1 /*
   2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.  Oracle designates this
   7  * particular file as subject to the "Classpath" exception as provided
   8  * by Oracle in the LICENSE file that accompanied this code.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  */
  24 
  25 /* png.h - header file for PNG reference library
  26  *
  27  * This file is available under and governed by the GNU General Public
  28  * License version 2 only, as published by the Free Software Foundation.
  29  * However, the following notice accompanied the original version of this
  30  * file and, per its terms, should not be removed:
  31  *
  32  * libpng version 1.6.23, June 9, 2016
  33  *
  34  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  35  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  36  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  37  *
  38  * This code is released under the libpng license (See LICENSE, below)
  39  *
  40  * Authors and maintainers:
  41  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  42  *   libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
  43  *   libpng versions 0.97, January 1998, through 1.6.23, June 9, 2016:
  44  *     Glenn Randers-Pehrson.
  45  *   See also "Contributing Authors", below.
  46  */
  47 
  48 /*
  49  * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
  50  *
  51  * If you modify libpng you may insert additional notices immediately following
  52  * this sentence.
  53  *
  54  * This code is released under the libpng license.
  55  *
  56  * Some files in the "contrib" directory and some configure-generated
  57  * files that are distributed with libpng have other copyright owners and
  58  * are released under other open source licenses.
  59  *
  60  * libpng versions 1.0.7, July 1, 2000 through 1.6.23, June 9, 2016 are
  61  * Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
  62  * derived from libpng-1.0.6, and are distributed according to the same
  63  * disclaimer and license as libpng-1.0.6 with the following individuals
  64  * added to the list of Contributing Authors:
  65  *
  66  *    Simon-Pierre Cadieux
  67  *    Eric S. Raymond
  68  *    Mans Rullgard
  69  *    Cosmin Truta
  70  *    Gilles Vollant
  71  *    James Yu
  72  *
  73  * and with the following additions to the disclaimer:
  74  *
  75  *    There is no warranty against interference with your enjoyment of the
  76  *    library or against infringement.  There is no warranty that our
  77  *    efforts or the library will fulfill any of your particular purposes
  78  *    or needs.  This library is provided with all faults, and the entire
  79  *    risk of satisfactory quality, performance, accuracy, and effort is with
  80  *    the user.
  81  *
  82  * Some files in the "contrib" directory have other copyright owners and
  83  * are released under other open source licenses.
  84  *
  85  *
  86  * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
  87  * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
  88  * libpng-0.96, and are distributed according to the same disclaimer and
  89  * license as libpng-0.96, with the following individuals added to the list
  90  * of Contributing Authors:
  91  *
  92  *    Tom Lane
  93  *    Glenn Randers-Pehrson
  94  *    Willem van Schaik
  95  *
  96  * Some files in the "scripts" directory have different copyright owners
  97  * but are also released under this license.
  98  *
  99  * libpng versions 0.89, June 1996, through 0.96, May 1997, are
 100  * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
 101  * and are distributed according to the same disclaimer and license as
 102  * libpng-0.88, with the following individuals added to the list of
 103  * Contributing Authors:
 104  *
 105  *    John Bowler
 106  *    Kevin Bracey
 107  *    Sam Bushell
 108  *    Magnus Holmgren
 109  *    Greg Roelofs
 110  *    Tom Tanner
 111  *
 112  * Some files in the "scripts" directory have other copyright owners
 113  * but are released under this license.
 114  *
 115  * libpng versions 0.5, May 1995, through 0.88, January 1996, are
 116  * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 117  *
 118  * For the purposes of this copyright and license, "Contributing Authors"
 119  * is defined as the following set of individuals:
 120  *
 121  *    Andreas Dilger
 122  *    Dave Martindale
 123  *    Guy Eric Schalnat
 124  *    Paul Schmidt
 125  *    Tim Wegner
 126  *
 127  * The PNG Reference Library is supplied "AS IS".  The Contributing Authors
 128  * and Group 42, Inc. disclaim all warranties, expressed or implied,
 129  * including, without limitation, the warranties of merchantability and of
 130  * fitness for any purpose.  The Contributing Authors and Group 42, Inc.
 131  * assume no liability for direct, indirect, incidental, special, exemplary,
 132  * or consequential damages, which may result from the use of the PNG
 133  * Reference Library, even if advised of the possibility of such damage.
 134  *
 135  * Permission is hereby granted to use, copy, modify, and distribute this
 136  * source code, or portions hereof, for any purpose, without fee, subject
 137  * to the following restrictions:
 138  *
 139  *   1. The origin of this source code must not be misrepresented.
 140  *
 141  *   2. Altered versions must be plainly marked as such and must not
 142  *      be misrepresented as being the original source.
 143  *
 144  *   3. This Copyright notice may not be removed or altered from any
 145  *      source or altered source distribution.
 146  *
 147  * The Contributing Authors and Group 42, Inc. specifically permit, without
 148  * fee, and encourage the use of this source code as a component to
 149  * supporting the PNG file format in commercial products.  If you use this
 150  * source code in a product, acknowledgment is not required but would be
 151  * appreciated.
 152  *
 153  * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
 154  *
 155  * TRADEMARK:
 156  *
 157  * The name "libpng" has not been registered by the Copyright owner
 158  * as a trademark in any jurisdiction.  However, because libpng has
 159  * been distributed and maintained world-wide, continually since 1995,
 160  * the Copyright owner claims "common-law trademark protection" in any
 161  * jurisdiction where common-law trademark is recognized.
 162  *
 163  * OSI CERTIFICATION:
 164  *
 165  * Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
 166  * a certification mark of the Open Source Initiative. OSI has not addressed
 167  * the additional disclaimers inserted at version 1.0.7.
 168  *
 169  * EXPORT CONTROL:
 170  *
 171  * The Copyright owner believes that the Export Control Classification
 172  * Number (ECCN) for libpng is EAR99, which means not subject to export
 173  * controls or International Traffic in Arms Regulations (ITAR) because
 174  * it is open source, publicly available software, that does not contain
 175  * any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
 176  * 734.7(b).
 177  */
 178 
 179 /*
 180  * A "png_get_copyright" function is available, for convenient use in "about"
 181  * boxes and the like:
 182  *
 183  *    printf("%s", png_get_copyright(NULL));
 184  *
 185  * Also, the PNG logo (in PNG format, of course) is supplied in the
 186  * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
 187  */
 188 
 189 /*
 190  * The contributing authors would like to thank all those who helped
 191  * with testing, bug fixes, and patience.  This wouldn't have been
 192  * possible without all of you.
 193  *
 194  * Thanks to Frank J. T. Wojcik for helping with the documentation.
 195  */
 196 
 197 /* Note about libpng version numbers:
 198  *
 199  *    Due to various miscommunications, unforeseen code incompatibilities
 200  *    and occasional factors outside the authors' control, version numbering
 201  *    on the library has not always been consistent and straightforward.
 202  *    The following table summarizes matters since version 0.89c, which was
 203  *    the first widely used release:
 204  *
 205  *    source                 png.h  png.h  shared-lib
 206  *    version                string   int  version
 207  *    -------                ------ -----  ----------
 208  *    0.89c "1.0 beta 3"     0.89      89  1.0.89
 209  *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
 210  *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
 211  *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
 212  *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
 213  *    0.97c                  0.97      97  2.0.97
 214  *    0.98                   0.98      98  2.0.98
 215  *    0.99                   0.99      98  2.0.99
 216  *    0.99a-m                0.99      99  2.0.99
 217  *    1.00                   1.00     100  2.1.0 [100 should be 10000]
 218  *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
 219  *    1.0.1       png.h string is   10001  2.1.0
 220  *    1.0.1a-e    identical to the  10002  from here on, the shared library
 221  *    1.0.2       source version)   10002  is 2.V where V is the source code
 222  *    1.0.2a-b                      10003  version, except as noted.
