glstuff

png.h (162093B)

---

 /* png.h - header file for PNG reference library
  *
  * libpng version 1.2.50 - July 10, 2012
  * Copyright (c) 1998-2012 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
  * This code is released under the libpng license (See LICENSE, below)
  *
  * Authors and maintainers:
  *  libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  *  libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
  *  libpng versions 0.97, January 1998, through 1.2.50 - July 10, 2012: Glenn
  *  See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
  *
  *    Due to various miscommunications, unforeseen code incompatibilities
  *    and occasional factors outside the authors' control, version numbering
  *    on the library has not always been consistent and straightforward.
  *    The following table summarizes matters since version 0.89c, which was
  *    the first widely used release:
  *
  *    source                 png.h  png.h  shared-lib
  *    version                string   int  version
  *    -------                ------ -----  ----------
  *    0.89c "1.0 beta 3"     0.89      89  1.0.89
  *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
  *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
  *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
  *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
  *    0.97c                  0.97      97  2.0.97
  *    0.98                   0.98      98  2.0.98
  *    0.99                   0.99      98  2.0.99
  *    0.99a-m                0.99      99  2.0.99
  *    1.00                   1.00     100  2.1.0 [100 should be 10000]
  *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
  *    1.0.1       png.h string is   10001  2.1.0
  *    1.0.1a-e    identical to the  10002  from here on, the shared library
  *    1.0.2       source version)   10002  is 2.V where V is the source code
  *    1.0.2a-b                      10003  version, except as noted.
  *    1.0.3                         10003
  *    1.0.3a-d                      10004
  *    1.0.4                         10004
  *    1.0.4a-f                      10005
  *    1.0.5 (+ 2 patches)           10005
  *    1.0.5a-d                      10006
  *    1.0.5e-r                      10100 (not source compatible)
  *    1.0.5s-v                      10006 (not binary compatible)
  *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)
  *    1.0.6d-f                      10007 (still binary incompatible)
  *    1.0.6g                        10007
  *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)
  *    1.0.6i                        10007  10.6i
  *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
  *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
  *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
  *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
  *    1.0.7                    1    10007  (still compatible)
  *    1.0.8beta1-4             1    10008  2.1.0.8beta1-4
  *    1.0.8rc1                 1    10008  2.1.0.8rc1
  *    1.0.8                    1    10008  2.1.0.8
  *    1.0.9beta1-6             1    10009  2.1.0.9beta1-6
  *    1.0.9rc1                 1    10009  2.1.0.9rc1
  *    1.0.9beta7-10            1    10009  2.1.0.9beta7-10
  *    1.0.9rc2                 1    10009  2.1.0.9rc2
  *    1.0.9                    1    10009  2.1.0.9
  *    1.0.10beta1              1    10010  2.1.0.10beta1
  *    1.0.10rc1                1    10010  2.1.0.10rc1
  *    1.0.10                   1    10010  2.1.0.10
  *    1.0.11beta1-3            1    10011  2.1.0.11beta1-3
  *    1.0.11rc1                1    10011  2.1.0.11rc1
  *    1.0.11                   1    10011  2.1.0.11
  *    1.0.12beta1-2            2    10012  2.1.0.12beta1-2
  *    1.0.12rc1                2    10012  2.1.0.12rc1
  *    1.0.12                   2    10012  2.1.0.12
  *    1.1.0a-f                 -    10100  2.1.1.0a-f (branch abandoned)
  *    1.2.0beta1-2             2    10200  2.1.2.0beta1-2
  *    1.2.0beta3-5             3    10200  3.1.2.0beta3-5
  *    1.2.0rc1                 3    10200  3.1.2.0rc1
  *    1.2.0                    3    10200  3.1.2.0
  *    1.2.1beta1-4             3    10201  3.1.2.1beta1-4
  *    1.2.1rc1-2               3    10201  3.1.2.1rc1-2
  *    1.2.1                    3    10201  3.1.2.1
  *    1.2.2beta1-6            12    10202  12.so.0.1.2.2beta1-6
  *    1.0.13beta1             10    10013  10.so.0.1.0.13beta1
  *    1.0.13rc1               10    10013  10.so.0.1.0.13rc1
  *    1.2.2rc1                12    10202  12.so.0.1.2.2rc1
  *    1.0.13                  10    10013  10.so.0.1.0.13
  *    1.2.2                   12    10202  12.so.0.1.2.2
  *    1.2.3rc1-6              12    10203  12.so.0.1.2.3rc1-6
  *    1.2.3                   12    10203  12.so.0.1.2.3
  *    1.2.4beta1-3            13    10204  12.so.0.1.2.4beta1-3
  *    1.0.14rc1               13    10014  10.so.0.1.0.14rc1
  *    1.2.4rc1                13    10204  12.so.0.1.2.4rc1
  *    1.0.14                  10    10014  10.so.0.1.0.14
  *    1.2.4                   13    10204  12.so.0.1.2.4
  *    1.2.5beta1-2            13    10205  12.so.0.1.2.5beta1-2
  *    1.0.15rc1-3             10    10015  10.so.0.1.0.15rc1-3
  *    1.2.5rc1-3              13    10205  12.so.0.1.2.5rc1-3
  *    1.0.15                  10    10015  10.so.0.1.0.15
  *    1.2.5                   13    10205  12.so.0.1.2.5
  *    1.2.6beta1-4            13    10206  12.so.0.1.2.6beta1-4
  *    1.0.16                  10    10016  10.so.0.1.0.16
  *    1.2.6                   13    10206  12.so.0.1.2.6
  *    1.2.7beta1-2            13    10207  12.so.0.1.2.7beta1-2
  *    1.0.17rc1               10    10017  10.so.0.1.0.17rc1
  *    1.2.7rc1                13    10207  12.so.0.1.2.7rc1
  *    1.0.17                  10    10017  10.so.0.1.0.17
  *    1.2.7                   13    10207  12.so.0.1.2.7
  *    1.2.8beta1-5            13    10208  12.so.0.1.2.8beta1-5
  *    1.0.18rc1-5             10    10018  10.so.0.1.0.18rc1-5
  *    1.2.8rc1-5              13    10208  12.so.0.1.2.8rc1-5
  *    1.0.18                  10    10018  10.so.0.1.0.18
  *    1.2.8                   13    10208  12.so.0.1.2.8
  *    1.2.9beta1-3            13    10209  12.so.0.1.2.9beta1-3
  *    1.2.9beta4-11           13    10209  12.so.0.9[.0]
  *    1.2.9rc1                13    10209  12.so.0.9[.0]
  *    1.2.9                   13    10209  12.so.0.9[.0]
  *    1.2.10beta1-8           13    10210  12.so.0.10[.0]
  *    1.2.10rc1-3             13    10210  12.so.0.10[.0]
  *    1.2.10                  13    10210  12.so.0.10[.0]
  *    1.2.11beta1-4           13    10211  12.so.0.11[.0]
  *    1.0.19rc1-5             10    10019  10.so.0.19[.0]
  *    1.2.11rc1-5             13    10211  12.so.0.11[.0]
  *    1.0.19                  10    10019  10.so.0.19[.0]
  *    1.2.11                  13    10211  12.so.0.11[.0]
  *    1.0.20                  10    10020  10.so.0.20[.0]
  *    1.2.12                  13    10212  12.so.0.12[.0]
  *    1.2.13beta1             13    10213  12.so.0.13[.0]
  *    1.0.21                  10    10021  10.so.0.21[.0]
  *    1.2.13                  13    10213  12.so.0.13[.0]
  *    1.2.14beta1-2           13    10214  12.so.0.14[.0]
  *    1.0.22rc1               10    10022  10.so.0.22[.0]
  *    1.2.14rc1               13    10214  12.so.0.14[.0]
  *    1.0.22                  10    10022  10.so.0.22[.0]
  *    1.2.14                  13    10214  12.so.0.14[.0]
  *    1.2.15beta1-6           13    10215  12.so.0.15[.0]
  *    1.0.23rc1-5             10    10023  10.so.0.23[.0]
  *    1.2.15rc1-5             13    10215  12.so.0.15[.0]
  *    1.0.23                  10    10023  10.so.0.23[.0]
  *    1.2.15                  13    10215  12.so.0.15[.0]
  *    1.2.16beta1-2           13    10216  12.so.0.16[.0]
  *    1.2.16rc1               13    10216  12.so.0.16[.0]
  *    1.0.24                  10    10024  10.so.0.24[.0]
  *    1.2.16                  13    10216  12.so.0.16[.0]
  *    1.2.17beta1-2           13    10217  12.so.0.17[.0]
  *    1.0.25rc1               10    10025  10.so.0.25[.0]
  *    1.2.17rc1-3             13    10217  12.so.0.17[.0]
  *    1.0.25                  10    10025  10.so.0.25[.0]
  *    1.2.17                  13    10217  12.so.0.17[.0]
  *    1.0.26                  10    10026  10.so.0.26[.0]
  *    1.2.18                  13    10218  12.so.0.18[.0]
  *    1.2.19beta1-31          13    10219  12.so.0.19[.0]
  *    1.0.27rc1-6             10    10027  10.so.0.27[.0]
  *    1.2.19rc1-6             13    10219  12.so.0.19[.0]
  *    1.0.27                  10    10027  10.so.0.27[.0]
  *    1.2.19                  13    10219  12.so.0.19[.0]
  *    1.2.20beta01-04         13    10220  12.so.0.20[.0]
  *    1.0.28rc1-6             10    10028  10.so.0.28[.0]
  *    1.2.20rc1-6             13    10220  12.so.0.20[.0]
  *    1.0.28                  10    10028  10.so.0.28[.0]
  *    1.2.20                  13    10220  12.so.0.20[.0]
  *    1.2.21beta1-2           13    10221  12.so.0.21[.0]
  *    1.2.21rc1-3             13    10221  12.so.0.21[.0]
  *    1.0.29                  10    10029  10.so.0.29[.0]
  *    1.2.21                  13    10221  12.so.0.21[.0]
  *    1.2.22beta1-4           13    10222  12.so.0.22[.0]
  *    1.0.30rc1               10    10030  10.so.0.30[.0]
  *    1.2.22rc1               13    10222  12.so.0.22[.0]
  *    1.0.30                  10    10030  10.so.0.30[.0]
  *    1.2.22                  13    10222  12.so.0.22[.0]
  *    1.2.23beta01-05         13    10223  12.so.0.23[.0]
  *    1.2.23rc01              13    10223  12.so.0.23[.0]
  *    1.2.23                  13    10223  12.so.0.23[.0]
  *    1.2.24beta01-02         13    10224  12.so.0.24[.0]
  *    1.2.24rc01              13    10224  12.so.0.24[.0]
  *    1.2.24                  13    10224  12.so.0.24[.0]
  *    1.2.25beta01-06         13    10225  12.so.0.25[.0]
  *    1.2.25rc01-02           13    10225  12.so.0.25[.0]
  *    1.0.31                  10    10031  10.so.0.31[.0]
  *    1.2.25                  13    10225  12.so.0.25[.0]
  *    1.2.26beta01-06         13    10226  12.so.0.26[.0]
  *    1.2.26rc01              13    10226  12.so.0.26[.0]
  *    1.2.26                  13    10226  12.so.0.26[.0]
  *    1.0.32                  10    10032  10.so.0.32[.0]
  *    1.2.27beta01-06         13    10227  12.so.0.27[.0]
  *    1.2.27rc01              13    10227  12.so.0.27[.0]
  *    1.0.33                  10    10033  10.so.0.33[.0]
  *    1.2.27                  13    10227  12.so.0.27[.0]
  *    1.0.34                  10    10034  10.so.0.34[.0]
  *    1.2.28                  13    10228  12.so.0.28[.0]
  *    1.2.29beta01-03         13    10229  12.so.0.29[.0]
  *    1.2.29rc01              13    10229  12.so.0.29[.0]
  *    1.0.35                  10    10035  10.so.0.35[.0]
  *    1.2.29                  13    10229  12.so.0.29[.0]
  *    1.0.37                  10    10037  10.so.0.37[.0]
  *    1.2.30beta01-04         13    10230  12.so.0.30[.0]
  *    1.0.38rc01-08           10    10038  10.so.0.38[.0]
  *    1.2.30rc01-08           13    10230  12.so.0.30[.0]
  *    1.0.38                  10    10038  10.so.0.38[.0]
  *    1.2.30                  13    10230  12.so.0.30[.0]
  *    1.0.39rc01-03           10    10039  10.so.0.39[.0]
  *    1.2.31rc01-03           13    10231  12.so.0.31[.0]
  *    1.0.39                  10    10039  10.so.0.39[.0]
  *    1.2.31                  13    10231  12.so.0.31[.0]
  *    1.2.32beta01-02         13    10232  12.so.0.32[.0]
  *    1.0.40rc01              10    10040  10.so.0.40[.0]
  *    1.2.32rc01              13    10232  12.so.0.32[.0]
  *    1.0.40                  10    10040  10.so.0.40[.0]
  *    1.2.32                  13    10232  12.so.0.32[.0]
  *    1.2.33beta01-02         13    10233  12.so.0.33[.0]
  *    1.2.33rc01-02           13    10233  12.so.0.33[.0]
  *    1.0.41rc01              10    10041  10.so.0.41[.0]
  *    1.2.33                  13    10233  12.so.0.33[.0]
  *    1.0.41                  10    10041  10.so.0.41[.0]
  *    1.2.34beta01-07         13    10234  12.so.0.34[.0]
  *    1.0.42rc01              10    10042  10.so.0.42[.0]
  *    1.2.34rc01              13    10234  12.so.0.34[.0]
  *    1.0.42                  10    10042  10.so.0.42[.0]
  *    1.2.34                  13    10234  12.so.0.34[.0]
  *    1.2.35beta01-03         13    10235  12.so.0.35[.0]
  *    1.0.43rc01-02           10    10043  10.so.0.43[.0]
  *    1.2.35rc01-02           13    10235  12.so.0.35[.0]
  *    1.0.43                  10    10043  10.so.0.43[.0]
  *    1.2.35                  13    10235  12.so.0.35[.0]
  *    1.2.36beta01-05         13    10236  12.so.0.36[.0]
  *    1.2.36rc01              13    10236  12.so.0.36[.0]
  *    1.0.44                  10    10044  10.so.0.44[.0]
  *    1.2.36                  13    10236  12.so.0.36[.0]
  *    1.2.37beta01-03         13    10237  12.so.0.37[.0]
  *    1.2.37rc01              13    10237  12.so.0.37[.0]
  *    1.2.37                  13    10237  12.so.0.37[.0]
  *    1.0.45                  10    10045  12.so.0.45[.0]
  *    1.0.46                  10    10046  10.so.0.46[.0]
  *    1.2.38beta01            13    10238  12.so.0.38[.0]
  *    1.2.38rc01-03           13    10238  12.so.0.38[.0]
  *    1.0.47                  10    10047  10.so.0.47[.0]
  *    1.2.38                  13    10238  12.so.0.38[.0]
  *    1.2.39beta01-05         13    10239  12.so.0.39[.0]
  *    1.2.39rc01              13    10239  12.so.0.39[.0]
  *    1.0.48                  10    10048  10.so.0.48[.0]
  *    1.2.39                  13    10239  12.so.0.39[.0]
  *    1.2.40beta01            13    10240  12.so.0.40[.0]
  *    1.2.40rc01              13    10240  12.so.0.40[.0]
  *    1.0.49                  10    10049  10.so.0.49[.0]
  *    1.2.40                  13    10240  12.so.0.40[.0]
  *    1.2.41beta01-18         13    10241  12.so.0.41[.0]
  *    1.0.51rc01              10    10051  10.so.0.51[.0]
  *    1.2.41rc01-03           13    10241  12.so.0.41[.0]
  *    1.0.51                  10    10051  10.so.0.51[.0]
  *    1.2.41                  13    10241  12.so.0.41[.0]
  *    1.2.42beta01-02         13    10242  12.so.0.42[.0]
  *    1.2.42rc01-05           13    10242  12.so.0.42[.0]
  *    1.0.52                  10    10052  10.so.0.52[.0]
  *    1.2.42                  13    10242  12.so.0.42[.0]
  *    1.2.43beta01-05         13    10243  12.so.0.43[.0]
  *    1.0.53rc01-02           10    10053  10.so.0.53[.0]
  *    1.2.43rc01-02           13    10243  12.so.0.43[.0]
  *    1.0.53                  10    10053  10.so.0.53[.0]
  *    1.2.43                  13    10243  12.so.0.43[.0]
  *    1.2.44beta01-03         13    10244  12.so.0.44[.0]
  *    1.2.44rc01-03           13    10244  12.so.0.44[.0]
  *    1.2.44                  13    10244  12.so.0.44[.0]
  *    1.2.45beta01-03         13    10245  12.so.0.45[.0]
  *    1.0.55rc01              10    10055  10.so.0.55[.0]
  *    1.2.45rc01              13    10245  12.so.0.45[.0]
  *    1.0.55                  10    10055  10.so.0.55[.0]
  *    1.2.45                  13    10245  12.so.0.45[.0]
  *    1.2.46rc01-02           13    10246  12.so.0.46[.0]
  *    1.0.56                  10    10056  10.so.0.56[.0]
  *    1.2.46                  13    10246  12.so.0.46[.0]
  *    1.2.47beta01            13    10247  12.so.0.47[.0]
  *    1.2.47rc01              13    10247  12.so.0.47[.0]
  *    1.0.57rc01              10    10057  10.so.0.57[.0]
  *    1.2.47                  13    10247  12.so.0.47[.0]
  *    1.0.57                  10    10057  10.so.0.57[.0]
  *    1.2.48beta01            13    10248  12.so.0.48[.0]
  *    1.2.48rc01-02           13    10248  12.so.0.48[.0]
  *    1.0.58                  10    10058  10.so.0.58[.0]
  *    1.2.48                  13    10248  12.so.0.48[.0]
  *    1.2.49rc01              13    10249  12.so.0.49[.0]
  *    1.0.59                  10    10059  10.so.0.59[.0]
  *    1.2.49                  13    10249  12.so.0.49[.0]
  *    1.0.60                  10    10060  10.so.0.60[.0]
  *    1.2.50                  13    10250  12.so.0.50[.0]
  *
  *    Henceforth the source version will match the shared-library major
  *    and minor numbers; the shared-library major version number will be
  *    used for changes in backward compatibility, as it is intended.  The
  *    PNG_LIBPNG_VER macro, which is not used within libpng but is available
  *    for applications, is an unsigned integer of the form xyyzz corresponding
  *    to the source version x.y.z (leading zeros in y and z).  Beta versions
  *    were given the previous public release number plus a letter, until
  *    version 1.0.6j; from then on they were given the upcoming public
  *    release number plus "betaNN" or "rcNN".
  *
  *    Binary incompatibility exists only when applications make direct access
  *    to the info_ptr or png_ptr members through png.h, and the compiled
  *    application is loaded with a different version of the library.
  *
  *    DLLNUM will change each time there are forward or backward changes
  *    in binary compatibility (e.g., when a new feature is added).
  *
  * See libpng.txt or libpng.3 for more information.  The PNG specification
  * is available as a W3C Recommendation and as an ISO Specification,
  * <http://www.w3.org/TR/2003/REC-PNG-20031110/
  */
 
 /*
  * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
  *
  * If you modify libpng you may insert additional notices immediately following
  * this sentence.
  *
  * This code is released under the libpng license.
  *
  * libpng versions 1.2.6, August 15, 2004, through 1.2.50, July 10, 2012, are
  * Copyright (c) 2004, 2006-2011 Glenn Randers-Pehrson, and are
  * distributed according to the same disclaimer and license as libpng-1.2.5
  * with the following individual added to the list of Contributing Authors:
  *
  *    Cosmin Truta
  *
  * libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are
  * Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
  * distributed according to the same disclaimer and license as libpng-1.0.6
  * with the following individuals added to the list of Contributing Authors:
  *
  *    Simon-Pierre Cadieux
  *    Eric S. Raymond
  *    Gilles Vollant
  *
  * and with the following additions to the disclaimer:
  *
  *    There is no warranty against interference with your enjoyment of the
  *    library or against infringement.  There is no warranty that our
  *    efforts or the library will fulfill any of your particular purposes
  *    or needs.  This library is provided with all faults, and the entire
  *    risk of satisfactory quality, performance, accuracy, and effort is with
  *    the user.
  *
  * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
  * Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson, and are
  * distributed according to the same disclaimer and license as libpng-0.96,
  * with the following individuals added to the list of Contributing Authors:
  *
  *    Tom Lane
  *    Glenn Randers-Pehrson
  *    Willem van Schaik
  *
  * libpng versions 0.89, June 1996, through 0.96, May 1997, are
  * Copyright (c) 1996, 1997 Andreas Dilger
  * Distributed according to the same disclaimer and license as libpng-0.88,
  * with the following individuals added to the list of Contributing Authors:
  *
  *    John Bowler
  *    Kevin Bracey
  *    Sam Bushell
  *    Magnus Holmgren
  *    Greg Roelofs
  *    Tom Tanner
  *
  * libpng versions 0.5, May 1995, through 0.88, January 1996, are
  * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
  *
  * For the purposes of this copyright and license, "Contributing Authors"
  * is defined as the following set of individuals:
  *
  *    Andreas Dilger
  *    Dave Martindale
  *    Guy Eric Schalnat
  *    Paul Schmidt
  *    Tim Wegner
  *
  * The PNG Reference Library is supplied "AS IS".  The Contributing Authors
  * and Group 42, Inc. disclaim all warranties, expressed or implied,
  * including, without limitation, the warranties of merchantability and of
  * fitness for any purpose.  The Contributing Authors and Group 42, Inc.
  * assume no liability for direct, indirect, incidental, special, exemplary,
  * or consequential damages, which may result from the use of the PNG
  * Reference Library, even if advised of the possibility of such damage.
  *
  * Permission is hereby granted to use, copy, modify, and distribute this
  * source code, or portions hereof, for any purpose, without fee, subject
  * to the following restrictions:
  *
  * 1. The origin of this source code must not be misrepresented.
  *
  * 2. Altered versions must be plainly marked as such and
  * must not be misrepresented as being the original source.
  *
  * 3. This Copyright notice may not be removed or altered from
  *    any source or altered source distribution.
  *
  * The Contributing Authors and Group 42, Inc. specifically permit, without
  * fee, and encourage the use of this source code as a component to
  * supporting the PNG file format in commercial products.  If you use this
  * source code in a product, acknowledgment is not required but would be
  * appreciated.
  */
 
