.  */
  531.  
  532. /* Section 2: type definitions, including structures and compile time
  533.  * constants.
  534.  * See pngconf.h for base types that vary by machine/system
  535.  */
  536.  
  537. /* This triggers a compiler error in png.c, if png.c and png.h
  538.  * do not agree upon the version number.
  539.  */
  540. typedef char* png_libpng_version_1_6_5;
  541.  
  542. /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
  543.  *
  544.  * png_struct is the cache of information used while reading or writing a single
  545.  * PNG file.  One of these is always required, although the simplified API
  546.  * (below) hides the creation and destruction of it.
  547.  */
  548. typedef struct png_struct_def png_struct;
  549. typedef const png_struct * png_const_structp;
  550. typedef png_struct * png_structp;
  551. typedef png_struct * * png_structpp;
  552.  
  553. /* png_info contains information read from or to be written to a PNG file.  One
  554.  * or more of these must exist while reading or creating a PNG file.  The
  555.  * information is not used by libpng during read but is used to control what
  556.  * gets written when a PNG file is created.  "png_get_" function calls read
  557.  * information during read and "png_set_" functions calls write information
  558.  * when creating a PNG.
  559.  * been moved into a separate header file that is not accessible to
  560.  * applications.  Read libpng-manual.txt or libpng.3 for more info.
  561.  */
  562. typedef struct png_info_def png_info;
  563. typedef png_info * png_infop;
  564. typedef const png_info * png_const_infop;
  565. typedef png_info * * png_infopp;
  566.  
  567. /* Types with names ending 'p' are pointer types.  The corresponding types with
  568.  * names ending 'rp' are identical pointer types except that the pointer is
  569.  * marked 'restrict', which means that it is the only pointer to the object
  570.  * passed to the function.  Applications should not use the 'restrict' types;
  571.  * it is always valid to pass 'p' to a pointer with a function argument of the
  572.  * corresponding 'rp' type.  Different compilers have different rules with
  573.  * regard to type matching in the presence of 'restrict'.  For backward
  574.  * compatibility libpng callbacks never have 'restrict' in their parameters and,
  575.  * consequentially, writing portable application code is extremely difficult if
  576.  * an attempt is made to use 'restrict'.
  577.  */
  578. typedef png_struct * PNG_RESTRICT png_structrp;
  579. typedef const png_struct * PNG_RESTRICT png_const_structrp;
  580. typedef png_info * PNG_RESTRICT png_inforp;
  581. typedef const png_info * PNG_RESTRICT png_const_inforp;
  582.  
  583. /* Three color definitions.  The order of the red, green, and blue, (and the
  584.  * exact size) is not important, although the size of the fields need to
  585.  * be png_byte or png_uint_16 (as defined below).
  586.  */
  587. typedef struct png_color_struct
  588. {
  589.    png_byte red;
  590.    png_byte green;
  591.    png_byte blue;
  592. } png_color;
  593. typedef png_color * png_colorp;
  594. typedef const png_color * png_const_colorp;
  595. typedef png_color * * png_colorpp;
  596.  
  597. typedef struct png_color_16_struct
  598. {
  599.    png_byte index;    /* used for palette files */
  600.    png_uint_16 red;   /* for use in red green blue files */
  601.    png_uint_16 green;
  602.    png_uint_16 blue;
  603.    png_uint_16 gray;  /* for use in grayscale files */
  604. } png_color_16;
  605. typedef png_color_16 * png_color_16p;
  606. typedef const png_color_16 * png_const_color_16p;
  607. typedef png_color_16 * * png_color_16pp;
  608.  
  609. typedef struct png_color_8_struct
  610. {
  611.    png_byte red;   /* for use in red green blue files */
  612.    png_byte green;
  613.    png_byte blue;
  614.    png_byte gray;  /* for use in grayscale files */
  615.    png_byte alpha; /* for alpha channel files */
  616. } png_color_8;
  617. typedef png_color_8 * png_color_8p;
  618. typedef const png_color_8 * png_const_color_8p;
  619. typedef png_color_8 * * png_color_8pp;
  620.  
  621. /*
  622.  * The following two structures are used for the in-core representation
  623.  * of sPLT chunks.
  624.  */
  625. typedef struct png_sPLT_entry_struct
  626. {
  627.    png_uint_16 red;
  628.    png_uint_16 green;
  629.    png_uint_16 blue;
  630.    png_uint_16 alpha;
  631.    png_uint_16 frequency;
  632. } png_sPLT_entry;
  633. typedef png_sPLT_entry * png_sPLT_entryp;
  634. typedef const png_sPLT_entry * png_const_sPLT_entryp;
  635. typedef png_sPLT_entry * * png_sPLT_entrypp;
  636.  
  637. /*  When the depth of the sPLT palette is 8 bits, the color and alpha samples
  638.  *  occupy the LSB of their respective members, and the MSB of each member
  639.  *  is zero-filled.  The frequency member always occupies the full 16 bits.
  640.  */
  641.  
  642. typedef struct png_sPLT_struct
  643. {
  644.    png_charp name;           /* palette name */
  645.    png_byte depth;           /* depth of palette samples */
  646.    png_sPLT_entryp entries;  /* palette entries */
  647.    png_int_32 nentries;      /* number of palette entries */
  648. } png_sPLT_t;
  649. typedef png_sPLT_t * png_sPLT_tp;
  650. typedef const png_sPLT_t * png_const_sPLT_tp;
  651. typedef png_sPLT_t * * png_sPLT_tpp;
  652.  
  653. #ifdef PNG_TEXT_SUPPORTED
  654. /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
  655.  * and whether that contents is compressed or not.  The "key" field
  656.  * points to a regular zero-terminated C string.  The "text" fields can be a
  657.  * regular C string, an empty string, or a NULL pointer.
  658.  * However, the structure returned by png_get_text() will always contain
  659.  * the "text" field as a regular zero-terminated C string (possibly
  660.  * empty), never a NULL pointer, so it can be safely used in printf() and
  661.  * other string-handling functions.  Note that the "itxt_length", "lang", and
  662.  * "lang_key" members of the structure only exist when the library is built
  663.  * with iTXt chunk support.  Prior to libpng-1.4.0 the library was built by
  664.  * default without iTXt support. Also note that when iTXt *is* supported,
  665.  * the "lang" and "lang_key" fields contain NULL pointers when the
  666.  * "compression" field contains * PNG_TEXT_COMPRESSION_NONE or
  667.  * PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the
  668.  * same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag"
  669.  * which is always 0 or 1, or its "compression method" which is always 0.
  670.  */
  671. typedef struct png_text_struct
  672. {
  673.    int  compression;       /* compression value:
  674.                              -1: tEXt, none
  675.                               0: zTXt, deflate
  676.                               1: iTXt, none
  677.                               2: iTXt, deflate  */
  678.    png_charp key;          /* keyword, 1-79 character description of "text" */
  679.    png_charp text;         /* comment, may be an empty string (ie "")
  680.                               or a NULL pointer */
  681.    png_size_t text_length; /* length of the text string */
  682.    png_size_t itxt_length; /* length of the itxt string */
  683.    png_charp lang;         /* language code, 0-79 characters
  684.                               or a NULL pointer */
  685.    png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more
  686.                               chars or a NULL pointer */
  687. } png_text;
  688. typedef png_text * png_textp;
  689. typedef const png_text * png_const_textp;
  690. typedef png_text * * png_textpp;
  691. #endif
  692.  
  693. /* Supported compression types for text in PNG files (tEXt, and zTXt).
  694.  * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
  695. #define PNG_TEXT_COMPRESSION_NONE_WR -3
  696. #define PNG_TEXT_COMPRESSION_zTXt_WR -2
  697. #define PNG_TEXT_COMPRESSION_NONE    -1
  698. #define PNG_TEXT_COMPRESSION_zTXt     0
  699. #define PNG_ITXT_COMPRESSION_NONE     1
  700. #define PNG_ITXT_COMPRESSION_zTXt     2
  701. #define PNG_TEXT_COMPRESSION_LAST     3  /* Not a valid value */
  702.  
  703. /* png_time is a way to hold the time in an machine independent way.
  704.  * Two conversions are provided, both from time_t and struct tm.  There
  705.  * is no portable way to convert to either of these structures, as far
  706.  * as I know.  If you know of a portable way, send it to me.  As a side
  707.  * note - PNG has always been Year 2000 compliant!
  708.  */
  709. typedef struct png_time_struct
  710. {
  711.    png_uint_16 year; /* full year, as in, 1995 */
  712.    png_byte month;   /* month of year, 1 - 12 */
  713.    png_byte day;     /* day of month, 1 - 31 */
  714.    png_byte hour;    /* hour of day, 0 - 23 */
  715.    png_byte minute;  /* minute of hour, 0 - 59 */
  716.    png_byte second;  /* second of minute, 0 - 60 (for leap seconds) */
  717. } png_time;
  718. typedef png_time * png_timep;
  719. typedef const png_time * png_const_timep;
  720. typedef png_time * * png_timepp;
  721.  
  722. #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
  723. /* png_unknown_chunk is a structure to hold queued chunks for which there is
  724.  * no specific support.  The idea is that we can use this to queue
  725.  * up private chunks for output even though the library doesn't actually
  726.  * know about their semantics.
  727.  *
  728.  * The data in the structure is set by libpng on read and used on write.
  729.  */
  730. typedef struct png_unknown_chunk_t
  731. {
  732.     png_byte name[5]; /* Textual chunk name with '\0' terminator */
  733.     png_byte *data;   /* Data, should not be modified on read! */
  734.     png_size_t size;
  735.  
  736.     /* On write 'location' must be set using the flag values listed below.
  737.      * Notice that on read it is set by libpng however the values stored have
  738.      * more bits set than are listed below.  Always treat the value as a
  739.      * bitmask.  On write set only one bit - setting multiple bits may cause the
  740.      * chunk to be written in multiple places.
  741.      */
  742.     png_byte location; /* mode of operation at read time */
  743. }
  744. png_unknown_chunk;
  745.  
  746. typedef png_unknown_chunk * png_unknown_chunkp;
  747. typedef const png_unknown_chunk * png_const_unknown_chunkp;
  748. typedef png_unknown_chunk * * png_unknown_chunkpp;
  749. #endif
  750.  
  751. /* Flag values for the unknown chunk location byte. */
  752. #define PNG_HAVE_IHDR  0x01
  753. #define PNG_HAVE_PLTE  0x02
  754. #define PNG_AFTER_IDAT 0x08
  755.  
  756. /* Maximum positive integer used in PNG is (2^31)-1 */
  757. #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
  758. #define PNG_UINT_32_MAX ((png_uint_32)(-1))
  759. #define PNG_SIZE_MAX ((png_size_t)(-1))
  760.  
  761. /* These are constants for fixed point values encoded in the
  762.  * PNG specification manner (x100000)
  763.  */
  764. #define PNG_FP_1    100000
  765. #define PNG_FP_HALF  50000
  766. #define PNG_FP_MAX  ((png_fixed_point)0x7fffffffL)
  767. #define PNG_FP_MIN  (-PNG_FP_MAX)
  768.  
  769. /* These describe the color_type field in png_info. */
  770. /* color type masks */
  771. #define PNG_COLOR_MASK_PALETTE    1
  772. #define PNG_COLOR_MASK_COLOR      2
  773. #define PNG_COLOR_MASK_ALPHA      4
  774.  
  775. /* color types.  Note that not all combinations are legal */
  776. #define PNG_COLOR_TYPE_GRAY 0
  777. #define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
  778. #define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)
  779. #define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
  780. #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
  781. /* aliases */
  782. #define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA
  783. #define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA
  784.  
  785. /* This is for compression type. PNG 1.0-1.2 only define the single type. */
  786. #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
  787. #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE
  788.  
  789. /* This is for filter type. PNG 1.0-1.2 only define the single type. */
  790. #define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */
  791. #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
  792. #define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE
  793.  
  794. /* These are for the interlacing type.  These values should NOT be changed. */
  795. #define PNG_INTERLACE_NONE        0 /* Non-interlaced image */
  796. #define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */
  797. #define PNG_INTERLACE_LAST        2 /* Not a valid value */
  798.  
  799. /* These are for the oFFs chunk.  These values should NOT be changed. */
  800. #define PNG_OFFSET_PIXEL          0 /* Offset in pixels */
  801. #define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */
  802. #define PNG_OFFSET_LAST           2 /* Not a valid value */
  803.  
  804. /* These are for the pCAL chunk.  These values should NOT be changed. */
  805. #define PNG_EQUATION_LINEAR       0 /* Linear transformation */
  806. #define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */
  807. #define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */
  808. #define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */
  809. #define PNG_EQUATION_LAST         4 /* Not a valid value */
  810.  
  811. /* These are for the sCAL chunk.  These values should NOT be changed. */
  812. #define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */
  813. #define PNG_SCALE_METER           1 /* meters per pixel */
  814. #define PNG_SCALE_RADIAN          2 /* radians per pixel */
  815. #define PNG_SCALE_LAST            3 /* Not a valid value */
  816.  
  817. /* These are for the pHYs chunk.  These values should NOT be changed. */
  818. #define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */
  819. #define PNG_RESOLUTION_METER      1 /* pixels/meter */
  820. #define PNG_RESOLUTION_LAST       2 /* Not a valid value */
  821.  
  822. /* These are for the sRGB chunk.  These values should NOT be changed. */
  823. #define PNG_sRGB_INTENT_PERCEPTUAL 0
  824. #define PNG_sRGB_INTENT_RELATIVE   1
  825. #define PNG_sRGB_INTENT_SATURATION 2
  826. #define PNG_sRGB_INTENT_ABSOLUTE   3
  827. #define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */
  828.  
  829. /* This is for text chunks */
  830. #define PNG_KEYWORD_MAX_LENGTH     79
  831.  
  832. /* Maximum number of entries in PLTE/sPLT/tRNS arrays */
  833. #define PNG_MAX_PALETTE_LENGTH    256
  834.  
  835. /* These determine if an ancillary chunk's data has been successfully read
  836.  * from the PNG header, or if the application has filled in the corresponding
  837.  * data in the info_struct to be written into the output file.  The values
  838.  * of the PNG_INFO_<chunk> defines should NOT be changed.
  839.  */
  840. #define PNG_INFO_gAMA 0x0001
  841. #define PNG_INFO_sBIT 0x0002
  842. #define PNG_INFO_cHRM 0x0004
  843. #define PNG_INFO_PLTE 0x0008
  844. #define PNG_INFO_tRNS 0x0010
  845. #define PNG_INFO_bKGD 0x0020
  846. #define PNG_INFO_hIST 0x0040
  847. #define PNG_INFO_pHYs 0x0080
  848. #define PNG_INFO_oFFs 0x0100
  849. #define PNG_INFO_tIME 0x0200
  850. #define PNG_INFO_pCAL 0x0400
  851. #define PNG_INFO_sRGB 0x0800   /* GR-P, 0.96a */
  852. #define PNG_INFO_iCCP 0x1000   /* ESR, 1.0.6 */
  853. #define PNG_INFO_sPLT 0x2000   /* ESR, 1.0.6 */
  854. #define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */
  855. #define PNG_INFO_IDAT 0x8000   /* ESR, 1.0.6 */
  856.  
  857. /* This is used for the transformation routines, as some of them
  858.  * change these values for the row.  It also should enable using
  859.  * the routines for other purposes.
  860.  */
  861. typedef struct png_row_info_struct
  862. {
  863.    png_uint_32 width;    /* width of row */
  864.    png_size_t rowbytes;  /* number of bytes in row */
  865.    png_byte color_type;  /* color type of row */
  866.    png_byte bit_depth;   /* bit depth of row */
  867.    png_byte channels;    /* number of channels (1, 2, 3, or 4) */
  868.    png_byte pixel_depth; /* bits per pixel (depth * channels) */
  869. } png_row_info;
  870.  
  871. typedef png_row_info * png_row_infop;
  872. typedef png_row_info * * png_row_infopp;
  873.  
  874. /* These are the function types for the I/O functions and for the functions
  875.  * that allow the user to override the default I/O functions with his or her
  876.  * own.  The png_error_ptr type should match that of user-supplied warning
  877.  * and error functions, while the png_rw_ptr type should match that of the
  878.  * user read/write data functions.  Note that the 'write' function must not
  879.  * modify the buffer it is passed. The 'read' function, on the other hand, is
  880.  * expected to return the read data in the buffer.
  881.  */
  882. typedef PNG_CALLBACK(void, *png_error_ptr, (png_structp, png_const_charp));
  883. typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, png_size_t));
  884. typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp));
  885. typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32,
  886.     int));
  887. typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32,
  888.     int));
  889.  