 223  *    1.0.3                         10003
 224  *    1.0.3a-d                      10004
 225  *    1.0.4                         10004
 226  *    1.0.4a-f                      10005
 227  *    1.0.5 (+ 2 patches)           10005
 228  *    1.0.5a-d                      10006
 229  *    1.0.5e-r                      10100 (not source compatible)
 230  *    1.0.5s-v                      10006 (not binary compatible)
 231  *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)
 232  *    1.0.6d-f                      10007 (still binary incompatible)
 233  *    1.0.6g                        10007
 234  *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)
 235  *    1.0.6i                        10007  10.6i
 236  *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
 237  *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
 238  *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
 239  *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
 240  *    1.0.7                    1    10007  (still compatible)
 241  *    ...
 242  *    1.0.19                  10    10019  10.so.0.19[.0]
 243  *    ...
 244  *    1.2.56                  13    10256  12.so.0.56[.0]
 245  *    ...
 246  *    1.5.27                  15    10527  15.so.15.27[.0]
 247  *    ...
 248  *    1.6.23                  16    10623  16.so.16.23[.0]
 249  *
 250  *    Henceforth the source version will match the shared-library major
 251  *    and minor numbers; the shared-library major version number will be
 252  *    used for changes in backward compatibility, as it is intended.  The
 253  *    PNG_LIBPNG_VER macro, which is not used within libpng but is available
 254  *    for applications, is an unsigned integer of the form xyyzz corresponding
 255  *    to the source version x.y.z (leading zeros in y and z).  Beta versions
 256  *    were given the previous public release number plus a letter, until
 257  *    version 1.0.6j; from then on they were given the upcoming public
 258  *    release number plus "betaNN" or "rcNN".
 259  *
 260  *    Binary incompatibility exists only when applications make direct access
 261  *    to the info_ptr or png_ptr members through png.h, and the compiled
 262  *    application is loaded with a different version of the library.
 263  *
 264  *    DLLNUM will change each time there are forward or backward changes
 265  *    in binary compatibility (e.g., when a new feature is added).
 266  *
 267  * See libpng.txt or libpng.3 for more information.  The PNG specification
 268  * is available as a W3C Recommendation and as an ISO Specification,
 269  * <http://www.w3.org/TR/2003/REC-PNG-20031110/
 270  */
 271 
 272 /*
 273  * Y2K compliance in libpng:
 274  * =========================
 275  *
 276  *    June 9, 2016
 277  *
 278  *    Since the PNG Development group is an ad-hoc body, we can't make
 279  *    an official declaration.
 280  *
 281  *    This is your unofficial assurance that libpng from version 0.71 and
 282  *    upward through 1.6.23 are Y2K compliant.  It is my belief that
 283  *    earlier versions were also Y2K compliant.
 284  *
 285  *    Libpng only has two year fields.  One is a 2-byte unsigned integer
 286  *    that will hold years up to 65535.  The other, which is deprecated,
 287  *    holds the date in text format, and will hold years up to 9999.
 288  *
 289  *    The integer is
 290  *        "png_uint_16 year" in png_time_struct.
 291  *
 292  *    The string is
 293  *        "char time_buffer[29]" in png_struct.  This is no longer used
 294  *    in libpng-1.6.x and will be removed from libpng-1.7.0.
 295  *
 296  *    There are seven time-related functions:
 297  *        png.c: png_convert_to_rfc_1123_buffer() in png.c
 298  *          (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
 299  *          png_convert_to_rfc_1152() in error prior to libpng-0.98)
 300  *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
 301  *        png_convert_from_time_t() in pngwrite.c
 302  *        png_get_tIME() in pngget.c
 303  *        png_handle_tIME() in pngrutil.c, called in pngread.c
 304  *        png_set_tIME() in pngset.c
 305  *        png_write_tIME() in pngwutil.c, called in pngwrite.c
 306  *
 307  *    All handle dates properly in a Y2K environment.  The
 308  *    png_convert_from_time_t() function calls gmtime() to convert from system
 309  *    clock time, which returns (year - 1900), which we properly convert to
 310  *    the full 4-digit year.  There is a possibility that libpng applications
 311  *    are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
 312  *    function, or that they are incorrectly passing only a 2-digit year
 313  *    instead of "year - 1900" into the png_convert_from_struct_tm() function,
 314  *    but this is not under our control.  The libpng documentation has always
 315  *    stated that it works with 4-digit years, and the APIs have been
 316  *    documented as such.
 317  *
 318  *    The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
 319  *    integer to hold the year, and can hold years as large as 65535.
 320  *
 321  *    zlib, upon which libpng depends, is also Y2K compliant.  It contains
 322  *    no date-related code.
 323  *
 324  *       Glenn Randers-Pehrson
 325  *       libpng maintainer
 326  *       PNG Development Group
 327  */
 328 
 329 #ifndef PNG_H
 330 #define PNG_H
 331 
 332 /* This is not the place to learn how to use libpng. The file libpng-manual.txt
 333  * describes how to use libpng, and the file example.c summarizes it
 334  * with some code on which to build.  This file is useful for looking
 335  * at the actual function definitions and structure components.  If that
 336  * file has been stripped from your copy of libpng, you can find it at
 337  * <http://www.libpng.org/pub/png/libpng-manual.txt>
 338  *
 339  * If you just need to read a PNG file and don't want to read the documentation
 340  * skip to the end of this file and read the section entitled 'simplified API'.
 341  */
 342 
 343 /* Version information for png.h - this should match the version in png.c */
 344 #define PNG_LIBPNG_VER_STRING "1.6.23"
 345 #define PNG_HEADER_VERSION_STRING \
 346      " libpng version 1.6.23 - June 9, 2016\n"
 347 
 348 #define PNG_LIBPNG_VER_SONUM   16
 349 #define PNG_LIBPNG_VER_DLLNUM  16
 350 
 351 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 352 #define PNG_LIBPNG_VER_MAJOR   1
 353 #define PNG_LIBPNG_VER_MINOR   6
 354 #define PNG_LIBPNG_VER_RELEASE 23
 355 
 356 /* This should match the numeric part of the final component of
 357  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
 358  */
 359 
 360 #define PNG_LIBPNG_VER_BUILD  0
 361 
 362 /* Release Status */
 363 #define PNG_LIBPNG_BUILD_ALPHA    1
 364 #define PNG_LIBPNG_BUILD_BETA     2
 365 #define PNG_LIBPNG_BUILD_RC       3
 366 #define PNG_LIBPNG_BUILD_STABLE   4
 367 #define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7
 368 
 369 /* Release-Specific Flags */
 370 #define PNG_LIBPNG_BUILD_PATCH    8 /* Can be OR'ed with
 371                                        PNG_LIBPNG_BUILD_STABLE only */
 372 #define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with
 373                                        PNG_LIBPNG_BUILD_SPECIAL */
 374 #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
 375                                        PNG_LIBPNG_BUILD_PRIVATE */
 376 
 377 #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
 378 
 379 /* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
 380  * We must not include leading zeros.
 381  * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
 382  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
 383  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
 384  */
 385 #define PNG_LIBPNG_VER 10623 /* 1.6.23 */
 386 
 387 /* Library configuration: these options cannot be changed after
 388  * the library has been built.
 389  */
 390 #ifndef PNGLCONF_H
 391     /* If pnglibconf.h is missing, you can
 392      * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
 393      */
 394 #   include "pnglibconf.h"
 395 #endif
 396 
 397 #ifndef PNG_VERSION_INFO_ONLY
 398    /* Machine specific configuration. */
 399 #  include "pngconf.h"
 400 #endif
 401 
 402 /*
 403  * Added at libpng-1.2.8
 404  *
 405  * Ref MSDN: Private as priority over Special
 406  * VS_FF_PRIVATEBUILD File *was not* built using standard release
 407  * procedures. If this value is given, the StringFileInfo block must
 408  * contain a PrivateBuild string.
 409  *
 410  * VS_FF_SPECIALBUILD File *was* built by the original company using
 411  * standard release procedures but is a variation of the standard
 412  * file of the same version number. If this value is given, the
 413  * StringFileInfo block must contain a SpecialBuild string.