 /*
  * A "png_get_copyright" function is available, for convenient use in "about"
  * boxes and the like:
  *
  * printf("%s",png_get_copyright(NULL));
  *
  * Also, the PNG logo (in PNG format, of course) is supplied in the
  * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
  */
 
 /*
  * Libpng is OSI Certified Open Source Software.  OSI Certified is a
  * certification mark of the Open Source Initiative.
  */
 
 /*
  * The contributing authors would like to thank all those who helped
  * with testing, bug fixes, and patience.  This wouldn't have been
  * possible without all of you.
  *
  * Thanks to Frank J. T. Wojcik for helping with the documentation.
  */
 
 /*
  * Y2K compliance in libpng:
  * =========================
  *
  *    July 10, 2012
  *
  *    Since the PNG Development group is an ad-hoc body, we can't make
  *    an official declaration.
  *
  *    This is your unofficial assurance that libpng from version 0.71 and
  *    upward through 1.2.50 are Y2K compliant.  It is my belief that earlier
  *    versions were also Y2K compliant.
  *
  *    Libpng only has three year fields.  One is a 2-byte unsigned integer
  *    that will hold years up to 65535.  The other two hold the date in text
  *    format, and will hold years up to 9999.
  *
  *    The integer is
  *        "png_uint_16 year" in png_time_struct.
  *
  *    The strings are
  *        "png_charp time_buffer" in png_struct and
  *        "near_time_buffer", which is a local character string in png.c.
  *
  *    There are seven time-related functions:
  *        png.c: png_convert_to_rfc_1123() in png.c
  *          (formerly png_convert_to_rfc_1152() in error)
  *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
  *        png_convert_from_time_t() in pngwrite.c
  *        png_get_tIME() in pngget.c
  *        png_handle_tIME() in pngrutil.c, called in pngread.c
  *        png_set_tIME() in pngset.c
  *        png_write_tIME() in pngwutil.c, called in pngwrite.c
  *
  *    All handle dates properly in a Y2K environment.  The
  *    png_convert_from_time_t() function calls gmtime() to convert from system
  *    clock time, which returns (year - 1900), which we properly convert to
  *    the full 4-digit year.  There is a possibility that applications using
  *    libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
  *    function, or that they are incorrectly passing only a 2-digit year
  *    instead of "year - 1900" into the png_convert_from_struct_tm() function,
  *    but this is not under our control.  The libpng documentation has always
  *    stated that it works with 4-digit years, and the APIs have been
  *    documented as such.
  *
  *    The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
  *    integer to hold the year, and can hold years as large as 65535.
  *
  *    zlib, upon which libpng depends, is also Y2K compliant.  It contains
  *    no date-related code.
  *
  *       Glenn Randers-Pehrson
  *       libpng maintainer
  *       PNG Development Group
  */
 
 #ifndef PNG_H
 #define PNG_H
 
 /* This is not the place to learn how to use libpng.  The file libpng.txt
  * describes how to use libpng, and the file example.c summarizes it
  * with some code on which to build.  This file is useful for looking
  * at the actual function definitions and structure components.
  */
 
 /* Version information for png.h - this should match the version in png.c */
 #define PNG_LIBPNG_VER_STRING "1.2.50"
 #define PNG_HEADER_VERSION_STRING \
    " libpng version 1.2.50 - July 10, 2012\n"
 
 #define PNG_LIBPNG_VER_SONUM   0
 #define PNG_LIBPNG_VER_DLLNUM  13
 
 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 #define PNG_LIBPNG_VER_MAJOR   1
 #define PNG_LIBPNG_VER_MINOR   2
 #define PNG_LIBPNG_VER_RELEASE 50
 /* This should match the numeric part of the final component of
  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
  */
 
 #define PNG_LIBPNG_VER_BUILD  0
 
 /* Release Status */
 #define PNG_LIBPNG_BUILD_ALPHA    1
 #define PNG_LIBPNG_BUILD_BETA     2
 #define PNG_LIBPNG_BUILD_RC       3
 #define PNG_LIBPNG_BUILD_STABLE   4
 #define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7
 
 /* Release-Specific Flags */
 #define PNG_LIBPNG_BUILD_PATCH    8 /* Can be OR'ed with
                                        PNG_LIBPNG_BUILD_STABLE only */
 #define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with
                                        PNG_LIBPNG_BUILD_SPECIAL */
 #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
                                        PNG_LIBPNG_BUILD_PRIVATE */
 
 #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
 
 /* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
  * We must not include leading zeros.
  * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
  */
 #define PNG_LIBPNG_VER 10250 /* 1.2.50 */
 
 #ifndef PNG_VERSION_INFO_ONLY
 /* Include the compression library's header */
 #include "zlib.h"
 #endif
 
 /* Include all user configurable info, including optional assembler routines */
 #include "pngconf.h"
 
 /*
  * Added at libpng-1.2.8 */
 /* Ref MSDN: Private as priority over Special
  * VS_FF_PRIVATEBUILD File *was not* built using standard release
  * procedures. If this value is given, the StringFileInfo block must
  * contain a PrivateBuild string.
  *
  * VS_FF_SPECIALBUILD File *was* built by the original company using
  * standard release procedures but is a variation of the standard
  * file of the same version number. If this value is given, the
  * StringFileInfo block must contain a SpecialBuild string.
  */
 
 #ifdef PNG_USER_PRIVATEBUILD
 #  define PNG_LIBPNG_BUILD_TYPE \
           (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
 #else
 #  ifdef PNG_LIBPNG_SPECIALBUILD
 #    define PNG_LIBPNG_BUILD_TYPE \
             (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
 #  else
 #    define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)
 #  endif
 #endif
 
 #ifndef PNG_VERSION_INFO_ONLY
 
 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
 #ifdef __cplusplus
 extern "C" {
 #endif /* __cplusplus */
 
 /* This file is arranged in several sections.  The first section contains
  * structure and type definitions.  The second section contains the external
  * library functions, while the third has the internal library functions,
  * which applications aren't expected to use directly.
  */
 
 #ifndef PNG_NO_TYPECAST_NULL
 #define int_p_NULL                (int *)NULL
 #define png_bytep_NULL            (png_bytep)NULL
 #define png_bytepp_NULL           (png_bytepp)NULL
 #define png_doublep_NULL          (png_doublep)NULL
 #define png_error_ptr_NULL        (png_error_ptr)NULL
 #define png_flush_ptr_NULL        (png_flush_ptr)NULL
 #define png_free_ptr_NULL         (png_free_ptr)NULL
 #define png_infopp_NULL           (png_infopp)NULL
 #define png_malloc_ptr_NULL       (png_malloc_ptr)NULL
 #define png_read_status_ptr_NULL  (png_read_status_ptr)NULL
 #define png_rw_ptr_NULL           (png_rw_ptr)NULL
 #define png_structp_NULL          (png_structp)NULL
 #define png_uint_16p_NULL         (png_uint_16p)NULL
 #define png_voidp_NULL            (png_voidp)NULL
 #define png_write_status_ptr_NULL (png_write_status_ptr)NULL
 #else
 #define int_p_NULL                NULL
 #define png_bytep_NULL            NULL
 #define png_bytepp_NULL           NULL
 #define png_doublep_NULL          NULL
 #define png_error_ptr_NULL        NULL
 #define png_flush_ptr_NULL        NULL
 #define png_free_ptr_NULL         NULL
 #define png_infopp_NULL           NULL
 #define png_malloc_ptr_NULL       NULL
 #define png_read_status_ptr_NULL  NULL
 #define png_rw_ptr_NULL           NULL
 #define png_structp_NULL          NULL
 #define png_uint_16p_NULL         NULL
 #define png_voidp_NULL            NULL
 #define png_write_status_ptr_NULL NULL
 #endif
 
 /* Variables declared in png.c - only it needs to define PNG_NO_EXTERN */
 #if !defined(PNG_NO_EXTERN) || defined(PNG_ALWAYS_EXTERN)
 /* Version information for C files, stored in png.c.  This had better match
  * the version above.
  */
 #ifdef PNG_USE_GLOBAL_ARRAYS
 PNG_EXPORT_VAR (PNG_CONST char) png_libpng_ver[18];
   /* Need room for 99.99.99beta99z */
 #else
 #define png_libpng_ver png_get_header_ver(NULL)
 #endif
 
 #ifdef PNG_USE_GLOBAL_ARRAYS
 /* This was removed in version 1.0.5c */
 /* Structures to facilitate easy interlacing.  See png.c for more details */
 PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_start[7];
 PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_inc[7];
 PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_ystart[7];
 PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_yinc[7];
 PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_mask[7];
 PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_dsp_mask[7];
 /* This isn't currently used.  If you need it, see png.c for more details.
 PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_height[7];
 */
 #endif
 
 #endif /* PNG_NO_EXTERN */
 
 /* Three color definitions.  The order of the red, green, and blue, (and the
  * exact size) is not important, although the size of the fields need to
  * be png_byte or png_uint_16 (as defined below).
  */
 typedef struct png_color_struct
 {
    png_byte red;
    png_byte green;
    png_byte blue;
 } png_color;
 typedef png_color FAR * png_colorp;
 typedef png_color FAR * FAR * png_colorpp;
 
 typedef struct png_color_16_struct
 {
    png_byte index;    /* used for palette files */
    png_uint_16 red;   /* for use in red green blue files */
    png_uint_16 green;
    png_uint_16 blue;
    png_uint_16 gray;  /* for use in grayscale files */
 } png_color_16;
 typedef png_color_16 FAR * png_color_16p;
 typedef png_color_16 FAR * FAR * png_color_16pp;
 
 typedef struct png_color_8_struct
 {
    png_byte red;   /* for use in red green blue files */
    png_byte green;
    png_byte blue;
    png_byte gray;  /* for use in grayscale files */
    png_byte alpha; /* for alpha channel files */
 } png_color_8;
 typedef png_color_8 FAR * png_color_8p;
 typedef png_color_8 FAR * FAR * png_color_8pp;
 
 /*
  * The following two structures are used for the in-core representation
  * of sPLT chunks.
  */
 typedef struct png_sPLT_entry_struct
 {
    png_uint_16 red;
    png_uint_16 green;
    png_uint_16 blue;
    png_uint_16 alpha;
    png_uint_16 frequency;
 } png_sPLT_entry;
 typedef png_sPLT_entry FAR * png_sPLT_entryp;
 typedef png_sPLT_entry FAR * FAR * png_sPLT_entrypp;
 
 /*  When the depth of the sPLT palette is 8 bits, the color and alpha samples
  *  occupy the LSB of their respective members, and the MSB of each member
  *  is zero-filled.  The frequency member always occupies the full 16 bits.
  */
 
 typedef struct png_sPLT_struct
 {
    png_charp name;           /* palette name */
    png_byte depth;           /* depth of palette samples */
    png_sPLT_entryp entries;  /* palette entries */
    png_int_32 nentries;      /* number of palette entries */
 } png_sPLT_t;
 typedef png_sPLT_t FAR * png_sPLT_tp;
 typedef png_sPLT_t FAR * FAR * png_sPLT_tpp;
 
 #ifdef PNG_TEXT_SUPPORTED
 /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
  * and whether that contents is compressed or not.  The "key" field
  * points to a regular zero-terminated C string.  The "text", "lang", and
  * "lang_key" fields can be regular C strings, empty strings, or NULL pointers.
  * However, the * structure returned by png_get_text() will always contain
  * regular zero-terminated C strings (possibly empty), never NULL pointers,
  * so they can be safely used in printf() and other string-handling functions.
  */
 typedef struct png_text_struct
 {
    int  compression;       /* compression value:
                              -1: tEXt, none
                               0: zTXt, deflate
                               1: iTXt, none
                               2: iTXt, deflate  */
    png_charp key;          /* keyword, 1-79 character description of "text" */
    png_charp text;         /* comment, may be an empty string (ie "")
                               or a NULL pointer */
    png_size_t text_length; /* length of the text string */
 #ifdef PNG_iTXt_SUPPORTED
    png_size_t itxt_length; /* length of the itxt string */
    png_charp lang;         /* language code, 0-79 characters
                               or a NULL pointer */
    png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more
                               chars or a NULL pointer */
 #endif
 } png_text;
 typedef png_text FAR * png_textp;
 typedef png_text FAR * FAR * png_textpp;
 #endif
 
 /* Supported compression types for text in PNG files (tEXt, and zTXt).
  * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed.
  */
 #define PNG_TEXT_COMPRESSION_NONE_WR -3
 #define PNG_TEXT_COMPRESSION_zTXt_WR -2
 #define PNG_TEXT_COMPRESSION_NONE    -1
 #define PNG_TEXT_COMPRESSION_zTXt     0
 #define PNG_ITXT_COMPRESSION_NONE     1
 #define PNG_ITXT_COMPRESSION_zTXt     2
 #define PNG_TEXT_COMPRESSION_LAST     3  /* Not a valid value */
 
 /* png_time is a way to hold the time in an machine independent way.
  * Two conversions are provided, both from time_t and struct tm.  There
  * is no portable way to convert to either of these structures, as far
  * as I know.  If you know of a portable way, send it to me.  As a side
  * note - PNG has always been Year 2000 compliant!
  */
 typedef struct png_time_struct
 {
    png_uint_16 year; /* full year, as in, 1995 */
    png_byte month;   /* month of year, 1 - 12 */
    png_byte day;     /* day of month, 1 - 31 */
    png_byte hour;    /* hour of day, 0 - 23 */
    png_byte minute;  /* minute of hour, 0 - 59 */
    png_byte second;  /* second of minute, 0 - 60 (for leap seconds) */
 } png_time;
 typedef png_time FAR * png_timep;
 typedef png_time FAR * FAR * png_timepp;
 
 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \
  defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
 /* png_unknown_chunk is a structure to hold queued chunks for which there is
  * no specific support.  The idea is that we can use this to queue
  * up private chunks for output even though the library doesn't actually
  * know about their semantics.
  */
 #define PNG_CHUNK_NAME_LENGTH 5
 typedef struct png_unknown_chunk_t
 {
     png_byte name[PNG_CHUNK_NAME_LENGTH];
     png_byte *data;
     png_size_t size;
 
     /* libpng-using applications should NOT directly modify this byte. */
     png_byte location; /* mode of operation at read time */
 }
 png_unknown_chunk;
 typedef png_unknown_chunk FAR * png_unknown_chunkp;
 typedef png_unknown_chunk FAR * FAR * png_unknown_chunkpp;
 #endif
 
 /* png_info is a structure that holds the information in a PNG file so
  * that the application can find out the characteristics of the image.
  * If you are reading the file, this structure will tell you what is
  * in the PNG file.  If you are writing the file, fill in the information
  * you want to put into the PNG file, then call png_write_info().
  * The names chosen should be very close to the PNG specification, so
  * consult that document for information about the meaning of each field.
  *
  * With libpng < 0.95, it was only possible to directly set and read the
  * the values in the png_info_struct, which meant that the contents and
  * order of the values had to remain fixed.  With libpng 0.95 and later,
  * however, there are now functions that abstract the contents of
  * png_info_struct from the application, so this makes it easier to use
  * libpng with dynamic libraries, and even makes it possible to use
  * libraries that don't have all of the libpng ancillary chunk-handing
  * functionality.
  *
  * In any case, the order of the parameters in png_info_struct should NOT
  * be changed for as long as possible to keep compatibility with applications
  * that use the old direct-access method with png_info_struct.
  *
  * The following members may have allocated storage attached that should be
  * cleaned up before the structure is discarded: palette, trans, text,
  * pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile,
  * splt_palettes, scal_unit, row_pointers, and unknowns.   By default, these
  * are automatically freed when the info structure is deallocated, if they were
  * allocated internally by libpng.  This behavior can be changed by means
  * of the png_data_freer() function.
  *
  * More allocation details: all the chunk-reading functions that
  * change these members go through the corresponding png_set_*
  * functions.  A function to clear these members is available: see
  * png_free_data().  The png_set_* functions do not depend on being
  * able to point info structure members to any of the storage they are
  * passed (they make their own copies), EXCEPT that the png_set_text
  * functions use the same storage passed to them in the text_ptr or
  * itxt_ptr structure argument, and the png_set_rows and png_set_unknowns
  * functions do not make their own copies.
  */
 typedef struct png_info_struct
 {
    /* The following are necessary for every PNG file */
    png_uint_32 width PNG_DEPSTRUCT;       /* width of image in pixels (from IHDR) */
    png_uint_32 height PNG_DEPSTRUCT;      /* height of image in pixels (from IHDR) */
    png_uint_32 valid PNG_DEPSTRUCT;       /* valid chunk data (see PNG_INFO_ below) */
    png_uint_32 rowbytes PNG_DEPSTRUCT;    /* bytes needed to hold an untransformed row */
    png_colorp palette PNG_DEPSTRUCT;      /* array of color values (valid & PNG_INFO_PLTE) */
    png_uint_16 num_palette PNG_DEPSTRUCT; /* number of color entries in "palette" (PLTE) */
    png_uint_16 num_trans PNG_DEPSTRUCT;   /* number of transparent palette color (tRNS) */
    png_byte bit_depth PNG_DEPSTRUCT;      /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */
    png_byte color_type PNG_DEPSTRUCT;     /* see PNG_COLOR_TYPE_ below (from IHDR) */
    /* The following three should have been named *_method not *_type */
    png_byte compression_type PNG_DEPSTRUCT; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */
    png_byte filter_type PNG_DEPSTRUCT;    /* must be PNG_FILTER_TYPE_BASE (from IHDR) */
    png_byte interlace_type PNG_DEPSTRUCT; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
 
    /* The following is informational only on read, and not used on writes. */
    png_byte channels PNG_DEPSTRUCT;       /* number of data channels per pixel (1, 2, 3, 4) */
    png_byte pixel_depth PNG_DEPSTRUCT;    /* number of bits per pixel */
    png_byte spare_byte PNG_DEPSTRUCT;     /* to align the data, and for future use */
    png_byte signature[8] PNG_DEPSTRUCT;   /* magic bytes read by libpng from start of file */
 
    /* The rest of the data is optional.  If you are reading, check the
     * valid field to see if the information in these are valid.  If you
     * are writing, set the valid field to those chunks you want written,
     * and initialize the appropriate fields below.
     */
 
 #if defined(PNG_gAMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
    /* The gAMA chunk describes the gamma characteristics of the system
     * on which the image was created, normally in the range [1.0, 2.5].
     * Data is valid if (valid & PNG_INFO_gAMA) is non-zero.
     */
    float gamma PNG_DEPSTRUCT; /* gamma value of image, if (valid & PNG_INFO_gAMA) */
 #endif
 
 #ifdef PNG_sRGB_SUPPORTED
     /* GR-P, 0.96a */
     /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */
    png_byte srgb_intent PNG_DEPSTRUCT; /* sRGB rendering intent [0, 1, 2, or 3] */
 #endif
 
 #ifdef PNG_TEXT_SUPPORTED
    /* The tEXt, and zTXt chunks contain human-readable textual data in
     * uncompressed, compressed, and optionally compressed forms, respectively.
     * The data in "text" is an array of pointers to uncompressed,
     * null-terminated C strings. Each chunk has a keyword that describes the
     * textual data contained in that chunk.  Keywords are not required to be
     * unique, and the text string may be empty.  Any number of text chunks may
     * be in an image.
     */
    int num_text PNG_DEPSTRUCT; /* number of comments read/to write */
    int max_text PNG_DEPSTRUCT; /* current size of text array */
    png_textp text PNG_DEPSTRUCT; /* array of comments read/to write */
 #endif /* PNG_TEXT_SUPPORTED */
 
 #ifdef PNG_tIME_SUPPORTED
    /* The tIME chunk holds the last time the displayed image data was
     * modified.  See the png_time struct for the contents of this struct.
     */
    png_time mod_time PNG_DEPSTRUCT;
 #endif
 