  890. #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
  891. typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
  892. typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
  893.  
  894. /* The following callback receives png_uint_32 row_number, int pass for the
  895.  * png_bytep data of the row.  When transforming an interlaced image the
  896.  * row number is the row number within the sub-image of the interlace pass, so
  897.  * the value will increase to the height of the sub-image (not the full image)
  898.  * then reset to 0 for the next pass.
  899.  *
  900.  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
  901.  * find the output pixel (x,y) given an interlaced sub-image pixel
  902.  * (row,col,pass).  (See below for these macros.)
  903.  */
  904. typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp, png_bytep,
  905.     png_uint_32, int));
  906. #endif
  907.  
  908. #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
  909.     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
  910. typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop,
  911.     png_bytep));
  912. #endif
  913.  
  914. #ifdef PNG_USER_CHUNKS_SUPPORTED
  915. typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,
  916.     png_unknown_chunkp));
  917. #endif
  918. #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
  919. /* not used anywhere */
  920. /* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
  921. #endif
  922.  
  923. #ifdef PNG_SETJMP_SUPPORTED
  924. /* This must match the function definition in <setjmp.h>, and the application
  925.  * must include this before png.h to obtain the definition of jmp_buf.  The
  926.  * function is required to be PNG_NORETURN, but this is not checked.  If the
  927.  * function does return the application will crash via an abort() or similar
  928.  * system level call.
  929.  *
  930.  * If you get a warning here while building the library you may need to make
  931.  * changes to ensure that pnglibconf.h records the calling convention used by
  932.  * your compiler.  This may be very difficult - try using a different compiler
  933.  * to build the library!
  934.  */
  935. PNG_FUNCTION(void, (PNGCAPI *png_longjmp_ptr), PNGARG((jmp_buf, int)), typedef);
  936. #endif
  937.  
  938. /* Transform masks for the high-level interface */
  939. #define PNG_TRANSFORM_IDENTITY       0x0000    /* read and write */
  940. #define PNG_TRANSFORM_STRIP_16       0x0001    /* read only */
  941. #define PNG_TRANSFORM_STRIP_ALPHA    0x0002    /* read only */
  942. #define PNG_TRANSFORM_PACKING        0x0004    /* read and write */
  943. #define PNG_TRANSFORM_PACKSWAP       0x0008    /* read and write */
  944. #define PNG_TRANSFORM_EXPAND         0x0010    /* read only */
  945. #define PNG_TRANSFORM_INVERT_MONO    0x0020    /* read and write */
  946. #define PNG_TRANSFORM_SHIFT          0x0040    /* read and write */
  947. #define PNG_TRANSFORM_BGR            0x0080    /* read and write */
  948. #define PNG_TRANSFORM_SWAP_ALPHA     0x0100    /* read and write */
  949. #define PNG_TRANSFORM_SWAP_ENDIAN    0x0200    /* read and write */
  950. #define PNG_TRANSFORM_INVERT_ALPHA   0x0400    /* read and write */
  951. #define PNG_TRANSFORM_STRIP_FILLER   0x0800    /* write only */
  952. /* Added to libpng-1.2.34 */
  953. #define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER
  954. #define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */
  955. /* Added to libpng-1.4.0 */
  956. #define PNG_TRANSFORM_GRAY_TO_RGB   0x2000      /* read only */
  957. /* Added to libpng-1.5.4 */
  958. #define PNG_TRANSFORM_EXPAND_16     0x4000      /* read only */
  959. #define PNG_TRANSFORM_SCALE_16      0x8000      /* read only */
  960.  
  961. /* Flags for MNG supported features */
  962. #define PNG_FLAG_MNG_EMPTY_PLTE     0x01
  963. #define PNG_FLAG_MNG_FILTER_64      0x04
  964. #define PNG_ALL_MNG_FEATURES        0x05
  965.  
  966. /* NOTE: prior to 1.5 these functions had no 'API' style declaration,
  967.  * this allowed the zlib default functions to be used on Windows
  968.  * platforms.  In 1.5 the zlib default malloc (which just calls malloc and
  969.  * ignores the first argument) should be completely compatible with the
  970.  * following.
  971.  */
  972. typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,
  973.     png_alloc_size_t));
  974. typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));
  975.  
  976. /* Section 3: exported functions
  977.  * Here are the function definitions most commonly used.  This is not
  978.  * the place to find out how to use libpng.  See libpng-manual.txt for the
  979.  * full explanation, see example.c for the summary.  This just provides
  980.  * a simple one line description of the use of each function.
  981.  *
  982.  * The PNG_EXPORT() and PNG_EXPORTA() macros used below are defined in
  983.  * pngconf.h and in the *.dfn files in the scripts directory.
  984.  *
  985.  *   PNG_EXPORT(ordinal, type, name, (args));
  986.  *
  987.  *       ordinal:    ordinal that is used while building
  988.  *                   *.def files. The ordinal value is only
  989.  *                   relevant when preprocessing png.h with
  990.  *                   the *.dfn files for building symbol table
  991.  *                   entries, and are removed by pngconf.h.
  992.  *       type:       return type of the function
  993.  *       name:       function name
  994.  *       args:       function arguments, with types
  995.  *
  996.  * When we wish to append attributes to a function prototype we use
  997.  * the PNG_EXPORTA() macro instead.
  998.  *
  999.  *   PNG_EXPORTA(ordinal, type, name, (args), attributes);
  1000.  *
  1001.  *       ordinal, type, name, and args: same as in PNG_EXPORT().
  1002.  *       attributes: function attributes
  1003.  */
  1004.  
  1005. /* Returns the version number of the library */
  1006. PNG_EXPORT(1, png_uint_32, png_access_version_number, (void));
  1007.  
  1008. /* Tell lib we have already handled the first <num_bytes> magic bytes.
  1009.  * Handling more than 8 bytes from the beginning of the file is an error.
  1010.  */
  1011. PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
  1012.  
  1013. /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
  1014.  * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG
  1015.  * signature, and non-zero otherwise.  Having num_to_check == 0 or
  1016.  * start > 7 will always fail (ie return non-zero).
  1017.  */
  1018. PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, png_size_t start,
  1019.     png_size_t num_to_check));
  1020.  
  1021. /* Simple signature checking function.  This is the same as calling
  1022.  * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
  1023.  */
  1024. #define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
  1025.  
  1026. /* Allocate and initialize png_ptr struct for reading, and any other memory. */
  1027. PNG_EXPORTA(4, png_structp, png_create_read_struct,
  1028.     (png_const_charp user_png_ver, png_voidp error_ptr,
  1029.     png_error_ptr error_fn, png_error_ptr warn_fn),
  1030.     PNG_ALLOCATED);
  1031.  
  1032. /* Allocate and initialize png_ptr struct for writing, and any other memory */
  1033. PNG_EXPORTA(5, png_structp, png_create_write_struct,
  1034.     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
  1035.     png_error_ptr warn_fn),
  1036.     PNG_ALLOCATED);
  1037.  
  1038. PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
  1039.     (png_const_structrp png_ptr));
  1040.  
  1041. PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
  1042.     png_size_t size));
  1043.  
  1044. /* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
  1045.  * match up.
  1046.  */
  1047. #ifdef PNG_SETJMP_SUPPORTED
  1048. /* This function returns the jmp_buf built in to *png_ptr.  It must be
  1049.  * supplied with an appropriate 'longjmp' function to use on that jmp_buf
  1050.  * unless the default error function is overridden in which case NULL is
  1051.  * acceptable.  The size of the jmp_buf is checked against the actual size
  1052.  * allocated by the library - the call will return NULL on a mismatch
  1053.  * indicating an ABI mismatch.
  1054.  */
  1055. PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structrp png_ptr,
  1056.     png_longjmp_ptr longjmp_fn, size_t jmp_buf_size));
  1057. #  define png_jmpbuf(png_ptr) \
  1058.       (*png_set_longjmp_fn((png_ptr), longjmp, (sizeof (jmp_buf))))
  1059. #else
  1060. #  define png_jmpbuf(png_ptr) \
  1061.       (LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP)
  1062. #endif
  1063. /* This function should be used by libpng applications in place of
  1064.  * longjmp(png_ptr->jmpbuf, val).  If longjmp_fn() has been set, it
  1065.  * will use it; otherwise it will call PNG_ABORT().  This function was
  1066.  * added in libpng-1.5.0.
  1067.  */
  1068. PNG_EXPORTA(9, void, png_longjmp, (png_const_structrp png_ptr, int val),
  1069.     PNG_NORETURN);
  1070.  
  1071. #ifdef PNG_READ_SUPPORTED
  1072. /* Reset the compression stream */
  1073. PNG_EXPORTA(10, int, png_reset_zstream, (png_structrp png_ptr), PNG_DEPRECATED);
  1074. #endif
  1075.  
  1076. /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
  1077. #ifdef PNG_USER_MEM_SUPPORTED
  1078. PNG_EXPORTA(11, png_structp, png_create_read_struct_2,
  1079.     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
  1080.     png_error_ptr warn_fn,
  1081.     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
  1082.     PNG_ALLOCATED);
  1083. PNG_EXPORTA(12, png_structp, png_create_write_struct_2,
  1084.     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
  1085.     png_error_ptr warn_fn,
  1086.     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
  1087.     PNG_ALLOCATED);
  1088. #endif
  1089.  
  1090. /* Write the PNG file signature. */
  1091. PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr));
  1092.  
  1093. /* Write a PNG chunk - size, type, (optional) data, CRC. */
  1094. PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep
  1095.     chunk_name, png_const_bytep data, png_size_t length));
  1096.  
  1097. /* Write the start of a PNG chunk - length and chunk name. */
  1098. PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
  1099.     png_const_bytep chunk_name, png_uint_32 length));
  1100.  
  1101. /* Write the data of a PNG chunk started with png_write_chunk_start(). */
  1102. PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr,
  1103.     png_const_bytep data, png_size_t length));
  1104.  
  1105. /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
  1106. PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr));
  1107.  
  1108. /* Allocate and initialize the info structure */
  1109. PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr),
  1110.     PNG_ALLOCATED);
  1111.  
  1112. /* DEPRECATED: this function allowed init structures to be created using the
  1113.  * default allocation method (typically malloc).  Use is deprecated in 1.6.0 and
  1114.  * the API will be removed in the future.
  1115.  */
  1116. PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr,
  1117.     png_size_t png_info_struct_size), PNG_DEPRECATED);
  1118.  
  1119. /* Writes all the PNG information before the image. */
  1120. PNG_EXPORT(20, void, png_write_info_before_PLTE,
  1121.     (png_structrp png_ptr, png_const_inforp info_ptr));
  1122. PNG_EXPORT(21, void, png_write_info,
  1123.     (png_structrp png_ptr, png_const_inforp info_ptr));
  1124.  
  1125. #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
  1126. /* Read the information before the actual image data. */
  1127. PNG_EXPORT(22, void, png_read_info,
  1128.     (png_structrp png_ptr, png_inforp info_ptr));
  1129. #endif
  1130.  
  1131. #ifdef PNG_TIME_RFC1123_SUPPORTED
  1132.    /* Convert to a US string format: there is no localization support in this
  1133.     * routine.  The original implementation used a 29 character buffer in
  1134.     * png_struct, this will be removed in future versions.
  1135.     */
  1136. #if PNG_LIBPNG_VER < 10700
  1137. /* To do: remove this from libpng17 (and from libpng17/png.c and pngstruct.h) */
  1138. PNG_EXPORTA(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr,
  1139.     png_const_timep ptime),PNG_DEPRECATED);
  1140. #endif
  1141. PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29],
  1142.     png_const_timep ptime));
  1143. #endif
  1144.  
  1145. #ifdef PNG_CONVERT_tIME_SUPPORTED
  1146. /* Convert from a struct tm to png_time */
  1147. PNG_EXPORT(24, void, png_convert_from_struct_tm, (png_timep ptime,
  1148.     const struct tm * ttime));
  1149.  
  1150. /* Convert from time_t to png_time.  Uses gmtime() */
  1151. PNG_EXPORT(25, void, png_convert_from_time_t, (png_timep ptime, time_t ttime));
  1152. #endif /* PNG_CONVERT_tIME_SUPPORTED */
  1153.  
  1154. #ifdef PNG_READ_EXPAND_SUPPORTED
  1155. /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
  1156. PNG_EXPORT(26, void, png_set_expand, (png_structrp png_ptr));
  1157. PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structrp png_ptr));
  1158. PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structrp png_ptr));
  1159. PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structrp png_ptr));
  1160. #endif
  1161.  
  1162. #ifdef PNG_READ_EXPAND_16_SUPPORTED
  1163. /* Expand to 16-bit channels, forces conversion of palette to RGB and expansion
  1164.  * of a tRNS chunk if present.
  1165.  */
  1166. PNG_EXPORT(221, void, png_set_expand_16, (png_structrp png_ptr));
  1167. #endif
  1168.  
  1169. #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
  1170. /* Use blue, green, red order for pixels. */
  1171. PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr));
  1172. #endif
  1173.  
  1174. #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
  1175. /* Expand the grayscale to 24-bit RGB if necessary. */
  1176. PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr));
  1177. #endif
  1178.  
  1179. #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
  1180. /* Reduce RGB to grayscale. */
  1181. #define PNG_ERROR_ACTION_NONE  1
  1182. #define PNG_ERROR_ACTION_WARN  2
  1183. #define PNG_ERROR_ACTION_ERROR 3
  1184. #define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/
  1185.  
  1186. PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structrp png_ptr,
  1187.     int error_action, double red, double green))
  1188. PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structrp png_ptr,
  1189.     int error_action, png_fixed_point red, png_fixed_point green))
  1190.  
  1191. PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp
  1192.     png_ptr));
  1193. #endif
  1194.  
  1195. #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
  1196. PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
  1197.     png_colorp palette));
  1198. #endif
  1199.  
  1200. #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
  1201. /* How the alpha channel is interpreted - this affects how the color channels of
  1202.  * a PNG file are returned when an alpha channel, or tRNS chunk in a palette
  1203.  * file, is present.
  1204.  *
  1205.  * This has no effect on the way pixels are written into a PNG output
  1206.  * datastream. The color samples in a PNG datastream are never premultiplied
  1207.  * with the alpha samples.
  1208.  *
  1209.  * The default is to return data according to the PNG specification: the alpha
  1210.  * channel is a linear measure of the contribution of the pixel to the
  1211.  * corresponding composited pixel.  The gamma encoded color channels must be
  1212.  * scaled according to the contribution and to do this it is necessary to undo
  1213.  * the encoding, scale the color values, perform the composition and reencode
  1214.  * the values.  This is the 'PNG' mode.
  1215.  *
  1216.  * The alternative is to 'associate' the alpha with the color information by
  1217.  * storing color channel values that have been scaled by the alpha.  The
  1218.  * advantage is that the color channels can be resampled (the image can be
  1219.  * scaled) in this form.  The disadvantage is that normal practice is to store
  1220.  * linear, not (gamma) encoded, values and this requires 16-bit channels for
  1221.  * still images rather than the 8-bit channels that are just about sufficient if
  1222.  * gamma encoding is used.  In addition all non-transparent pixel values,
  1223.  * including completely opaque ones, must be gamma encoded to produce the final
  1224.  * image.  This is the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' mode (the
  1225.  * latter being the two common names for associated alpha color channels.)
  1226.  *
  1227.  * Since it is not necessary to perform arithmetic on opaque color values so
  1228.  * long as they are not to be resampled and are in the final color space it is
  1229.  * possible to optimize the handling of alpha by storing the opaque pixels in
  1230.  * the PNG format (adjusted for the output color space) while storing partially
  1231.  * opaque pixels in the standard, linear, format.  The accuracy required for
  1232.  * standard alpha composition is relatively low, because the pixels are
  1233.  * isolated, therefore typically the accuracy loss in storing 8-bit linear
  1234.  * values is acceptable.  (This is not true if the alpha channel is used to
  1235.  * simulate transparency over large areas - use 16 bits or the PNG mode in
  1236.  * this case!)  This is the 'OPTIMIZED' mode.  For this mode a pixel is
  1237.  * treated as opaque only if the alpha value is equal to the maximum value.
  1238.  *
  1239.  * The final choice is to gamma encode the alpha channel as well.  This is
  1240.  * broken because, in practice, no implementation that uses this choice
  1241.  * correctly undoes the encoding before handling alpha composition.  Use this
  1242.  * choice only if other serious errors in the software or hardware you use
  1243.  * mandate it; the typical serious error is for dark halos to appear around
  1244.  * opaque areas of the composited PNG image because of arithmetic overflow.