 414  */
 415 
 416 #ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */
 417 #  define PNG_LIBPNG_BUILD_TYPE \
 418        (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
 419 #else
 420 #  ifdef PNG_LIBPNG_SPECIALBUILD
 421 #    define PNG_LIBPNG_BUILD_TYPE \
 422          (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
 423 #  else
 424 #    define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)
 425 #  endif
 426 #endif
 427 
 428 #ifndef PNG_VERSION_INFO_ONLY
 429 
 430 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
 431 #ifdef __cplusplus
 432 extern "C" {
 433 #endif /* __cplusplus */
 434 
 435 /* Version information for C files, stored in png.c.  This had better match
 436  * the version above.
 437  */
 438 #define png_libpng_ver png_get_header_ver(NULL)
 439 
 440 /* This file is arranged in several sections:
 441  *
 442  * 1. [omitted]
 443  * 2. Any configuration options that can be specified by for the application
 444  *    code when it is built.  (Build time configuration is in pnglibconf.h)
 445  * 3. Type definitions (base types are defined in pngconf.h), structure
 446  *    definitions.
 447  * 4. Exported library functions.
 448  * 5. Simplified API.
 449  * 6. Implementation options.
 450  *
 451  * The library source code has additional files (principally pngpriv.h) that
 452  * allow configuration of the library.
 453  */
 454 
 455 /* Section 1: [omitted] */
 456 
 457 /* Section 2: run time configuration
 458  * See pnglibconf.h for build time configuration
 459  *
 460  * Run time configuration allows the application to choose between
 461  * implementations of certain arithmetic APIs.  The default is set
 462  * at build time and recorded in pnglibconf.h, but it is safe to
 463  * override these (and only these) settings.  Note that this won't
 464  * change what the library does, only application code, and the
 465  * settings can (and probably should) be made on a per-file basis
 466  * by setting the #defines before including png.h
 467  *
 468  * Use macros to read integers from PNG data or use the exported
 469  * functions?
 470  *   PNG_USE_READ_MACROS: use the macros (see below)  Note that
 471  *     the macros evaluate their argument multiple times.
 472  *   PNG_NO_USE_READ_MACROS: call the relevant library function.
 473  *
 474  * Use the alternative algorithm for compositing alpha samples that
 475  * does not use division?
 476  *   PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division'
 477  *      algorithm.
 478  *   PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm.
 479  *
 480  * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is
 481  * false?
 482  *   PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error
 483  *      APIs to png_warning.
 484  * Otherwise the calls are mapped to png_error.
 485  */
 486 
 487 /* Section 3: type definitions, including structures and compile time
 488  * constants.
 489  * See pngconf.h for base types that vary by machine/system
 490  */
 491 
 492 /* This triggers a compiler error in png.c, if png.c and png.h
 493  * do not agree upon the version number.
 494  */
 495 typedef char* png_libpng_version_1_6_23;
 496 
 497 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
 498  *
 499  * png_struct is the cache of information used while reading or writing a single
 500  * PNG file.  One of these is always required, although the simplified API
 501  * (below) hides the creation and destruction of it.
 502  */
 503 typedef struct png_struct_def png_struct;
 504 typedef const png_struct * png_const_structp;
 505 typedef png_struct * png_structp;
 506 typedef png_struct * * png_structpp;
 507 
 508 /* png_info contains information read from or to be written to a PNG file.  One
 509  * or more of these must exist while reading or creating a PNG file.  The
 510  * information is not used by libpng during read but is used to control what
 511  * gets written when a PNG file is created.  "png_get_" function calls read
 512  * information during read and "png_set_" functions calls write information
 513  * when creating a PNG.
 514  * been moved into a separate header file that is not accessible to
 515  * applications.  Read libpng-manual.txt or libpng.3 for more info.
 516  */
 517 typedef struct png_info_def png_info;
 518 typedef png_info * png_infop;
 519 typedef const png_info * png_const_infop;
 520 typedef png_info * * png_infopp;
 521 
 522 /* Types with names ending 'p' are pointer types.  The corresponding types with
 523  * names ending 'rp' are identical pointer types except that the pointer is
 524  * marked 'restrict', which means that it is the only pointer to the object
 525  * passed to the function.  Applications should not use the 'restrict' types;
 526  * it is always valid to pass 'p' to a pointer with a function argument of the
 527  * corresponding 'rp' type.  Different compilers have different rules with
 528  * regard to type matching in the presence of 'restrict'.  For backward
 529  * compatibility libpng callbacks never have 'restrict' in their parameters and,
 530  * consequentially, writing portable application code is extremely difficult if
 531  * an attempt is made to use 'restrict'.
 532  */
 533 typedef png_struct * PNG_RESTRICT png_structrp;
 534 typedef const png_struct * PNG_RESTRICT png_const_structrp;
 535 typedef png_info * PNG_RESTRICT png_inforp;
 536 typedef const png_info * PNG_RESTRICT png_const_inforp;
 537 
 538 /* Three color definitions.  The order of the red, green, and blue, (and the
 539  * exact size) is not important, although the size of the fields need to
 540  * be png_byte or png_uint_16 (as defined below).
 541  */
 542 typedef struct png_color_struct
 543 {
 544    png_byte red;
 545    png_byte green;
 546    png_byte blue;
 547 } png_color;
 548 typedef png_color * png_colorp;
 549 typedef const png_color * png_const_colorp;
 550 typedef png_color * * png_colorpp;
 551 
 552 typedef struct png_color_16_struct
 553 {
 554    png_byte index;    /* used for palette files */
 555    png_uint_16 red;   /* for use in red green blue files */
 556    png_uint_16 green;
 557    png_uint_16 blue;
 558    png_uint_16 gray;  /* for use in grayscale files */
 559 } png_color_16;
 560 typedef png_color_16 * png_color_16p;
 561 typedef const png_color_16 * png_const_color_16p;
 562 typedef png_color_16 * * png_color_16pp;
 563 
 564 typedef struct png_color_8_struct
 565 {
 566    png_byte red;   /* for use in red green blue files */
 567    png_byte green;
 568    png_byte blue;
 569    png_byte gray;  /* for use in grayscale files */
 570    png_byte alpha; /* for alpha channel files */
 571 } png_color_8;
 572 typedef png_color_8 * png_color_8p;
 573 typedef const png_color_8 * png_const_color_8p;
 574 typedef png_color_8 * * png_color_8pp;
 575 
 576 /*
 577  * The following two structures are used for the in-core representation
 578  * of sPLT chunks.
 579  */
 580 typedef struct png_sPLT_entry_struct
 581 {
 582    png_uint_16 red;
 583    png_uint_16 green;
 584    png_uint_16 blue;
 585    png_uint_16 alpha;
 586    png_uint_16 frequency;
 587 } png_sPLT_entry;
 588 typedef png_sPLT_entry * png_sPLT_entryp;
 589 typedef const png_sPLT_entry * png_const_sPLT_entryp;
 590 typedef png_sPLT_entry * * png_sPLT_entrypp;
 591 
 592 /*  When the depth of the sPLT palette is 8 bits, the color and alpha samples
 593  *  occupy the LSB of their respective members, and the MSB of each member
 594  *  is zero-filled.  The frequency member always occupies the full 16 bits.
 595  */
 596 
 597 typedef struct png_sPLT_struct
 598 {
 599    png_charp name;           /* palette name */
 600    png_byte depth;           /* depth of palette samples */
 601    png_sPLT_entryp entries;  /* palette entries */
 602    png_int_32 nentries;      /* number of palette entries */
 603 } png_sPLT_t;
 604 typedef png_sPLT_t * png_sPLT_tp;
 605 typedef const png_sPLT_t * png_const_sPLT_tp;
 606 typedef png_sPLT_t * * png_sPLT_tpp;
 607 
 608 #ifdef PNG_TEXT_SUPPORTED
 609 /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
 610  * and whether that contents is compressed or not.  The "key" field
 611  * points to a regular zero-terminated C string.  The "text" fields can be a
 612  * regular C string, an empty string, or a NULL pointer.