 #ifdef PNG_sBIT_SUPPORTED
    /* The sBIT chunk specifies the number of significant high-order bits
     * in the pixel data.  Values are in the range [1, bit_depth], and are
     * only specified for the channels in the pixel data.  The contents of
     * the low-order bits is not specified.  Data is valid if
     * (valid & PNG_INFO_sBIT) is non-zero.
     */
    png_color_8 sig_bit PNG_DEPSTRUCT; /* significant bits in color channels */
 #endif
 
 #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \
 defined(PNG_READ_BACKGROUND_SUPPORTED)
    /* The tRNS chunk supplies transparency data for paletted images and
     * other image types that don't need a full alpha channel.  There are
     * "num_trans" transparency values for a paletted image, stored in the
     * same order as the palette colors, starting from index 0.  Values
     * for the data are in the range [0, 255], ranging from fully transparent
     * to fully opaque, respectively.  For non-paletted images, there is a
     * single color specified that should be treated as fully transparent.
     * Data is valid if (valid & PNG_INFO_tRNS) is non-zero.
     */
    png_bytep trans PNG_DEPSTRUCT; /* transparent values for paletted image */
    png_color_16 trans_values PNG_DEPSTRUCT; /* transparent color for non-palette image */
 #endif
 
 #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
    /* The bKGD chunk gives the suggested image background color if the
     * display program does not have its own background color and the image
     * is needs to composited onto a background before display.  The colors
     * in "background" are normally in the same color space/depth as the
     * pixel data.  Data is valid if (valid & PNG_INFO_bKGD) is non-zero.
     */
    png_color_16 background PNG_DEPSTRUCT;
 #endif
 
 #ifdef PNG_oFFs_SUPPORTED
    /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
     * and downwards from the top-left corner of the display, page, or other
     * application-specific co-ordinate space.  See the PNG_OFFSET_ defines
     * below for the unit types.  Valid if (valid & PNG_INFO_oFFs) non-zero.
     */
    png_int_32 x_offset PNG_DEPSTRUCT; /* x offset on page */
    png_int_32 y_offset PNG_DEPSTRUCT; /* y offset on page */
    png_byte offset_unit_type PNG_DEPSTRUCT; /* offset units type */
 #endif
 
 #ifdef PNG_pHYs_SUPPORTED
    /* The pHYs chunk gives the physical pixel density of the image for
     * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
     * defines below).  Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
     */
    png_uint_32 x_pixels_per_unit PNG_DEPSTRUCT; /* horizontal pixel density */
    png_uint_32 y_pixels_per_unit PNG_DEPSTRUCT; /* vertical pixel density */
    png_byte phys_unit_type PNG_DEPSTRUCT; /* resolution type (see PNG_RESOLUTION_ below) */
 #endif
 
 #ifdef PNG_hIST_SUPPORTED
    /* The hIST chunk contains the relative frequency or importance of the
     * various palette entries, so that a viewer can intelligently select a
     * reduced-color palette, if required.  Data is an array of "num_palette"
     * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)
     * is non-zero.
     */
    png_uint_16p hist PNG_DEPSTRUCT;
 #endif
 
 #ifdef PNG_cHRM_SUPPORTED
    /* The cHRM chunk describes the CIE color characteristics of the monitor
     * on which the PNG was created.  This data allows the viewer to do gamut
     * mapping of the input image to ensure that the viewer sees the same
     * colors in the image as the creator.  Values are in the range
     * [0.0, 0.8].  Data valid if (valid & PNG_INFO_cHRM) non-zero.
     */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
    float x_white PNG_DEPSTRUCT;
    float y_white PNG_DEPSTRUCT;
    float x_red PNG_DEPSTRUCT;
    float y_red PNG_DEPSTRUCT;
    float x_green PNG_DEPSTRUCT;
    float y_green PNG_DEPSTRUCT;
    float x_blue PNG_DEPSTRUCT;
    float y_blue PNG_DEPSTRUCT;
 #endif
 #endif
 
 #ifdef PNG_pCAL_SUPPORTED
    /* The pCAL chunk describes a transformation between the stored pixel
     * values and original physical data values used to create the image.
     * The integer range [0, 2^bit_depth - 1] maps to the floating-point
     * range given by [pcal_X0, pcal_X1], and are further transformed by a
     * (possibly non-linear) transformation function given by "pcal_type"
     * and "pcal_params" into "pcal_units".  Please see the PNG_EQUATION_
     * defines below, and the PNG-Group's PNG extensions document for a
     * complete description of the transformations and how they should be
     * implemented, and for a description of the ASCII parameter strings.
     * Data values are valid if (valid & PNG_INFO_pCAL) non-zero.
     */
    png_charp pcal_purpose PNG_DEPSTRUCT;  /* pCAL chunk description string */
    png_int_32 pcal_X0 PNG_DEPSTRUCT;      /* minimum value */
    png_int_32 pcal_X1 PNG_DEPSTRUCT;      /* maximum value */
    png_charp pcal_units PNG_DEPSTRUCT;    /* Latin-1 string giving physical units */
    png_charpp pcal_params PNG_DEPSTRUCT;  /* ASCII strings containing parameter values */
    png_byte pcal_type PNG_DEPSTRUCT;      /* equation type (see PNG_EQUATION_ below) */
    png_byte pcal_nparams PNG_DEPSTRUCT;   /* number of parameters given in pcal_params */
 #endif
 
 /* New members added in libpng-1.0.6 */
 #ifdef PNG_FREE_ME_SUPPORTED
    png_uint_32 free_me PNG_DEPSTRUCT;     /* flags items libpng is responsible for freeing */
 #endif
 
 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \
  defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
    /* Storage for unknown chunks that the library doesn't recognize. */
    png_unknown_chunkp unknown_chunks PNG_DEPSTRUCT;
    png_size_t unknown_chunks_num PNG_DEPSTRUCT;
 #endif
 
 #ifdef PNG_iCCP_SUPPORTED
    /* iCCP chunk data. */
    png_charp iccp_name PNG_DEPSTRUCT;     /* profile name */
    png_charp iccp_profile PNG_DEPSTRUCT;  /* International Color Consortium profile data */
                             /* Note to maintainer: should be png_bytep */
    png_uint_32 iccp_proflen PNG_DEPSTRUCT;  /* ICC profile data length */
    png_byte iccp_compression PNG_DEPSTRUCT; /* Always zero */
 #endif
 
 #ifdef PNG_sPLT_SUPPORTED
    /* Data on sPLT chunks (there may be more than one). */
    png_sPLT_tp splt_palettes PNG_DEPSTRUCT;
    png_uint_32 splt_palettes_num PNG_DEPSTRUCT;
 #endif
 
 #ifdef PNG_sCAL_SUPPORTED
    /* The sCAL chunk describes the actual physical dimensions of the
     * subject matter of the graphic.  The chunk contains a unit specification
     * a byte value, and two ASCII strings representing floating-point
     * values.  The values are width and height corresponsing to one pixel
     * in the image.  This external representation is converted to double
     * here.  Data values are valid if (valid & PNG_INFO_sCAL) is non-zero.
     */
    png_byte scal_unit PNG_DEPSTRUCT;         /* unit of physical scale */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
    double scal_pixel_width PNG_DEPSTRUCT;    /* width of one pixel */
    double scal_pixel_height PNG_DEPSTRUCT;   /* height of one pixel */
 #endif
 #ifdef PNG_FIXED_POINT_SUPPORTED
    png_charp scal_s_width PNG_DEPSTRUCT;     /* string containing height */
    png_charp scal_s_height PNG_DEPSTRUCT;    /* string containing width */
 #endif
 #endif
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
    /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS) non-zero */
    /* Data valid if (valid & PNG_INFO_IDAT) non-zero */
    png_bytepp row_pointers PNG_DEPSTRUCT;        /* the image bits */
 #endif
 
 #if defined(PNG_FIXED_POINT_SUPPORTED) && defined(PNG_gAMA_SUPPORTED)
    png_fixed_point int_gamma PNG_DEPSTRUCT; /* gamma of image, if (valid & PNG_INFO_gAMA) */
 #endif
 
 #if defined(PNG_cHRM_SUPPORTED) && defined(PNG_FIXED_POINT_SUPPORTED)
    png_fixed_point int_x_white PNG_DEPSTRUCT;
    png_fixed_point int_y_white PNG_DEPSTRUCT;
    png_fixed_point int_x_red PNG_DEPSTRUCT;
    png_fixed_point int_y_red PNG_DEPSTRUCT;
    png_fixed_point int_x_green PNG_DEPSTRUCT;
    png_fixed_point int_y_green PNG_DEPSTRUCT;
    png_fixed_point int_x_blue PNG_DEPSTRUCT;
    png_fixed_point int_y_blue PNG_DEPSTRUCT;
 #endif
 
 } png_info;
 
 typedef png_info FAR * png_infop;
 typedef png_info FAR * FAR * png_infopp;
 
 /* Maximum positive integer used in PNG is (2^31)-1 */
 #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
 #define PNG_UINT_32_MAX ((png_uint_32)(-1))
 #define PNG_SIZE_MAX ((png_size_t)(-1))
 #if defined(PNG_1_0_X) || defined (PNG_1_2_X)
 /* PNG_MAX_UINT is deprecated; use PNG_UINT_31_MAX instead. */
 #define PNG_MAX_UINT PNG_UINT_31_MAX
 #endif
 
 /* These describe the color_type field in png_info. */
 /* color type masks */
 #define PNG_COLOR_MASK_PALETTE    1
 #define PNG_COLOR_MASK_COLOR      2
 #define PNG_COLOR_MASK_ALPHA      4
 
 /* color types.  Note that not all combinations are legal */
 #define PNG_COLOR_TYPE_GRAY 0
 #define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
 #define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)
 #define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
 #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
 /* aliases */
 #define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA
 #define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA
 
 /* This is for compression type. PNG 1.0-1.2 only define the single type. */
 #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
 #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE
 
 /* This is for filter type. PNG 1.0-1.2 only define the single type. */
 #define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */
 #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
 #define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE
 
 /* These are for the interlacing type.  These values should NOT be changed. */
 #define PNG_INTERLACE_NONE        0 /* Non-interlaced image */
 #define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */
 #define PNG_INTERLACE_LAST        2 /* Not a valid value */
 
 /* These are for the oFFs chunk.  These values should NOT be changed. */
 #define PNG_OFFSET_PIXEL          0 /* Offset in pixels */
 #define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */
 #define PNG_OFFSET_LAST           2 /* Not a valid value */
 
 /* These are for the pCAL chunk.  These values should NOT be changed. */
 #define PNG_EQUATION_LINEAR       0 /* Linear transformation */
 #define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */
 #define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */
 #define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */
 #define PNG_EQUATION_LAST         4 /* Not a valid value */
 
 /* These are for the sCAL chunk.  These values should NOT be changed. */
 #define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */
 #define PNG_SCALE_METER           1 /* meters per pixel */
 #define PNG_SCALE_RADIAN          2 /* radians per pixel */
 #define PNG_SCALE_LAST            3 /* Not a valid value */
 
 /* These are for the pHYs chunk.  These values should NOT be changed. */
 #define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */
 #define PNG_RESOLUTION_METER      1 /* pixels/meter */
 #define PNG_RESOLUTION_LAST       2 /* Not a valid value */
 
 /* These are for the sRGB chunk.  These values should NOT be changed. */
 #define PNG_sRGB_INTENT_PERCEPTUAL 0
 #define PNG_sRGB_INTENT_RELATIVE   1
 #define PNG_sRGB_INTENT_SATURATION 2
 #define PNG_sRGB_INTENT_ABSOLUTE   3
 #define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */
 
 /* This is for text chunks */
 #define PNG_KEYWORD_MAX_LENGTH     79
 
 /* Maximum number of entries in PLTE/sPLT/tRNS arrays */
 #define PNG_MAX_PALETTE_LENGTH    256
 
 /* These determine if an ancillary chunk's data has been successfully read
  * from the PNG header, or if the application has filled in the corresponding
  * data in the info_struct to be written into the output file.  The values
  * of the PNG_INFO_<chunk> defines should NOT be changed.
  */
 #define PNG_INFO_gAMA 0x0001
 #define PNG_INFO_sBIT 0x0002
 #define PNG_INFO_cHRM 0x0004
 #define PNG_INFO_PLTE 0x0008
 #define PNG_INFO_tRNS 0x0010
 #define PNG_INFO_bKGD 0x0020
 #define PNG_INFO_hIST 0x0040
 #define PNG_INFO_pHYs 0x0080
 #define PNG_INFO_oFFs 0x0100
 #define PNG_INFO_tIME 0x0200
 #define PNG_INFO_pCAL 0x0400
 #define PNG_INFO_sRGB 0x0800   /* GR-P, 0.96a */
 #define PNG_INFO_iCCP 0x1000   /* ESR, 1.0.6 */
 #define PNG_INFO_sPLT 0x2000   /* ESR, 1.0.6 */
 #define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */
 #define PNG_INFO_IDAT 0x8000L  /* ESR, 1.0.6 */
 
 /* This is used for the transformation routines, as some of them
  * change these values for the row.  It also should enable using
  * the routines for other purposes.
  */
 typedef struct png_row_info_struct
 {
    png_uint_32 width; /* width of row */
    png_uint_32 rowbytes; /* number of bytes in row */
    png_byte color_type; /* color type of row */
    png_byte bit_depth; /* bit depth of row */
    png_byte channels; /* number of channels (1, 2, 3, or 4) */
    png_byte pixel_depth; /* bits per pixel (depth * channels) */
 } png_row_info;
 
 typedef png_row_info FAR * png_row_infop;
 typedef png_row_info FAR * FAR * png_row_infopp;
 
 /* These are the function types for the I/O functions and for the functions
  * that allow the user to override the default I/O functions with his or her
  * own.  The png_error_ptr type should match that of user-supplied warning
  * and error functions, while the png_rw_ptr type should match that of the
  * user read/write data functions.
  */
 typedef struct png_struct_def png_struct;
 typedef png_struct FAR * png_structp;
 
 typedef void (PNGAPI *png_error_ptr) PNGARG((png_structp, png_const_charp));
 typedef void (PNGAPI *png_rw_ptr) PNGARG((png_structp, png_bytep, png_size_t));
 typedef void (PNGAPI *png_flush_ptr) PNGARG((png_structp));
 typedef void (PNGAPI *png_read_status_ptr) PNGARG((png_structp, png_uint_32,
    int));
 typedef void (PNGAPI *png_write_status_ptr) PNGARG((png_structp, png_uint_32,
    int));
 
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 typedef void (PNGAPI *png_progressive_info_ptr) PNGARG((png_structp, png_infop));
 typedef void (PNGAPI *png_progressive_end_ptr) PNGARG((png_structp, png_infop));
 typedef void (PNGAPI *png_progressive_row_ptr) PNGARG((png_structp, png_bytep,
    png_uint_32, int));
 #endif
 
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_LEGACY_SUPPORTED)
 typedef void (PNGAPI *png_user_transform_ptr) PNGARG((png_structp,
     png_row_infop, png_bytep));
 #endif
 
 #ifdef PNG_USER_CHUNKS_SUPPORTED
 typedef int (PNGAPI *png_user_chunk_ptr) PNGARG((png_structp, png_unknown_chunkp));
 #endif
 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
 typedef void (PNGAPI *png_unknown_chunk_ptr) PNGARG((png_structp));
 #endif
 
 /* Transform masks for the high-level interface */
 #define PNG_TRANSFORM_IDENTITY       0x0000    /* read and write */
 #define PNG_TRANSFORM_STRIP_16       0x0001    /* read only */
 #define PNG_TRANSFORM_STRIP_ALPHA    0x0002    /* read only */
 #define PNG_TRANSFORM_PACKING        0x0004    /* read and write */
 #define PNG_TRANSFORM_PACKSWAP       0x0008    /* read and write */
 #define PNG_TRANSFORM_EXPAND         0x0010    /* read only */
 #define PNG_TRANSFORM_INVERT_MONO    0x0020    /* read and write */
 #define PNG_TRANSFORM_SHIFT          0x0040    /* read and write */
 #define PNG_TRANSFORM_BGR            0x0080    /* read and write */
 #define PNG_TRANSFORM_SWAP_ALPHA     0x0100    /* read and write */
 #define PNG_TRANSFORM_SWAP_ENDIAN    0x0200    /* read and write */
 #define PNG_TRANSFORM_INVERT_ALPHA   0x0400    /* read and write */
 #define PNG_TRANSFORM_STRIP_FILLER   0x0800    /* write only, deprecated */
 /* Added to libpng-1.2.34 */
 #define PNG_TRANSFORM_STRIP_FILLER_BEFORE 0x0800  /* write only */
 #define PNG_TRANSFORM_STRIP_FILLER_AFTER  0x1000  /* write only */
 /* Added to libpng-1.2.41 */
 #define PNG_TRANSFORM_GRAY_TO_RGB   0x2000      /* read only */
 
 /* Flags for MNG supported features */
 #define PNG_FLAG_MNG_EMPTY_PLTE     0x01
 #define PNG_FLAG_MNG_FILTER_64      0x04
 #define PNG_ALL_MNG_FEATURES        0x05
 
 typedef png_voidp (*png_malloc_ptr) PNGARG((png_structp, png_size_t));
 typedef void (*png_free_ptr) PNGARG((png_structp, png_voidp));
 
 /* The structure that holds the information to read and write PNG files.
  * The only people who need to care about what is inside of this are the
  * people who will be modifying the library for their own special needs.
  * It should NOT be accessed directly by an application, except to store
  * the jmp_buf.
  */
 
 struct png_struct_def
 {
 #ifdef PNG_SETJMP_SUPPORTED
    jmp_buf jmpbuf;            /* used in png_error */
 #endif
    png_error_ptr error_fn PNG_DEPSTRUCT;    /* function for printing errors and aborting */
    png_error_ptr warning_fn PNG_DEPSTRUCT;  /* function for printing warnings */
    png_voidp error_ptr PNG_DEPSTRUCT;       /* user supplied struct for error functions */
    png_rw_ptr write_data_fn PNG_DEPSTRUCT;  /* function for writing output data */
    png_rw_ptr read_data_fn PNG_DEPSTRUCT;   /* function for reading input data */
    png_voidp io_ptr PNG_DEPSTRUCT;          /* ptr to application struct for I/O functions */
 
 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
    png_user_transform_ptr read_user_transform_fn PNG_DEPSTRUCT; /* user read transform */
 #endif
 
 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
    png_user_transform_ptr write_user_transform_fn PNG_DEPSTRUCT; /* user write transform */
 #endif
 
 /* These were added in libpng-1.0.2 */
 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
    png_voidp user_transform_ptr PNG_DEPSTRUCT; /* user supplied struct for user transform */
    png_byte user_transform_depth PNG_DEPSTRUCT;    /* bit depth of user transformed pixels */
    png_byte user_transform_channels PNG_DEPSTRUCT; /* channels in user transformed pixels */
 #endif
 #endif
 
    png_uint_32 mode PNG_DEPSTRUCT;          /* tells us where we are in the PNG file */
    png_uint_32 flags PNG_DEPSTRUCT;         /* flags indicating various things to libpng */
    png_uint_32 transformations PNG_DEPSTRUCT; /* which transformations to perform */
 
    z_stream zstream PNG_DEPSTRUCT;          /* pointer to decompression structure (below) */
    png_bytep zbuf PNG_DEPSTRUCT;            /* buffer for zlib */
    png_size_t zbuf_size PNG_DEPSTRUCT;      /* size of zbuf */
    int zlib_level PNG_DEPSTRUCT;            /* holds zlib compression level */
    int zlib_method PNG_DEPSTRUCT;           /* holds zlib compression method */
    int zlib_window_bits PNG_DEPSTRUCT;      /* holds zlib compression window bits */
    int zlib_mem_level PNG_DEPSTRUCT;        /* holds zlib compression memory level */
    int zlib_strategy PNG_DEPSTRUCT;         /* holds zlib compression strategy */
 
    png_uint_32 width PNG_DEPSTRUCT;         /* width of image in pixels */
    png_uint_32 height PNG_DEPSTRUCT;        /* height of image in pixels */
    png_uint_32 num_rows PNG_DEPSTRUCT;      /* number of rows in current pass */
    png_uint_32 usr_width PNG_DEPSTRUCT;     /* width of row at start of write */
    png_uint_32 rowbytes PNG_DEPSTRUCT;      /* size of row in bytes */
 #if 0 /* Replaced with the following in libpng-1.2.43 */
    png_size_t irowbytes PNG_DEPSTRUCT;
 #endif
 /* Added in libpng-1.2.43 */
 #ifdef PNG_USER_LIMITS_SUPPORTED
    /* Added in libpng-1.4.0: Total number of sPLT, text, and unknown
     * chunks that can be stored (0 means unlimited).
     */
    png_uint_32 user_chunk_cache_max PNG_DEPSTRUCT;
 #endif
    png_uint_32 iwidth PNG_DEPSTRUCT;        /* width of current interlaced row in pixels */
    png_uint_32 row_number PNG_DEPSTRUCT;    /* current row in interlace pass */
    png_bytep prev_row PNG_DEPSTRUCT;        /* buffer to save previous (unfiltered) row */
    png_bytep row_buf PNG_DEPSTRUCT;         /* buffer to save current (unfiltered) row */
 #ifndef PNG_NO_WRITE_FILTER
    png_bytep sub_row PNG_DEPSTRUCT;         /* buffer to save "sub" row when filtering */
    png_bytep up_row PNG_DEPSTRUCT;          /* buffer to save "up" row when filtering */
    png_bytep avg_row PNG_DEPSTRUCT;         /* buffer to save "avg" row when filtering */
    png_bytep paeth_row PNG_DEPSTRUCT;       /* buffer to save "Paeth" row when filtering */
 #endif
    png_row_info row_info PNG_DEPSTRUCT;     /* used for transformation routines */
 
    png_uint_32 idat_size PNG_DEPSTRUCT;     /* current IDAT size for read */
    png_uint_32 crc PNG_DEPSTRUCT;           /* current chunk CRC value */
    png_colorp palette PNG_DEPSTRUCT;        /* palette from the input file */
    png_uint_16 num_palette PNG_DEPSTRUCT;   /* number of color entries in palette */
    png_uint_16 num_trans PNG_DEPSTRUCT;     /* number of transparency values */
    png_byte chunk_name[5] PNG_DEPSTRUCT;    /* null-terminated name of current chunk */
    png_byte compression PNG_DEPSTRUCT;      /* file compression type (always 0) */
    png_byte filter PNG_DEPSTRUCT;           /* file filter type (always 0) */
    png_byte interlaced PNG_DEPSTRUCT;       /* PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
    png_byte pass PNG_DEPSTRUCT;             /* current interlace pass (0 - 6) */
    png_byte do_filter PNG_DEPSTRUCT;        /* row filter flags (see PNG_FILTER_ below ) */
    png_byte color_type PNG_DEPSTRUCT;       /* color type of file */
    png_byte bit_depth PNG_DEPSTRUCT;        /* bit depth of file */
    png_byte usr_bit_depth PNG_DEPSTRUCT;    /* bit depth of users row */
    png_byte pixel_depth PNG_DEPSTRUCT;      /* number of bits per pixel */
    png_byte channels PNG_DEPSTRUCT;         /* number of channels in file */
    png_byte usr_channels PNG_DEPSTRUCT;     /* channels at start of write */
    png_byte sig_bytes PNG_DEPSTRUCT;        /* magic bytes read/written from start of file */
 