  1245.  *
  1246.  * The API function png_set_alpha_mode specifies which of these choices to use
  1247.  * with an enumerated 'mode' value and the gamma of the required output:
  1248.  */
  1249. #define PNG_ALPHA_PNG           0 /* according to the PNG standard */
  1250. #define PNG_ALPHA_STANDARD      1 /* according to Porter/Duff */
  1251. #define PNG_ALPHA_ASSOCIATED    1 /* as above; this is the normal practice */
  1252. #define PNG_ALPHA_PREMULTIPLIED 1 /* as above */
  1253. #define PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */
  1254. #define PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */
  1255.  
  1256. PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structrp png_ptr, int mode,
  1257.     double output_gamma))
  1258. PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
  1259.     int mode, png_fixed_point output_gamma))
  1260. #endif
  1261.  
  1262. #if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
  1263. /* The output_gamma value is a screen gamma in libpng terminology: it expresses
  1264.  * how to decode the output values, not how they are encoded.  The values used
  1265.  * correspond to the normal numbers used to describe the overall gamma of a
  1266.  * computer display system; for example 2.2 for an sRGB conformant system.  The
  1267.  * values are scaled by 100000 in the _fixed version of the API (so 220000 for
  1268.  * sRGB.)
  1269.  *
  1270.  * The inverse of the value is always used to provide a default for the PNG file
  1271.  * encoding if it has no gAMA chunk and if png_set_gamma() has not been called
  1272.  * to override the PNG gamma information.
  1273.  *
  1274.  * When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
  1275.  * opaque pixels however pixels with lower alpha values are not encoded,
  1276.  * regardless of the output gamma setting.
  1277.  *
  1278.  * When the standard Porter Duff handling is requested with mode 1 the output
  1279.  * encoding is set to be linear and the output_gamma value is only relevant
  1280.  * as a default for input data that has no gamma information.  The linear output
  1281.  * encoding will be overridden if png_set_gamma() is called - the results may be
  1282.  * highly unexpected!
  1283.  *
  1284.  * The following numbers are derived from the sRGB standard and the research
  1285.  * behind it.  sRGB is defined to be approximated by a PNG gAMA chunk value of
  1286.  * 0.45455 (1/2.2) for PNG.  The value implicitly includes any viewing
  1287.  * correction required to take account of any differences in the color
  1288.  * environment of the original scene and the intended display environment; the
  1289.  * value expresses how to *decode* the image for display, not how the original
  1290.  * data was *encoded*.
  1291.  *
  1292.  * sRGB provides a peg for the PNG standard by defining a viewing environment.
  1293.  * sRGB itself, and earlier TV standards, actually use a more complex transform
  1294.  * (a linear portion then a gamma 2.4 power law) than PNG can express.  (PNG is
  1295.  * limited to simple power laws.)  By saying that an image for direct display on
  1296.  * an sRGB conformant system should be stored with a gAMA chunk value of 45455
  1297.  * (11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification
  1298.  * makes it possible to derive values for other display systems and
  1299.  * environments.
  1300.  *
  1301.  * The Mac value is deduced from the sRGB based on an assumption that the actual
  1302.  * extra viewing correction used in early Mac display systems was implemented as
  1303.  * a power 1.45 lookup table.
  1304.  *
  1305.  * Any system where a programmable lookup table is used or where the behavior of
  1306.  * the final display device characteristics can be changed requires system
  1307.  * specific code to obtain the current characteristic.  However this can be
  1308.  * difficult and most PNG gamma correction only requires an approximate value.
  1309.  *
  1310.  * By default, if png_set_alpha_mode() is not called, libpng assumes that all
  1311.  * values are unencoded, linear, values and that the output device also has a
  1312.  * linear characteristic.  This is only very rarely correct - it is invariably
  1313.  * better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
  1314.  * default if you don't know what the right answer is!
  1315.  *
  1316.  * The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
  1317.  * 10.6) which used a correction table to implement a somewhat lower gamma on an
  1318.  * otherwise sRGB system.
  1319.  *
  1320.  * Both these values are reserved (not simple gamma values) in order to allow
  1321.  * more precise correction internally in the future.
  1322.  *
  1323.  * NOTE: the following values can be passed to either the fixed or floating
  1324.  * point APIs, but the floating point API will also accept floating point
  1325.  * values.
  1326.  */
  1327. #define PNG_DEFAULT_sRGB -1       /* sRGB gamma and color space */
  1328. #define PNG_GAMMA_MAC_18 -2       /* Old Mac '1.8' gamma and color space */
  1329. #define PNG_GAMMA_sRGB   220000   /* Television standards--matches sRGB gamma */
  1330. #define PNG_GAMMA_LINEAR PNG_FP_1 /* Linear */
  1331. #endif
  1332.  
  1333. /* The following are examples of calls to png_set_alpha_mode to achieve the
  1334.  * required overall gamma correction and, where necessary, alpha
  1335.  * premultiplication.
  1336.  *
  1337.  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
  1338.  *    This is the default libpng handling of the alpha channel - it is not
  1339.  *    pre-multiplied into the color components.  In addition the call states
  1340.  *    that the output is for a sRGB system and causes all PNG files without gAMA
  1341.  *    chunks to be assumed to be encoded using sRGB.
  1342.  *
  1343.  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
  1344.  *    In this case the output is assumed to be something like an sRGB conformant
  1345.  *    display preceeded by a power-law lookup table of power 1.45.  This is how
  1346.  *    early Mac systems behaved.
  1347.  *
  1348.  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
  1349.  *    This is the classic Jim Blinn approach and will work in academic
  1350.  *    environments where everything is done by the book.  It has the shortcoming
  1351.  *    of assuming that input PNG data with no gamma information is linear - this
  1352.  *    is unlikely to be correct unless the PNG files where generated locally.
  1353.  *    Most of the time the output precision will be so low as to show
  1354.  *    significant banding in dark areas of the image.
  1355.  *
  1356.  * png_set_expand_16(pp);
  1357.  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
  1358.  *    This is a somewhat more realistic Jim Blinn inspired approach.  PNG files
  1359.  *    are assumed to have the sRGB encoding if not marked with a gamma value and
  1360.  *    the output is always 16 bits per component.  This permits accurate scaling
  1361.  *    and processing of the data.  If you know that your input PNG files were
  1362.  *    generated locally you might need to replace PNG_DEFAULT_sRGB with the
  1363.  *    correct value for your system.
  1364.  *
  1365.  * png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
  1366.  *    If you just need to composite the PNG image onto an existing background
  1367.  *    and if you control the code that does this you can use the optimization
  1368.  *    setting.  In this case you just copy completely opaque pixels to the
  1369.  *    output.  For pixels that are not completely transparent (you just skip
  1370.  *    those) you do the composition math using png_composite or png_composite_16
  1371.  *    below then encode the resultant 8-bit or 16-bit values to match the output
  1372.  *    encoding.
  1373.  *
  1374.  * Other cases
  1375.  *    If neither the PNG nor the standard linear encoding work for you because
  1376.  *    of the software or hardware you use then you have a big problem.  The PNG
  1377.  *    case will probably result in halos around the image.  The linear encoding
  1378.  *    will probably result in a washed out, too bright, image (it's actually too
  1379.  *    contrasty.)  Try the ALPHA_OPTIMIZED mode above - this will probably
  1380.  *    substantially reduce the halos.  Alternatively try:
  1381.  *
  1382.  * png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
  1383.  *    This option will also reduce the halos, but there will be slight dark
  1384.  *    halos round the opaque parts of the image where the background is light.
  1385.  *    In the OPTIMIZED mode the halos will be light halos where the background
  1386.  *    is dark.  Take your pick - the halos are unavoidable unless you can get
  1387.  *    your hardware/software fixed!  (The OPTIMIZED approach is slightly
  1388.  *    faster.)
  1389.  *
  1390.  * When the default gamma of PNG files doesn't match the output gamma.
  1391.  *    If you have PNG files with no gamma information png_set_alpha_mode allows
  1392.  *    you to provide a default gamma, but it also sets the ouput gamma to the
  1393.  *    matching value.  If you know your PNG files have a gamma that doesn't
  1394.  *    match the output you can take advantage of the fact that
  1395.  *    png_set_alpha_mode always sets the output gamma but only sets the PNG
  1396.  *    default if it is not already set:
  1397.  *
  1398.  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
  1399.  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
  1400.  *    The first call sets both the default and the output gamma values, the
  1401.  *    second call overrides the output gamma without changing the default.  This
  1402.  *    is easier than achieving the same effect with png_set_gamma.  You must use
  1403.  *    PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
  1404.  *    fire if more than one call to png_set_alpha_mode and png_set_background is
  1405.  *    made in the same read operation, however multiple calls with PNG_ALPHA_PNG
  1406.  *    are ignored.
  1407.  */
  1408.  
  1409. #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
  1410. PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
  1411. #endif
  1412.  
  1413. #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
  1414.     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
  1415. PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr));
  1416. #endif
  1417.  
  1418. #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
  1419.     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
  1420. PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
  1421. #endif
  1422.  
  1423. #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
  1424. /* Add a filler byte to 8-bit Gray or 24-bit RGB images. */
  1425. PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler,
  1426.     int flags));
  1427. /* The values of the PNG_FILLER_ defines should NOT be changed */
  1428. #  define PNG_FILLER_BEFORE 0
  1429. #  define PNG_FILLER_AFTER 1
  1430. /* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
  1431. PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
  1432.     png_uint_32 filler, int flags));
  1433. #endif /* PNG_READ_FILLER_SUPPORTED || PNG_WRITE_FILLER_SUPPORTED */
  1434.  
  1435. #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
  1436. /* Swap bytes in 16-bit depth files. */
  1437. PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr));
  1438. #endif
  1439.  
  1440. #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
  1441. /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
  1442. PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr));
  1443. #endif
  1444.  
  1445. #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
  1446.     defined(PNG_WRITE_PACKSWAP_SUPPORTED)
  1447. /* Swap packing order of pixels in bytes. */
  1448. PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr));
  1449. #endif
  1450.  
  1451. #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
  1452. /* Converts files to legal bit depths. */
  1453. PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p
  1454.     true_bits));
  1455. #endif
  1456.  
  1457. #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
  1458.     defined(PNG_WRITE_INTERLACING_SUPPORTED)
  1459. /* Have the code handle the interlacing.  Returns the number of passes.
  1460.  * MUST be called before png_read_update_info or png_start_read_image,
  1461.  * otherwise it will not have the desired effect.  Note that it is still
  1462.  * necessary to call png_read_row or png_read_rows png_get_image_height
  1463.  * times for each pass.
  1464. */
  1465. PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr));
  1466. #endif
  1467.  
  1468. #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
  1469. /* Invert monochrome files */
  1470. PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
  1471. #endif
  1472.  
  1473. #ifdef PNG_READ_BACKGROUND_SUPPORTED
  1474. /* Handle alpha and tRNS by replacing with a background color.  Prior to
  1475.  * libpng-1.5.4 this API must not be called before the PNG file header has been
  1476.  * read.  Doing so will result in unexpected behavior and possible warnings or
  1477.  * errors if the PNG file contains a bKGD chunk.
  1478.  */
  1479. PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr,
  1480.     png_const_color_16p background_color, int background_gamma_code,
  1481.     int need_expand, double background_gamma))
  1482. PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr,
  1483.     png_const_color_16p background_color, int background_gamma_code,
  1484.     int need_expand, png_fixed_point background_gamma))
  1485. #endif
  1486. #ifdef PNG_READ_BACKGROUND_SUPPORTED
  1487. #  define PNG_BACKGROUND_GAMMA_UNKNOWN 0
  1488. #  define PNG_BACKGROUND_GAMMA_SCREEN  1
  1489. #  define PNG_BACKGROUND_GAMMA_FILE    2
  1490. #  define PNG_BACKGROUND_GAMMA_UNIQUE  3
  1491. #endif
  1492.  
  1493. #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
  1494. /* Scale a 16-bit depth file down to 8-bit, accurately. */
  1495. PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
  1496. #endif
  1497.  
  1498. #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
  1499. #define PNG_READ_16_TO_8 SUPPORTED /* Name prior to 1.5.4 */
  1500. /* Strip the second byte of information from a 16-bit depth file. */
  1501. PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
  1502. #endif
  1503.  
  1504. #ifdef PNG_READ_QUANTIZE_SUPPORTED
  1505. /* Turn on quantizing, and reduce the palette to the number of colors
  1506.  * available.
  1507.  */
  1508. PNG_EXPORT(49, void, png_set_quantize, (png_structrp png_ptr,
  1509.     png_colorp palette, int num_palette, int maximum_colors,
  1510.     png_const_uint_16p histogram, int full_quantize));
  1511. #endif
  1512.  
  1513. #ifdef PNG_READ_GAMMA_SUPPORTED
  1514. /* The threshold on gamma processing is configurable but hard-wired into the
  1515.  * library.  The following is the floating point variant.
  1516.  */
  1517. #define PNG_GAMMA_THRESHOLD (PNG_GAMMA_THRESHOLD_FIXED*.00001)
  1518.  
  1519. /* Handle gamma correction. Screen_gamma=(display_exponent).
  1520.  * NOTE: this API simply sets the screen and file gamma values. It will
  1521.  * therefore override the value for gamma in a PNG file if it is called after
  1522.  * the file header has been read - use with care  - call before reading the PNG
  1523.  * file for best results!
  1524.  *
  1525.  * These routines accept the same gamma values as png_set_alpha_mode (described
  1526.  * above).  The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either
  1527.  * API (floating point or fixed.)  Notice, however, that the 'file_gamma' value
  1528.  * is the inverse of a 'screen gamma' value.
  1529.  */
  1530. PNG_FP_EXPORT(50, void, png_set_gamma, (png_structrp png_ptr,
  1531.     double screen_gamma, double override_file_gamma))
  1532. PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structrp png_ptr,
  1533.     png_fixed_point screen_gamma, png_fixed_point override_file_gamma))
  1534. #endif
  1535.  
  1536. #ifdef PNG_WRITE_FLUSH_SUPPORTED
  1537. /* Set how many lines between output flushes - 0 for no flushing */
  1538. PNG_EXPORT(51, void, png_set_flush, (png_structrp png_ptr, int nrows));
  1539. /* Flush the current PNG output buffer */
  1540. PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr));
  1541. #endif
  1542.  
  1543. /* Optional update palette with requested transformations */
  1544. PNG_EXPORT(53, void, png_start_read_image, (png_structrp png_ptr));
  1545.  
  1546. /* Optional call to update the users info structure */
  1547. PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr,
  1548.     png_inforp info_ptr));
  1549.  
  1550. #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
  1551. /* Read one or more rows of image data. */
  1552. PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row,
  1553.     png_bytepp display_row, png_uint_32 num_rows));
  1554. #endif
  1555.  
  1556. #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
  1557. /* Read a row of data. */
  1558. PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
  1559.     png_bytep display_row));
  1560. #endif
  1561.  
  1562. #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
  1563. /* Read the whole image into memory at once. */
  1564. PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
  1565. #endif
  1566.  
  1567. /* Write a row of image data */
  1568. PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr,
  1569.     png_const_bytep row));
  1570.  
  1571. /* Write a few rows of image data: (*row) is not written; however, the type
  1572.  * is declared as writeable to maintain compatibility with previous versions
  1573.  * of libpng and to allow the 'display_row' array from read_rows to be passed
  1574.  * unchanged to write_rows.
  1575.  */
  1576. PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row,
  1577.     png_uint_32 num_rows));
  1578.  
  1579. /* Write the image data */
  1580. PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image));
  1581.  
  1582. /* Write the end of the PNG file. */
  1583. PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr,
  1584.     png_inforp info_ptr));
  1585.  
  1586. #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
  1587. /* Read the end of the PNG file. */
  1588. PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
  1589. #endif
  1590.  
  1591. /* Free any memory associated with the png_info_struct */
  1592. PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr,
  1593.     png_infopp info_ptr_ptr));
  1594.  
  1595. /* Free any memory associated with the png_struct and the png_info_structs */
  1596. PNG_EXPORT(64, void, png_destroy_read_struct, (png_structpp png_ptr_ptr,
  1597.     png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));
  1598.  
  1599. /* Free any memory associated with the png_struct and the png_info_structs */
  1600. PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr,
  1601.     png_infopp info_ptr_ptr));
  1602.  
  1603. /* Set the libpng method of handling chunk CRC errors */
  1604. PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
  1605.     int ancil_action));
  1606.  