 613  * However, the structure returned by png_get_text() will always contain
 614  * the "text" field as a regular zero-terminated C string (possibly
 615  * empty), never a NULL pointer, so it can be safely used in printf() and
 616  * other string-handling functions.  Note that the "itxt_length", "lang", and
 617  * "lang_key" members of the structure only exist when the library is built
 618  * with iTXt chunk support.  Prior to libpng-1.4.0 the library was built by
 619  * default without iTXt support. Also note that when iTXt *is* supported,
 620  * the "lang" and "lang_key" fields contain NULL pointers when the
 621  * "compression" field contains * PNG_TEXT_COMPRESSION_NONE or
 622  * PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the
 623  * same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag"
 624  * which is always 0 or 1, or its "compression method" which is always 0.
 625  */
 626 typedef struct png_text_struct
 627 {
 628    int  compression;       /* compression value:
 629                              -1: tEXt, none
 630                               0: zTXt, deflate
 631                               1: iTXt, none
 632                               2: iTXt, deflate  */
 633    png_charp key;          /* keyword, 1-79 character description of "text" */
 634    png_charp text;         /* comment, may be an empty string (ie "")
 635                               or a NULL pointer */
 636    png_size_t text_length; /* length of the text string */
 637    png_size_t itxt_length; /* length of the itxt string */
 638    png_charp lang;         /* language code, 0-79 characters
 639                               or a NULL pointer */
 640    png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more
 641                               chars or a NULL pointer */
 642 } png_text;
 643 typedef png_text * png_textp;
 644 typedef const png_text * png_const_textp;
 645 typedef png_text * * png_textpp;
 646 #endif
 647 
 648 /* Supported compression types for text in PNG files (tEXt, and zTXt).
 649  * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
 650 #define PNG_TEXT_COMPRESSION_NONE_WR -3
 651 #define PNG_TEXT_COMPRESSION_zTXt_WR -2
 652 #define PNG_TEXT_COMPRESSION_NONE    -1
 653 #define PNG_TEXT_COMPRESSION_zTXt     0
 654 #define PNG_ITXT_COMPRESSION_NONE     1
 655 #define PNG_ITXT_COMPRESSION_zTXt     2
 656 #define PNG_TEXT_COMPRESSION_LAST     3  /* Not a valid value */
 657 
 658 /* png_time is a way to hold the time in an machine independent way.
 659  * Two conversions are provided, both from time_t and struct tm.  There
 660  * is no portable way to convert to either of these structures, as far
 661  * as I know.  If you know of a portable way, send it to me.  As a side
 662  * note - PNG has always been Year 2000 compliant!
 663  */
 664 typedef struct png_time_struct
 665 {
 666    png_uint_16 year; /* full year, as in, 1995 */
 667    png_byte month;   /* month of year, 1 - 12 */
 668    png_byte day;     /* day of month, 1 - 31 */
 669    png_byte hour;    /* hour of day, 0 - 23 */
 670    png_byte minute;  /* minute of hour, 0 - 59 */
 671    png_byte second;  /* second of minute, 0 - 60 (for leap seconds) */
 672 } png_time;
 673 typedef png_time * png_timep;
 674 typedef const png_time * png_const_timep;
 675 typedef png_time * * png_timepp;
 676 
 677 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) ||\
 678    defined(PNG_USER_CHUNKS_SUPPORTED)
 679 /* png_unknown_chunk is a structure to hold queued chunks for which there is
 680  * no specific support.  The idea is that we can use this to queue
 681  * up private chunks for output even though the library doesn't actually
 682  * know about their semantics.
 683  *
 684  * The data in the structure is set by libpng on read and used on write.
 685  */
 686 typedef struct png_unknown_chunk_t
 687 {
 688     png_byte name[5]; /* Textual chunk name with '\0' terminator */
 689     png_byte *data;   /* Data, should not be modified on read! */
 690     png_size_t size;
 691 
 692     /* On write 'location' must be set using the flag values listed below.
 693      * Notice that on read it is set by libpng however the values stored have
 694      * more bits set than are listed below.  Always treat the value as a
 695      * bitmask.  On write set only one bit - setting multiple bits may cause the
 696      * chunk to be written in multiple places.
 697      */
 698     png_byte location; /* mode of operation at read time */
 699 }
 700 png_unknown_chunk;
 701 
 702 typedef png_unknown_chunk * png_unknown_chunkp;
 703 typedef const png_unknown_chunk * png_const_unknown_chunkp;
 704 typedef png_unknown_chunk * * png_unknown_chunkpp;
 705 #endif
 706 
 707 /* Flag values for the unknown chunk location byte. */
 708 #define PNG_HAVE_IHDR  0x01
 709 #define PNG_HAVE_PLTE  0x02
 710 #define PNG_AFTER_IDAT 0x08
 711 
 712 /* Maximum positive integer used in PNG is (2^31)-1 */
 713 #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
 714 #define PNG_UINT_32_MAX ((png_uint_32)(-1))
 715 #define PNG_SIZE_MAX ((png_size_t)(-1))
 716 
 717 /* These are constants for fixed point values encoded in the
 718  * PNG specification manner (x100000)
 719  */
 720 #define PNG_FP_1    100000
 721 #define PNG_FP_HALF  50000
 722 #define PNG_FP_MAX  ((png_fixed_point)0x7fffffffL)
 723 #define PNG_FP_MIN  (-PNG_FP_MAX)
 724 
 725 /* These describe the color_type field in png_info. */
 726 /* color type masks */
 727 #define PNG_COLOR_MASK_PALETTE    1
 728 #define PNG_COLOR_MASK_COLOR      2
 729 #define PNG_COLOR_MASK_ALPHA      4
 730 
 731 /* color types.  Note that not all combinations are legal */
 732 #define PNG_COLOR_TYPE_GRAY 0
 733 #define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
 734 #define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)
 735 #define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
 736 #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
 737 /* aliases */
 738 #define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA
 739 #define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA
 740 
 741 /* This is for compression type. PNG 1.0-1.2 only define the single type. */
 742 #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
 743 #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE
 744 
 745 /* This is for filter type. PNG 1.0-1.2 only define the single type. */
 746 #define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */
 747 #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
 748 #define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE
 749 
 750 /* These are for the interlacing type.  These values should NOT be changed. */
 751 #define PNG_INTERLACE_NONE        0 /* Non-interlaced image */
 752 #define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */
 753 #define PNG_INTERLACE_LAST        2 /* Not a valid value */
 754 
 755 /* These are for the oFFs chunk.  These values should NOT be changed. */
 756 #define PNG_OFFSET_PIXEL          0 /* Offset in pixels */
 757 #define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */
 758 #define PNG_OFFSET_LAST           2 /* Not a valid value */
 759 
 760 /* These are for the pCAL chunk.  These values should NOT be changed. */
 761 #define PNG_EQUATION_LINEAR       0 /* Linear transformation */
 762 #define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */
 763 #define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */
 764 #define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */
 765 #define PNG_EQUATION_LAST         4 /* Not a valid value */
 766 
 767 /* These are for the sCAL chunk.  These values should NOT be changed. */
 768 #define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */
 769 #define PNG_SCALE_METER           1 /* meters per pixel */
 770 #define PNG_SCALE_RADIAN          2 /* radians per pixel */
 771 #define PNG_SCALE_LAST            3 /* Not a valid value */
 772 
 773 /* These are for the pHYs chunk.  These values should NOT be changed. */
 774 #define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */
 775 #define PNG_RESOLUTION_METER      1 /* pixels/meter */
 776 #define PNG_RESOLUTION_LAST       2 /* Not a valid value */
 777 
 778 /* These are for the sRGB chunk.  These values should NOT be changed. */
 779 #define PNG_sRGB_INTENT_PERCEPTUAL 0
 780 #define PNG_sRGB_INTENT_RELATIVE   1
 781 #define PNG_sRGB_INTENT_SATURATION 2
 782 #define PNG_sRGB_INTENT_ABSOLUTE   3
 783 #define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */
 784 
 785 /* This is for text chunks */
 786 #define PNG_KEYWORD_MAX_LENGTH     79
 787 
 788 /* Maximum number of entries in PLTE/sPLT/tRNS arrays */
 789 #define PNG_MAX_PALETTE_LENGTH    256
 790 
 791 /* These determine if an ancillary chunk's data has been successfully read
 792  * from the PNG header, or if the application has filled in the corresponding
 793  * data in the info_struct to be written into the output file.  The values
 794  * of the PNG_INFO_<chunk> defines should NOT be changed.