 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
 #ifdef PNG_LEGACY_SUPPORTED
    png_byte filler PNG_DEPSTRUCT;           /* filler byte for pixel expansion */
 #else
    png_uint_16 filler PNG_DEPSTRUCT;           /* filler bytes for pixel expansion */
 #endif
 #endif
 
 #ifdef PNG_bKGD_SUPPORTED
    png_byte background_gamma_type PNG_DEPSTRUCT;
 #  ifdef PNG_FLOATING_POINT_SUPPORTED
    float background_gamma PNG_DEPSTRUCT;
 #  endif
    png_color_16 background PNG_DEPSTRUCT;   /* background color in screen gamma space */
 #ifdef PNG_READ_GAMMA_SUPPORTED
    png_color_16 background_1 PNG_DEPSTRUCT; /* background normalized to gamma 1.0 */
 #endif
 #endif /* PNG_bKGD_SUPPORTED */
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
    png_flush_ptr output_flush_fn PNG_DEPSTRUCT; /* Function for flushing output */
    png_uint_32 flush_dist PNG_DEPSTRUCT;    /* how many rows apart to flush, 0 - no flush */
    png_uint_32 flush_rows PNG_DEPSTRUCT;    /* number of rows written since last flush */
 #endif
 
 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
    int gamma_shift PNG_DEPSTRUCT;      /* number of "insignificant" bits 16-bit gamma */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
    float gamma PNG_DEPSTRUCT;          /* file gamma value */
    float screen_gamma PNG_DEPSTRUCT;   /* screen gamma value (display_exponent) */
 #endif
 #endif
 
 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_bytep gamma_table PNG_DEPSTRUCT;     /* gamma table for 8-bit depth files */
    png_bytep gamma_from_1 PNG_DEPSTRUCT;    /* converts from 1.0 to screen */
    png_bytep gamma_to_1 PNG_DEPSTRUCT;      /* converts from file to 1.0 */
    png_uint_16pp gamma_16_table PNG_DEPSTRUCT; /* gamma table for 16-bit depth files */
    png_uint_16pp gamma_16_from_1 PNG_DEPSTRUCT; /* converts from 1.0 to screen */
    png_uint_16pp gamma_16_to_1 PNG_DEPSTRUCT; /* converts from file to 1.0 */
 #endif
 
 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_sBIT_SUPPORTED)
    png_color_8 sig_bit PNG_DEPSTRUCT;       /* significant bits in each available channel */
 #endif
 
 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
    png_color_8 shift PNG_DEPSTRUCT;         /* shift for significant bit tranformation */
 #endif
 
 #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) \
  || defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_bytep trans PNG_DEPSTRUCT;           /* transparency values for paletted files */
    png_color_16 trans_values PNG_DEPSTRUCT; /* transparency values for non-paletted files */
 #endif
 
    png_read_status_ptr read_row_fn PNG_DEPSTRUCT;   /* called after each row is decoded */
    png_write_status_ptr write_row_fn PNG_DEPSTRUCT; /* called after each row is encoded */
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    png_progressive_info_ptr info_fn PNG_DEPSTRUCT; /* called after header data fully read */
    png_progressive_row_ptr row_fn PNG_DEPSTRUCT;   /* called after each prog. row is decoded */
    png_progressive_end_ptr end_fn PNG_DEPSTRUCT;   /* called after image is complete */
    png_bytep save_buffer_ptr PNG_DEPSTRUCT;        /* current location in save_buffer */
    png_bytep save_buffer PNG_DEPSTRUCT;            /* buffer for previously read data */
    png_bytep current_buffer_ptr PNG_DEPSTRUCT;     /* current location in current_buffer */
    png_bytep current_buffer PNG_DEPSTRUCT;         /* buffer for recently used data */
    png_uint_32 push_length PNG_DEPSTRUCT;          /* size of current input chunk */
    png_uint_32 skip_length PNG_DEPSTRUCT;          /* bytes to skip in input data */
    png_size_t save_buffer_size PNG_DEPSTRUCT;      /* amount of data now in save_buffer */
    png_size_t save_buffer_max PNG_DEPSTRUCT;       /* total size of save_buffer */
    png_size_t buffer_size PNG_DEPSTRUCT;           /* total amount of available input data */
    png_size_t current_buffer_size PNG_DEPSTRUCT;   /* amount of data now in current_buffer */
    int process_mode PNG_DEPSTRUCT;                 /* what push library is currently doing */
    int cur_palette PNG_DEPSTRUCT;                  /* current push library palette index */
 
 #  ifdef PNG_TEXT_SUPPORTED
      png_size_t current_text_size PNG_DEPSTRUCT;   /* current size of text input data */
      png_size_t current_text_left PNG_DEPSTRUCT;   /* how much text left to read in input */
      png_charp current_text PNG_DEPSTRUCT;         /* current text chunk buffer */
      png_charp current_text_ptr PNG_DEPSTRUCT;     /* current location in current_text */
 #  endif /* PNG_TEXT_SUPPORTED */
 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
 
 #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
 /* for the Borland special 64K segment handler */
    png_bytepp offset_table_ptr PNG_DEPSTRUCT;
    png_bytep offset_table PNG_DEPSTRUCT;
    png_uint_16 offset_table_number PNG_DEPSTRUCT;
    png_uint_16 offset_table_count PNG_DEPSTRUCT;
    png_uint_16 offset_table_count_free PNG_DEPSTRUCT;
 #endif
 
 #ifdef PNG_READ_DITHER_SUPPORTED
    png_bytep palette_lookup PNG_DEPSTRUCT;         /* lookup table for dithering */
    png_bytep dither_index PNG_DEPSTRUCT;           /* index translation for palette files */
 #endif
 
 #if defined(PNG_READ_DITHER_SUPPORTED) || defined(PNG_hIST_SUPPORTED)
    png_uint_16p hist PNG_DEPSTRUCT;                /* histogram */
 #endif
 
 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
    png_byte heuristic_method PNG_DEPSTRUCT;        /* heuristic for row filter selection */
    png_byte num_prev_filters PNG_DEPSTRUCT;        /* number of weights for previous rows */
    png_bytep prev_filters PNG_DEPSTRUCT;           /* filter type(s) of previous row(s) */
    png_uint_16p filter_weights PNG_DEPSTRUCT;      /* weight(s) for previous line(s) */
    png_uint_16p inv_filter_weights PNG_DEPSTRUCT;  /* 1/weight(s) for previous line(s) */
    png_uint_16p filter_costs PNG_DEPSTRUCT;        /* relative filter calculation cost */
    png_uint_16p inv_filter_costs PNG_DEPSTRUCT;    /* 1/relative filter calculation cost */
 #endif
 
 #ifdef PNG_TIME_RFC1123_SUPPORTED
    png_charp time_buffer PNG_DEPSTRUCT;            /* String to hold RFC 1123 time text */
 #endif
 
 /* New members added in libpng-1.0.6 */
 
 #ifdef PNG_FREE_ME_SUPPORTED
    png_uint_32 free_me PNG_DEPSTRUCT;   /* flags items libpng is responsible for freeing */
 #endif
 
 #ifdef PNG_USER_CHUNKS_SUPPORTED
    png_voidp user_chunk_ptr PNG_DEPSTRUCT;
    png_user_chunk_ptr read_user_chunk_fn PNG_DEPSTRUCT; /* user read chunk handler */
 #endif
 
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
    int num_chunk_list PNG_DEPSTRUCT;
    png_bytep chunk_list PNG_DEPSTRUCT;
 #endif
 
 /* New members added in libpng-1.0.3 */
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
    png_byte rgb_to_gray_status PNG_DEPSTRUCT;
    /* These were changed from png_byte in libpng-1.0.6 */
    png_uint_16 rgb_to_gray_red_coeff PNG_DEPSTRUCT;
    png_uint_16 rgb_to_gray_green_coeff PNG_DEPSTRUCT;
    png_uint_16 rgb_to_gray_blue_coeff PNG_DEPSTRUCT;
 #endif
 
 /* New member added in libpng-1.0.4 (renamed in 1.0.9) */
 #if defined(PNG_MNG_FEATURES_SUPPORTED) || \
     defined(PNG_READ_EMPTY_PLTE_SUPPORTED) || \
     defined(PNG_WRITE_EMPTY_PLTE_SUPPORTED)
 /* Changed from png_byte to png_uint_32 at version 1.2.0 */
 #ifdef PNG_1_0_X
    png_byte mng_features_permitted PNG_DEPSTRUCT;
 #else
    png_uint_32 mng_features_permitted PNG_DEPSTRUCT;
 #endif /* PNG_1_0_X */
 #endif
 
 /* New member added in libpng-1.0.7 */
 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_fixed_point int_gamma PNG_DEPSTRUCT;
 #endif
 
 /* New member added in libpng-1.0.9, ifdef'ed out in 1.0.12, enabled in 1.2.0 */
 #ifdef PNG_MNG_FEATURES_SUPPORTED
    png_byte filter_type PNG_DEPSTRUCT;
 #endif
 
 #ifdef PNG_1_0_X
 /* New member added in libpng-1.0.10, ifdef'ed out in 1.2.0 */
    png_uint_32 row_buf_size PNG_DEPSTRUCT;
 #endif
 
 /* New members added in libpng-1.2.0 */
 #ifdef PNG_ASSEMBLER_CODE_SUPPORTED
 #  ifndef PNG_1_0_X
 #    ifdef PNG_MMX_CODE_SUPPORTED
    png_byte     mmx_bitdepth_threshold PNG_DEPSTRUCT;
    png_uint_32  mmx_rowbytes_threshold PNG_DEPSTRUCT;
 #    endif
    png_uint_32  asm_flags PNG_DEPSTRUCT;
 #  endif
 #endif
 
 /* New members added in libpng-1.0.2 but first enabled by default in 1.2.0 */
 #ifdef PNG_USER_MEM_SUPPORTED
    png_voidp mem_ptr PNG_DEPSTRUCT;            /* user supplied struct for mem functions */
    png_malloc_ptr malloc_fn PNG_DEPSTRUCT;     /* function for allocating memory */
    png_free_ptr free_fn PNG_DEPSTRUCT;         /* function for freeing memory */
 #endif
 
 /* New member added in libpng-1.0.13 and 1.2.0 */
    png_bytep big_row_buf PNG_DEPSTRUCT;        /* buffer to save current (unfiltered) row */
 
 #ifdef PNG_READ_DITHER_SUPPORTED
 /* The following three members were added at version 1.0.14 and 1.2.4 */
    png_bytep dither_sort PNG_DEPSTRUCT;        /* working sort array */
    png_bytep index_to_palette PNG_DEPSTRUCT;   /* where the original index currently is */
                                  /* in the palette */
    png_bytep palette_to_index PNG_DEPSTRUCT;   /* which original index points to this */
                                  /* palette color */
 #endif
 
 /* New members added in libpng-1.0.16 and 1.2.6 */
    png_byte compression_type PNG_DEPSTRUCT;
 
 #ifdef PNG_USER_LIMITS_SUPPORTED
    png_uint_32 user_width_max PNG_DEPSTRUCT;
    png_uint_32 user_height_max PNG_DEPSTRUCT;
 #endif
 
 /* New member added in libpng-1.0.25 and 1.2.17 */
 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
    /* Storage for unknown chunk that the library doesn't recognize. */
    png_unknown_chunk unknown_chunk PNG_DEPSTRUCT;
 #endif
 
 /* New members added in libpng-1.2.26 */
   png_uint_32 old_big_row_buf_size PNG_DEPSTRUCT;
   png_uint_32 old_prev_row_size PNG_DEPSTRUCT;
 
 /* New member added in libpng-1.2.30 */
   png_charp chunkdata PNG_DEPSTRUCT;  /* buffer for reading chunk data */
 
 
 };
 
 
 /* This triggers a compiler error in png.c, if png.c and png.h
  * do not agree upon the version number.
  */
 typedef png_structp version_1_2_50;
 
 typedef png_struct FAR * FAR * png_structpp;
 
 /* Here are the function definitions most commonly used.  This is not
  * the place to find out how to use libpng.  See libpng.txt for the
  * full explanation, see example.c for the summary.  This just provides
  * a simple one line description of the use of each function.
  */
 
 /* Returns the version number of the library */
 extern PNG_EXPORT(png_uint_32,png_access_version_number) PNGARG((void));
 
 /* Tell lib we have already handled the first <num_bytes> magic bytes.
  * Handling more than 8 bytes from the beginning of the file is an error.
  */
 extern PNG_EXPORT(void,png_set_sig_bytes) PNGARG((png_structp png_ptr,
    int num_bytes));
 
 /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
  * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG
  * signature, and non-zero otherwise.  Having num_to_check == 0 or
  * start > 7 will always fail (ie return non-zero).
  */
 extern PNG_EXPORT(int,png_sig_cmp) PNGARG((png_bytep sig, png_size_t start,
    png_size_t num_to_check));
 
 /* Simple signature checking function.  This is the same as calling
  * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
  */
 extern PNG_EXPORT(int,png_check_sig) PNGARG((png_bytep sig, int num)) PNG_DEPRECATED;
 
 /* Allocate and initialize png_ptr struct for reading, and any other memory. */
 extern PNG_EXPORT(png_structp,png_create_read_struct)
    PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
    png_error_ptr error_fn, png_error_ptr warn_fn)) PNG_ALLOCATED;
 
 /* Allocate and initialize png_ptr struct for writing, and any other memory */
 extern PNG_EXPORT(png_structp,png_create_write_struct)
    PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
    png_error_ptr error_fn, png_error_ptr warn_fn)) PNG_ALLOCATED;
 
 #ifdef PNG_WRITE_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_compression_buffer_size)
    PNGARG((png_structp png_ptr));
 #endif
 
 #ifdef PNG_WRITE_SUPPORTED
 extern PNG_EXPORT(void,png_set_compression_buffer_size)
    PNGARG((png_structp png_ptr, png_uint_32 size));
 #endif
 
 /* Reset the compression stream */
 extern PNG_EXPORT(int,png_reset_zstream) PNGARG((png_structp png_ptr));
 
 /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
 #ifdef PNG_USER_MEM_SUPPORTED
 extern PNG_EXPORT(png_structp,png_create_read_struct_2)
    PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
    png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
    png_malloc_ptr malloc_fn, png_free_ptr free_fn)) PNG_ALLOCATED;
 extern PNG_EXPORT(png_structp,png_create_write_struct_2)
    PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
    png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
    png_malloc_ptr malloc_fn, png_free_ptr free_fn)) PNG_ALLOCATED;
 #endif
 
 /* Write a PNG chunk - size, type, (optional) data, CRC. */
 extern PNG_EXPORT(void,png_write_chunk) PNGARG((png_structp png_ptr,
    png_bytep chunk_name, png_bytep data, png_size_t length));
 
 /* Write the start of a PNG chunk - length and chunk name. */
 extern PNG_EXPORT(void,png_write_chunk_start) PNGARG((png_structp png_ptr,
    png_bytep chunk_name, png_uint_32 length));
 
 /* Write the data of a PNG chunk started with png_write_chunk_start(). */
 extern PNG_EXPORT(void,png_write_chunk_data) PNGARG((png_structp png_ptr,
    png_bytep data, png_size_t length));
 
 /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
 extern PNG_EXPORT(void,png_write_chunk_end) PNGARG((png_structp png_ptr));
 
 /* Allocate and initialize the info structure */
 extern PNG_EXPORT(png_infop,png_create_info_struct)
    PNGARG((png_structp png_ptr)) PNG_ALLOCATED;
 
 #if defined(PNG_1_0_X) || defined (PNG_1_2_X)
 /* Initialize the info structure (old interface - DEPRECATED) */
 extern PNG_EXPORT(void,png_info_init) PNGARG((png_infop info_ptr))
     PNG_DEPRECATED;
 #undef png_info_init
 #define png_info_init(info_ptr) png_info_init_3(&info_ptr,\
     png_sizeof(png_info));
 #endif
 
 extern PNG_EXPORT(void,png_info_init_3) PNGARG((png_infopp info_ptr,
     png_size_t png_info_struct_size));
 
 /* Writes all the PNG information before the image. */
 extern PNG_EXPORT(void,png_write_info_before_PLTE) PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 extern PNG_EXPORT(void,png_write_info) PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 
 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
 /* Read the information before the actual image data. */
 extern PNG_EXPORT(void,png_read_info) PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 #endif
 
 #ifdef PNG_TIME_RFC1123_SUPPORTED
 extern PNG_EXPORT(png_charp,png_convert_to_rfc1123)
    PNGARG((png_structp png_ptr, png_timep ptime));
 #endif
 
 #ifdef PNG_CONVERT_tIME_SUPPORTED
 /* Convert from a struct tm to png_time */
 extern PNG_EXPORT(void,png_convert_from_struct_tm) PNGARG((png_timep ptime,
    struct tm FAR * ttime));
 
 /* Convert from time_t to png_time.  Uses gmtime() */
 extern PNG_EXPORT(void,png_convert_from_time_t) PNGARG((png_timep ptime,
    time_t ttime));
 #endif /* PNG_CONVERT_tIME_SUPPORTED */
 
 #ifdef PNG_READ_EXPAND_SUPPORTED
 /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
 extern PNG_EXPORT(void,png_set_expand) PNGARG((png_structp png_ptr));
 #ifndef PNG_1_0_X
 extern PNG_EXPORT(void,png_set_expand_gray_1_2_4_to_8) PNGARG((png_structp
   png_ptr));
 #endif
 extern PNG_EXPORT(void,png_set_palette_to_rgb) PNGARG((png_structp png_ptr));
 extern PNG_EXPORT(void,png_set_tRNS_to_alpha) PNGARG((png_structp png_ptr));
 #if defined(PNG_1_0_X) || defined (PNG_1_2_X)
 /* Deprecated */
 extern PNG_EXPORT(void,png_set_gray_1_2_4_to_8) PNGARG((png_structp
     png_ptr)) PNG_DEPRECATED;
 #endif
 #endif
 
 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
 /* Use blue, green, red order for pixels. */
 extern PNG_EXPORT(void,png_set_bgr) PNGARG((png_structp png_ptr));
 #endif
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 /* Expand the grayscale to 24-bit RGB if necessary. */
 extern PNG_EXPORT(void,png_set_gray_to_rgb) PNGARG((png_structp png_ptr));
 #endif
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 /* Reduce RGB to grayscale. */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_rgb_to_gray) PNGARG((png_structp png_ptr,
    int error_action, double red, double green ));
 #endif
 extern PNG_EXPORT(void,png_set_rgb_to_gray_fixed) PNGARG((png_structp png_ptr,
    int error_action, png_fixed_point red, png_fixed_point green ));
 extern PNG_EXPORT(png_byte,png_get_rgb_to_gray_status) PNGARG((png_structp
    png_ptr));
 #endif
 
 extern PNG_EXPORT(void,png_build_grayscale_palette) PNGARG((int bit_depth,
    png_colorp palette));
 
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
 extern PNG_EXPORT(void,png_set_strip_alpha) PNGARG((png_structp png_ptr));
 #endif
 