  1607. /* Values for png_set_crc_action() say how to handle CRC errors in
  1608.  * ancillary and critical chunks, and whether to use the data contained
  1609.  * therein.  Note that it is impossible to "discard" data in a critical
  1610.  * chunk.  For versions prior to 0.90, the action was always error/quit,
  1611.  * whereas in version 0.90 and later, the action for CRC errors in ancillary
  1612.  * chunks is warn/discard.  These values should NOT be changed.
  1613.  *
  1614.  *      value                       action:critical     action:ancillary
  1615.  */
  1616. #define PNG_CRC_DEFAULT       0  /* error/quit          warn/discard data */
  1617. #define PNG_CRC_ERROR_QUIT    1  /* error/quit          error/quit        */
  1618. #define PNG_CRC_WARN_DISCARD  2  /* (INVALID)           warn/discard data */
  1619. #define PNG_CRC_WARN_USE      3  /* warn/use data       warn/use data     */
  1620. #define PNG_CRC_QUIET_USE     4  /* quiet/use data      quiet/use data    */
  1621. #define PNG_CRC_NO_CHANGE     5  /* use current value   use current value */
  1622.  
  1623. /* These functions give the user control over the scan-line filtering in
  1624.  * libpng and the compression methods used by zlib.  These functions are
  1625.  * mainly useful for testing, as the defaults should work with most users.
  1626.  * Those users who are tight on memory or want faster performance at the
  1627.  * expense of compression can modify them.  See the compression library
  1628.  * header file (zlib.h) for an explination of the compression functions.
  1629.  */
  1630.  
  1631. /* Set the filtering method(s) used by libpng.  Currently, the only valid
  1632.  * value for "method" is 0.
  1633.  */
  1634. PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
  1635.     int filters));
  1636.  
  1637. /* Flags for png_set_filter() to say which filters to use.  The flags
  1638.  * are chosen so that they don't conflict with real filter types
  1639.  * below, in case they are supplied instead of the #defined constants.
  1640.  * These values should NOT be changed.
  1641.  */
  1642. #define PNG_NO_FILTERS     0x00
  1643. #define PNG_FILTER_NONE    0x08
  1644. #define PNG_FILTER_SUB     0x10
  1645. #define PNG_FILTER_UP      0x20
  1646. #define PNG_FILTER_AVG     0x40
  1647. #define PNG_FILTER_PAETH   0x80
  1648. #define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
  1649.                          PNG_FILTER_AVG | PNG_FILTER_PAETH)
  1650.  
  1651. /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
  1652.  * These defines should NOT be changed.
  1653.  */
  1654. #define PNG_FILTER_VALUE_NONE  0
  1655. #define PNG_FILTER_VALUE_SUB   1
  1656. #define PNG_FILTER_VALUE_UP    2
  1657. #define PNG_FILTER_VALUE_AVG   3
  1658. #define PNG_FILTER_VALUE_PAETH 4
  1659. #define PNG_FILTER_VALUE_LAST  5
  1660.  
  1661. #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* EXPERIMENTAL */
  1662. /* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
  1663.  * defines, either the default (minimum-sum-of-absolute-differences), or
  1664.  * the experimental method (weighted-minimum-sum-of-absolute-differences).
  1665.  *
  1666.  * Weights are factors >= 1.0, indicating how important it is to keep the
  1667.  * filter type consistent between rows.  Larger numbers mean the current
  1668.  * filter is that many times as likely to be the same as the "num_weights"
  1669.  * previous filters.  This is cumulative for each previous row with a weight.
  1670.  * There needs to be "num_weights" values in "filter_weights", or it can be
  1671.  * NULL if the weights aren't being specified.  Weights have no influence on
  1672.  * the selection of the first row filter.  Well chosen weights can (in theory)
  1673.  * improve the compression for a given image.
  1674.  *
  1675.  * Costs are factors >= 1.0 indicating the relative decoding costs of a
  1676.  * filter type.  Higher costs indicate more decoding expense, and are
  1677.  * therefore less likely to be selected over a filter with lower computational
  1678.  * costs.  There needs to be a value in "filter_costs" for each valid filter
  1679.  * type (given by PNG_FILTER_VALUE_LAST), or it can be NULL if you aren't
  1680.  * setting the costs.  Costs try to improve the speed of decompression without
  1681.  * unduly increasing the compressed image size.
  1682.  *
  1683.  * A negative weight or cost indicates the default value is to be used, and
  1684.  * values in the range [0.0, 1.0) indicate the value is to remain unchanged.
  1685.  * The default values for both weights and costs are currently 1.0, but may
  1686.  * change if good general weighting/cost heuristics can be found.  If both
  1687.  * the weights and costs are set to 1.0, this degenerates the WEIGHTED method
  1688.  * to the UNWEIGHTED method, but with added encoding time/computation.
  1689.  */
  1690. PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr,
  1691.     int heuristic_method, int num_weights, png_const_doublep filter_weights,
  1692.     png_const_doublep filter_costs))
  1693. PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
  1694.     (png_structrp png_ptr, int heuristic_method, int num_weights,
  1695.     png_const_fixed_point_p filter_weights,
  1696.     png_const_fixed_point_p filter_costs))
  1697. #endif /*  PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
  1698.  
  1699. /* Heuristic used for row filter selection.  These defines should NOT be
  1700.  * changed.
  1701.  */
  1702. #define PNG_FILTER_HEURISTIC_DEFAULT    0  /* Currently "UNWEIGHTED" */
  1703. #define PNG_FILTER_HEURISTIC_UNWEIGHTED 1  /* Used by libpng < 0.95 */
  1704. #define PNG_FILTER_HEURISTIC_WEIGHTED   2  /* Experimental feature */
  1705. #define PNG_FILTER_HEURISTIC_LAST       3  /* Not a valid value */
  1706.  
  1707. #ifdef PNG_WRITE_SUPPORTED
  1708. /* Set the library compression level.  Currently, valid values range from
  1709.  * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
  1710.  * (0 - no compression, 9 - "maximal" compression).  Note that tests have
  1711.  * shown that zlib compression levels 3-6 usually perform as well as level 9
  1712.  * for PNG images, and do considerably fewer caclulations.  In the future,
  1713.  * these values may not correspond directly to the zlib compression levels.
  1714.  */
  1715. PNG_EXPORT(69, void, png_set_compression_level, (png_structrp png_ptr,
  1716.     int level));
  1717.  
  1718. PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structrp png_ptr,
  1719.     int mem_level));
  1720.  
  1721. PNG_EXPORT(71, void, png_set_compression_strategy, (png_structrp png_ptr,
  1722.     int strategy));
  1723.  
  1724. /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
  1725.  * smaller value of window_bits if it can do so safely.
  1726.  */
  1727. PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
  1728.     int window_bits));
  1729.  
  1730. PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr,
  1731.     int method));
  1732. #endif
  1733.  
  1734. #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
  1735. /* Also set zlib parameters for compressing non-IDAT chunks */
  1736. PNG_EXPORT(222, void, png_set_text_compression_level, (png_structrp png_ptr,
  1737.     int level));
  1738.  
  1739. PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structrp png_ptr,
  1740.     int mem_level));
  1741.  
  1742. PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structrp png_ptr,
  1743.     int strategy));
  1744.  
  1745. /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
  1746.  * smaller value of window_bits if it can do so safely.
  1747.  */
  1748. PNG_EXPORT(225, void, png_set_text_compression_window_bits,
  1749.     (png_structrp png_ptr, int window_bits));
  1750.  
  1751. PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr,
  1752.     int method));
  1753. #endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
  1754.  
  1755. /* These next functions are called for input/output, memory, and error
  1756.  * handling.  They are in the file pngrio.c, pngwio.c, and pngerror.c,
  1757.  * and call standard C I/O routines such as fread(), fwrite(), and
  1758.  * fprintf().  These functions can be made to use other I/O routines
  1759.  * at run time for those applications that need to handle I/O in a
  1760.  * different manner by calling png_set_???_fn().  See libpng-manual.txt for
  1761.  * more information.
  1762.  */
  1763.  
  1764. #ifdef PNG_STDIO_SUPPORTED
  1765. /* Initialize the input/output for the PNG file to the default functions. */
  1766. PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp));
  1767. #endif
  1768.  
  1769. /* Replace the (error and abort), and warning functions with user
  1770.  * supplied functions.  If no messages are to be printed you must still
  1771.  * write and use replacement functions. The replacement error_fn should
  1772.  * still do a longjmp to the last setjmp location if you are using this
  1773.  * method of error handling.  If error_fn or warning_fn is NULL, the
  1774.  * default function will be used.
  1775.  */
  1776.  
  1777. PNG_EXPORT(75, void, png_set_error_fn, (png_structrp png_ptr,
  1778.     png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
  1779.  
  1780. /* Return the user pointer associated with the error functions */
  1781. PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structrp png_ptr));
  1782.  
  1783. /* Replace the default data output functions with a user supplied one(s).
  1784.  * If buffered output is not used, then output_flush_fn can be set to NULL.
  1785.  * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
  1786.  * output_flush_fn will be ignored (and thus can be NULL).
  1787.  * It is probably a mistake to use NULL for output_flush_fn if
  1788.  * write_data_fn is not also NULL unless you have built libpng with
  1789.  * PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's
  1790.  * default flush function, which uses the standard *FILE structure, will
  1791.  * be used.
  1792.  */
  1793. PNG_EXPORT(77, void, png_set_write_fn, (png_structrp png_ptr, png_voidp io_ptr,
  1794.     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
  1795.  
  1796. /* Replace the default data input function with a user supplied one. */
  1797. PNG_EXPORT(78, void, png_set_read_fn, (png_structrp png_ptr, png_voidp io_ptr,
  1798.     png_rw_ptr read_data_fn));
  1799.  
  1800. /* Return the user pointer associated with the I/O functions */
  1801. PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_const_structrp png_ptr));
  1802.  
  1803. PNG_EXPORT(80, void, png_set_read_status_fn, (png_structrp png_ptr,
  1804.     png_read_status_ptr read_row_fn));
  1805.  
  1806. PNG_EXPORT(81, void, png_set_write_status_fn, (png_structrp png_ptr,
  1807.     png_write_status_ptr write_row_fn));
  1808.  
  1809. #ifdef PNG_USER_MEM_SUPPORTED
  1810. /* Replace the default memory allocation functions with user supplied one(s). */
  1811. PNG_EXPORT(82, void, png_set_mem_fn, (png_structrp png_ptr, png_voidp mem_ptr,
  1812.     png_malloc_ptr malloc_fn, png_free_ptr free_fn));
  1813. /* Return the user pointer associated with the memory functions */
  1814. PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structrp png_ptr));
  1815. #endif
  1816.  
  1817. #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
  1818. PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr,
  1819.     png_user_transform_ptr read_user_transform_fn));
  1820. #endif
  1821.  
  1822. #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
  1823. PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr,
  1824.     png_user_transform_ptr write_user_transform_fn));
  1825. #endif
  1826.  
  1827. #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
  1828. PNG_EXPORT(86, void, png_set_user_transform_info, (png_structrp png_ptr,
  1829.     png_voidp user_transform_ptr, int user_transform_depth,
  1830.     int user_transform_channels));
  1831. /* Return the user pointer associated with the user transform functions */
  1832. PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr,
  1833.     (png_const_structrp png_ptr));
  1834. #endif
  1835.  
  1836. #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
  1837. /* Return information about the row currently being processed.  Note that these
  1838.  * APIs do not fail but will return unexpected results if called outside a user
  1839.  * transform callback.  Also note that when transforming an interlaced image the
  1840.  * row number is the row number within the sub-image of the interlace pass, so
  1841.  * the value will increase to the height of the sub-image (not the full image)
  1842.  * then reset to 0 for the next pass.
  1843.  *
  1844.  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
  1845.  * find the output pixel (x,y) given an interlaced sub-image pixel
  1846.  * (row,col,pass).  (See below for these macros.)
  1847.  */
  1848. PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structrp));
  1849. PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
  1850. #endif
  1851.  
  1852. #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
  1853. /* This callback is called only for *unknown* chunks.  If
  1854.  * PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
  1855.  * chunks to be treated as unknown, however in this case the callback must do
  1856.  * any processing required by the chunk (e.g. by calling the appropriate
  1857.  * png_set_ APIs.)
  1858.  *
  1859.  * There is no write support - on write, by default, all the chunks in the
  1860.  * 'unknown' list are written in the specified position.
  1861.  *
  1862.  * The integer return from the callback function is interpreted thus:
  1863.  *
  1864.  * negative: An error occured, png_chunk_error will be called.
  1865.  *     zero: The chunk was not handled, the chunk will be saved. A critical
  1866.  *           chunk will cause an error at this point unless it is to be saved.
  1867.  * positive: The chunk was handled, libpng will ignore/discard it.
  1868.  *
  1869.  * See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
  1870.  * how this behavior will change in libpng 1.7
  1871.  */
  1872. PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
  1873.     png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
  1874. #endif
  1875.  
  1876. #ifdef PNG_USER_CHUNKS_SUPPORTED
  1877. PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr));
  1878. #endif
  1879.  
  1880. #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
  1881. /* Sets the function callbacks for the push reader, and a pointer to a
  1882.  * user-defined structure available to the callback functions.
  1883.  */
  1884. PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structrp png_ptr,
  1885.     png_voidp progressive_ptr, png_progressive_info_ptr info_fn,
  1886.     png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn));
  1887.  
  1888. /* Returns the user pointer associated with the push read functions */
  1889. PNG_EXPORT(91, png_voidp, png_get_progressive_ptr,
  1890.     (png_const_structrp png_ptr));
  1891.  
  1892. /* Function to be called when data becomes available */
  1893. PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
  1894.     png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size));
  1895.  
  1896. /* A function which may be called *only* within png_process_data to stop the
  1897.  * processing of any more data.  The function returns the number of bytes
  1898.  * remaining, excluding any that libpng has cached internally.  A subsequent
  1899.  * call to png_process_data must supply these bytes again.  If the argument
  1900.  * 'save' is set to true the routine will first save all the pending data and
  1901.  * will always return 0.
  1902.  */
  1903. PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save));
  1904.  
  1905. /* A function which may be called *only* outside (after) a call to
  1906.  * png_process_data.  It returns the number of bytes of data to skip in the
  1907.  * input.  Normally it will return 0, but if it returns a non-zero value the
  1908.  * application must skip than number of bytes of input data and pass the
  1909.  * following data to the next call to png_process_data.
  1910.  */
  1911. PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structrp));
  1912.  
  1913. #ifdef PNG_READ_INTERLACING_SUPPORTED
  1914. /* Function that combines rows.  'new_row' is a flag that should come from
  1915.  * the callback and be non-NULL if anything needs to be done; the library
  1916.  * stores its own version of the new data internally and ignores the passed
  1917.  * in value.
  1918.  */
  1919. PNG_EXPORT(93, void, png_progressive_combine_row, (png_const_structrp png_ptr,
  1920.     png_bytep old_row, png_const_bytep new_row));
  1921. #endif /* PNG_READ_INTERLACING_SUPPORTED */
  1922. #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
  1923.  
  1924. PNG_EXPORTA(94, png_voidp, png_malloc, (png_const_structrp png_ptr,
  1925.     png_alloc_size_t size), PNG_ALLOCATED);
  1926. /* Added at libpng version 1.4.0 */
  1927. PNG_EXPORTA(95, png_voidp, png_calloc, (png_const_structrp png_ptr,
  1928.     png_alloc_size_t size), PNG_ALLOCATED);
  1929.  
  1930. /* Added at libpng version 1.2.4 */
  1931. PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_const_structrp png_ptr,
  1932.     png_alloc_size_t size), PNG_ALLOCATED);
  1933.  
  1934. /* Frees a pointer allocated by png_malloc() */
  1935. PNG_EXPORT(97, void, png_free, (png_const_structrp png_ptr, png_voidp ptr));
  1936.  
  1937. /* Free data that was allocated internally */
  1938. PNG_EXPORT(98, void, png_free_data, (png_const_structrp png_ptr,
  1939.     png_inforp info_ptr, png_uint_32 free_me, int num));
  1940.  
  1941. /* Reassign responsibility for freeing existing data, whether allocated
  1942.  * by libpng or by the application; this works on the png_info structure passed
  1943.  * in, it does not change the state for other png_info structures.
  1944.  *
  1945.  * It is unlikely that this function works correctly as of 1.6.0 and using it
  1946.  * may result either in memory leaks or double free of allocated data.