 795  */
 796 #define PNG_INFO_gAMA 0x0001U
 797 #define PNG_INFO_sBIT 0x0002U
 798 #define PNG_INFO_cHRM 0x0004U
 799 #define PNG_INFO_PLTE 0x0008U
 800 #define PNG_INFO_tRNS 0x0010U
 801 #define PNG_INFO_bKGD 0x0020U
 802 #define PNG_INFO_hIST 0x0040U
 803 #define PNG_INFO_pHYs 0x0080U
 804 #define PNG_INFO_oFFs 0x0100U
 805 #define PNG_INFO_tIME 0x0200U
 806 #define PNG_INFO_pCAL 0x0400U
 807 #define PNG_INFO_sRGB 0x0800U  /* GR-P, 0.96a */
 808 #define PNG_INFO_iCCP 0x1000U  /* ESR, 1.0.6 */
 809 #define PNG_INFO_sPLT 0x2000U  /* ESR, 1.0.6 */
 810 #define PNG_INFO_sCAL 0x4000U  /* ESR, 1.0.6 */
 811 #define PNG_INFO_IDAT 0x8000U  /* ESR, 1.0.6 */
 812 
 813 /* This is used for the transformation routines, as some of them
 814  * change these values for the row.  It also should enable using
 815  * the routines for other purposes.
 816  */
 817 typedef struct png_row_info_struct
 818 {
 819    png_uint_32 width;    /* width of row */
 820    png_size_t rowbytes;  /* number of bytes in row */
 821    png_byte color_type;  /* color type of row */
 822    png_byte bit_depth;   /* bit depth of row */
 823    png_byte channels;    /* number of channels (1, 2, 3, or 4) */
 824    png_byte pixel_depth; /* bits per pixel (depth * channels) */
 825 } png_row_info;
 826 
 827 typedef png_row_info * png_row_infop;
 828 typedef png_row_info * * png_row_infopp;
 829 
 830 /* These are the function types for the I/O functions and for the functions
 831  * that allow the user to override the default I/O functions with his or her
 832  * own.  The png_error_ptr type should match that of user-supplied warning
 833  * and error functions, while the png_rw_ptr type should match that of the
 834  * user read/write data functions.  Note that the 'write' function must not
 835  * modify the buffer it is passed. The 'read' function, on the other hand, is
 836  * expected to return the read data in the buffer.
 837  */
 838 typedef PNG_CALLBACK(void, *png_error_ptr, (png_structp, png_const_charp));
 839 typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, png_size_t));
 840 typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp));
 841 typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32,
 842     int));
 843 typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32,
 844     int));
 845 
 846 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 847 typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
 848 typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
 849 
 850 /* The following callback receives png_uint_32 row_number, int pass for the
 851  * png_bytep data of the row.  When transforming an interlaced image the
 852  * row number is the row number within the sub-image of the interlace pass, so
 853  * the value will increase to the height of the sub-image (not the full image)
 854  * then reset to 0 for the next pass.
 855  *
 856  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
 857  * find the output pixel (x,y) given an interlaced sub-image pixel
 858  * (row,col,pass).  (See below for these macros.)
 859  */
 860 typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp, png_bytep,
 861     png_uint_32, int));
 862 #endif
 863 
 864 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
 865     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
 866 typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop,
 867     png_bytep));
 868 #endif
 869 
 870 #ifdef PNG_USER_CHUNKS_SUPPORTED
 871 typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,
 872     png_unknown_chunkp));
 873 #endif
 874 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
 875 /* not used anywhere */
 876 /* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
 877 #endif
 878 
 879 #ifdef PNG_SETJMP_SUPPORTED
 880 /* This must match the function definition in <setjmp.h>, and the application
 881  * must include this before png.h to obtain the definition of jmp_buf.  The
 882  * function is required to be PNG_NORETURN, but this is not checked.  If the
 883  * function does return the application will crash via an abort() or similar
 884  * system level call.
 885  *
 886  * If you get a warning here while building the library you may need to make
 887  * changes to ensure that pnglibconf.h records the calling convention used by
 888  * your compiler.  This may be very difficult - try using a different compiler
 889  * to build the library!
 890  */
 891 PNG_FUNCTION(void, (PNGCAPI *png_longjmp_ptr), PNGARG((jmp_buf, int)), typedef);
 892 #endif
 893 
 894 /* Transform masks for the high-level interface */
 895 #define PNG_TRANSFORM_IDENTITY       0x0000    /* read and write */
 896 #define PNG_TRANSFORM_STRIP_16       0x0001    /* read only */
 897 #define PNG_TRANSFORM_STRIP_ALPHA    0x0002    /* read only */
 898 #define PNG_TRANSFORM_PACKING        0x0004    /* read and write */
 899 #define PNG_TRANSFORM_PACKSWAP       0x0008    /* read and write */
 900 #define PNG_TRANSFORM_EXPAND         0x0010    /* read only */
 901 #define PNG_TRANSFORM_INVERT_MONO    0x0020    /* read and write */
 902 #define PNG_TRANSFORM_SHIFT          0x0040    /* read and write */
 903 #define PNG_TRANSFORM_BGR            0x0080    /* read and write */
 904 #define PNG_TRANSFORM_SWAP_ALPHA     0x0100    /* read and write */
 905 #define PNG_TRANSFORM_SWAP_ENDIAN    0x0200    /* read and write */
 906 #define PNG_TRANSFORM_INVERT_ALPHA   0x0400    /* read and write */
 907 #define PNG_TRANSFORM_STRIP_FILLER   0x0800    /* write only */
 908 /* Added to libpng-1.2.34 */
 909 #define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER
 910 #define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */
 911 /* Added to libpng-1.4.0 */
 912 #define PNG_TRANSFORM_GRAY_TO_RGB   0x2000      /* read only */
 913 /* Added to libpng-1.5.4 */
 914 #define PNG_TRANSFORM_EXPAND_16     0x4000      /* read only */
 915 #if INT_MAX >= 0x8000 /* else this might break */
 916 #define PNG_TRANSFORM_SCALE_16      0x8000      /* read only */
 917 #endif
 918 
 919 /* Flags for MNG supported features */
 920 #define PNG_FLAG_MNG_EMPTY_PLTE     0x01
 921 #define PNG_FLAG_MNG_FILTER_64      0x04
 922 #define PNG_ALL_MNG_FEATURES        0x05
 923 
 924 /* NOTE: prior to 1.5 these functions had no 'API' style declaration,
 925  * this allowed the zlib default functions to be used on Windows
 926  * platforms.  In 1.5 the zlib default malloc (which just calls malloc and
 927  * ignores the first argument) should be completely compatible with the
 928  * following.
 929  */
 930 typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,
 931     png_alloc_size_t));
 932 typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));
 933 
 934 /* Section 4: exported functions
 935  * Here are the function definitions most commonly used.  This is not
 936  * the place to find out how to use libpng.  See libpng-manual.txt for the
 937  * full explanation, see example.c for the summary.  This just provides
 938  * a simple one line description of the use of each function.
 939  *
 940  * The PNG_EXPORT() and PNG_EXPORTA() macros used below are defined in
 941  * pngconf.h and in the *.dfn files in the scripts directory.
 942  *
 943  *   PNG_EXPORT(ordinal, type, name, (args));
 944  *
 945  *       ordinal:    ordinal that is used while building
 946  *                   *.def files. The ordinal value is only
 947  *                   relevant when preprocessing png.h with
 948  *                   the *.dfn files for building symbol table
 949  *                   entries, and are removed by pngconf.h.