 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
 extern PNG_EXPORT(void,png_set_swap_alpha) PNGARG((png_structp png_ptr));
 #endif
 
 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
 extern PNG_EXPORT(void,png_set_invert_alpha) PNGARG((png_structp png_ptr));
 #endif
 
 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
 /* Add a filler byte to 8-bit Gray or 24-bit RGB images. */
 extern PNG_EXPORT(void,png_set_filler) PNGARG((png_structp png_ptr,
    png_uint_32 filler, int flags));
 /* The values of the PNG_FILLER_ defines should NOT be changed */
 #define PNG_FILLER_BEFORE 0
 #define PNG_FILLER_AFTER 1
 /* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
 #ifndef PNG_1_0_X
 extern PNG_EXPORT(void,png_set_add_alpha) PNGARG((png_structp png_ptr,
    png_uint_32 filler, int flags));
 #endif
 #endif /* PNG_READ_FILLER_SUPPORTED || PNG_WRITE_FILLER_SUPPORTED */
 
 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
 /* Swap bytes in 16-bit depth files. */
 extern PNG_EXPORT(void,png_set_swap) PNGARG((png_structp png_ptr));
 #endif
 
 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
 /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
 extern PNG_EXPORT(void,png_set_packing) PNGARG((png_structp png_ptr));
 #endif
 
 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || defined(PNG_WRITE_PACKSWAP_SUPPORTED)
 /* Swap packing order of pixels in bytes. */
 extern PNG_EXPORT(void,png_set_packswap) PNGARG((png_structp png_ptr));
 #endif
 
 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
 /* Converts files to legal bit depths. */
 extern PNG_EXPORT(void,png_set_shift) PNGARG((png_structp png_ptr,
    png_color_8p true_bits));
 #endif
 
 #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
     defined(PNG_WRITE_INTERLACING_SUPPORTED)
 /* Have the code handle the interlacing.  Returns the number of passes. */
 extern PNG_EXPORT(int,png_set_interlace_handling) PNGARG((png_structp png_ptr));
 #endif
 
 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
 /* Invert monochrome files */
 extern PNG_EXPORT(void,png_set_invert_mono) PNGARG((png_structp png_ptr));
 #endif
 
 #ifdef PNG_READ_BACKGROUND_SUPPORTED
 /* Handle alpha and tRNS by replacing with a background color. */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_background) PNGARG((png_structp png_ptr,
    png_color_16p background_color, int background_gamma_code,
    int need_expand, double background_gamma));
 #endif
 #define PNG_BACKGROUND_GAMMA_UNKNOWN 0
 #define PNG_BACKGROUND_GAMMA_SCREEN  1
 #define PNG_BACKGROUND_GAMMA_FILE    2
 #define PNG_BACKGROUND_GAMMA_UNIQUE  3
 #endif
 
 #ifdef PNG_READ_16_TO_8_SUPPORTED
 /* Strip the second byte of information from a 16-bit depth file. */
 extern PNG_EXPORT(void,png_set_strip_16) PNGARG((png_structp png_ptr));
 #endif
 
 #ifdef PNG_READ_DITHER_SUPPORTED
 /* Turn on dithering, and reduce the palette to the number of colors available. */
 extern PNG_EXPORT(void,png_set_dither) PNGARG((png_structp png_ptr,
    png_colorp palette, int num_palette, int maximum_colors,
    png_uint_16p histogram, int full_dither));
 #endif
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
 /* Handle gamma correction. Screen_gamma=(display_exponent) */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_gamma) PNGARG((png_structp png_ptr,
    double screen_gamma, double default_file_gamma));
 #endif
 #endif
 
 #if defined(PNG_1_0_X) || defined (PNG_1_2_X)
 #if defined(PNG_READ_EMPTY_PLTE_SUPPORTED) || \
     defined(PNG_WRITE_EMPTY_PLTE_SUPPORTED)
 /* Permit or disallow empty PLTE (0: not permitted, 1: permitted) */
 /* Deprecated and will be removed.  Use png_permit_mng_features() instead. */
 extern PNG_EXPORT(void,png_permit_empty_plte) PNGARG((png_structp png_ptr,
    int empty_plte_permitted)) PNG_DEPRECATED;
 #endif
 #endif
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 /* Set how many lines between output flushes - 0 for no flushing */
 extern PNG_EXPORT(void,png_set_flush) PNGARG((png_structp png_ptr, int nrows));
 /* Flush the current PNG output buffer */
 extern PNG_EXPORT(void,png_write_flush) PNGARG((png_structp png_ptr));
 #endif
 
 /* Optional update palette with requested transformations */
 extern PNG_EXPORT(void,png_start_read_image) PNGARG((png_structp png_ptr));
 
 /* Optional call to update the users info structure */
 extern PNG_EXPORT(void,png_read_update_info) PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 
 #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 /* Read one or more rows of image data. */
 extern PNG_EXPORT(void,png_read_rows) PNGARG((png_structp png_ptr,
    png_bytepp row, png_bytepp display_row, png_uint_32 num_rows));
 #endif
 
 #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 /* Read a row of data. */
 extern PNG_EXPORT(void,png_read_row) PNGARG((png_structp png_ptr,
    png_bytep row,
    png_bytep display_row));
 #endif
 
 #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 /* Read the whole image into memory at once. */
 extern PNG_EXPORT(void,png_read_image) PNGARG((png_structp png_ptr,
    png_bytepp image));
 #endif
 
 /* Write a row of image data */
 extern PNG_EXPORT(void,png_write_row) PNGARG((png_structp png_ptr,
    png_bytep row));
 
 /* Write a few rows of image data */
 extern PNG_EXPORT(void,png_write_rows) PNGARG((png_structp png_ptr,
    png_bytepp row, png_uint_32 num_rows));
 
 /* Write the image data */
 extern PNG_EXPORT(void,png_write_image) PNGARG((png_structp png_ptr,
    png_bytepp image));
 
 /* Writes the end of the PNG file. */
 extern PNG_EXPORT(void,png_write_end) PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 
 #ifndef PNG_NO_SEQUENTIAL_READ_SUPPORTED
 /* Read the end of the PNG file. */
 extern PNG_EXPORT(void,png_read_end) PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 #endif
 
 /* Free any memory associated with the png_info_struct */
 extern PNG_EXPORT(void,png_destroy_info_struct) PNGARG((png_structp png_ptr,
    png_infopp info_ptr_ptr));
 
 /* Free any memory associated with the png_struct and the png_info_structs */
 extern PNG_EXPORT(void,png_destroy_read_struct) PNGARG((png_structpp
    png_ptr_ptr, png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));
 
 /* Free all memory used by the read (old method - NOT DLL EXPORTED) */
 extern void png_read_destroy PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_infop end_info_ptr)) PNG_DEPRECATED;
 
 /* Free any memory associated with the png_struct and the png_info_structs */
 extern PNG_EXPORT(void,png_destroy_write_struct)
    PNGARG((png_structpp png_ptr_ptr, png_infopp info_ptr_ptr));
 
 /* Free any memory used in png_ptr struct (old method - NOT DLL EXPORTED) */
 extern void png_write_destroy PNGARG((png_structp png_ptr)) PNG_DEPRECATED;
 
 /* Set the libpng method of handling chunk CRC errors */
 extern PNG_EXPORT(void,png_set_crc_action) PNGARG((png_structp png_ptr,
    int crit_action, int ancil_action));
 
 /* Values for png_set_crc_action() to say how to handle CRC errors in
  * ancillary and critical chunks, and whether to use the data contained
  * therein.  Note that it is impossible to "discard" data in a critical
  * chunk.  For versions prior to 0.90, the action was always error/quit,
  * whereas in version 0.90 and later, the action for CRC errors in ancillary
  * chunks is warn/discard.  These values should NOT be changed.
  *
  *      value                       action:critical     action:ancillary
  */
 #define PNG_CRC_DEFAULT       0  /* error/quit          warn/discard data */
 #define PNG_CRC_ERROR_QUIT    1  /* error/quit          error/quit        */
 #define PNG_CRC_WARN_DISCARD  2  /* (INVALID)           warn/discard data */
 #define PNG_CRC_WARN_USE      3  /* warn/use data       warn/use data     */
 #define PNG_CRC_QUIET_USE     4  /* quiet/use data      quiet/use data    */
 #define PNG_CRC_NO_CHANGE     5  /* use current value   use current value */
 
 /* These functions give the user control over the scan-line filtering in
  * libpng and the compression methods used by zlib.  These functions are
  * mainly useful for testing, as the defaults should work with most users.
  * Those users who are tight on memory or want faster performance at the
  * expense of compression can modify them.  See the compression library
  * header file (zlib.h) for an explination of the compression functions.
  */
 
 /* Set the filtering method(s) used by libpng.  Currently, the only valid
  * value for "method" is 0.
  */
 extern PNG_EXPORT(void,png_set_filter) PNGARG((png_structp png_ptr, int method,
    int filters));
 
 /* Flags for png_set_filter() to say which filters to use.  The flags
  * are chosen so that they don't conflict with real filter types
  * below, in case they are supplied instead of the #defined constants.
  * These values should NOT be changed.
  */
 #define PNG_NO_FILTERS     0x00
 #define PNG_FILTER_NONE    0x08
 #define PNG_FILTER_SUB     0x10
 #define PNG_FILTER_UP      0x20
 #define PNG_FILTER_AVG     0x40
 #define PNG_FILTER_PAETH   0x80
 #define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
                          PNG_FILTER_AVG | PNG_FILTER_PAETH)
 
 /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
  * These defines should NOT be changed.
  */
 #define PNG_FILTER_VALUE_NONE  0
 #define PNG_FILTER_VALUE_SUB   1
 #define PNG_FILTER_VALUE_UP    2
 #define PNG_FILTER_VALUE_AVG   3
 #define PNG_FILTER_VALUE_PAETH 4
 #define PNG_FILTER_VALUE_LAST  5
 
 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED) /* EXPERIMENTAL */
 /* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
  * defines, either the default (minimum-sum-of-absolute-differences), or
  * the experimental method (weighted-minimum-sum-of-absolute-differences).
  *
  * Weights are factors >= 1.0, indicating how important it is to keep the
  * filter type consistent between rows.  Larger numbers mean the current
  * filter is that many times as likely to be the same as the "num_weights"
  * previous filters.  This is cumulative for each previous row with a weight.
  * There needs to be "num_weights" values in "filter_weights", or it can be
  * NULL if the weights aren't being specified.  Weights have no influence on
  * the selection of the first row filter.  Well chosen weights can (in theory)
  * improve the compression for a given image.
  *
  * Costs are factors >= 1.0 indicating the relative decoding costs of a
  * filter type.  Higher costs indicate more decoding expense, and are
  * therefore less likely to be selected over a filter with lower computational
  * costs.  There needs to be a value in "filter_costs" for each valid filter
  * type (given by PNG_FILTER_VALUE_LAST), or it can be NULL if you aren't
  * setting the costs.  Costs try to improve the speed of decompression without
  * unduly increasing the compressed image size.
  *
  * A negative weight or cost indicates the default value is to be used, and
  * values in the range [0.0, 1.0) indicate the value is to remain unchanged.
  * The default values for both weights and costs are currently 1.0, but may
  * change if good general weighting/cost heuristics can be found.  If both
  * the weights and costs are set to 1.0, this degenerates the WEIGHTED method
  * to the UNWEIGHTED method, but with added encoding time/computation.
  */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_filter_heuristics) PNGARG((png_structp png_ptr,
    int heuristic_method, int num_weights, png_doublep filter_weights,
    png_doublep filter_costs));
 #endif
 #endif /*  PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
 
 /* Heuristic used for row filter selection.  These defines should NOT be
  * changed.
  */
 #define PNG_FILTER_HEURISTIC_DEFAULT    0  /* Currently "UNWEIGHTED" */
 #define PNG_FILTER_HEURISTIC_UNWEIGHTED 1  /* Used by libpng < 0.95 */
 #define PNG_FILTER_HEURISTIC_WEIGHTED   2  /* Experimental feature */
 #define PNG_FILTER_HEURISTIC_LAST       3  /* Not a valid value */
 
 /* Set the library compression level.  Currently, valid values range from
  * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
  * (0 - no compression, 9 - "maximal" compression).  Note that tests have
  * shown that zlib compression levels 3-6 usually perform as well as level 9
  * for PNG images, and do considerably fewer caclulations.  In the future,
  * these values may not correspond directly to the zlib compression levels.
  */
 extern PNG_EXPORT(void,png_set_compression_level) PNGARG((png_structp png_ptr,
    int level));
 
 extern PNG_EXPORT(void,png_set_compression_mem_level)
    PNGARG((png_structp png_ptr, int mem_level));
 
 extern PNG_EXPORT(void,png_set_compression_strategy)
    PNGARG((png_structp png_ptr, int strategy));
 
 extern PNG_EXPORT(void,png_set_compression_window_bits)
    PNGARG((png_structp png_ptr, int window_bits));
 
 extern PNG_EXPORT(void,png_set_compression_method) PNGARG((png_structp png_ptr,
    int method));
 
 /* These next functions are called for input/output, memory, and error
  * handling.  They are in the file pngrio.c, pngwio.c, and pngerror.c,
  * and call standard C I/O routines such as fread(), fwrite(), and
  * fprintf().  These functions can be made to use other I/O routines
  * at run time for those applications that need to handle I/O in a
  * different manner by calling png_set_???_fn().  See libpng.txt for
  * more information.
  */
 
 #ifdef PNG_STDIO_SUPPORTED
 /* Initialize the input/output for the PNG file to the default functions. */
 extern PNG_EXPORT(void,png_init_io) PNGARG((png_structp png_ptr, png_FILE_p fp));
 #endif
 
 /* Replace the (error and abort), and warning functions with user
  * supplied functions.  If no messages are to be printed you must still
  * write and use replacement functions. The replacement error_fn should
  * still do a longjmp to the last setjmp location if you are using this
  * method of error handling.  If error_fn or warning_fn is NULL, the
  * default function will be used.
  */
 
 extern PNG_EXPORT(void,png_set_error_fn) PNGARG((png_structp png_ptr,
    png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
 
 /* Return the user pointer associated with the error functions */
 extern PNG_EXPORT(png_voidp,png_get_error_ptr) PNGARG((png_structp png_ptr));
 
 /* Replace the default data output functions with a user supplied one(s).
  * If buffered output is not used, then output_flush_fn can be set to NULL.
  * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
  * output_flush_fn will be ignored (and thus can be NULL).
  * It is probably a mistake to use NULL for output_flush_fn if
  * write_data_fn is not also NULL unless you have built libpng with
  * PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's
  * default flush function, which uses the standard *FILE structure, will
  * be used.
  */
 extern PNG_EXPORT(void,png_set_write_fn) PNGARG((png_structp png_ptr,
    png_voidp io_ptr, png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
 
 /* Replace the default data input function with a user supplied one. */
 extern PNG_EXPORT(void,png_set_read_fn) PNGARG((png_structp png_ptr,
    png_voidp io_ptr, png_rw_ptr read_data_fn));
 
 /* Return the user pointer associated with the I/O functions */
 extern PNG_EXPORT(png_voidp,png_get_io_ptr) PNGARG((png_structp png_ptr));
 
 extern PNG_EXPORT(void,png_set_read_status_fn) PNGARG((png_structp png_ptr,
    png_read_status_ptr read_row_fn));
 
 extern PNG_EXPORT(void,png_set_write_status_fn) PNGARG((png_structp png_ptr,
    png_write_status_ptr write_row_fn));
 
 #ifdef PNG_USER_MEM_SUPPORTED
 /* Replace the default memory allocation functions with user supplied one(s). */
 extern PNG_EXPORT(void,png_set_mem_fn) PNGARG((png_structp png_ptr,
    png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn));
 /* Return the user pointer associated with the memory functions */
 extern PNG_EXPORT(png_voidp,png_get_mem_ptr) PNGARG((png_structp png_ptr));
 #endif
 
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_LEGACY_SUPPORTED)
 extern PNG_EXPORT(void,png_set_read_user_transform_fn) PNGARG((png_structp
    png_ptr, png_user_transform_ptr read_user_transform_fn));
 #endif
 
 #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_LEGACY_SUPPORTED)
 extern PNG_EXPORT(void,png_set_write_user_transform_fn) PNGARG((png_structp
    png_ptr, png_user_transform_ptr write_user_transform_fn));
 #endif
 
 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
     defined(PNG_LEGACY_SUPPORTED)
 extern PNG_EXPORT(void,png_set_user_transform_info) PNGARG((png_structp
    png_ptr, png_voidp user_transform_ptr, int user_transform_depth,
    int user_transform_channels));
 /* Return the user pointer associated with the user transform functions */
 extern PNG_EXPORT(png_voidp,png_get_user_transform_ptr)
    PNGARG((png_structp png_ptr));
 #endif
 
 #ifdef PNG_USER_CHUNKS_SUPPORTED
 extern PNG_EXPORT(void,png_set_read_user_chunk_fn) PNGARG((png_structp png_ptr,
    png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
 extern PNG_EXPORT(png_voidp,png_get_user_chunk_ptr) PNGARG((png_structp
    png_ptr));
 #endif
 
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 /* Sets the function callbacks for the push reader, and a pointer to a
  * user-defined structure available to the callback functions.
  */
 extern PNG_EXPORT(void,png_set_progressive_read_fn) PNGARG((png_structp png_ptr,
    png_voidp progressive_ptr,
    png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
    png_progressive_end_ptr end_fn));
 
 /* Returns the user pointer associated with the push read functions */
 extern PNG_EXPORT(png_voidp,png_get_progressive_ptr)
    PNGARG((png_structp png_ptr));
 
 /* Function to be called when data becomes available */
 extern PNG_EXPORT(void,png_process_data) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_bytep buffer, png_size_t buffer_size));
 
 /* Function that combines rows.  Not very much different than the
  * png_combine_row() call.  Is this even used?????
  */
 extern PNG_EXPORT(void,png_progressive_combine_row) PNGARG((png_structp png_ptr,
    png_bytep old_row, png_bytep new_row));
 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
 
 extern PNG_EXPORT(png_voidp,png_malloc) PNGARG((png_structp png_ptr,
    png_uint_32 size)) PNG_ALLOCATED;
 
 #ifdef PNG_1_0_X
 #  define png_malloc_warn png_malloc
 #else
 /* Added at libpng version 1.2.4 */
 extern PNG_EXPORT(png_voidp,png_malloc_warn) PNGARG((png_structp png_ptr,
    png_uint_32 size)) PNG_ALLOCATED;
 #endif
 
 /* Frees a pointer allocated by png_malloc() */
 extern PNG_EXPORT(void,png_free) PNGARG((png_structp png_ptr, png_voidp ptr));
 
 #ifdef PNG_1_0_X
 /* Function to allocate memory for zlib. */
 extern PNG_EXPORT(voidpf,png_zalloc) PNGARG((voidpf png_ptr, uInt items,
    uInt size));
 
 /* Function to free memory for zlib */
 extern PNG_EXPORT(void,png_zfree) PNGARG((voidpf png_ptr, voidpf ptr));
 #endif
 
 /* Free data that was allocated internally */
 extern PNG_EXPORT(void,png_free_data) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 free_me, int num));
 #ifdef PNG_FREE_ME_SUPPORTED
 /* Reassign responsibility for freeing existing data, whether allocated
  * by libpng or by the application
  */
 extern PNG_EXPORT(void,png_data_freer) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int freer, png_uint_32 mask));
 #endif
 /* Assignments for png_data_freer */
 #define PNG_DESTROY_WILL_FREE_DATA 1
 #define PNG_SET_WILL_FREE_DATA 1
 #define PNG_USER_WILL_FREE_DATA 2
 /* Flags for png_ptr->free_me and info_ptr->free_me */
 #define PNG_FREE_HIST 0x0008
 #define PNG_FREE_ICCP 0x0010
 #define PNG_FREE_SPLT 0x0020
 #define PNG_FREE_ROWS 0x0040
 #define PNG_FREE_PCAL 0x0080
 #define PNG_FREE_SCAL 0x0100
 #define PNG_FREE_UNKN 0x0200
 #define PNG_FREE_LIST 0x0400
 #define PNG_FREE_PLTE 0x1000
 #define PNG_FREE_TRNS 0x2000
 #define PNG_FREE_TEXT 0x4000
 #define PNG_FREE_ALL  0x7fff
 #define PNG_FREE_MUL  0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
 
 #ifdef PNG_USER_MEM_SUPPORTED
 extern PNG_EXPORT(png_voidp,png_malloc_default) PNGARG((png_structp png_ptr,
    png_uint_32 size)) PNG_ALLOCATED;
 extern PNG_EXPORT(void,png_free_default) PNGARG((png_structp png_ptr,
    png_voidp ptr));
 #endif
 
 extern PNG_EXPORT(png_voidp,png_memcpy_check) PNGARG((png_structp png_ptr,
    png_voidp s1, png_voidp s2, png_uint_32 size)) PNG_DEPRECATED;
 
 extern PNG_EXPORT(png_voidp,png_memset_check) PNGARG((png_structp png_ptr,
    png_voidp s1, int value, png_uint_32 size)) PNG_DEPRECATED;
 