  1947.  */
  1948. PNG_EXPORTA(99, void, png_data_freer, (png_const_structrp png_ptr,
  1949.     png_inforp info_ptr, int freer, png_uint_32 mask), PNG_DEPRECATED);
  1950.  
  1951. /* Assignments for png_data_freer */
  1952. #define PNG_DESTROY_WILL_FREE_DATA 1
  1953. #define PNG_SET_WILL_FREE_DATA 1
  1954. #define PNG_USER_WILL_FREE_DATA 2
  1955. /* Flags for png_ptr->free_me and info_ptr->free_me */
  1956. #define PNG_FREE_HIST 0x0008
  1957. #define PNG_FREE_ICCP 0x0010
  1958. #define PNG_FREE_SPLT 0x0020
  1959. #define PNG_FREE_ROWS 0x0040
  1960. #define PNG_FREE_PCAL 0x0080
  1961. #define PNG_FREE_SCAL 0x0100
  1962. #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
  1963. #  define PNG_FREE_UNKN 0x0200
  1964. #endif
  1965. /*      PNG_FREE_LIST 0x0400    removed in 1.6.0 because it is ignored */
  1966. #define PNG_FREE_PLTE 0x1000
  1967. #define PNG_FREE_TRNS 0x2000
  1968. #define PNG_FREE_TEXT 0x4000
  1969. #define PNG_FREE_ALL  0x7fff
  1970. #define PNG_FREE_MUL  0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
  1971.  
  1972. #ifdef PNG_USER_MEM_SUPPORTED
  1973. PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
  1974.     png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED);
  1975. PNG_EXPORTA(101, void, png_free_default, (png_const_structrp png_ptr,
  1976.     png_voidp ptr), PNG_DEPRECATED);
  1977. #endif
  1978.  
  1979. #ifdef PNG_ERROR_TEXT_SUPPORTED
  1980. /* Fatal error in PNG image of libpng - can't continue */
  1981. PNG_EXPORTA(102, void, png_error, (png_const_structrp png_ptr,
  1982.     png_const_charp error_message), PNG_NORETURN);
  1983.  
  1984. /* The same, but the chunk name is prepended to the error string. */
  1985. PNG_EXPORTA(103, void, png_chunk_error, (png_const_structrp png_ptr,
  1986.     png_const_charp error_message), PNG_NORETURN);
  1987.  
  1988. #else
  1989. /* Fatal error in PNG image of libpng - can't continue */
  1990. PNG_EXPORTA(104, void, png_err, (png_const_structrp png_ptr), PNG_NORETURN);
  1991. #endif
  1992.  
  1993. #ifdef PNG_WARNINGS_SUPPORTED
  1994. /* Non-fatal error in libpng.  Can continue, but may have a problem. */
  1995. PNG_EXPORT(105, void, png_warning, (png_const_structrp png_ptr,
  1996.     png_const_charp warning_message));
  1997.  
  1998. /* Non-fatal error in libpng, chunk name is prepended to message. */
  1999. PNG_EXPORT(106, void, png_chunk_warning, (png_const_structrp png_ptr,
  2000.     png_const_charp warning_message));
  2001. #endif
  2002.  
  2003. #ifdef PNG_BENIGN_ERRORS_SUPPORTED
  2004. /* Benign error in libpng.  Can continue, but may have a problem.
  2005.  * User can choose whether to handle as a fatal error or as a warning. */
  2006. PNG_EXPORT(107, void, png_benign_error, (png_const_structrp png_ptr,
  2007.     png_const_charp warning_message));
  2008.  
  2009. #ifdef PNG_READ_SUPPORTED
  2010. /* Same, chunk name is prepended to message (only during read) */
  2011. PNG_EXPORT(108, void, png_chunk_benign_error, (png_const_structrp png_ptr,
  2012.     png_const_charp warning_message));
  2013. #endif
  2014.  
  2015. PNG_EXPORT(109, void, png_set_benign_errors,
  2016.     (png_structrp png_ptr, int allowed));
  2017. #else
  2018. #  ifdef PNG_ALLOW_BENIGN_ERRORS
  2019. #    define png_benign_error png_warning
  2020. #    define png_chunk_benign_error png_chunk_warning
  2021. #  else
  2022. #    define png_benign_error png_error
  2023. #    define png_chunk_benign_error png_chunk_error
  2024. #  endif
  2025. #endif
  2026.  
  2027. /* The png_set_<chunk> functions are for storing values in the png_info_struct.
  2028.  * Similarly, the png_get_<chunk> calls are used to read values from the
  2029.  * png_info_struct, either storing the parameters in the passed variables, or
  2030.  * setting pointers into the png_info_struct where the data is stored.  The
  2031.  * png_get_<chunk> functions return a non-zero value if the data was available
  2032.  * in info_ptr, or return zero and do not change any of the parameters if the
  2033.  * data was not available.
  2034.  *
  2035.  * These functions should be used instead of directly accessing png_info
  2036.  * to avoid problems with future changes in the size and internal layout of
  2037.  * png_info_struct.
  2038.  */
  2039. /* Returns "flag" if chunk data is valid in info_ptr. */
  2040. PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr,
  2041.     png_const_inforp info_ptr, png_uint_32 flag));
  2042.  
  2043. /* Returns number of bytes needed to hold a transformed row. */
  2044. PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
  2045.     png_const_inforp info_ptr));
  2046.  
  2047. #ifdef PNG_INFO_IMAGE_SUPPORTED
  2048. /* Returns row_pointers, which is an array of pointers to scanlines that was
  2049.  * returned from png_read_png().
  2050.  */
  2051. PNG_EXPORT(112, png_bytepp, png_get_rows, (png_const_structrp png_ptr,
  2052.     png_const_inforp info_ptr));
  2053.  
  2054. /* Set row_pointers, which is an array of pointers to scanlines for use
  2055.  * by png_write_png().
  2056.  */
  2057. PNG_EXPORT(113, void, png_set_rows, (png_const_structrp png_ptr,
  2058.     png_inforp info_ptr, png_bytepp row_pointers));
  2059. #endif
  2060.  
  2061. /* Returns number of color channels in image. */
  2062. PNG_EXPORT(114, png_byte, png_get_channels, (png_const_structrp png_ptr,
  2063.     png_const_inforp info_ptr));
  2064.  
  2065. #ifdef PNG_EASY_ACCESS_SUPPORTED
  2066. /* Returns image width in pixels. */
  2067. PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structrp png_ptr,
  2068.     png_const_inforp info_ptr));
  2069.  
  2070. /* Returns image height in pixels. */
  2071. PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structrp png_ptr,
  2072.     png_const_inforp info_ptr));
  2073.  
  2074. /* Returns image bit_depth. */
  2075. PNG_EXPORT(117, png_byte, png_get_bit_depth, (png_const_structrp png_ptr,
  2076.     png_const_inforp info_ptr));
  2077.  
  2078. /* Returns image color_type. */
  2079. PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structrp png_ptr,
  2080.     png_const_inforp info_ptr));
  2081.  
  2082. /* Returns image filter_type. */
  2083. PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structrp png_ptr,
  2084.     png_const_inforp info_ptr));
  2085.  
  2086. /* Returns image interlace_type. */
  2087. PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structrp png_ptr,
  2088.     png_const_inforp info_ptr));
  2089.  
  2090. /* Returns image compression_type. */
  2091. PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structrp png_ptr,
  2092.     png_const_inforp info_ptr));
  2093.  
  2094. /* Returns image resolution in pixels per meter, from pHYs chunk data. */
  2095. PNG_EXPORT(122, png_uint_32, png_get_pixels_per_meter,
  2096.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2097. PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter,
  2098.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2099. PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter,
  2100.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2101.  
  2102. /* Returns pixel aspect ratio, computed from pHYs chunk data.  */
  2103. PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio,
  2104.     (png_const_structrp png_ptr, png_const_inforp info_ptr))
  2105. PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed,
  2106.     (png_const_structrp png_ptr, png_const_inforp info_ptr))
  2107.  
  2108. /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
  2109. PNG_EXPORT(126, png_int_32, png_get_x_offset_pixels,
  2110.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2111. PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels,
  2112.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2113. PNG_EXPORT(128, png_int_32, png_get_x_offset_microns,
  2114.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2115. PNG_EXPORT(129, png_int_32, png_get_y_offset_microns,
  2116.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2117.  
  2118. #endif /* PNG_EASY_ACCESS_SUPPORTED */
  2119.  
  2120. #ifdef PNG_READ_SUPPORTED
  2121. /* Returns pointer to signature string read from PNG header */
  2122. PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr,
  2123.     png_const_inforp info_ptr));
  2124. #endif
  2125.  
  2126. #ifdef PNG_bKGD_SUPPORTED
  2127. PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
  2128.     png_inforp info_ptr, png_color_16p *background));
  2129. #endif
  2130.  
  2131. #ifdef PNG_bKGD_SUPPORTED
  2132. PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
  2133.     png_inforp info_ptr, png_const_color_16p background));
  2134. #endif
  2135.  
  2136. #ifdef PNG_cHRM_SUPPORTED
  2137. PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr,
  2138.     png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x,
  2139.     double *red_y, double *green_x, double *green_y, double *blue_x,
  2140.     double *blue_y))
  2141. PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr,
  2142.     png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z,
  2143.     double *green_X, double *green_Y, double *green_Z, double *blue_X,
  2144.     double *blue_Y, double *blue_Z))
  2145. PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed,
  2146.     (png_const_structrp png_ptr, png_const_inforp info_ptr,
  2147.     png_fixed_point *int_white_x, png_fixed_point *int_white_y,
  2148.     png_fixed_point *int_red_x, png_fixed_point *int_red_y,
  2149.     png_fixed_point *int_green_x, png_fixed_point *int_green_y,
  2150.     png_fixed_point *int_blue_x, png_fixed_point *int_blue_y))
  2151. PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed,
  2152.     (png_const_structrp png_ptr, png_const_inforp info_ptr,
  2153.     png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
  2154.     png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
  2155.     png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
  2156.     png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
  2157.     png_fixed_point *int_blue_Z))
  2158. #endif
  2159.  
  2160. #ifdef PNG_cHRM_SUPPORTED
  2161. PNG_FP_EXPORT(135, void, png_set_cHRM, (png_const_structrp png_ptr,
  2162.     png_inforp info_ptr,
  2163.     double white_x, double white_y, double red_x, double red_y, double green_x,
  2164.     double green_y, double blue_x, double blue_y))
  2165. PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_const_structrp png_ptr,
  2166.     png_inforp info_ptr, double red_X, double red_Y, double red_Z,
  2167.     double green_X, double green_Y, double green_Z, double blue_X,
  2168.     double blue_Y, double blue_Z))
  2169. PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_const_structrp png_ptr,
  2170.     png_inforp info_ptr, png_fixed_point int_white_x,
  2171.     png_fixed_point int_white_y, png_fixed_point int_red_x,
  2172.     png_fixed_point int_red_y, png_fixed_point int_green_x,
  2173.     png_fixed_point int_green_y, png_fixed_point int_blue_x,
  2174.     png_fixed_point int_blue_y))
  2175. PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
  2176.     png_inforp info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y,
  2177.     png_fixed_point int_red_Z, png_fixed_point int_green_X,
  2178.     png_fixed_point int_green_Y, png_fixed_point int_green_Z,
  2179.     png_fixed_point int_blue_X, png_fixed_point int_blue_Y,
  2180.     png_fixed_point int_blue_Z))
  2181. #endif
  2182.  
  2183. #ifdef PNG_gAMA_SUPPORTED
  2184. PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
  2185.     png_const_inforp info_ptr, double *file_gamma))
  2186. PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed,
  2187.     (png_const_structrp png_ptr, png_const_inforp info_ptr,
  2188.     png_fixed_point *int_file_gamma))
  2189. #endif
  2190.  
  2191. #ifdef PNG_gAMA_SUPPORTED
  2192. PNG_FP_EXPORT(139, void, png_set_gAMA, (png_const_structrp png_ptr,
  2193.     png_inforp info_ptr, double file_gamma))
  2194. PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
  2195.     png_inforp info_ptr, png_fixed_point int_file_gamma))
  2196. #endif
  2197.  
  2198. #ifdef PNG_hIST_SUPPORTED
  2199. PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
  2200.     png_inforp info_ptr, png_uint_16p *hist));
  2201. #endif
  2202.  
  2203. #ifdef PNG_hIST_SUPPORTED
  2204. PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
  2205.     png_inforp info_ptr, png_const_uint_16p hist));
  2206. #endif
  2207.  
  2208. PNG_EXPORT(143, png_uint_32, png_get_IHDR, (png_const_structrp png_ptr,
  2209.     png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height,
  2210.     int *bit_depth, int *color_type, int *interlace_method,
  2211.     int *compression_method, int *filter_method));
  2212.  
  2213. PNG_EXPORT(144, void, png_set_IHDR, (png_const_structrp png_ptr,
  2214.     png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
  2215.     int color_type, int interlace_method, int compression_method,
  2216.     int filter_method));
  2217.  
  2218. #ifdef PNG_oFFs_SUPPORTED
  2219. PNG_EXPORT(145, png_uint_32, png_get_oFFs, (png_const_structrp png_ptr,
  2220.    png_const_inforp info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
  2221.    int *unit_type));
  2222. #endif
  2223.  
  2224. #ifdef PNG_oFFs_SUPPORTED
  2225. PNG_EXPORT(146, void, png_set_oFFs, (png_const_structrp png_ptr,
  2226.     png_inforp info_ptr, png_int_32 offset_x, png_int_32 offset_y,
  2227.     int unit_type));
  2228. #endif
  2229.  
  2230. #ifdef PNG_pCAL_SUPPORTED
  2231. PNG_EXPORT(147, png_uint_32, png_get_pCAL, (png_const_structrp png_ptr,
  2232.     png_inforp info_ptr, png_charp *purpose, png_int_32 *X0,
  2233.     png_int_32 *X1, int *type, int *nparams, png_charp *units,
  2234.     png_charpp *params));
  2235. #endif
  2236.  
  2237. #ifdef PNG_pCAL_SUPPORTED
  2238. PNG_EXPORT(148, void, png_set_pCAL, (png_const_structrp png_ptr,
  2239.     png_inforp info_ptr, png_const_charp purpose, png_int_32 X0, png_int_32 X1,
  2240.     int type, int nparams, png_const_charp units, png_charpp params));
  2241. #endif
  2242.  
  2243. #ifdef PNG_pHYs_SUPPORTED
  2244. PNG_EXPORT(149, png_uint_32, png_get_pHYs, (png_const_structrp png_ptr,
  2245.     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
  2246.     int *unit_type));
  2247. #endif
  2248.  
  2249. #ifdef PNG_pHYs_SUPPORTED
  2250. PNG_EXPORT(150, void, png_set_pHYs, (png_const_structrp png_ptr,
  2251.     png_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
  2252. #endif
  2253.  
  2254. PNG_EXPORT(151, png_uint_32, png_get_PLTE, (png_const_structrp png_ptr,
  2255.    png_inforp info_ptr, png_colorp *palette, int *num_palette));
  2256.  
  2257. PNG_EXPORT(152, void, png_set_PLTE, (png_structrp png_ptr,
  2258.     png_inforp info_ptr, png_const_colorp palette, int num_palette));
  2259.  
  2260. #ifdef PNG_sBIT_SUPPORTED
  2261. PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr,
  2262.     png_inforp info_ptr, png_color_8p *sig_bit));
  2263. #endif
  2264.  
  2265. #ifdef PNG_sBIT_SUPPORTED
  2266. PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr,
  2267.     png_inforp info_ptr, png_const_color_8p sig_bit));
  2268. #endif
  2269.  
  2270. #ifdef PNG_sRGB_SUPPORTED
  2271. PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr,
  2272.     png_const_inforp info_ptr, int *file_srgb_intent));
  2273. #endif
  2274.  
  2275. #ifdef PNG_sRGB_SUPPORTED
  2276. PNG_EXPORT(156, void, png_set_sRGB, (png_const_structrp png_ptr,
  2277.     png_inforp info_ptr, int srgb_intent));
  2278. PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_const_structrp png_ptr,
  2279.     png_inforp info_ptr, int srgb_intent));
  2280. #endif
  2281.  
  2282. #ifdef PNG_iCCP_SUPPORTED
  2283. PNG_EXPORT(158, png_uint_32, png_get_iCCP, (png_const_structrp png_ptr,
  2284.     png_inforp info_ptr, png_charpp name, int *compression_type,
  2285.     png_bytepp profile, png_uint_32 *proflen));
  2286. #endif
  2287.  