 950  *       type:       return type of the function
 951  *       name:       function name
 952  *       args:       function arguments, with types
 953  *
 954  * When we wish to append attributes to a function prototype we use
 955  * the PNG_EXPORTA() macro instead.
 956  *
 957  *   PNG_EXPORTA(ordinal, type, name, (args), attributes);
 958  *
 959  *       ordinal, type, name, and args: same as in PNG_EXPORT().
 960  *       attributes: function attributes
 961  */
 962 
 963 /* Returns the version number of the library */
 964 PNG_EXPORT(1, png_uint_32, png_access_version_number, (void));
 965 
 966 /* Tell lib we have already handled the first <num_bytes> magic bytes.
 967  * Handling more than 8 bytes from the beginning of the file is an error.
 968  */
 969 PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
 970 
 971 /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
 972  * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG
 973  * signature, and non-zero otherwise.  Having num_to_check == 0 or
 974  * start > 7 will always fail (ie return non-zero).
 975  */
 976 PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, png_size_t start,
 977     png_size_t num_to_check));
 978 
 979 /* Simple signature checking function.  This is the same as calling
 980  * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
 981  */
 982 #define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
 983 
 984 /* Allocate and initialize png_ptr struct for reading, and any other memory. */
 985 PNG_EXPORTA(4, png_structp, png_create_read_struct,
 986     (png_const_charp user_png_ver, png_voidp error_ptr,
 987     png_error_ptr error_fn, png_error_ptr warn_fn),
 988     PNG_ALLOCATED);
 989 
 990 /* Allocate and initialize png_ptr struct for writing, and any other memory */
 991 PNG_EXPORTA(5, png_structp, png_create_write_struct,
 992     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
 993     png_error_ptr warn_fn),
 994     PNG_ALLOCATED);
 995 
 996 PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
 997     (png_const_structrp png_ptr));
 998 
 999 PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
1000     png_size_t size));
1001 
1002 /* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
1003  * match up.
1004  */
1005 #ifdef PNG_SETJMP_SUPPORTED
1006 /* This function returns the jmp_buf built in to *png_ptr.  It must be
1007  * supplied with an appropriate 'longjmp' function to use on that jmp_buf
1008  * unless the default error function is overridden in which case NULL is
1009  * acceptable.  The size of the jmp_buf is checked against the actual size
1010  * allocated by the library - the call will return NULL on a mismatch
1011  * indicating an ABI mismatch.
1012  */
1013 PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structrp png_ptr,
1014     png_longjmp_ptr longjmp_fn, size_t jmp_buf_size));
1015 #  define png_jmpbuf(png_ptr) \
1016       (*png_set_longjmp_fn((png_ptr), longjmp, (sizeof (jmp_buf))))
1017 #else
1018 #  define png_jmpbuf(png_ptr) \
1019       (LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP)
1020 #endif
1021 /* This function should be used by libpng applications in place of
1022  * longjmp(png_ptr->jmpbuf, val).  If longjmp_fn() has been set, it
1023  * will use it; otherwise it will call PNG_ABORT().  This function was
1024  * added in libpng-1.5.0.
1025  */
1026 PNG_EXPORTA(9, void, png_longjmp, (png_const_structrp png_ptr, int val),
1027     PNG_NORETURN);
1028 
1029 #ifdef PNG_READ_SUPPORTED
1030 /* Reset the compression stream */
1031 PNG_EXPORTA(10, int, png_reset_zstream, (png_structrp png_ptr), PNG_DEPRECATED);
1032 #endif
1033 
1034 /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
1035 #ifdef PNG_USER_MEM_SUPPORTED
1036 PNG_EXPORTA(11, png_structp, png_create_read_struct_2,
1037     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
1038     png_error_ptr warn_fn,
1039     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
1040     PNG_ALLOCATED);
1041 PNG_EXPORTA(12, png_structp, png_create_write_struct_2,
1042     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
1043     png_error_ptr warn_fn,
1044     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
1045     PNG_ALLOCATED);
1046 #endif
1047 
1048 /* Write the PNG file signature. */
1049 PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr));
1050 
1051 /* Write a PNG chunk - size, type, (optional) data, CRC. */
1052 PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep
1053     chunk_name, png_const_bytep data, png_size_t length));
1054 
1055 /* Write the start of a PNG chunk - length and chunk name. */
1056 PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
1057     png_const_bytep chunk_name, png_uint_32 length));
1058 
1059 /* Write the data of a PNG chunk started with png_write_chunk_start(). */
1060 PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr,
1061     png_const_bytep data, png_size_t length));
1062 
1063 /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
1064 PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr));
1065 
1066 /* Allocate and initialize the info structure */
1067 PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr),
1068     PNG_ALLOCATED);
1069 
1070 /* DEPRECATED: this function allowed init structures to be created using the
1071  * default allocation method (typically malloc).  Use is deprecated in 1.6.0 and
1072  * the API will be removed in the future.
1073  */
1074 PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr,
1075     png_size_t png_info_struct_size), PNG_DEPRECATED);
1076 
1077 /* Writes all the PNG information before the image. */
1078 PNG_EXPORT(20, void, png_write_info_before_PLTE,
1079     (png_structrp png_ptr, png_const_inforp info_ptr));
1080 PNG_EXPORT(21, void, png_write_info,
1081     (png_structrp png_ptr, png_const_inforp info_ptr));
1082 
1083 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1084 /* Read the information before the actual image data. */
1085 PNG_EXPORT(22, void, png_read_info,
1086     (png_structrp png_ptr, png_inforp info_ptr));
1087 #endif
1088 
1089 #ifdef PNG_TIME_RFC1123_SUPPORTED
1090    /* Convert to a US string format: there is no localization support in this
1091     * routine.  The original implementation used a 29 character buffer in
1092     * png_struct, this will be removed in future versions.
1093     */
1094 #if PNG_LIBPNG_VER < 10700
1095 /* To do: remove this from libpng17 (and from libpng17/png.c and pngstruct.h) */
1096 PNG_EXPORTA(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr,
1097     png_const_timep ptime),PNG_DEPRECATED);
1098 #endif
1099 PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29],
1100     png_const_timep ptime));
1101 #endif
1102 
1103 #ifdef PNG_CONVERT_tIME_SUPPORTED
1104 /* Convert from a struct tm to png_time */
1105 PNG_EXPORT(24, void, png_convert_from_struct_tm, (png_timep ptime,
1106     const struct tm * ttime));
1107 
1108 /* Convert from time_t to png_time.  Uses gmtime() */
1109 PNG_EXPORT(25, void, png_convert_from_time_t, (png_timep ptime, time_t ttime));
1110 #endif /* CONVERT_tIME */
1111 
1112 #ifdef PNG_READ_EXPAND_SUPPORTED
1113 /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
1114 PNG_EXPORT(26, void, png_set_expand, (png_structrp png_ptr));
1115 PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structrp png_ptr));
1116 PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structrp png_ptr));
1117 PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structrp png_ptr));
1118 #endif
1119 
1120 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1121 /* Expand to 16-bit channels, forces conversion of palette to RGB and expansion
1122  * of a tRNS chunk if present.
1123  */
1124 PNG_EXPORT(221, void, png_set_expand_16, (png_structrp png_ptr));
1125 #endif
1126 
1127 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
1128 /* Use blue, green, red order for pixels. */
1129 PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr));
1130 #endif
1131 
1132 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1133 /* Expand the grayscale to 24-bit RGB if necessary. */
1134 PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr));
1135 #endif
1136 
1137 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1138 /* Reduce RGB to grayscale. */
1139 #define PNG_ERROR_ACTION_NONE  1
1140 #define PNG_ERROR_ACTION_WARN  2
1141 #define PNG_ERROR_ACTION_ERROR 3
1142 #define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/
1143 
1144 PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structrp png_ptr,
1145     int error_action, double red, double green))
1146 PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structrp png_ptr,
1147     int error_action, png_fixed_point red, png_fixed_point green))
1148 
1149 PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp
1150     png_ptr));
1151 #endif
1152 
1153 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
1154 PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
1155     png_colorp palette));
1156 #endif
1157 
1158 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1159 /* How the alpha channel is interpreted - this affects how the color channels
1160  * of a PNG file are returned to the calling application when an alpha channel,
1161  * or a tRNS chunk in a palette file, is present.