 #if defined(USE_FAR_KEYWORD)  /* memory model conversion function */
 extern void *png_far_to_near PNGARG((png_structp png_ptr,png_voidp ptr,
    int check));
 #endif /* USE_FAR_KEYWORD */
 
 #ifndef PNG_NO_ERROR_TEXT
 /* Fatal error in PNG image of libpng - can't continue */
 extern PNG_EXPORT(void,png_error) PNGARG((png_structp png_ptr,
    png_const_charp error_message)) PNG_NORETURN;
 
 /* The same, but the chunk name is prepended to the error string. */
 extern PNG_EXPORT(void,png_chunk_error) PNGARG((png_structp png_ptr,
    png_const_charp error_message)) PNG_NORETURN;
 #else
 /* Fatal error in PNG image of libpng - can't continue */
 extern PNG_EXPORT(void,png_err) PNGARG((png_structp png_ptr)) PNG_NORETURN;
 #endif
 
 #ifndef PNG_NO_WARNINGS
 /* Non-fatal error in libpng.  Can continue, but may have a problem. */
 extern PNG_EXPORT(void,png_warning) PNGARG((png_structp png_ptr,
    png_const_charp warning_message));
 
 #ifdef PNG_READ_SUPPORTED
 /* Non-fatal error in libpng, chunk name is prepended to message. */
 extern PNG_EXPORT(void,png_chunk_warning) PNGARG((png_structp png_ptr,
    png_const_charp warning_message));
 #endif /* PNG_READ_SUPPORTED */
 #endif /* PNG_NO_WARNINGS */
 
 /* The png_set_<chunk> functions are for storing values in the png_info_struct.
  * Similarly, the png_get_<chunk> calls are used to read values from the
  * png_info_struct, either storing the parameters in the passed variables, or
  * setting pointers into the png_info_struct where the data is stored.  The
  * png_get_<chunk> functions return a non-zero value if the data was available
  * in info_ptr, or return zero and do not change any of the parameters if the
  * data was not available.
  *
  * These functions should be used instead of directly accessing png_info
  * to avoid problems with future changes in the size and internal layout of
  * png_info_struct.
  */
 /* Returns "flag" if chunk data is valid in info_ptr. */
 extern PNG_EXPORT(png_uint_32,png_get_valid) PNGARG((png_structp png_ptr,
 png_infop info_ptr, png_uint_32 flag));
 
 /* Returns number of bytes needed to hold a transformed row. */
 extern PNG_EXPORT(png_uint_32,png_get_rowbytes) PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 /* Returns row_pointers, which is an array of pointers to scanlines that was
  * returned from png_read_png().
  */
 extern PNG_EXPORT(png_bytepp,png_get_rows) PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 /* Set row_pointers, which is an array of pointers to scanlines for use
  * by png_write_png().
  */
 extern PNG_EXPORT(void,png_set_rows) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_bytepp row_pointers));
 #endif
 
 /* Returns number of color channels in image. */
 extern PNG_EXPORT(png_byte,png_get_channels) PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
 #ifdef PNG_EASY_ACCESS_SUPPORTED
 /* Returns image width in pixels. */
 extern PNG_EXPORT(png_uint_32, png_get_image_width) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 
 /* Returns image height in pixels. */
 extern PNG_EXPORT(png_uint_32, png_get_image_height) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 
 /* Returns image bit_depth. */
 extern PNG_EXPORT(png_byte, png_get_bit_depth) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 
 /* Returns image color_type. */
 extern PNG_EXPORT(png_byte, png_get_color_type) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 
 /* Returns image filter_type. */
 extern PNG_EXPORT(png_byte, png_get_filter_type) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 
 /* Returns image interlace_type. */
 extern PNG_EXPORT(png_byte, png_get_interlace_type) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 
 /* Returns image compression_type. */
 extern PNG_EXPORT(png_byte, png_get_compression_type) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 
 /* Returns image resolution in pixels per meter, from pHYs chunk data. */
 extern PNG_EXPORT(png_uint_32, png_get_pixels_per_meter) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 extern PNG_EXPORT(png_uint_32, png_get_x_pixels_per_meter) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 extern PNG_EXPORT(png_uint_32, png_get_y_pixels_per_meter) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 
 /* Returns pixel aspect ratio, computed from pHYs chunk data.  */
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(float, png_get_pixel_aspect_ratio) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 #endif
 
 /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
 extern PNG_EXPORT(png_int_32, png_get_x_offset_pixels) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 extern PNG_EXPORT(png_int_32, png_get_y_offset_pixels) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 extern PNG_EXPORT(png_int_32, png_get_x_offset_microns) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 extern PNG_EXPORT(png_int_32, png_get_y_offset_microns) PNGARG((png_structp
 png_ptr, png_infop info_ptr));
 
 #endif /* PNG_EASY_ACCESS_SUPPORTED */
 
 /* Returns pointer to signature string read from PNG header */
 extern PNG_EXPORT(png_bytep,png_get_signature) PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
 #ifdef PNG_bKGD_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_bKGD) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_color_16p *background));
 #endif
 
 #ifdef PNG_bKGD_SUPPORTED
 extern PNG_EXPORT(void,png_set_bKGD) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_color_16p background));
 #endif
 
 #ifdef PNG_cHRM_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_cHRM) PNGARG((png_structp png_ptr,
    png_infop info_ptr, double *white_x, double *white_y, double *red_x,
    double *red_y, double *green_x, double *green_y, double *blue_x,
    double *blue_y));
 #endif
 #ifdef PNG_FIXED_POINT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_cHRM_fixed) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_fixed_point *int_white_x, png_fixed_point
    *int_white_y, png_fixed_point *int_red_x, png_fixed_point *int_red_y,
    png_fixed_point *int_green_x, png_fixed_point *int_green_y, png_fixed_point
    *int_blue_x, png_fixed_point *int_blue_y));
 #endif
 #endif
 
 #ifdef PNG_cHRM_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_cHRM) PNGARG((png_structp png_ptr,
    png_infop info_ptr, double white_x, double white_y, double red_x,
    double red_y, double green_x, double green_y, double blue_x, double blue_y));
 #endif
 #ifdef PNG_FIXED_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_cHRM_fixed) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_fixed_point int_white_x, png_fixed_point int_white_y,
    png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
    int_green_x, png_fixed_point int_green_y, png_fixed_point int_blue_x,
    png_fixed_point int_blue_y));
 #endif
 #endif
 
 #ifdef PNG_gAMA_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_gAMA) PNGARG((png_structp png_ptr,
    png_infop info_ptr, double *file_gamma));
 #endif
 extern PNG_EXPORT(png_uint_32,png_get_gAMA_fixed) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_fixed_point *int_file_gamma));
 #endif
 
 #ifdef PNG_gAMA_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_gAMA) PNGARG((png_structp png_ptr,
    png_infop info_ptr, double file_gamma));
 #endif
 extern PNG_EXPORT(void,png_set_gAMA_fixed) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_fixed_point int_file_gamma));
 #endif
 
 #ifdef PNG_hIST_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_hIST) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_16p *hist));
 #endif
 
 #ifdef PNG_hIST_SUPPORTED
 extern PNG_EXPORT(void,png_set_hIST) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_16p hist));
 #endif
 
 extern PNG_EXPORT(png_uint_32,png_get_IHDR) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 *width, png_uint_32 *height,
    int *bit_depth, int *color_type, int *interlace_method,
    int *compression_method, int *filter_method));
 
 extern PNG_EXPORT(void,png_set_IHDR) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
    int color_type, int interlace_method, int compression_method,
    int filter_method));
 
 #ifdef PNG_oFFs_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_oFFs) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
    int *unit_type));
 #endif
 
 #ifdef PNG_oFFs_SUPPORTED
 extern PNG_EXPORT(void,png_set_oFFs) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_int_32 offset_x, png_int_32 offset_y,
    int unit_type));
 #endif
 
 #ifdef PNG_pCAL_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_pCAL) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_charp *purpose, png_int_32 *X0, png_int_32 *X1,
    int *type, int *nparams, png_charp *units, png_charpp *params));
 #endif
 
 #ifdef PNG_pCAL_SUPPORTED
 extern PNG_EXPORT(void,png_set_pCAL) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_charp purpose, png_int_32 X0, png_int_32 X1,
    int type, int nparams, png_charp units, png_charpp params));
 #endif
 
 #ifdef PNG_pHYs_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_pHYs) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type));
 #endif
 
 #ifdef PNG_pHYs_SUPPORTED
 extern PNG_EXPORT(void,png_set_pHYs) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
 #endif
 
 extern PNG_EXPORT(png_uint_32,png_get_PLTE) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_colorp *palette, int *num_palette));
 
 extern PNG_EXPORT(void,png_set_PLTE) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_colorp palette, int num_palette));
 
 #ifdef PNG_sBIT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_sBIT) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_color_8p *sig_bit));
 #endif
 
 #ifdef PNG_sBIT_SUPPORTED
 extern PNG_EXPORT(void,png_set_sBIT) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_color_8p sig_bit));
 #endif
 
 #ifdef PNG_sRGB_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_sRGB) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int *intent));
 #endif
 
 #ifdef PNG_sRGB_SUPPORTED
 extern PNG_EXPORT(void,png_set_sRGB) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int intent));
 extern PNG_EXPORT(void,png_set_sRGB_gAMA_and_cHRM) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int intent));
 #endif
 
 #ifdef PNG_iCCP_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_iCCP) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_charpp name, int *compression_type,
    png_charpp profile, png_uint_32 *proflen));
    /* Note to maintainer: profile should be png_bytepp */
 #endif
 
 #ifdef PNG_iCCP_SUPPORTED
 extern PNG_EXPORT(void,png_set_iCCP) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_charp name, int compression_type,
    png_charp profile, png_uint_32 proflen));
    /* Note to maintainer: profile should be png_bytep */
 #endif
 
 #ifdef PNG_sPLT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_sPLT) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_sPLT_tpp entries));
 #endif
 
 #ifdef PNG_sPLT_SUPPORTED
 extern PNG_EXPORT(void,png_set_sPLT) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_sPLT_tp entries, int nentries));
 #endif
 
 #ifdef PNG_TEXT_SUPPORTED
 /* png_get_text also returns the number of text chunks in *num_text */
 extern PNG_EXPORT(png_uint_32,png_get_text) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_textp *text_ptr, int *num_text));
 #endif
 
 /*
  *  Note while png_set_text() will accept a structure whose text,
  *  language, and  translated keywords are NULL pointers, the structure
  *  returned by png_get_text will always contain regular
  *  zero-terminated C strings.  They might be empty strings but
  *  they will never be NULL pointers.
  */
 
 #ifdef PNG_TEXT_SUPPORTED
 extern PNG_EXPORT(void,png_set_text) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_textp text_ptr, int num_text));
 #endif
 
 #ifdef PNG_tIME_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_tIME) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_timep *mod_time));
 #endif
 
 #ifdef PNG_tIME_SUPPORTED
 extern PNG_EXPORT(void,png_set_tIME) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_timep mod_time));
 #endif
 
 #ifdef PNG_tRNS_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_tRNS) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_bytep *trans, int *num_trans,
    png_color_16p *trans_values));
 #endif
 
 #ifdef PNG_tRNS_SUPPORTED
 extern PNG_EXPORT(void,png_set_tRNS) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_bytep trans, int num_trans,
    png_color_16p trans_values));
 #endif
 
 #ifdef PNG_tRNS_SUPPORTED
 #endif
 
 #ifdef PNG_sCAL_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_sCAL) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int *unit, double *width, double *height));
 #else
 #ifdef PNG_FIXED_POINT_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_get_sCAL_s) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int *unit, png_charpp swidth, png_charpp sheight));
 #endif
 #endif
 #endif /* PNG_sCAL_SUPPORTED */
 
 #ifdef PNG_sCAL_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_sCAL) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int unit, double width, double height));
 #else
 #ifdef PNG_FIXED_POINT_SUPPORTED
 extern PNG_EXPORT(void,png_set_sCAL_s) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int unit, png_charp swidth, png_charp sheight));
 #endif
 #endif
 #endif /* PNG_sCAL_SUPPORTED || PNG_WRITE_sCAL_SUPPORTED */
 
 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
 /* Provide a list of chunks and how they are to be handled, if the built-in
    handling or default unknown chunk handling is not desired.  Any chunks not
    listed will be handled in the default manner.  The IHDR and IEND chunks
    must not be listed.
       keep = 0: follow default behaviour
            = 1: do not keep
            = 2: keep only if safe-to-copy
            = 3: keep even if unsafe-to-copy
 */
 extern PNG_EXPORT(void, png_set_keep_unknown_chunks) PNGARG((png_structp
    png_ptr, int keep, png_bytep chunk_list, int num_chunks));
 PNG_EXPORT(int,png_handle_as_unknown) PNGARG((png_structp png_ptr, png_bytep
    chunk_name));
 #endif
 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
 extern PNG_EXPORT(void, png_set_unknown_chunks) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_unknown_chunkp unknowns, int num_unknowns));
 extern PNG_EXPORT(void, png_set_unknown_chunk_location)
    PNGARG((png_structp png_ptr, png_infop info_ptr, int chunk, int location));
 extern PNG_EXPORT(png_uint_32,png_get_unknown_chunks) PNGARG((png_structp
    png_ptr, png_infop info_ptr, png_unknown_chunkpp entries));
 #endif
 
 /* Png_free_data() will turn off the "valid" flag for anything it frees.
  * If you need to turn it off for a chunk that your application has freed,
  * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
  */
 extern PNG_EXPORT(void, png_set_invalid) PNGARG((png_structp png_ptr,
    png_infop info_ptr, int mask));
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
 /* The "params" pointer is currently not used and is for future expansion. */
 extern PNG_EXPORT(void, png_read_png) PNGARG((png_structp png_ptr,
                         png_infop info_ptr,
                         int transforms,
                         png_voidp params));
 extern PNG_EXPORT(void, png_write_png) PNGARG((png_structp png_ptr,
                         png_infop info_ptr,
                         int transforms,
                         png_voidp params));
 #endif
 
 /* Define PNG_DEBUG at compile time for debugging information.  Higher
  * numbers for PNG_DEBUG mean more debugging information.  This has
  * only been added since version 0.95 so it is not implemented throughout
  * libpng yet, but more support will be added as needed.
  */
 #ifdef PNG_DEBUG
 #if (PNG_DEBUG > 0)
 #if !defined(PNG_DEBUG_FILE) && defined(_MSC_VER)
 #include <crtdbg.h>
 #if (PNG_DEBUG > 1)
 #ifndef _DEBUG
 #  define _DEBUG
 #endif
 #ifndef png_debug
 #define png_debug(l,m)  _RPT0(_CRT_WARN,m PNG_STRING_NEWLINE)
 #endif
 #ifndef png_debug1
 #define png_debug1(l,m,p1)  _RPT1(_CRT_WARN,m PNG_STRING_NEWLINE,p1)
 #endif
 #ifndef png_debug2
 #define png_debug2(l,m,p1,p2) _RPT2(_CRT_WARN,m PNG_STRING_NEWLINE,p1,p2)
 #endif
 #endif
 #else /* PNG_DEBUG_FILE || !_MSC_VER */
 #ifndef PNG_DEBUG_FILE
 #define PNG_DEBUG_FILE stderr
 #endif /* PNG_DEBUG_FILE */
 
 #if (PNG_DEBUG > 1)
 /* Note: ["%s"m PNG_STRING_NEWLINE] probably does not work on non-ISO
  * compilers.
  */
 #  ifdef __STDC__
 #    ifndef png_debug
 #      define png_debug(l,m) \
        { \
        int num_tabs=l; \
        fprintf(PNG_DEBUG_FILE,"%s"m PNG_STRING_NEWLINE,(num_tabs==1 ? "\t" : \
          (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":"")))); \
        }
 #    endif
 #    ifndef png_debug1
 #      define png_debug1(l,m,p1) \
        { \
        int num_tabs=l; \
        fprintf(PNG_DEBUG_FILE,"%s"m PNG_STRING_NEWLINE,(num_tabs==1 ? "\t" : \
          (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1); \
        }
 #    endif
 #    ifndef png_debug2
 #      define png_debug2(l,m,p1,p2) \
        { \
        int num_tabs=l; \
        fprintf(PNG_DEBUG_FILE,"%s"m PNG_STRING_NEWLINE,(num_tabs==1 ? "\t" : \
          (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1,p2); \
        }
 #    endif
 #  else /* __STDC __ */
 #    ifndef png_debug
 #      define png_debug(l,m) \
        { \
        int num_tabs=l; \
        char format[256]; \
        snprintf(format,256,"%s%s%s",(num_tabs==1 ? "\t" : \
          (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))), \
          m,PNG_STRING_NEWLINE); \
        fprintf(PNG_DEBUG_FILE,format); \
        }
 #    endif
 #    ifndef png_debug1
 #      define png_debug1(l,m,p1) \
        { \
        int num_tabs=l; \
        char format[256]; \
        snprintf(format,256,"%s%s%s",(num_tabs==1 ? "\t" : \
          (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))), \
          m,PNG_STRING_NEWLINE); \
        fprintf(PNG_DEBUG_FILE,format,p1); \
        }
 #    endif
 #    ifndef png_debug2
 #      define png_debug2(l,m,p1,p2) \
        { \
        int num_tabs=l; \
        char format[256]; \
        snprintf(format,256,"%s%s%s",(num_tabs==1 ? "\t" : \
          (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))), \
          m,PNG_STRING_NEWLINE); \
        fprintf(PNG_DEBUG_FILE,format,p1,p2); \
        }
 #    endif
 #  endif /* __STDC __ */
 #endif /* (PNG_DEBUG > 1) */
 
 #endif /* _MSC_VER */
 #endif /* (PNG_DEBUG > 0) */
 #endif /* PNG_DEBUG */
 #ifndef png_debug
 #define png_debug(l, m)
 #endif
 #ifndef png_debug1
 #define png_debug1(l, m, p1)
 #endif
 #ifndef png_debug2
 #define png_debug2(l, m, p1, p2)
 #endif
 
 extern PNG_EXPORT(png_charp,png_get_copyright) PNGARG((png_structp png_ptr));
 extern PNG_EXPORT(png_charp,png_get_header_ver) PNGARG((png_structp png_ptr));
 extern PNG_EXPORT(png_charp,png_get_header_version) PNGARG((png_structp png_ptr));
 extern PNG_EXPORT(png_charp,png_get_libpng_ver) PNGARG((png_structp png_ptr));
 
 #ifdef PNG_MNG_FEATURES_SUPPORTED
 extern PNG_EXPORT(png_uint_32,png_permit_mng_features) PNGARG((png_structp
    png_ptr, png_uint_32 mng_features_permitted));
 #endif
 
 /* For use in png_set_keep_unknown, added to version 1.2.6 */
 #define PNG_HANDLE_CHUNK_AS_DEFAULT   0
 #define PNG_HANDLE_CHUNK_NEVER        1
 #define PNG_HANDLE_CHUNK_IF_SAFE      2
 #define PNG_HANDLE_CHUNK_ALWAYS       3
 
 /* Added to version 1.2.0 */
 #ifdef PNG_ASSEMBLER_CODE_SUPPORTED
 #ifdef PNG_MMX_CODE_SUPPORTED
 #define PNG_ASM_FLAG_MMX_SUPPORT_COMPILED  0x01  /* not user-settable */
 #define PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU    0x02  /* not user-settable */
 #define PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  0x04
 #define PNG_ASM_FLAG_MMX_READ_INTERLACE    0x08
 #define PNG_ASM_FLAG_MMX_READ_FILTER_SUB   0x10
 #define PNG_ASM_FLAG_MMX_READ_FILTER_UP    0x20
 #define PNG_ASM_FLAG_MMX_READ_FILTER_AVG   0x40
 #define PNG_ASM_FLAG_MMX_READ_FILTER_PAETH 0x80
 #define PNG_ASM_FLAGS_INITIALIZED          0x80000000  /* not user-settable */
 
 #define PNG_MMX_READ_FLAGS ( PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  \
                            | PNG_ASM_FLAG_MMX_READ_INTERLACE    \
                            | PNG_ASM_FLAG_MMX_READ_FILTER_SUB   \
                            | PNG_ASM_FLAG_MMX_READ_FILTER_UP    \
                            | PNG_ASM_FLAG_MMX_READ_FILTER_AVG   \
                            | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH )
 #define PNG_MMX_WRITE_FLAGS ( 0 )
 
 #define PNG_MMX_FLAGS ( PNG_ASM_FLAG_MMX_SUPPORT_COMPILED \
                       | PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU   \
                       | PNG_MMX_READ_FLAGS                \
                       | PNG_MMX_WRITE_FLAGS )
 
 #define PNG_SELECT_READ   1
 #define PNG_SELECT_WRITE  2
 #endif /* PNG_MMX_CODE_SUPPORTED */
 
 #ifndef PNG_1_0_X
 /* pngget.c */
 extern PNG_EXPORT(png_uint_32,png_get_mmx_flagmask)
    PNGARG((int flag_select, int *compilerID));
 
 /* pngget.c */
 extern PNG_EXPORT(png_uint_32,png_get_asm_flagmask)
    PNGARG((int flag_select));
 
 /* pngget.c */
 extern PNG_EXPORT(png_uint_32,png_get_asm_flags)
    PNGARG((png_structp png_ptr));
 