  2288. #ifdef PNG_iCCP_SUPPORTED
  2289. PNG_EXPORT(159, void, png_set_iCCP, (png_const_structrp png_ptr,
  2290.     png_inforp info_ptr, png_const_charp name, int compression_type,
  2291.     png_const_bytep profile, png_uint_32 proflen));
  2292. #endif
  2293.  
  2294. #ifdef PNG_sPLT_SUPPORTED
  2295. PNG_EXPORT(160, int, png_get_sPLT, (png_const_structrp png_ptr,
  2296.     png_inforp info_ptr, png_sPLT_tpp entries));
  2297. #endif
  2298.  
  2299. #ifdef PNG_sPLT_SUPPORTED
  2300. PNG_EXPORT(161, void, png_set_sPLT, (png_const_structrp png_ptr,
  2301.     png_inforp info_ptr, png_const_sPLT_tp entries, int nentries));
  2302. #endif
  2303.  
  2304. #ifdef PNG_TEXT_SUPPORTED
  2305. /* png_get_text also returns the number of text chunks in *num_text */
  2306. PNG_EXPORT(162, int, png_get_text, (png_const_structrp png_ptr,
  2307.     png_inforp info_ptr, png_textp *text_ptr, int *num_text));
  2308. #endif
  2309.  
  2310. /* Note while png_set_text() will accept a structure whose text,
  2311.  * language, and  translated keywords are NULL pointers, the structure
  2312.  * returned by png_get_text will always contain regular
  2313.  * zero-terminated C strings.  They might be empty strings but
  2314.  * they will never be NULL pointers.
  2315.  */
  2316.  
  2317. #ifdef PNG_TEXT_SUPPORTED
  2318. PNG_EXPORT(163, void, png_set_text, (png_const_structrp png_ptr,
  2319.     png_inforp info_ptr, png_const_textp text_ptr, int num_text));
  2320. #endif
  2321.  
  2322. #ifdef PNG_tIME_SUPPORTED
  2323. PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr,
  2324.     png_inforp info_ptr, png_timep *mod_time));
  2325. #endif
  2326.  
  2327. #ifdef PNG_tIME_SUPPORTED
  2328. PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr,
  2329.     png_inforp info_ptr, png_const_timep mod_time));
  2330. #endif
  2331.  
  2332. #ifdef PNG_tRNS_SUPPORTED
  2333. PNG_EXPORT(166, png_uint_32, png_get_tRNS, (png_const_structrp png_ptr,
  2334.     png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans,
  2335.     png_color_16p *trans_color));
  2336. #endif
  2337.  
  2338. #ifdef PNG_tRNS_SUPPORTED
  2339. PNG_EXPORT(167, void, png_set_tRNS, (png_structrp png_ptr,
  2340.     png_inforp info_ptr, png_const_bytep trans_alpha, int num_trans,
  2341.     png_const_color_16p trans_color));
  2342. #endif
  2343.  
  2344. #ifdef PNG_sCAL_SUPPORTED
  2345. PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL, (png_const_structrp png_ptr,
  2346.     png_const_inforp info_ptr, int *unit, double *width, double *height))
  2347. #if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
  2348.    defined(PNG_FLOATING_POINT_SUPPORTED)
  2349. /* NOTE: this API is currently implemented using floating point arithmetic,
  2350.  * consequently it can only be used on systems with floating point support.
  2351.  * In any case the range of values supported by png_fixed_point is small and it
  2352.  * is highly recommended that png_get_sCAL_s be used instead.
  2353.  */
  2354. PNG_FIXED_EXPORT(214, png_uint_32, png_get_sCAL_fixed,
  2355.     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
  2356.     png_fixed_point *width, png_fixed_point *height))
  2357. #endif
  2358. PNG_EXPORT(169, png_uint_32, png_get_sCAL_s,
  2359.     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
  2360.     png_charpp swidth, png_charpp sheight));
  2361.  
  2362. PNG_FP_EXPORT(170, void, png_set_sCAL, (png_const_structrp png_ptr,
  2363.     png_inforp info_ptr, int unit, double width, double height))
  2364. PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_const_structrp png_ptr,
  2365.    png_inforp info_ptr, int unit, png_fixed_point width,
  2366.    png_fixed_point height))
  2367. PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
  2368.     png_inforp info_ptr, int unit,
  2369.     png_const_charp swidth, png_const_charp sheight));
  2370. #endif /* PNG_sCAL_SUPPORTED */
  2371.  
  2372. #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
  2373. /* Provide the default handling for all unknown chunks or, optionally, for
  2374.  * specific unknown chunks.
  2375.  *
  2376.  * NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
  2377.  * ignored and the default was used, the per-chunk setting only had an effect on
  2378.  * write.  If you wish to have chunk-specific handling on read in code that must
  2379.  * work on earlier versions you must use a user chunk callback to specify the
  2380.  * desired handling (keep or discard.)
  2381.  *
  2382.  * The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below.  The
  2383.  * parameter is interpreted as follows:
  2384.  *
  2385.  * READ:
  2386.  *    PNG_HANDLE_CHUNK_AS_DEFAULT:
  2387.  *       Known chunks: do normal libpng processing, do not keep the chunk (but
  2388.  *          see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
  2389.  *       Unknown chunks: for a specific chunk use the global default, when used
  2390.  *          as the default discard the chunk data.
  2391.  *    PNG_HANDLE_CHUNK_NEVER:
  2392.  *       Discard the chunk data.
  2393.  *    PNG_HANDLE_CHUNK_IF_SAFE:
  2394.  *       Keep the chunk data if the chunk is not critical else raise a chunk
  2395.  *       error.
  2396.  *    PNG_HANDLE_CHUNK_ALWAYS:
  2397.  *       Keep the chunk data.
  2398.  *
  2399.  * If the chunk data is saved it can be retrieved using png_get_unknown_chunks,
  2400.  * below.  Notice that specifying "AS_DEFAULT" as a global default is equivalent
  2401.  * to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
  2402.  * it simply resets the behavior to the libpng default.
  2403.  *
  2404.  * INTERACTION WTIH USER CHUNK CALLBACKS:
  2405.  * The per-chunk handling is always used when there is a png_user_chunk_ptr
  2406.  * callback and the callback returns 0; the chunk is then always stored *unless*
  2407.  * it is critical and the per-chunk setting is other than ALWAYS.  Notice that
  2408.  * the global default is *not* used in this case.  (In effect the per-chunk
  2409.  * value is incremented to at least IF_SAFE.)
  2410.  *
  2411.  * IMPORTANT NOTE: this behavior will change in libpng 1.7 - the global and
  2412.  * per-chunk defaults will be honored.  If you want to preserve the current
  2413.  * behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE
  2414.  * as the default - if you don't do this libpng 1.6 will issue a warning.
  2415.  *
  2416.  * If you want unhandled unknown chunks to be discarded in libpng 1.6 and
  2417.  * earlier simply return '1' (handled).
  2418.  *
  2419.  * PNG_HANDLE_AS_UNKNOWN_SUPPORTED:
  2420.  *    If this is *not* set known chunks will always be handled by libpng and
  2421.  *    will never be stored in the unknown chunk list.  Known chunks listed to
  2422.  *    png_set_keep_unknown_chunks will have no effect.  If it is set then known
  2423.  *    chunks listed with a keep other than AS_DEFAULT will *never* be processed
  2424.  *    by libpng, in addition critical chunks must either be processed by the
  2425.  *    callback or saved.
  2426.  *
  2427.  *    The IHDR and IEND chunks must not be listed.  Because this turns off the
  2428.  *    default handling for chunks that would otherwise be recognized the
  2429.  *    behavior of libpng transformations may well become incorrect!
  2430.  *
  2431.  * WRITE:
  2432.  *    When writing chunks the options only apply to the chunks specified by
  2433.  *    png_set_unknown_chunks (below), libpng will *always* write known chunks
  2434.  *    required by png_set_ calls and will always write the core critical chunks
  2435.  *    (as required for PLTE).
  2436.  *
  2437.  *    Each chunk in the png_set_unknown_chunks list is looked up in the
  2438.  *    png_set_keep_unknown_chunks list to find the keep setting, this is then
  2439.  *    interpreted as follows:
  2440.  *
  2441.  *    PNG_HANDLE_CHUNK_AS_DEFAULT:
  2442.  *       Write safe-to-copy chunks and write other chunks if the global
  2443.  *       default is set to _ALWAYS, otherwise don't write this chunk.
  2444.  *    PNG_HANDLE_CHUNK_NEVER:
  2445.  *       Do not write the chunk.
  2446.  *    PNG_HANDLE_CHUNK_IF_SAFE:
  2447.  *       Write the chunk if it is safe-to-copy, otherwise do not write it.
  2448.  *    PNG_HANDLE_CHUNK_ALWAYS:
  2449.  *       Write the chunk.
  2450.  *
  2451.  * Note that the default behavior is effectively the opposite of the read case -
  2452.  * in read unknown chunks are not stored by default, in write they are written
  2453.  * by default.  Also the behavior of PNG_HANDLE_CHUNK_IF_SAFE is very different
  2454.  * - on write the safe-to-copy bit is checked, on read the critical bit is
  2455.  * checked and on read if the chunk is critical an error will be raised.
  2456.  *
  2457.  * num_chunks:
  2458.  * ===========
  2459.  *    If num_chunks is positive, then the "keep" parameter specifies the manner
  2460.  *    for handling only those chunks appearing in the chunk_list array,
  2461.  *    otherwise the chunk list array is ignored.
  2462.  *
  2463.  *    If num_chunks is 0 the "keep" parameter specifies the default behavior for
  2464.  *    unknown chunks, as described above.
  2465.  *
  2466.  *    If num_chunks is negative, then the "keep" parameter specifies the manner
  2467.  *    for handling all unknown chunks plus all chunks recognized by libpng
  2468.  *    except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
  2469.  *    be processed by libpng.
  2470.  */
  2471. PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
  2472.     int keep, png_const_bytep chunk_list, int num_chunks));
  2473.  
  2474. /* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
  2475.  * the result is therefore true (non-zero) if special handling is required,
  2476.  * false for the default handling.
  2477.  */
  2478. PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
  2479.     png_const_bytep chunk_name));
  2480. #endif
  2481.  
  2482. #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
  2483. PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
  2484.     png_inforp info_ptr, png_const_unknown_chunkp unknowns,
  2485.     int num_unknowns));
  2486.    /* NOTE: prior to 1.6.0 this routine set the 'location' field of the added
  2487.     * unknowns to the location currently stored in the png_struct.  This is
  2488.     * invariably the wrong value on write.  To fix this call the following API
  2489.     * for each chunk in the list with the correct location.  If you know your
  2490.     * code won't be compiled on earlier versions you can rely on
  2491.     * png_set_unknown_chunks(write-ptr, png_get_unknown_chunks(read-ptr)) doing
  2492.     * the correct thing.
  2493.     */
  2494.  
  2495. PNG_EXPORT(175, void, png_set_unknown_chunk_location,
  2496.     (png_const_structrp png_ptr, png_inforp info_ptr, int chunk, int location));
  2497.  
  2498. PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structrp png_ptr,
  2499.     png_inforp info_ptr, png_unknown_chunkpp entries));
  2500. #endif
  2501.  
  2502. /* Png_free_data() will turn off the "valid" flag for anything it frees.
  2503.  * If you need to turn it off for a chunk that your application has freed,
  2504.  * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
  2505.  */
  2506. PNG_EXPORT(177, void, png_set_invalid, (png_const_structrp png_ptr,
  2507.     png_inforp info_ptr, int mask));
  2508.  
  2509. #ifdef PNG_INFO_IMAGE_SUPPORTED
  2510. /* The "params" pointer is currently not used and is for future expansion. */
  2511. PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr,
  2512.     int transforms, png_voidp params));
  2513. PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr,
  2514.     int transforms, png_voidp params));
  2515. #endif
  2516.  
  2517. PNG_EXPORT(180, png_const_charp, png_get_copyright,
  2518.     (png_const_structrp png_ptr));
  2519. PNG_EXPORT(181, png_const_charp, png_get_header_ver,
  2520.     (png_const_structrp png_ptr));
  2521. PNG_EXPORT(182, png_const_charp, png_get_header_version,
  2522.     (png_const_structrp png_ptr));
  2523. PNG_EXPORT(183, png_const_charp, png_get_libpng_ver,
  2524.     (png_const_structrp png_ptr));
  2525.  
  2526. #ifdef PNG_MNG_FEATURES_SUPPORTED
  2527. PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr,
  2528.     png_uint_32 mng_features_permitted));
  2529. #endif
  2530.  
  2531. /* For use in png_set_keep_unknown, added to version 1.2.6 */
  2532. #define PNG_HANDLE_CHUNK_AS_DEFAULT   0
  2533. #define PNG_HANDLE_CHUNK_NEVER        1
  2534. #define PNG_HANDLE_CHUNK_IF_SAFE      2
  2535. #define PNG_HANDLE_CHUNK_ALWAYS       3
  2536. #define PNG_HANDLE_CHUNK_LAST         4
  2537.  
  2538. /* Strip the prepended error numbers ("#nnn ") from error and warning
  2539.  * messages before passing them to the error or warning handler.
  2540.  */
  2541. #ifdef PNG_ERROR_NUMBERS_SUPPORTED
  2542. PNG_EXPORT(185, void, png_set_strip_error_numbers, (png_structrp png_ptr,
  2543.     png_uint_32 strip_mode));
  2544. #endif
  2545.  
  2546. /* Added in libpng-1.2.6 */
  2547. #ifdef PNG_SET_USER_LIMITS_SUPPORTED
  2548. PNG_EXPORT(186, void, png_set_user_limits, (png_structrp png_ptr,
  2549.     png_uint_32 user_width_max, png_uint_32 user_height_max));
  2550. PNG_EXPORT(187, png_uint_32, png_get_user_width_max,
  2551.     (png_const_structrp png_ptr));
  2552. PNG_EXPORT(188, png_uint_32, png_get_user_height_max,
  2553.     (png_const_structrp png_ptr));
  2554. /* Added in libpng-1.4.0 */
  2555. PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structrp png_ptr,
  2556.     png_uint_32 user_chunk_cache_max));
  2557. PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max,
  2558.     (png_const_structrp png_ptr));
  2559. /* Added in libpng-1.4.1 */
  2560. PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structrp png_ptr,
  2561.     png_alloc_size_t user_chunk_cache_max));
  2562. PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max,
  2563.     (png_const_structrp png_ptr));
  2564. #endif
  2565.  
  2566. #if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
  2567. PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch,
  2568.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2569.  
  2570. PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch,
  2571.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2572.  
  2573. PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch,
  2574.     (png_const_structrp png_ptr, png_const_inforp info_ptr));
  2575.  
  2576. PNG_FP_EXPORT(196, float, png_get_x_offset_inches,
  2577.     (png_const_structrp png_ptr, png_const_inforp info_ptr))
  2578. #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
  2579. PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed,
  2580.     (png_const_structrp png_ptr, png_const_inforp info_ptr))
  2581. #endif
  2582.  
  2583. PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structrp png_ptr,
  2584.     png_const_inforp info_ptr))
  2585. #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
  2586. PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed,
  2587.     (png_const_structrp png_ptr, png_const_inforp info_ptr))
  2588. #endif
  2589.  
  2590. #  ifdef PNG_pHYs_SUPPORTED
  2591. PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structrp png_ptr,
  2592.     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
  2593.     int *unit_type));
  2594. #  endif /* PNG_pHYs_SUPPORTED */
  2595. #endif  /* PNG_INCH_CONVERSIONS_SUPPORTED */
  2596.  
  2597. /* Added in libpng-1.4.0 */
  2598. #ifdef PNG_IO_STATE_SUPPORTED
  2599. PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_const_structrp png_ptr));
  2600.  
  2601. /* Removed from libpng 1.6; use png_get_io_chunk_type. */
  2602. PNG_REMOVED(200, png_const_bytep, png_get_io_chunk_name, (png_structrp png_ptr),
  2603.     PNG_DEPRECATED)
  2604.  
  2605. PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
  2606.     (png_const_structrp png_ptr));
  2607.  