1162  *
1163  * This has no effect on the way pixels are written into a PNG output
1164  * datastream. The color samples in a PNG datastream are never premultiplied
1165  * with the alpha samples.
1166  *
1167  * The default is to return data according to the PNG specification: the alpha
1168  * channel is a linear measure of the contribution of the pixel to the
1169  * corresponding composited pixel, and the color channels are unassociated
1170  * (not premultiplied).  The gamma encoded color channels must be scaled
1171  * according to the contribution and to do this it is necessary to undo
1172  * the encoding, scale the color values, perform the composition and reencode
1173  * the values.  This is the 'PNG' mode.
1174  *
1175  * The alternative is to 'associate' the alpha with the color information by
1176  * storing color channel values that have been scaled by the alpha.
1177  * image.  These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
1178  * (the latter being the two common names for associated alpha color channels).
1179  *
1180  * For the 'OPTIMIZED' mode, a pixel is treated as opaque only if the alpha
1181  * value is equal to the maximum value.
1182  *
1183  * The final choice is to gamma encode the alpha channel as well.  This is
1184  * broken because, in practice, no implementation that uses this choice
1185  * correctly undoes the encoding before handling alpha composition.  Use this
1186  * choice only if other serious errors in the software or hardware you use
1187  * mandate it; the typical serious error is for dark halos to appear around
1188  * opaque areas of the composited PNG image because of arithmetic overflow.
1189  *
1190  * The API function png_set_alpha_mode specifies which of these choices to use
1191  * with an enumerated 'mode' value and the gamma of the required output:
1192  */
1193 #define PNG_ALPHA_PNG           0 /* according to the PNG standard */
1194 #define PNG_ALPHA_STANDARD      1 /* according to Porter/Duff */
1195 #define PNG_ALPHA_ASSOCIATED    1 /* as above; this is the normal practice */
1196 #define PNG_ALPHA_PREMULTIPLIED 1 /* as above */
1197 #define PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */
1198 #define PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */
1199 
1200 PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structrp png_ptr, int mode,
1201     double output_gamma))
1202 PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
1203     int mode, png_fixed_point output_gamma))
1204 #endif
1205 
1206 #if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1207 /* The output_gamma value is a screen gamma in libpng terminology: it expresses
1208  * how to decode the output values, not how they are encoded.
1209  */
1210 #define PNG_DEFAULT_sRGB -1       /* sRGB gamma and color space */
1211 #define PNG_GAMMA_MAC_18 -2       /* Old Mac '1.8' gamma and color space */
1212 #define PNG_GAMMA_sRGB   220000   /* Television standards--matches sRGB gamma */
1213 #define PNG_GAMMA_LINEAR PNG_FP_1 /* Linear */
1214 #endif
1215 
1216 /* The following are examples of calls to png_set_alpha_mode to achieve the
1217  * required overall gamma correction and, where necessary, alpha
1218  * premultiplication.
1219  *
1220  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1221  *    This is the default libpng handling of the alpha channel - it is not
1222  *    pre-multiplied into the color components.  In addition the call states
1223  *    that the output is for a sRGB system and causes all PNG files without gAMA
1224  *    chunks to be assumed to be encoded using sRGB.
1225  *
1226  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1227  *    In this case the output is assumed to be something like an sRGB conformant
1228  *    display preceeded by a power-law lookup table of power 1.45.  This is how
1229  *    early Mac systems behaved.
1230  *
1231  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
1232  *    This is the classic Jim Blinn approach and will work in academic
1233  *    environments where everything is done by the book.  It has the shortcoming
1234  *    of assuming that input PNG data with no gamma information is linear - this
1235  *    is unlikely to be correct unless the PNG files where generated locally.
1236  *    Most of the time the output precision will be so low as to show
1237  *    significant banding in dark areas of the image.
1238  *
1239  * png_set_expand_16(pp);
1240  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
1241  *    This is a somewhat more realistic Jim Blinn inspired approach.  PNG files
1242  *    are assumed to have the sRGB encoding if not marked with a gamma value and
1243  *    the output is always 16 bits per component.  This permits accurate scaling
1244  *    and processing of the data.  If you know that your input PNG files were
1245  *    generated locally you might need to replace PNG_DEFAULT_sRGB with the
1246  *    correct value for your system.
1247  *
1248  * png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
1249  *    If you just need to composite the PNG image onto an existing background
1250  *    and if you control the code that does this you can use the optimization
1251  *    setting.  In this case you just copy completely opaque pixels to the
1252  *    output.  For pixels that are not completely transparent (you just skip
1253  *    those) you do the composition math using png_composite or png_composite_16
1254  *    below then encode the resultant 8-bit or 16-bit values to match the output
1255  *    encoding.
1256  *
1257  * Other cases
1258  *    If neither the PNG nor the standard linear encoding work for you because
1259  *    of the software or hardware you use then you have a big problem.  The PNG
1260  *    case will probably result in halos around the image.  The linear encoding
1261  *    will probably result in a washed out, too bright, image (it's actually too
1262  *    contrasty.)  Try the ALPHA_OPTIMIZED mode above - this will probably
1263  *    substantially reduce the halos.  Alternatively try:
1264  *
1265  * png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
1266  *    This option will also reduce the halos, but there will be slight dark
1267  *    halos round the opaque parts of the image where the background is light.
1268  *    In the OPTIMIZED mode the halos will be light halos where the background
1269  *    is dark.  Take your pick - the halos are unavoidable unless you can get
1270  *    your hardware/software fixed!  (The OPTIMIZED approach is slightly
1271  *    faster.)
1272  *
1273  * When the default gamma of PNG files doesn't match the output gamma.
1274  *    If you have PNG files with no gamma information png_set_alpha_mode allows
1275  *    you to provide a default gamma, but it also sets the ouput gamma to the
1276  *    matching value.  If you know your PNG files have a gamma that doesn't
1277  *    match the output you can take advantage of the fact that
1278  *    png_set_alpha_mode always sets the output gamma but only sets the PNG
1279  *    default if it is not already set:
1280  *
1281  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1282  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1283  *    The first call sets both the default and the output gamma values, the
1284  *    second call overrides the output gamma without changing the default.  This
1285  *    is easier than achieving the same effect with png_set_gamma.  You must use
1286  *    PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
1287  *    fire if more than one call to png_set_alpha_mode and png_set_background is
1288  *    made in the same read operation, however multiple calls with PNG_ALPHA_PNG
1289  *    are ignored.
1290  */
1291 
1292 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1293 PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
1294 #endif
1295 
1296 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
1297     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
1298 PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr));
1299 #endif
1300 
1301 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
1302     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
1303 PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
1304 #endif
1305 
1306 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
1307 /* Add a filler byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
1308 PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler,
1309     int flags));
1310 /* The values of the PNG_FILLER_ defines should NOT be changed */
1311 #  define PNG_FILLER_BEFORE 0
1312 #  define PNG_FILLER_AFTER 1
1313 /* Add an alpha byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
1314 PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
1315     png_uint_32 filler, int flags));
1316 #endif /* READ_FILLER || WRITE_FILLER */
1317 
1318 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
1319 /* Swap bytes in 16-bit depth files. */
1320 PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr));
1321 #endif
1322 
1323 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
1324 /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
1325 PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr));
1326 #endif
1327 
1328 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
1329     defined(PNG_WRITE_PACKSWAP_SUPPORTED)
1330 /* Swap packing order of pixels in bytes. */
1331 PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr));
1332 #endif
1333 
1334 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
1335 /* Converts files to legal bit depths. */
1336 PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p
1337     true_bits));
1338 #endif
1339 
1340 #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
1341     defined(PNG_WRITE_INTERLACING_SUPPORTED)
1342 /* Have the code handle the interlacing.  Returns the number of passes.