 /* pngget.c */
 extern PNG_EXPORT(png_byte,png_get_mmx_bitdepth_threshold)
    PNGARG((png_structp png_ptr));
 
 /* pngget.c */
 extern PNG_EXPORT(png_uint_32,png_get_mmx_rowbytes_threshold)
    PNGARG((png_structp png_ptr));
 
 /* pngset.c */
 extern PNG_EXPORT(void,png_set_asm_flags)
    PNGARG((png_structp png_ptr, png_uint_32 asm_flags));
 
 /* pngset.c */
 extern PNG_EXPORT(void,png_set_mmx_thresholds)
    PNGARG((png_structp png_ptr, png_byte mmx_bitdepth_threshold,
    png_uint_32 mmx_rowbytes_threshold));
 
 #endif /* PNG_1_0_X */
 
 #ifndef PNG_1_0_X
 /* png.c, pnggccrd.c, or pngvcrd.c */
 extern PNG_EXPORT(int,png_mmx_support) PNGARG((void));
 #endif /* PNG_1_0_X */
 #endif /* PNG_ASSEMBLER_CODE_SUPPORTED */
 
 /* Strip the prepended error numbers ("#nnn ") from error and warning
  * messages before passing them to the error or warning handler.
  */
 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
 extern PNG_EXPORT(void,png_set_strip_error_numbers) PNGARG((png_structp
    png_ptr, png_uint_32 strip_mode));
 #endif
 
 /* Added at libpng-1.2.6 */
 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
 extern PNG_EXPORT(void,png_set_user_limits) PNGARG((png_structp
    png_ptr, png_uint_32 user_width_max, png_uint_32 user_height_max));
 extern PNG_EXPORT(png_uint_32,png_get_user_width_max) PNGARG((png_structp
    png_ptr));
 extern PNG_EXPORT(png_uint_32,png_get_user_height_max) PNGARG((png_structp
    png_ptr));
 #endif
 /* Maintainer: Put new public prototypes here ^, in libpng.3, and in
  * project defs
  */
 
 #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
 /* With these routines we avoid an integer divide, which will be slower on
  * most machines.  However, it does take more operations than the corresponding
  * divide method, so it may be slower on a few RISC systems.  There are two
  * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
  *
  * Note that the rounding factors are NOT supposed to be the same!  128 and
  * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
  * standard method.
  *
  * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
  */
 
  /* fg and bg should be in `gamma 1.0' space; alpha is the opacity          */
 
 #  define png_composite(composite, fg, alpha, bg)                            \
      { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) * (png_uint_16)(alpha) \
                         +        (png_uint_16)(bg)*(png_uint_16)(255 -       \
                         (png_uint_16)(alpha)) + (png_uint_16)128);           \
        (composite) = (png_byte)((temp + (temp >> 8)) >> 8); }
 
 #  define png_composite_16(composite, fg, alpha, bg)                         \
      { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg) * (png_uint_32)(alpha) \
                         + (png_uint_32)(bg)*(png_uint_32)(65535L -           \
                         (png_uint_32)(alpha)) + (png_uint_32)32768L);        \
        (composite) = (png_uint_16)((temp + (temp >> 16)) >> 16); }
 
 #else  /* Standard method using integer division */
 
 #  define png_composite(composite, fg, alpha, bg)                            \
      (composite) = (png_byte)(((png_uint_16)(fg) * (png_uint_16)(alpha) +    \
        (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) +       \
        (png_uint_16)127) / 255)
 
 #  define png_composite_16(composite, fg, alpha, bg)                         \
      (composite) = (png_uint_16)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \
        (png_uint_32)(bg)*(png_uint_32)(65535L - (png_uint_32)(alpha)) +      \
        (png_uint_32)32767) / (png_uint_32)65535L)
 
 #endif /* PNG_READ_COMPOSITE_NODIV_SUPPORTED */
 
 /* Inline macros to do direct reads of bytes from the input buffer.  These
  * require that you are using an architecture that uses PNG byte ordering
  * (MSB first) and supports unaligned data storage.  I think that PowerPC
  * in big-endian mode and 680x0 are the only ones that will support this.
  * The x86 line of processors definitely do not.  The png_get_int_32()
  * routine also assumes we are using two's complement format for negative
  * values, which is almost certainly true.
  */
 #ifdef PNG_READ_BIG_ENDIAN_SUPPORTED
 #  define png_get_uint_32(buf) ( *((png_uint_32p) (buf)))
 #  define png_get_uint_16(buf) ( *((png_uint_16p) (buf)))
 #  define png_get_int_32(buf)  ( *((png_int_32p)  (buf)))
 #else
 extern PNG_EXPORT(png_uint_32,png_get_uint_32) PNGARG((png_bytep buf));
 extern PNG_EXPORT(png_uint_16,png_get_uint_16) PNGARG((png_bytep buf));
 extern PNG_EXPORT(png_int_32,png_get_int_32) PNGARG((png_bytep buf));
 #endif /* !PNG_READ_BIG_ENDIAN_SUPPORTED */
 extern PNG_EXPORT(png_uint_32,png_get_uint_31)
   PNGARG((png_structp png_ptr, png_bytep buf));
 /* No png_get_int_16 -- may be added if there's a real need for it. */
 
 /* Place a 32-bit number into a buffer in PNG byte order (big-endian).
  */
 extern PNG_EXPORT(void,png_save_uint_32)
    PNGARG((png_bytep buf, png_uint_32 i));
 extern PNG_EXPORT(void,png_save_int_32)
    PNGARG((png_bytep buf, png_int_32 i));
 
 /* Place a 16-bit number into a buffer in PNG byte order.
  * The parameter is declared unsigned int, not png_uint_16,
  * just to avoid potential problems on pre-ANSI C compilers.
  */
 extern PNG_EXPORT(void,png_save_uint_16)
    PNGARG((png_bytep buf, unsigned int i));
 /* No png_save_int_16 -- may be added if there's a real need for it. */
 
 /* ************************************************************************* */
 
 /* These next functions are used internally in the code.  They generally
  * shouldn't be used unless you are writing code to add or replace some
  * functionality in libpng.  More information about most functions can
  * be found in the files where the functions are located.
  */
 
 
 /* Various modes of operation, that are visible to applications because
  * they are used for unknown chunk location.
  */
 #define PNG_HAVE_IHDR               0x01
 #define PNG_HAVE_PLTE               0x02
 #define PNG_HAVE_IDAT               0x04
 #define PNG_AFTER_IDAT              0x08 /* Have complete zlib datastream */
 #define PNG_HAVE_IEND               0x10
 
 #ifdef PNG_INTERNAL
 
 /* More modes of operation.  Note that after an init, mode is set to
  * zero automatically when the structure is created.
  */
 #define PNG_HAVE_gAMA               0x20
 #define PNG_HAVE_cHRM               0x40
 #define PNG_HAVE_sRGB               0x80
 #define PNG_HAVE_CHUNK_HEADER      0x100
 #define PNG_WROTE_tIME             0x200
 #define PNG_WROTE_INFO_BEFORE_PLTE 0x400
 #define PNG_BACKGROUND_IS_GRAY     0x800
 #define PNG_HAVE_PNG_SIGNATURE    0x1000
 #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
 
 /* Flags for the transformations the PNG library does on the image data */
 #define PNG_BGR                0x0001
 #define PNG_INTERLACE          0x0002
 #define PNG_PACK               0x0004
 #define PNG_SHIFT              0x0008
 #define PNG_SWAP_BYTES         0x0010
 #define PNG_INVERT_MONO        0x0020
 #define PNG_DITHER             0x0040
 #define PNG_BACKGROUND         0x0080
 #define PNG_BACKGROUND_EXPAND  0x0100
                           /*   0x0200 unused */
 #define PNG_16_TO_8            0x0400
 #define PNG_RGBA               0x0800
 #define PNG_EXPAND             0x1000
 #define PNG_GAMMA              0x2000
 #define PNG_GRAY_TO_RGB        0x4000
 #define PNG_FILLER             0x8000L
 #define PNG_PACKSWAP          0x10000L
 #define PNG_SWAP_ALPHA        0x20000L
 #define PNG_STRIP_ALPHA       0x40000L
 #define PNG_INVERT_ALPHA      0x80000L
 #define PNG_USER_TRANSFORM   0x100000L
 #define PNG_RGB_TO_GRAY_ERR  0x200000L
 #define PNG_RGB_TO_GRAY_WARN 0x400000L
 #define PNG_RGB_TO_GRAY      0x600000L  /* two bits, RGB_TO_GRAY_ERR|WARN */
                        /*    0x800000L     Unused */
 #define PNG_ADD_ALPHA       0x1000000L  /* Added to libpng-1.2.7 */
 #define PNG_EXPAND_tRNS     0x2000000L  /* Added to libpng-1.2.9 */
 #define PNG_PREMULTIPLY_ALPHA 0x4000000L  /* Added to libpng-1.2.41 */
                                           /* by volker */
                        /*   0x8000000L  unused */
                        /*  0x10000000L  unused */
                        /*  0x20000000L  unused */
                        /*  0x40000000L  unused */
 
 /* Flags for png_create_struct */
 #define PNG_STRUCT_PNG   0x0001
 #define PNG_STRUCT_INFO  0x0002
 
 /* Scaling factor for filter heuristic weighting calculations */
 #define PNG_WEIGHT_SHIFT 8
 #define PNG_WEIGHT_FACTOR (1<<(PNG_WEIGHT_SHIFT))
 #define PNG_COST_SHIFT 3
 #define PNG_COST_FACTOR (1<<(PNG_COST_SHIFT))
 
 /* Flags for the png_ptr->flags rather than declaring a byte for each one */
 #define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
 #define PNG_FLAG_ZLIB_CUSTOM_LEVEL        0x0002
 #define PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL    0x0004
 #define PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS  0x0008
 #define PNG_FLAG_ZLIB_CUSTOM_METHOD       0x0010
 #define PNG_FLAG_ZLIB_FINISHED            0x0020
 #define PNG_FLAG_ROW_INIT                 0x0040
 #define PNG_FLAG_FILLER_AFTER             0x0080
 #define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
 #define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
 #define PNG_FLAG_CRC_CRITICAL_USE         0x0400
 #define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
 #define PNG_FLAG_FREE_PLTE                0x1000
 #define PNG_FLAG_FREE_TRNS                0x2000
 #define PNG_FLAG_FREE_HIST                0x4000
 #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000L
 #define PNG_FLAG_KEEP_UNSAFE_CHUNKS       0x10000L
 #define PNG_FLAG_LIBRARY_MISMATCH         0x20000L
 #define PNG_FLAG_STRIP_ERROR_NUMBERS      0x40000L
 #define PNG_FLAG_STRIP_ERROR_TEXT         0x80000L
 #define PNG_FLAG_MALLOC_NULL_MEM_OK       0x100000L
 #define PNG_FLAG_ADD_ALPHA                0x200000L  /* Added to libpng-1.2.8 */
 #define PNG_FLAG_STRIP_ALPHA              0x400000L  /* Added to libpng-1.2.8 */
                                   /*      0x800000L  unused */
                                   /*     0x1000000L  unused */
                                   /*     0x2000000L  unused */
                                   /*     0x4000000L  unused */
                                   /*     0x8000000L  unused */
                                   /*    0x10000000L  unused */
                                   /*    0x20000000L  unused */
                                   /*    0x40000000L  unused */
 
 #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
                                      PNG_FLAG_CRC_ANCILLARY_NOWARN)
 
 #define PNG_FLAG_CRC_CRITICAL_MASK  (PNG_FLAG_CRC_CRITICAL_USE | \
                                      PNG_FLAG_CRC_CRITICAL_IGNORE)
 
 #define PNG_FLAG_CRC_MASK           (PNG_FLAG_CRC_ANCILLARY_MASK | \
                                      PNG_FLAG_CRC_CRITICAL_MASK)
 
 /* Save typing and make code easier to understand */
 
 #define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
    abs((int)((c1).green) - (int)((c2).green)) + \
    abs((int)((c1).blue) - (int)((c2).blue)))
 
 /* Added to libpng-1.2.6 JB */
 #define PNG_ROWBYTES(pixel_bits, width) \
     ((pixel_bits) >= 8 ? \
     ((width) * (((png_uint_32)(pixel_bits)) >> 3)) : \
     (( ((width) * ((png_uint_32)(pixel_bits))) + 7) >> 3) )
 
 /* PNG_OUT_OF_RANGE returns true if value is outside the range
  * ideal-delta..ideal+delta.  Each argument is evaluated twice.
  * "ideal" and "delta" should be constants, normally simple
  * integers, "value" a variable. Added to libpng-1.2.6 JB
  */
 #define PNG_OUT_OF_RANGE(value, ideal, delta) \
         ( (value) < (ideal)-(delta) || (value) > (ideal)+(delta) )
 
 /* Variables declared in png.c - only it needs to define PNG_NO_EXTERN */
 #if !defined(PNG_NO_EXTERN) || defined(PNG_ALWAYS_EXTERN)
 /* Place to hold the signature string for a PNG file. */
 #ifdef PNG_USE_GLOBAL_ARRAYS
    PNG_EXPORT_VAR (PNG_CONST png_byte FARDATA) png_sig[8];
 #else
 #endif
 #endif /* PNG_NO_EXTERN */
 
 /* Constant strings for known chunk types.  If you need to add a chunk,
  * define the name here, and add an invocation of the macro in png.c and
  * wherever it's needed.
  */
 #define PNG_IHDR png_byte png_IHDR[5] = { 73,  72,  68,  82, '\0'}
 #define PNG_IDAT png_byte png_IDAT[5] = { 73,  68,  65,  84, '\0'}
 #define PNG_IEND png_byte png_IEND[5] = { 73,  69,  78,  68, '\0'}
 #define PNG_PLTE png_byte png_PLTE[5] = { 80,  76,  84,  69, '\0'}
 #define PNG_bKGD png_byte png_bKGD[5] = { 98,  75,  71,  68, '\0'}
 #define PNG_cHRM png_byte png_cHRM[5] = { 99,  72,  82,  77, '\0'}
 #define PNG_gAMA png_byte png_gAMA[5] = {103,  65,  77,  65, '\0'}
 #define PNG_hIST png_byte png_hIST[5] = {104,  73,  83,  84, '\0'}
 #define PNG_iCCP png_byte png_iCCP[5] = {105,  67,  67,  80, '\0'}
 #define PNG_iTXt png_byte png_iTXt[5] = {105,  84,  88, 116, '\0'}
 #define PNG_oFFs png_byte png_oFFs[5] = {111,  70,  70, 115, '\0'}
 #define PNG_pCAL png_byte png_pCAL[5] = {112,  67,  65,  76, '\0'}
 #define PNG_sCAL png_byte png_sCAL[5] = {115,  67,  65,  76, '\0'}
 #define PNG_pHYs png_byte png_pHYs[5] = {112,  72,  89, 115, '\0'}
 #define PNG_sBIT png_byte png_sBIT[5] = {115,  66,  73,  84, '\0'}
 #define PNG_sPLT png_byte png_sPLT[5] = {115,  80,  76,  84, '\0'}
 #define PNG_sRGB png_byte png_sRGB[5] = {115,  82,  71,  66, '\0'}
 #define PNG_tEXt png_byte png_tEXt[5] = {116,  69,  88, 116, '\0'}
 #define PNG_tIME png_byte png_tIME[5] = {116,  73,  77,  69, '\0'}
 #define PNG_tRNS png_byte png_tRNS[5] = {116,  82,  78,  83, '\0'}
 #define PNG_zTXt png_byte png_zTXt[5] = {122,  84,  88, 116, '\0'}
 
 #ifdef PNG_USE_GLOBAL_ARRAYS
 PNG_EXPORT_VAR (png_byte FARDATA) png_IHDR[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_IDAT[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_IEND[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_PLTE[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_bKGD[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_cHRM[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_gAMA[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_hIST[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_iCCP[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_iTXt[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_oFFs[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_pCAL[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_sCAL[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_pHYs[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_sBIT[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_sPLT[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_sRGB[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_tEXt[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_tIME[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_tRNS[5];
 PNG_EXPORT_VAR (png_byte FARDATA) png_zTXt[5];
 #endif /* PNG_USE_GLOBAL_ARRAYS */
 
 #if defined(PNG_1_0_X) || defined (PNG_1_2_X)
 /* Initialize png_ptr struct for reading, and allocate any other memory.
  * (old interface - DEPRECATED - use png_create_read_struct instead).
  */
 extern PNG_EXPORT(void,png_read_init) PNGARG((png_structp png_ptr))
     PNG_DEPRECATED;
 #undef png_read_init
 #define png_read_init(png_ptr) png_read_init_3(&png_ptr, \
     PNG_LIBPNG_VER_STRING,  png_sizeof(png_struct));
 #endif
 
 extern PNG_EXPORT(void,png_read_init_3) PNGARG((png_structpp ptr_ptr,
     png_const_charp user_png_ver, png_size_t png_struct_size));
 #if defined(PNG_1_0_X) || defined (PNG_1_2_X)
 extern PNG_EXPORT(void,png_read_init_2) PNGARG((png_structp png_ptr,
     png_const_charp user_png_ver, png_size_t png_struct_size, png_size_t
     png_info_size));
 #endif
 
 #if defined(PNG_1_0_X) || defined (PNG_1_2_X)
 /* Initialize png_ptr struct for writing, and allocate any other memory.
  * (old interface - DEPRECATED - use png_create_write_struct instead).
  */
 extern PNG_EXPORT(void,png_write_init) PNGARG((png_structp png_ptr))
     PNG_DEPRECATED;
 #undef png_write_init
 #define png_write_init(png_ptr) png_write_init_3(&png_ptr, \
     PNG_LIBPNG_VER_STRING, png_sizeof(png_struct));
 #endif
 
 extern PNG_EXPORT(void,png_write_init_3) PNGARG((png_structpp ptr_ptr,
     png_const_charp user_png_ver, png_size_t png_struct_size));
 extern PNG_EXPORT(void,png_write_init_2) PNGARG((png_structp png_ptr,
     png_const_charp user_png_ver, png_size_t png_struct_size, png_size_t
     png_info_size));
 
 /* Allocate memory for an internal libpng struct */
 PNG_EXTERN png_voidp png_create_struct PNGARG((int type)) PNG_PRIVATE;
 
 /* Free memory from internal libpng struct */
 PNG_EXTERN void png_destroy_struct PNGARG((png_voidp struct_ptr)) PNG_PRIVATE;
 
 PNG_EXTERN png_voidp png_create_struct_2 PNGARG((int type, png_malloc_ptr
   malloc_fn, png_voidp mem_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_destroy_struct_2 PNGARG((png_voidp struct_ptr,
    png_free_ptr free_fn, png_voidp mem_ptr)) PNG_PRIVATE;
 
 /* Free any memory that info_ptr points to and reset struct. */
 PNG_EXTERN void png_info_destroy PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 
 #ifndef PNG_1_0_X
 /* Function to allocate memory for zlib. */
 PNG_EXTERN voidpf png_zalloc PNGARG((voidpf png_ptr, uInt items,
    uInt size)) PNG_PRIVATE;
 
 /* Function to free memory for zlib */
 PNG_EXTERN void png_zfree PNGARG((voidpf png_ptr, voidpf ptr)) PNG_PRIVATE;
 
 #ifdef PNG_SIZE_T
 /* Function to convert a sizeof an item to png_sizeof item */
    PNG_EXTERN png_size_t PNGAPI png_convert_size PNGARG((size_t size))
       PNG_PRIVATE;
 #endif
 
 /* Next four functions are used internally as callbacks.  PNGAPI is required
  * but not PNG_EXPORT.  PNGAPI added at libpng version 1.2.3.
  */
 
 PNG_EXTERN void PNGAPI png_default_read_data PNGARG((png_structp png_ptr,
    png_bytep data, png_size_t length)) PNG_PRIVATE;
 
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 PNG_EXTERN void PNGAPI png_push_fill_buffer PNGARG((png_structp png_ptr,
    png_bytep buffer, png_size_t length)) PNG_PRIVATE;
 #endif
 
 PNG_EXTERN void PNGAPI png_default_write_data PNGARG((png_structp png_ptr,
    png_bytep data, png_size_t length)) PNG_PRIVATE;
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 #ifdef PNG_STDIO_SUPPORTED
 PNG_EXTERN void PNGAPI png_default_flush PNGARG((png_structp png_ptr))
    PNG_PRIVATE;
 #endif
 #endif
 #else /* PNG_1_0_X */
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 PNG_EXTERN void png_push_fill_buffer PNGARG((png_structp png_ptr,
    png_bytep buffer, png_size_t length)) PNG_PRIVATE;
 #endif
 #endif /* PNG_1_0_X */
 
 /* Reset the CRC variable */
 PNG_EXTERN void png_reset_crc PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 
 /* Write the "data" buffer to whatever output you are using. */
 PNG_EXTERN void png_write_data PNGARG((png_structp png_ptr, png_bytep data,
    png_size_t length)) PNG_PRIVATE;
 
 /* Read data from whatever input you are using into the "data" buffer */
 PNG_EXTERN void png_read_data PNGARG((png_structp png_ptr, png_bytep data,
    png_size_t length)) PNG_PRIVATE;
 