  2608. /* The flags returned by png_get_io_state() are the following: */
  2609. #  define PNG_IO_NONE        0x0000   /* no I/O at this moment */
  2610. #  define PNG_IO_READING     0x0001   /* currently reading */
  2611. #  define PNG_IO_WRITING     0x0002   /* currently writing */
  2612. #  define PNG_IO_SIGNATURE   0x0010   /* currently at the file signature */
  2613. #  define PNG_IO_CHUNK_HDR   0x0020   /* currently at the chunk header */
  2614. #  define PNG_IO_CHUNK_DATA  0x0040   /* currently at the chunk data */
  2615. #  define PNG_IO_CHUNK_CRC   0x0080   /* currently at the chunk crc */
  2616. #  define PNG_IO_MASK_OP     0x000f   /* current operation: reading/writing */
  2617. #  define PNG_IO_MASK_LOC    0x00f0   /* current location: sig/hdr/data/crc */
  2618. #endif /* ?PNG_IO_STATE_SUPPORTED */
  2619.  
  2620. /* Interlace support.  The following macros are always defined so that if
  2621.  * libpng interlace handling is turned off the macros may be used to handle
  2622.  * interlaced images within the application.
  2623.  */
  2624. #define PNG_INTERLACE_ADAM7_PASSES 7
  2625.  
  2626. /* Two macros to return the first row and first column of the original,
  2627.  * full, image which appears in a given pass.  'pass' is in the range 0
  2628.  * to 6 and the result is in the range 0 to 7.
  2629.  */
  2630. #define PNG_PASS_START_ROW(pass) (((1&~(pass))<<(3-((pass)>>1)))&7)
  2631. #define PNG_PASS_START_COL(pass) (((1& (pass))<<(3-(((pass)+1)>>1)))&7)
  2632.  
  2633. /* A macro to return the offset between pixels in the output row for a pair of
  2634.  * pixels in the input - effectively the inverse of the 'COL_SHIFT' macro that
  2635.  * follows.  Note that ROW_OFFSET is the offset from one row to the next whereas
  2636.  * COL_OFFSET is from one column to the next, within a row.
  2637.  */
  2638. #define PNG_PASS_ROW_OFFSET(pass) ((pass)>2?(8>>(((pass)-1)>>1)):8)
  2639. #define PNG_PASS_COL_OFFSET(pass) (1<<((7-(pass))>>1))
  2640.  
  2641. /* Two macros to help evaluate the number of rows or columns in each
  2642.  * pass.  This is expressed as a shift - effectively log2 of the number or
  2643.  * rows or columns in each 8x8 tile of the original image.
  2644.  */
  2645. #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
  2646. #define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
  2647.  
  2648. /* Hence two macros to determine the number of rows or columns in a given
  2649.  * pass of an image given its height or width.  In fact these macros may
  2650.  * return non-zero even though the sub-image is empty, because the other
  2651.  * dimension may be empty for a small image.
  2652.  */
  2653. #define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
  2654.    -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
  2655. #define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
  2656.    -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
  2657.  
  2658. /* For the reader row callbacks (both progressive and sequential) it is
  2659.  * necessary to find the row in the output image given a row in an interlaced
  2660.  * image, so two more macros:
  2661.  */
  2662. #define PNG_ROW_FROM_PASS_ROW(y_in, pass) \
  2663.    (((y_in)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
  2664. #define PNG_COL_FROM_PASS_COL(x_in, pass) \
  2665.    (((x_in)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
  2666.  
  2667. /* Two macros which return a boolean (0 or 1) saying whether the given row
  2668.  * or column is in a particular pass.  These use a common utility macro that
  2669.  * returns a mask for a given pass - the offset 'off' selects the row or
  2670.  * column version.  The mask has the appropriate bit set for each column in
  2671.  * the tile.
  2672.  */
  2673. #define PNG_PASS_MASK(pass,off) ( \
  2674.    ((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \
  2675.    ((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0))
  2676.  
  2677. #define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
  2678.    ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
  2679. #define PNG_COL_IN_INTERLACE_PASS(x, pass) \
  2680.    ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
  2681.  
  2682. #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
  2683. /* With these routines we avoid an integer divide, which will be slower on
  2684.  * most machines.  However, it does take more operations than the corresponding
  2685.  * divide method, so it may be slower on a few RISC systems.  There are two
  2686.  * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
  2687.  *
  2688.  * Note that the rounding factors are NOT supposed to be the same!  128 and
  2689.  * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
  2690.  * standard method.
  2691.  *
  2692.  * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
  2693.  */
  2694.  
  2695.  /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
  2696.  
  2697. #  define png_composite(composite, fg, alpha, bg)         \
  2698.      { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
  2699.            * (png_uint_16)(alpha)                         \
  2700.            + (png_uint_16)(bg)*(png_uint_16)(255          \
  2701.            - (png_uint_16)(alpha)) + 128);                \
  2702.        (composite) = (png_byte)((temp + (temp >> 8)) >> 8); }
  2703.  
  2704. #  define png_composite_16(composite, fg, alpha, bg)       \
  2705.      { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg)  \
  2706.            * (png_uint_32)(alpha)                          \
  2707.            + (png_uint_32)(bg)*(65535                      \
  2708.            - (png_uint_32)(alpha)) + 32768);               \
  2709.        (composite) = (png_uint_16)((temp + (temp >> 16)) >> 16); }
  2710.  
  2711. #else  /* Standard method using integer division */
  2712.  
  2713. #  define png_composite(composite, fg, alpha, bg)                          \
  2714.      (composite) = (png_byte)(((png_uint_16)(fg) * (png_uint_16)(alpha) +  \
  2715.      (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) +       \
  2716.      127) / 255)
  2717.  
  2718. #  define png_composite_16(composite, fg, alpha, bg)                         \
  2719.      (composite) = (png_uint_16)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \
  2720.      (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) +         \
  2721.      32767) / 65535)
  2722. #endif /* PNG_READ_COMPOSITE_NODIV_SUPPORTED */
  2723.  
  2724. #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
  2725. PNG_EXPORT(201, png_uint_32, png_get_uint_32, (png_const_bytep buf));
  2726. PNG_EXPORT(202, png_uint_16, png_get_uint_16, (png_const_bytep buf));
  2727. PNG_EXPORT(203, png_int_32, png_get_int_32, (png_const_bytep buf));
  2728. #endif
  2729.  
  2730. PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_const_structrp png_ptr,
  2731.     png_const_bytep buf));
  2732. /* No png_get_int_16 -- may be added if there's a real need for it. */
  2733.  
  2734. /* Place a 32-bit number into a buffer in PNG byte order (big-endian). */
  2735. #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
  2736. PNG_EXPORT(205, void, png_save_uint_32, (png_bytep buf, png_uint_32 i));
  2737. #endif
  2738. #ifdef PNG_SAVE_INT_32_SUPPORTED
  2739. PNG_EXPORT(206, void, png_save_int_32, (png_bytep buf, png_int_32 i));
  2740. #endif
  2741.  
  2742. /* Place a 16-bit number into a buffer in PNG byte order.
  2743.  * The parameter is declared unsigned int, not png_uint_16,
  2744.  * just to avoid potential problems on pre-ANSI C compilers.
  2745.  */
  2746. #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
  2747. PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
  2748. /* No png_save_int_16 -- may be added if there's a real need for it. */
  2749. #endif
  2750.  
  2751. #ifdef PNG_USE_READ_MACROS
  2752. /* Inline macros to do direct reads of bytes from the input buffer.
  2753.  * The png_get_int_32() routine assumes we are using two's complement
  2754.  * format for negative values, which is almost certainly true.
  2755.  */
  2756. #  define PNG_get_uint_32(buf) \
  2757.      (((png_uint_32)(*(buf)) << 24) + \
  2758.       ((png_uint_32)(*((buf) + 1)) << 16) + \
  2759.       ((png_uint_32)(*((buf) + 2)) << 8) + \
  2760.       ((png_uint_32)(*((buf) + 3))))
  2761.  
  2762.    /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
  2763.     * function) incorrectly returned a value of type png_uint_32.
  2764.     */
  2765. #  define PNG_get_uint_16(buf) \
  2766.      ((png_uint_16) \
  2767.       (((unsigned int)(*(buf)) << 8) + \
  2768.        ((unsigned int)(*((buf) + 1)))))
  2769.  
  2770. #  define PNG_get_int_32(buf) \
  2771.      ((png_int_32)((*(buf) & 0x80) \
  2772.       ? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffffL) + 1)) \
  2773.       : (png_int_32)png_get_uint_32(buf)))
  2774.  
  2775.    /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
  2776.     * but defining a macro name prefixed with PNG_PREFIX.
  2777.     */
  2778. #  ifndef PNG_PREFIX
  2779. #     define png_get_uint_32(buf) PNG_get_uint_32(buf)
  2780. #     define png_get_uint_16(buf) PNG_get_uint_16(buf)
  2781. #     define png_get_int_32(buf)  PNG_get_int_32(buf)
  2782. #  endif
  2783. #else
  2784. #  ifdef PNG_PREFIX
  2785.       /* No macros; revert to the (redefined) function */
  2786. #     define PNG_get_uint_32 (png_get_uint_32)
  2787. #     define PNG_get_uint_16 (png_get_uint_16)
  2788. #     define PNG_get_int_32  (png_get_int_32)
  2789. #  endif
  2790. #endif
  2791.  
  2792. /*******************************************************************************
  2793.  *  SIMPLIFIED API
  2794.  *******************************************************************************
  2795.  *
  2796.  * Please read the documentation in libpng-manual.txt (TODO: write said
  2797.  * documentation) if you don't understand what follows.
  2798.  *
  2799.  * The simplified API hides the details of both libpng and the PNG file format
  2800.  * itself.  It allows PNG files to be read into a very limited number of
  2801.  * in-memory bitmap formats or to be written from the same formats.  If these
  2802.  * formats do not accomodate your needs then you can, and should, use the more
  2803.  * sophisticated APIs above - these support a wide variety of in-memory formats
  2804.  * and a wide variety of sophisticated transformations to those formats as well
  2805.  * as a wide variety of APIs to manipulate ancillary information.
  2806.  *
  2807.  * To read a PNG file using the simplified API:
  2808.  *
  2809.  * 1) Declare a 'png_image' structure (see below) on the stack and set the
  2810.  *    version field to PNG_IMAGE_VERSION.
  2811.  * 2) Call the appropriate png_image_begin_read... function.
  2812.  * 3) Set the png_image 'format' member to the required sample format.
  2813.  * 4) Allocate a buffer for the image and, if required, the color-map.
  2814.  * 5) Call png_image_finish_read to read the image and, if required, the
  2815.  *    color-map into your buffers.
  2816.  *
  2817.  * There are no restrictions on the format of the PNG input itself; all valid
  2818.  * color types, bit depths, and interlace methods are acceptable, and the
  2819.  * input image is transformed as necessary to the requested in-memory format
  2820.  * during the png_image_finish_read() step.  The only caveat is that if you
  2821.  * request a color-mapped image from a PNG that is full-color or makes
  2822.  * complex use of an alpha channel the transformation is extremely lossy and the
  2823.  * result may look terrible.
  2824.  *
  2825.  * To write a PNG file using the simplified API:
  2826.  *
  2827.  * 1) Declare a 'png_image' structure on the stack and memset() it to all zero.
  2828.  * 2) Initialize the members of the structure that describe the image, setting
  2829.  *    the 'format' member to the format of the image samples.
  2830.  * 3) Call the appropriate png_image_write... function with a pointer to the
  2831.  *    image and, if necessary, the color-map to write the PNG data.
  2832.  *
  2833.  * png_image is a structure that describes the in-memory format of an image
  2834.  * when it is being read or defines the in-memory format of an image that you
  2835.  * need to write:
  2836.  */
  2837. #define PNG_IMAGE_VERSION 1
  2838.  
  2839. typedef struct png_control *png_controlp;
  2840. typedef struct
  2841. {
  2842.    png_controlp opaque;    /* Initialize to NULL, free with png_image_free */
  2843.    png_uint_32  version;   /* Set to PNG_IMAGE_VERSION */
  2844.    png_uint_32  width;     /* Image width in pixels (columns) */
  2845.    png_uint_32  height;    /* Image height in pixels (rows) */
  2846.    png_uint_32  format;    /* Image format as defined below */
  2847.    png_uint_32  flags;     /* A bit mask containing informational flags */
  2848.    png_uint_32  colormap_entries;
  2849.                            /* Number of entries in the color-map */
  2850.  
  2851.    /* In the event of an error or warning the following field will be set to a
  2852.     * non-zero value and the 'message' field will contain a '\0' terminated
  2853.     * string with the libpng error or warning message.  If both warnings and
  2854.     * an error were encountered, only the error is recorded.  If there
  2855.     * are multiple warnings, only the first one is recorded.
  2856.     *
  2857.     * The upper 30 bits of this value are reserved, the low two bits contain
  2858.     * a value as follows:
  2859.     */
  2860. #  define PNG_IMAGE_WARNING 1
  2861. #  define PNG_IMAGE_ERROR 2
  2862.    /*
  2863.     * The result is a two bit code such that a value more than 1 indicates
  2864.     * a failure in the API just called:
  2865.     *
  2866.     *    0 - no warning or error
  2867.     *    1 - warning
  2868.     *    2 - error
  2869.     *    3 - error preceded by warning
  2870.     */
  2871. #  define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1)
  2872.  
  2873.    png_uint_32  warning_or_error;
  2874.  
  2875.    char         message[64];
  2876. } png_image, *png_imagep;
  2877.  
  2878. /* The samples of the image have one to four channels whose components have
  2879.  * original values in the range 0 to 1.0:
  2880.  *
  2881.  * 1: A single gray or luminance channel (G).
  2882.  * 2: A gray/luminance channel and an alpha channel (GA).
  2883.  * 3: Three red, green, blue color channels (RGB).
  2884.  * 4: Three color channels and an alpha channel (RGBA).
  2885.  *
  2886.  * The components are encoded in one of two ways:
  2887.  *
  2888.  * a) As a small integer, value 0..255, contained in a single byte.  For the
  2889.  * alpha channel the original value is simply value/255.  For the color or
  2890.  * luminance channels the value is encoded according to the sRGB specification
  2891.  * and matches the 8-bit format expected by typical display devices.
  2892.  *
  2893.  * The color/gray channels are not scaled (pre-multiplied) by the alpha
  2894.  * channel and are suitable for passing to color management software.
  2895.  *
  2896.  * b) As a value in the range 0..65535, contained in a 2-byte integer.  All
  2897.  * channels can be converted to the original value by dividing by 65535; all
  2898.  * channels are linear.  Color channels use the RGB encoding (RGB end-points) of
  2899.  * the sRGB specification.  This encoding is identified by the
  2900.  * PNG_FORMAT_FLAG_LINEAR flag below.
  2901.  *
  2902.  * When the simplified API needs to convert between sRGB and linear colorspaces,
  2903.  * the actual sRGB transfer curve defined in the sRGB specification (see the
  2904.  * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
  2905.  * approximation used elsewhere in libpng.
  2906.  *
  2907.  * When an alpha channel is present it is expected to denote pixel coverage
  2908.  * of the color or luminance channels and is returned as an associated alpha
  2909.  * channel: the color/gray channels are scaled (pre-multiplied) by the alpha
  2910.  * value.
  2911.  *
  2912.  * The samples are either contained directly in the image data, between 1 and 8
  2913.  * bytes per pixel according to the encoding, or are held in a color-map indexed
  2914.  * by bytes in the image data.  In the case of a color-map the color-map entries
  2915.  * are individual samples, encoded as above, and the image data has one byte per
  2916.  * pixel to select the relevant sample from the color-map.
  2917.  */
  2918.  
  2919. /* PNG_FORMAT_*
  2920.  *
  2921.  * #defines to be used in png_image::format.  Each #define identifies a
  2922.  * particular layout of sample data and, if present, alpha values.  There are
  2923.  * separate defines for each of the two component encodings.
  2924.  *
  2925.  * A format is built up using single bit flag values.  All combinations are
  2926.  * valid.  Formats can be built up from the flag values or you can use one of
  2927.  * the predefined values below.  When testing formats always use the FORMAT_FLAG
  2928.  * macros to test for individual features - future versions of the library may
  2929.  * add new flags.
  2930.  *
  2931.  * When reading or writing color-mapped images the format should be set to the
  2932.  * format of the entries in the color-map then png_image_{read,write}_colormap
  2933.  * called to read or write the color-map and set the format correctly for the
  2934.  * image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
  2935.  *
  2936.  * NOTE: libpng can be built with particular features disabled, if you see
  2937.  * compiler errors because the definition of one of the following flags has been
  2938.  * compiled out it is because libpng does not have the required support.  It is
  2939.  * possible, however, for the libpng configuration to enable the format on just
  2940.  * read or just write; in that case you may see an error at run time.  You can
  2941.  * guard against this by checking for the definition of the appropriate
  2942.  * "_SUPPORTED" macro, one of:
  2943.  *
  2944.  *    PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
  2945.  */
  2946. #define PNG_FORMAT_FLAG_ALPHA    0x01U /* format with an alpha channel */
  2947. #define PNG_FORMAT_FLAG_COLOR    0x02U /* color format: otherwise grayscale */
  2948. #define PNG_FORMAT_FLAG_LINEAR   0x04U /* 2 byte channels else 1 byte */
  2949. #define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
  2950.  
  2951. #ifdef PNG_FORMAT_BGR_SUPPORTED
  2952. #  define PNG_FORMAT_FLAG_BGR    0x10U /* BGR colors, else order is RGB */
  2953. #endif
  2954.  
  2955. #ifdef PNG_FORMAT_AFIRST_SUPPORTED
  2956. #  define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
  2957. #endif
  2958.  
  2959. /* Commonly used formats have predefined macros.
  2960.  *
  2961.  * First the single byte (sRGB) formats:
  2962.  */
  2963. #define PNG_FORMAT_GRAY 0
  2964. #define PNG_FORMAT_GA   PNG_FORMAT_FLAG_ALPHA
  2965. #define PNG_FORMAT_AG   (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
  2966. #define PNG_FORMAT_RGB  PNG_FORMAT_FLAG_COLOR
  2967. #define PNG_FORMAT_BGR  (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
  2968. #define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
  2969. #define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
  2970. #define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
  2971. #define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
  2972.  
  2973. /* Then the linear 2-byte formats.  When naming these "Y" is used to
  2974.  * indicate a luminance (gray) channel.
  2975.  */
  2976. #define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
  2977. #define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
  2978. #define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
  2979. #define PNG_FORMAT_LINEAR_RGB_ALPHA \
  2980.    (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA)
  2981.  
  2982. /* With color-mapped formats the image data is one byte for each pixel, the byte
  2983.  * is an index into the color-map which is formatted as above.  To obtain a
  2984.  * color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
  2985.  * to one of the above definitions, or you can use one of the definitions below.
  2986.  */
  2987. #define PNG_FORMAT_RGB_COLORMAP  (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP)
  2988. #define PNG_FORMAT_BGR_COLORMAP  (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP)
  2989. #define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP)
  2990. #define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP)
  2991. #define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP)
  2992. #define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP)
  2993.  
  2994. /* PNG_IMAGE macros
  2995.  *
  2996.  * These are convenience macros to derive information from a png_image
  2997.  * structure.  The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
  2998.  * actual image sample values - either the entries in the color-map or the
  2999.  * pixels in the image.  The PNG_IMAGE_PIXEL_ macros return corresponding values
  3000.  * for the pixels and will always return 1 for color-mapped formats.  The
  3001.  * remaining macros return information about the rows in the image and the
  3002.  * complete image.
  3003.  *
  3004.  * NOTE: All the macros that take a png_image::format parameter are compile time
  3005.  * constants if the format parameter is, itself, a constant.  Therefore these
  3006.  * macros can be used in array declarations and case labels where required.
  3007.  * Similarly the macros are also pre-processor constants (sizeof is not used) so
  3008.  * they can be used in #if tests.
  3009.  *
  3010.  * First the information about the samples.
  3011.  */
  3012. #define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\
  3013.    (((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1)
  3014.    /* Return the total number of channels in a given format: 1..4 */
  3015.  
  3016. #define PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)\
  3017.    ((((fmt) & PNG_FORMAT_FLAG_LINEAR) >> 2)+1)
  3018.    /* Return the size in bytes of a single component of a pixel or color-map
  3019.     * entry (as appropriate) in the image: 1 or 2.
  3020.     */
  3021.  
  3022. #define PNG_IMAGE_SAMPLE_SIZE(fmt)\
  3023.    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt))
  3024.    /* This is the size of the sample data for one sample.  If the image is
  3025.     * color-mapped it is the size of one color-map entry (and image pixels are
  3026.     * one byte in size), otherwise it is the size of one image pixel.
  3027.     */
  3028.  
  3029. #define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
  3030.    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
  3031.    /* The maximum size of the color-map required by the format expressed in a
  3032.     * count of components.  This can be used to compile-time allocate a
  3033.     * color-map:
  3034.     *
  3035.     * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
  3036.     *
  3037.     * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
  3038.     *
  3039.     * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
  3040.     * information from one of the png_image_begin_read_ APIs and dynamically
  3041.     * allocate the required memory.
  3042.     */
  3043.  
  3044. /* Corresponding information about the pixels */
  3045. #define PNG_IMAGE_PIXEL_(test,fmt)\
  3046.    (((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt))
  3047.  
  3048. #define PNG_IMAGE_PIXEL_CHANNELS(fmt)\
  3049.    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt)
  3050.    /* The number of separate channels (components) in a pixel; 1 for a
  3051.     * color-mapped image.
  3052.     */
  3053.  
  3054. #define PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
  3055.    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_COMPONENT_SIZE,fmt)
  3056.    /* The size, in bytes, of each component in a pixel; 1 for a color-mapped
  3057.     * image.
  3058.     */
  3059.  
  3060. #define PNG_IMAGE_PIXEL_SIZE(fmt) PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_SIZE,fmt)
  3061.    /* The size, in bytes, of a complete pixel; 1 for a color-mapped image. */
  3062.  
  3063. /* Information about the whole row, or whole image */
  3064. #define PNG_IMAGE_ROW_STRIDE(image)\
  3065.    (PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width)
  3066.    /* Return the total number of components in a single row of the image; this
  3067.     * is the minimum 'row stride', the minimum count of components between each
  3068.     * row.  For a color-mapped image this is the minimum number of bytes in a
  3069.     * row.
  3070.     */
  3071.  
  3072. #define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
  3073.    (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
  3074.    /* Return the size, in bytes, of an image buffer given a png_image and a row
  3075.     * stride - the number of components to leave space for in each row.
  3076.     */
  3077.  
  3078. #define PNG_IMAGE_SIZE(image)\
  3079.    PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image))
  3080.    /* Return the size, in bytes, of the image in memory given just a png_image;
  3081.     * the row stride is the minimum stride required for the image.
  3082.     */
  3083.  
  3084. #define PNG_IMAGE_COLORMAP_SIZE(image)\
  3085.    (PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries)
  3086.    /* Return the size, in bytes, of the color-map of this image.  If the image
  3087.     * format is not a color-map format this will return a size sufficient for
  3088.     * 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
  3089.     * you don't want to allocate a color-map in this case.
  3090.     */
  3091.  
  3092. /* PNG_IMAGE_FLAG_*
  3093.  *
  3094.  * Flags containing additional information about the image are held in the
  3095.  * 'flags' field of png_image.
  3096.  */
  3097. #define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
  3098.    /* This indicates the the RGB values of the in-memory bitmap do not
  3099.     * correspond to the red, green and blue end-points defined by sRGB.
  3100.     */
  3101.  
  3102. #define PNG_IMAGE_FLAG_FAST 0x02
  3103.    /* On write emphasise speed over compression; the resultant PNG file will be
  3104.     * larger but will be produced significantly faster, particular for large
  3105.     * images.  Do not use this option for images which will be distributed, only
  3106.     * used it when producing intermediate files that will be read back in
  3107.     * repeatedly.  For a typical 24-bit image the option will double the read
  3108.     * speed at the cost of increasing the image size by 25%, however for many
  3109.     * more compressible images the PNG file can be 10 times larger with only a
  3110.     * slight speed gain.
  3111.     */
  3112.  
  3113. #define PNG_IMAGE_FLAG_16BIT_sRGB 0x04
  3114.    /* On read if the image is a 16-bit per component image and there is no gAMA
  3115.     * or sRGB chunk assume that the components are sRGB encoded.  Notice that
  3116.     * images output by the simplified API always have gamma information; setting
  3117.     * this flag only affects the interpretation of 16-bit images from an
  3118.     * external source.  It is recommended that the application expose this flag
  3119.     * to the user; the user can normally easily recognize the difference between
  3120.     * linear and sRGB encoding.  This flag has no effect on write - the data
  3121.     * passed to the write APIs must have the correct encoding (as defined
  3122.     * above.)
  3123.     *
  3124.     * If the flag is not set (the default) input 16-bit per component data is
  3125.     * assumed to be linear.
  3126.     *
  3127.     * NOTE: the flag can only be set after the png_image_begin_read_ call,
  3128.     * because that call initializes the 'flags' field.
  3129.     */
  3130.  
  3131. #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
  3132. /* READ APIs
  3133.  * ---------
  3134.  *
  3135.  * The png_image passed to the read APIs must have been initialized by setting
  3136.  * the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.)
  3137.  */
  3138. #ifdef PNG_STDIO_SUPPORTED
  3139. PNG_EXPORT(234, int, png_image_begin_read_from_file, (png_imagep image,
  3140.    const char *file_name));
  3141.    /* The named file is opened for read and the image header is filled in
  3142.     * from the PNG header in the file.
  3143.     */
  3144.  
  3145. PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
  3146.    FILE* file));
  3147.    /* The PNG header is read from the stdio FILE object. */
  3148. #endif /* PNG_STDIO_SUPPORTED */
  3149.  
  3150. PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
  3151.    png_const_voidp memory, png_size_t size));
  3152.    /* The PNG header is read from the given memory buffer. */
  3153.  
  3154. PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
  3155.    png_const_colorp background, void *buffer, png_int_32 row_stride,
  3156.    void *colormap));
  3157.    /* Finish reading the image into the supplied buffer and clean up the
  3158.     * png_image structure.
  3159.     *
  3160.     * row_stride is the step, in byte or 2-byte units as appropriate,
  3161.     * between adjacent rows.  A positive stride indicates that the top-most row
  3162.     * is first in the buffer - the normal top-down arrangement.  A negative
  3163.     * stride indicates that the bottom-most row is first in the buffer.
  3164.     *
  3165.     * background need only be supplied if an alpha channel must be removed from
  3166.     * a png_byte format and the removal is to be done by compositing on a solid
  3167.     * color; otherwise it may be NULL and any composition will be done directly
  3168.     * onto the buffer.  The value is an sRGB color to use for the background,
  3169.     * for grayscale output the green channel is used.
  3170.     *
  3171.     * background must be supplied when an alpha channel must be removed from a
  3172.     * single byte color-mapped output format, in other words if:
  3173.     *
  3174.     * 1) The original format from png_image_begin_read_from_* had
  3175.     *    PNG_FORMAT_FLAG_ALPHA set.
  3176.     * 2) The format set by the application does not.
  3177.     * 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
  3178.     *    PNG_FORMAT_FLAG_LINEAR *not* set.
  3179.     *
  3180.     * For linear output removing the alpha channel is always done by compositing
  3181.     * on black and background is ignored.
  3182.     *
  3183.     * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set.  It must
  3184.     * be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
  3185.     * image->colormap_entries will be updated to the actual number of entries
  3186.     * written to the colormap; this may be less than the original value.
  3187.     */
  3188.  
  3189. PNG_EXPORT(238, void, png_image_free, (png_imagep image));
  3190.    /* Free any data allocated by libpng in image->opaque, setting the pointer to
  3191.     * NULL.  May be called at any time after the structure is initialized.
  3192.     */
  3193. #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */
  3194.  
  3195. #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
  3196. #ifdef PNG_STDIO_SUPPORTED
  3197. /* WRITE APIS
  3198.  * ----------
  3199.  * For write you must initialize a png_image structure to describe the image to
  3200.  * be written.  To do this use memset to set the whole structure to 0 then
  3201.  * initialize fields describing your image.
  3202.  *
  3203.  * version: must be set to PNG_IMAGE_VERSION
  3204.  * opaque: must be initialized to NULL
  3205.  * width: image width in pixels
  3206.  * height: image height in rows
  3207.  * format: the format of the data (image and color-map) you wish to write
  3208.  * flags: set to 0 unless one of the defined flags applies; set
  3209.  *    PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB
  3210.  *    values do not correspond to the colors in sRGB.
  3211.  * colormap_entries: set to the number of entries in the color-map (0 to 256)
  3212.  */
  3213. PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
  3214.    const char *file, int convert_to_8bit, const void *buffer,
  3215.    png_int_32 row_stride, const void *colormap));
  3216.    /* Write the image to the named file. */
  3217.  
  3218. PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
  3219.    int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
  3220.    const void *colormap));
  3221.    /* Write the image to the given (FILE*). */
  3222.  
  3223. /* With both write APIs if image is in one of the linear formats with 16-bit
  3224.  * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
  3225.  * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
  3226.  * encoded PNG file is written.
  3227.  *
  3228.  * With color-mapped data formats the colormap parameter point to a color-map
  3229.  * with at least image->colormap_entries encoded in the specified format.  If
  3230.  * the format is linear the written PNG color-map will be converted to sRGB
  3231.  * regardless of the convert_to_8_bit flag.
  3232.  *
  3233.  * With all APIs row_stride is handled as in the read APIs - it is the spacing
  3234.  * from one row to the next in component sized units (1 or 2 bytes) and if
  3235.  * negative indicates a bottom-up row layout in the buffer.
  3236.  *
  3237.  * Note that the write API does not support interlacing or sub-8-bit pixels.
  3238.  */
  3239. #endif /* PNG_STDIO_SUPPORTED */
  3240. #endif /* PNG_SIMPLIFIED_WRITE_SUPPORTED */
  3241. /*******************************************************************************
  3242.  *  END OF SIMPLIFIED API
  3243.  ******************************************************************************/
  3244.  
  3245. #ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
  3246. PNG_EXPORT(242, void, png_set_check_for_invalid_index,
  3247.     (png_structrp png_ptr, int allowed));
  3248. #  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
  3249. PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
  3250.     png_const_infop info_ptr));
  3251. #  endif
  3252. #endif /* CHECK_FOR_INVALID_INDEX */
  3253.  
  3254. /*******************************************************************************
  3255.  *  IMPLEMENTATION OPTIONS
  3256.  *******************************************************************************
  3257.  *
  3258.  * Support for arbitrary implementation-specific optimizations.  The API allows
  3259.  * particular options to be turned on or off.  'Option' is the number of the
  3260.  * option and 'onoff' is 0 (off) or non-0 (on).  The value returned is given
  3261.  * by the PNG_OPTION_ defines below.
  3262.  *
  3263.  * HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
  3264.  *           are detected at run time, however sometimes it may be impossible
  3265.  *           to do this in user mode, in which case it is necessary to discover
  3266.  *           the capabilities in an OS specific way.  Such capabilities are
  3267.  *           listed here when libpng has support for them and must be turned
  3268.  *           ON by the application if present.
  3269.  *
  3270.  * SOFTWARE: sometimes software optimizations actually result in performance
  3271.  *           decrease on some architectures or systems, or with some sets of
  3272.  *           PNG images.  'Software' options allow such optimizations to be
  3273.  *           selected at run time.
  3274.  */
  3275. #ifdef PNG_SET_OPTION_SUPPORTED
  3276. #ifdef PNG_ARM_NEON_API_SUPPORTED
  3277. #  define PNG_ARM_NEON   0 /* HARDWARE: ARM Neon SIMD instructions supported */
  3278. #endif
  3279. #define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
  3280. #define PNG_OPTION_NEXT  4 /* Next option - numbers must be even */
  3281.  
  3282. /* Return values: NOTE: there are four values and 'off' is *not* zero */
  3283. #define PNG_OPTION_UNSET   0 /* Unset - defaults to off */
  3284. #define PNG_OPTION_INVALID 1 /* Option number out of range */
  3285. #define PNG_OPTION_OFF     2
  3286. #define PNG_OPTION_ON      3
  3287.  
  3288. PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
  3289.    int onoff));
  3290. #endif
  3291.  
  3292. /*******************************************************************************
  3293.  *  END OF HARDWARE OPTIONS
  3294.  ******************************************************************************/
  3295.  
  3296. /* Maintainer: Put new public prototypes here ^, in libpng.3, and project
  3297.  * defs, scripts/pnglibconf.h, and scripts/pnglibconf.h.prebuilt
  3298.  */
  3299.  
  3300. /* The last ordinal number (this is the *last* one already used; the next
  3301.  * one to use is one more than this.)  Maintainer, remember to add an entry to
  3302.  * scripts/symbols.def as well.
  3303.  */
  3304. #ifdef PNG_EXPORT_LAST_ORDINAL
  3305.   PNG_EXPORT_LAST_ORDINAL(244);
  3306. #endif
  3307.  
  3308. #ifdef __cplusplus
  3309. }
  3310. #endif
  3311.  
  3312. #endif /* PNG_VERSION_INFO_ONLY */
  3313. /* Do not put anything past this line */
  3314. #endif /* PNG_H */
  3315.