 /* Read bytes into buf, and update png_ptr->crc */
 PNG_EXTERN void png_crc_read PNGARG((png_structp png_ptr, png_bytep buf,
    png_size_t length)) PNG_PRIVATE;
 
 /* Decompress data in a chunk that uses compression */
 #if defined(PNG_zTXt_SUPPORTED) || defined(PNG_iTXt_SUPPORTED) || \
     defined(PNG_iCCP_SUPPORTED) || defined(PNG_sPLT_SUPPORTED)
 PNG_EXTERN void png_decompress_chunk PNGARG((png_structp png_ptr,
    int comp_type, png_size_t chunklength,
    png_size_t prefix_length, png_size_t *data_length)) PNG_PRIVATE;
 #endif
 
 /* Read "skip" bytes, read the file crc, and (optionally) verify png_ptr->crc */
 PNG_EXTERN int png_crc_finish PNGARG((png_structp png_ptr, png_uint_32 skip)
    PNG_PRIVATE);
 
 /* Read the CRC from the file and compare it to the libpng calculated CRC */
 PNG_EXTERN int png_crc_error PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 
 /* Calculate the CRC over a section of data.  Note that we are only
  * passing a maximum of 64K on systems that have this as a memory limit,
  * since this is the maximum buffer size we can specify.
  */
 PNG_EXTERN void png_calculate_crc PNGARG((png_structp png_ptr, png_bytep ptr,
    png_size_t length)) PNG_PRIVATE;
 
 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 PNG_EXTERN void png_flush PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 #endif
 
 /* Simple function to write the signature */
 PNG_EXTERN void png_write_sig PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 
 /* Write various chunks */
 
 /* Write the IHDR chunk, and update the png_struct with the necessary
  * information.
  */
 PNG_EXTERN void png_write_IHDR PNGARG((png_structp png_ptr, png_uint_32 width,
    png_uint_32 height,
    int bit_depth, int color_type, int compression_method, int filter_method,
    int interlace_method)) PNG_PRIVATE;
 
 PNG_EXTERN void png_write_PLTE PNGARG((png_structp png_ptr, png_colorp palette,
    png_uint_32 num_pal)) PNG_PRIVATE;
 
 PNG_EXTERN void png_write_IDAT PNGARG((png_structp png_ptr, png_bytep data,
    png_size_t length)) PNG_PRIVATE;
 
 PNG_EXTERN void png_write_IEND PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 
 #ifdef PNG_WRITE_gAMA_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 PNG_EXTERN void png_write_gAMA PNGARG((png_structp png_ptr, double file_gamma))
     PNG_PRIVATE;
 #endif
 #ifdef PNG_FIXED_POINT_SUPPORTED
 PNG_EXTERN void png_write_gAMA_fixed PNGARG((png_structp png_ptr,
     png_fixed_point file_gamma)) PNG_PRIVATE;
 #endif
 #endif
 
 #ifdef PNG_WRITE_sBIT_SUPPORTED
 PNG_EXTERN void png_write_sBIT PNGARG((png_structp png_ptr, png_color_8p sbit,
    int color_type)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_cHRM_SUPPORTED
 #ifdef PNG_FLOATING_POINT_SUPPORTED
 PNG_EXTERN void png_write_cHRM PNGARG((png_structp png_ptr,
    double white_x, double white_y,
    double red_x, double red_y, double green_x, double green_y,
    double blue_x, double blue_y)) PNG_PRIVATE;
 #endif
 #ifdef PNG_FIXED_POINT_SUPPORTED
 PNG_EXTERN void png_write_cHRM_fixed PNGARG((png_structp png_ptr,
    png_fixed_point int_white_x, png_fixed_point int_white_y,
    png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
    int_green_x, png_fixed_point int_green_y, png_fixed_point int_blue_x,
    png_fixed_point int_blue_y)) PNG_PRIVATE;
 #endif
 #endif
 
 #ifdef PNG_WRITE_sRGB_SUPPORTED
 PNG_EXTERN void png_write_sRGB PNGARG((png_structp png_ptr,
    int intent)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_iCCP_SUPPORTED
 PNG_EXTERN void png_write_iCCP PNGARG((png_structp png_ptr,
    png_charp name, int compression_type,
    png_charp profile, int proflen)) PNG_PRIVATE;
    /* Note to maintainer: profile should be png_bytep */
 #endif
 
 #ifdef PNG_WRITE_sPLT_SUPPORTED
 PNG_EXTERN void png_write_sPLT PNGARG((png_structp png_ptr,
    png_sPLT_tp palette)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_tRNS_SUPPORTED
 PNG_EXTERN void png_write_tRNS PNGARG((png_structp png_ptr, png_bytep trans,
    png_color_16p values, int number, int color_type)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_bKGD_SUPPORTED
 PNG_EXTERN void png_write_bKGD PNGARG((png_structp png_ptr,
    png_color_16p values, int color_type)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_hIST_SUPPORTED
 PNG_EXTERN void png_write_hIST PNGARG((png_structp png_ptr, png_uint_16p hist,
    int num_hist)) PNG_PRIVATE;
 #endif
 
 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
     defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
 PNG_EXTERN png_size_t png_check_keyword PNGARG((png_structp png_ptr,
    png_charp key, png_charpp new_key)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_tEXt_SUPPORTED
 PNG_EXTERN void png_write_tEXt PNGARG((png_structp png_ptr, png_charp key,
    png_charp text, png_size_t text_len)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_zTXt_SUPPORTED
 PNG_EXTERN void png_write_zTXt PNGARG((png_structp png_ptr, png_charp key,
    png_charp text, png_size_t text_len, int compression)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_iTXt_SUPPORTED
 PNG_EXTERN void png_write_iTXt PNGARG((png_structp png_ptr,
    int compression, png_charp key, png_charp lang, png_charp lang_key,
    png_charp text)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_TEXT_SUPPORTED  /* Added at version 1.0.14 and 1.2.4 */
 PNG_EXTERN int png_set_text_2 PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_textp text_ptr, int num_text)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_oFFs_SUPPORTED
 PNG_EXTERN void png_write_oFFs PNGARG((png_structp png_ptr,
    png_int_32 x_offset, png_int_32 y_offset, int unit_type)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_pCAL_SUPPORTED
 PNG_EXTERN void png_write_pCAL PNGARG((png_structp png_ptr, png_charp purpose,
    png_int_32 X0, png_int_32 X1, int type, int nparams,
    png_charp units, png_charpp params)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_pHYs_SUPPORTED
 PNG_EXTERN void png_write_pHYs PNGARG((png_structp png_ptr,
    png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit,
    int unit_type)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_tIME_SUPPORTED
 PNG_EXTERN void png_write_tIME PNGARG((png_structp png_ptr,
    png_timep mod_time)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_sCAL_SUPPORTED
 #if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
 PNG_EXTERN void png_write_sCAL PNGARG((png_structp png_ptr,
    int unit, double width, double height)) PNG_PRIVATE;
 #else
 #ifdef PNG_FIXED_POINT_SUPPORTED
 PNG_EXTERN void png_write_sCAL_s PNGARG((png_structp png_ptr,
    int unit, png_charp width, png_charp height)) PNG_PRIVATE;
 #endif
 #endif
 #endif
 
 /* Called when finished processing a row of data */
 PNG_EXTERN void png_write_finish_row PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 
 /* Internal use only.   Called before first row of data */
 PNG_EXTERN void png_write_start_row PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
 PNG_EXTERN void png_build_gamma_table PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 #endif
 
 /* Combine a row of data, dealing with alpha, etc. if requested */
 PNG_EXTERN void png_combine_row PNGARG((png_structp png_ptr, png_bytep row,
    int mask)) PNG_PRIVATE;
 
 #ifdef PNG_READ_INTERLACING_SUPPORTED
 /* Expand an interlaced row */
 /* OLD pre-1.0.9 interface:
 PNG_EXTERN void png_do_read_interlace PNGARG((png_row_infop row_info,
    png_bytep row, int pass, png_uint_32 transformations)) PNG_PRIVATE;
  */
 PNG_EXTERN void png_do_read_interlace PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 #endif
 
 /* GRR TO DO (2.0 or whenever):  simplify other internal calling interfaces */
 
 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
 /* Grab pixels out of a row for an interlaced pass */
 PNG_EXTERN void png_do_write_interlace PNGARG((png_row_infop row_info,
    png_bytep row, int pass)) PNG_PRIVATE;
 #endif
 
 /* Unfilter a row */
 PNG_EXTERN void png_read_filter_row PNGARG((png_structp png_ptr,
    png_row_infop row_info, png_bytep row, png_bytep prev_row,
    int filter)) PNG_PRIVATE;
 
 /* Choose the best filter to use and filter the row data */
 PNG_EXTERN void png_write_find_filter PNGARG((png_structp png_ptr,
    png_row_infop row_info)) PNG_PRIVATE;
 
 /* Write out the filtered row. */
 PNG_EXTERN void png_write_filtered_row PNGARG((png_structp png_ptr,
    png_bytep filtered_row)) PNG_PRIVATE;
 /* Finish a row while reading, dealing with interlacing passes, etc. */
 PNG_EXTERN void png_read_finish_row PNGARG((png_structp png_ptr));
 
 /* Initialize the row buffers, etc. */
 PNG_EXTERN void png_read_start_row PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 /* Optional call to update the users info structure */
 PNG_EXTERN void png_read_transform_info PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 
 /* These are the functions that do the transformations */
 #ifdef PNG_READ_FILLER_SUPPORTED
 PNG_EXTERN void png_do_read_filler PNGARG((png_row_infop row_info,
    png_bytep row, png_uint_32 filler, png_uint_32 flags)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
 PNG_EXTERN void png_do_read_swap_alpha PNGARG((png_row_infop row_info,
    png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
 PNG_EXTERN void png_do_write_swap_alpha PNGARG((png_row_infop row_info,
    png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
 PNG_EXTERN void png_do_read_invert_alpha PNGARG((png_row_infop row_info,
    png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
 PNG_EXTERN void png_do_write_invert_alpha PNGARG((png_row_infop row_info,
    png_bytep row)) PNG_PRIVATE;
 #endif
 
 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
     defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
 PNG_EXTERN void png_do_strip_filler PNGARG((png_row_infop row_info,
    png_bytep row, png_uint_32 flags)) PNG_PRIVATE;
 #endif
 
 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
 PNG_EXTERN void png_do_swap PNGARG((png_row_infop row_info,
     png_bytep row)) PNG_PRIVATE;
 #endif
 
 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || defined(PNG_WRITE_PACKSWAP_SUPPORTED)
 PNG_EXTERN void png_do_packswap PNGARG((png_row_infop row_info,
     png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 PNG_EXTERN int png_do_rgb_to_gray PNGARG((png_structp png_ptr, png_row_infop
    row_info, png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 PNG_EXTERN void png_do_gray_to_rgb PNGARG((png_row_infop row_info,
    png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_PACK_SUPPORTED
 PNG_EXTERN void png_do_unpack PNGARG((png_row_infop row_info,
     png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_SHIFT_SUPPORTED
 PNG_EXTERN void png_do_unshift PNGARG((png_row_infop row_info, png_bytep row,
    png_color_8p sig_bits)) PNG_PRIVATE;
 #endif
 
 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
 PNG_EXTERN void png_do_invert PNGARG((png_row_infop row_info,
     png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_16_TO_8_SUPPORTED
 PNG_EXTERN void png_do_chop PNGARG((png_row_infop row_info,
     png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_DITHER_SUPPORTED
 PNG_EXTERN void png_do_dither PNGARG((png_row_infop row_info,
    png_bytep row, png_bytep palette_lookup,
     png_bytep dither_lookup)) PNG_PRIVATE;
 
 #  ifdef PNG_CORRECT_PALETTE_SUPPORTED
 PNG_EXTERN void png_correct_palette PNGARG((png_structp png_ptr,
    png_colorp palette, int num_palette)) PNG_PRIVATE;
 #  endif
 #endif
 
 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
 PNG_EXTERN void png_do_bgr PNGARG((png_row_infop row_info,
     png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_PACK_SUPPORTED
 PNG_EXTERN void png_do_pack PNGARG((png_row_infop row_info,
    png_bytep row, png_uint_32 bit_depth)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_WRITE_SHIFT_SUPPORTED
 PNG_EXTERN void png_do_shift PNGARG((png_row_infop row_info, png_bytep row,
    png_color_8p bit_depth)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_BACKGROUND_SUPPORTED
 #ifdef PNG_READ_GAMMA_SUPPORTED
 PNG_EXTERN void png_do_background PNGARG((png_row_infop row_info, png_bytep row,
    png_color_16p trans_values, png_color_16p background,
    png_color_16p background_1,
    png_bytep gamma_table, png_bytep gamma_from_1, png_bytep gamma_to_1,
    png_uint_16pp gamma_16, png_uint_16pp gamma_16_from_1,
    png_uint_16pp gamma_16_to_1, int gamma_shift)) PNG_PRIVATE;
 #else
 PNG_EXTERN void png_do_background PNGARG((png_row_infop row_info, png_bytep row,
    png_color_16p trans_values, png_color_16p background)) PNG_PRIVATE;
 #endif
 #endif
 
 #ifdef PNG_READ_GAMMA_SUPPORTED
 PNG_EXTERN void png_do_gamma PNGARG((png_row_infop row_info, png_bytep row,
    png_bytep gamma_table, png_uint_16pp gamma_16_table,
    int gamma_shift)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_EXPAND_SUPPORTED
 PNG_EXTERN void png_do_expand_palette PNGARG((png_row_infop row_info,
    png_bytep row, png_colorp palette, png_bytep trans,
    int num_trans)) PNG_PRIVATE;
 PNG_EXTERN void png_do_expand PNGARG((png_row_infop row_info,
    png_bytep row, png_color_16p trans_value)) PNG_PRIVATE;
 #endif
 
 /* The following decodes the appropriate chunks, and does error correction,
  * then calls the appropriate callback for the chunk if it is valid.
  */
 
 /* Decode the IHDR chunk */
 PNG_EXTERN void png_handle_IHDR PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 PNG_EXTERN void png_handle_PLTE PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 PNG_EXTERN void png_handle_IEND PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 
 #ifdef PNG_READ_bKGD_SUPPORTED
 PNG_EXTERN void png_handle_bKGD PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_cHRM_SUPPORTED
 PNG_EXTERN void png_handle_cHRM PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_gAMA_SUPPORTED
 PNG_EXTERN void png_handle_gAMA PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_hIST_SUPPORTED
 PNG_EXTERN void png_handle_hIST PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_iCCP_SUPPORTED
 extern void png_handle_iCCP PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif /* PNG_READ_iCCP_SUPPORTED */
 
 #ifdef PNG_READ_iTXt_SUPPORTED
 PNG_EXTERN void png_handle_iTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_oFFs_SUPPORTED
 PNG_EXTERN void png_handle_oFFs PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_pCAL_SUPPORTED
 PNG_EXTERN void png_handle_pCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_pHYs_SUPPORTED
 PNG_EXTERN void png_handle_pHYs PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_sBIT_SUPPORTED
 PNG_EXTERN void png_handle_sBIT PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_sCAL_SUPPORTED
 PNG_EXTERN void png_handle_sCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_sPLT_SUPPORTED
 extern void png_handle_sPLT PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif /* PNG_READ_sPLT_SUPPORTED */
 
 #ifdef PNG_READ_sRGB_SUPPORTED
 PNG_EXTERN void png_handle_sRGB PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_tEXt_SUPPORTED
 PNG_EXTERN void png_handle_tEXt PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_tIME_SUPPORTED
 PNG_EXTERN void png_handle_tIME PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_tRNS_SUPPORTED
 PNG_EXTERN void png_handle_tRNS PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_READ_zTXt_SUPPORTED
 PNG_EXTERN void png_handle_zTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 #endif
 
 PNG_EXTERN void png_handle_unknown PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 length)) PNG_PRIVATE;
 
 PNG_EXTERN void png_check_chunk_name PNGARG((png_structp png_ptr,
    png_bytep chunk_name)) PNG_PRIVATE;
 
 /* Handle the transformations for reading and writing */
 PNG_EXTERN void png_do_read_transformations
    PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_do_write_transformations
    PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 
 PNG_EXTERN void png_init_read_transformations
    PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 
 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 PNG_EXTERN void png_push_read_chunk PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_push_read_sig PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_push_check_crc PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_push_crc_skip PNGARG((png_structp png_ptr,
    png_uint_32 length)) PNG_PRIVATE;
 PNG_EXTERN void png_push_crc_finish PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_push_save_buffer PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_push_restore_buffer PNGARG((png_structp png_ptr,
    png_bytep buffer, png_size_t buffer_length)) PNG_PRIVATE;
 PNG_EXTERN void png_push_read_IDAT PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_process_IDAT_data PNGARG((png_structp png_ptr,
    png_bytep buffer, png_size_t buffer_length)) PNG_PRIVATE;
 PNG_EXTERN void png_push_process_row PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_push_handle_unknown PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 length)) PNG_PRIVATE;
 PNG_EXTERN void png_push_have_info PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_push_have_end PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_push_have_row PNGARG((png_structp png_ptr,
    png_bytep row)) PNG_PRIVATE;
 PNG_EXTERN void png_push_read_end PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_process_some_data PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 PNG_EXTERN void png_read_push_finish_row
    PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 #ifdef PNG_READ_tEXt_SUPPORTED
 PNG_EXTERN void png_push_handle_tEXt PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 length)) PNG_PRIVATE;
 PNG_EXTERN void png_push_read_tEXt PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 #endif
 #ifdef PNG_READ_zTXt_SUPPORTED
 PNG_EXTERN void png_push_handle_zTXt PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 length)) PNG_PRIVATE;
 PNG_EXTERN void png_push_read_zTXt PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 #endif
 #ifdef PNG_READ_iTXt_SUPPORTED
 PNG_EXTERN void png_push_handle_iTXt PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_uint_32 length)) PNG_PRIVATE;
 PNG_EXTERN void png_push_read_iTXt PNGARG((png_structp png_ptr,
    png_infop info_ptr)) PNG_PRIVATE;
 #endif
 
 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
 
 #ifdef PNG_MNG_FEATURES_SUPPORTED
 PNG_EXTERN void png_do_read_intrapixel PNGARG((png_row_infop row_info,
    png_bytep row)) PNG_PRIVATE;
 PNG_EXTERN void png_do_write_intrapixel PNGARG((png_row_infop row_info,
    png_bytep row)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_ASSEMBLER_CODE_SUPPORTED
 #ifdef PNG_MMX_CODE_SUPPORTED
 /* png.c */ /* PRIVATE */
 PNG_EXTERN void png_init_mmx_flags PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 #endif
 #endif
 
 
 /* The following six functions will be exported in libpng-1.4.0. */
 #if defined(PNG_INCH_CONVERSIONS) && defined(PNG_FLOATING_POINT_SUPPORTED)
 PNG_EXTERN png_uint_32 png_get_pixels_per_inch PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
 PNG_EXTERN png_uint_32 png_get_x_pixels_per_inch PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
 PNG_EXTERN png_uint_32 png_get_y_pixels_per_inch PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
 PNG_EXTERN float png_get_x_offset_inches PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
 PNG_EXTERN float png_get_y_offset_inches PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
 #ifdef PNG_pHYs_SUPPORTED
 PNG_EXTERN png_uint_32 png_get_pHYs_dpi PNGARG((png_structp png_ptr,
 png_infop info_ptr, png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type));
 #endif /* PNG_pHYs_SUPPORTED */
 #endif  /* PNG_INCH_CONVERSIONS && PNG_FLOATING_POINT_SUPPORTED */
 
 /* Read the chunk header (length + type name) */
 PNG_EXTERN png_uint_32 png_read_chunk_header
    PNGARG((png_structp png_ptr)) PNG_PRIVATE;
 
 /* Added at libpng version 1.2.34 */
 #ifdef PNG_cHRM_SUPPORTED
 PNG_EXTERN int png_check_cHRM_fixed PNGARG((png_structp png_ptr,
    png_fixed_point int_white_x, png_fixed_point int_white_y,
    png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
    int_green_x, png_fixed_point int_green_y, png_fixed_point int_blue_x,
    png_fixed_point int_blue_y)) PNG_PRIVATE;
 #endif
 
 #ifdef PNG_cHRM_SUPPORTED
 #ifdef PNG_CHECK_cHRM_SUPPORTED
 /* Added at libpng version 1.2.34 */
 PNG_EXTERN void png_64bit_product PNGARG((long v1, long v2,
    unsigned long *hi_product, unsigned long *lo_product)) PNG_PRIVATE;
 #endif
 #endif
 
 /* Added at libpng version 1.2.41 */
 PNG_EXTERN void png_check_IHDR PNGARG((png_structp png_ptr,
    png_uint_32 width, png_uint_32 height, int bit_depth,
    int color_type, int interlace_type, int compression_type,
    int filter_type)) PNG_PRIVATE;
 
 /* Added at libpng version 1.2.41 */
 PNG_EXTERN png_voidp png_calloc PNGARG((png_structp png_ptr,
    png_uint_32 size));
 
 /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */
 
 #endif /* PNG_INTERNAL */
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif /* PNG_VERSION_INFO_ONLY */
 /* Do not put anything past this line */
 #endif /* PNG_H */