1343  * MUST be called before png_read_update_info or png_start_read_image,
1344  * otherwise it will not have the desired effect.  Note that it is still
1345  * necessary to call png_read_row or png_read_rows png_get_image_height
1346  * times for each pass.
1347 */
1348 PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr));
1349 #endif
1350 
1351 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
1352 /* Invert monochrome files */
1353 PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
1354 #endif
1355 
1356 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1357 /* Handle alpha and tRNS by replacing with a background color.  Prior to
1358  * libpng-1.5.4 this API must not be called before the PNG file header has been
1359  * read.  Doing so will result in unexpected behavior and possible warnings or
1360  * errors if the PNG file contains a bKGD chunk.
1361  */
1362 PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr,
1363     png_const_color_16p background_color, int background_gamma_code,
1364     int need_expand, double background_gamma))
1365 PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr,
1366     png_const_color_16p background_color, int background_gamma_code,
1367     int need_expand, png_fixed_point background_gamma))
1368 #endif
1369 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1370 #  define PNG_BACKGROUND_GAMMA_UNKNOWN 0
1371 #  define PNG_BACKGROUND_GAMMA_SCREEN  1
1372 #  define PNG_BACKGROUND_GAMMA_FILE    2
1373 #  define PNG_BACKGROUND_GAMMA_UNIQUE  3
1374 #endif
1375 
1376 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1377 /* Scale a 16-bit depth file down to 8-bit, accurately. */
1378 PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
1379 #endif
1380 
1381 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1382 #define PNG_READ_16_TO_8_SUPPORTED /* Name prior to 1.5.4 */
1383 /* Strip the second byte of information from a 16-bit depth file. */
1384 PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
1385 #endif
1386 
1387 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1388 /* Turn on quantizing, and reduce the palette to the number of colors
1389  * available.
1390  */
1391 PNG_EXPORT(49, void, png_set_quantize, (png_structrp png_ptr,
1392     png_colorp palette, int num_palette, int maximum_colors,
1393     png_const_uint_16p histogram, int full_quantize));
1394 #endif
1395 
1396 #ifdef PNG_READ_GAMMA_SUPPORTED
1397 /* The threshold on gamma processing is configurable but hard-wired into the
1398  * library.  The following is the floating point variant.
1399  */
1400 #define PNG_GAMMA_THRESHOLD (PNG_GAMMA_THRESHOLD_FIXED*.00001)
1401 
1402 /* Handle gamma correction. Screen_gamma=(display_exponent).
1403  * NOTE: this API simply sets the screen and file gamma values. It will
1404  * therefore override the value for gamma in a PNG file if it is called after
1405  * the file header has been read - use with care  - call before reading the PNG
1406  * file for best results!
1407  *
1408  * These routines accept the same gamma values as png_set_alpha_mode (described
1409  * above).  The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either
1410  * API (floating point or fixed.)  Notice, however, that the 'file_gamma' value
1411  * is the inverse of a 'screen gamma' value.
1412  */
1413 PNG_FP_EXPORT(50, void, png_set_gamma, (png_structrp png_ptr,
1414     double screen_gamma, double override_file_gamma))
1415 PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structrp png_ptr,
1416     png_fixed_point screen_gamma, png_fixed_point override_file_gamma))
1417 #endif
1418 
1419 #ifdef PNG_WRITE_FLUSH_SUPPORTED
1420 /* Set how many lines between output flushes - 0 for no flushing */
1421 PNG_EXPORT(51, void, png_set_flush, (png_structrp png_ptr, int nrows));
1422 /* Flush the current PNG output buffer */
1423 PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr));
1424 #endif
1425 
1426 /* Optional update palette with requested transformations */
1427 PNG_EXPORT(53, void, png_start_read_image, (png_structrp png_ptr));
1428 
1429 /* Optional call to update the users info structure */
1430 PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr,
1431     png_inforp info_ptr));
1432 
1433 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1434 /* Read one or more rows of image data. */
1435 PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row,
1436     png_bytepp display_row, png_uint_32 num_rows));
1437 #endif
1438 
1439 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1440 /* Read a row of data. */
1441 PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
1442     png_bytep display_row));
1443 #endif
1444 
1445 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1446 /* Read the whole image into memory at once. */
1447 PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
1448 #endif
1449 
1450 /* Write a row of image data */
1451 PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr,
1452     png_const_bytep row));
1453 
1454 /* Write a few rows of image data: (*row) is not written; however, the type
1455  * is declared as writeable to maintain compatibility with previous versions
1456  * of libpng and to allow the 'display_row' array from read_rows to be passed
1457  * unchanged to write_rows.
1458  */
1459 PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row,
1460     png_uint_32 num_rows));
1461 
1462 /* Write the image data */
1463 PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image));
1464 
1465 /* Write the end of the PNG file. */
1466 PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr,
1467     png_inforp info_ptr));
1468 
1469 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1470 /* Read the end of the PNG file. */
1471 PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
1472 #endif
1473 
1474 /* Free any memory associated with the png_info_struct */
1475 PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr,
1476     png_infopp info_ptr_ptr));
1477 
1478 /* Free any memory associated with the png_struct and the png_info_structs */
1479 PNG_EXPORT(64, void, png_destroy_read_struct, (png_structpp png_ptr_ptr,
1480     png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));
1481 
1482 /* Free any memory associated with the png_struct and the png_info_structs */
1483 PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr,
1484     png_infopp info_ptr_ptr));
1485 
1486 /* Set the libpng method of handling chunk CRC errors */
1487 PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
1488     int ancil_action));
1489 
1490 /* Values for png_set_crc_action() say how to handle CRC errors in
1491  * ancillary and critical chunks, and whether to use the data contained
1492  * therein.  Note that it is impossible to "discard" data in a critical
1493  * chunk.  For versions prior to 0.90, the action was always error/quit,
1494  * whereas in version 0.90 and later, the action for CRC errors in ancillary
1495  * chunks is warn/discard.  These values should NOT be changed.
1496  *
1497  *      value                       action:critical     action:ancillary
1498  */
1499 #define PNG_CRC_DEFAULT       0  /* error/quit          warn/discard data */
1500 #define PNG_CRC_ERROR_QUIT    1  /* error/quit          error/quit        */
1501 #define PNG_CRC_WARN_DISCARD  2  /* (INVALID)           warn/discard data */
1502 #define PNG_CRC_WARN_USE      3  /* warn/use data       warn/use data     */
1503 #define PNG_CRC_QUIET_USE     4  /* quiet/use data      quiet/use data    */
1504 #define PNG_CRC_NO_CHANGE     5  /* use current value   use current value */
1505 
1506 #ifdef PNG_WRITE_SUPPORTED
1507 /* These functions give the user control over the scan-line filtering in
1508  * libpng and the compression methods used by zlib.  These functions are
1509  * mainly useful for testing, as the defaults should work with most users.
1510  * Those users who are tight on memory or want faster performance at the
1511  * expense of compression can modify them.  See the compression library
1512  * header file (zlib.h) for an explination of the compression functions.
1513  */
1514 
1515 /* Set the filtering method(s) used by libpng.  Currently, the only valid
1516  * value for "method" is 0.
1517  */
1518 PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
1519     int filters));
1520 #endif /* WRITE */
1521 
1522 /* Flags for png_set_filter() to say which filters to use.  The flags
1523  * are chosen so that they don't conflict with real filter types
1524  * below, in case they are supplied instead of the #defined constants.
1525  * These values should NOT be changed.
1526  */
1527 #define PNG_NO_FILTERS     0x00
1528 #define PNG_FILTER_NONE    0x08
1529 #define PNG_FILTER_SUB     0x10
1530 #define PNG_FILTER_UP      0x20
1531 #define PNG_FILTER_AVG     0x40
1532 #define PNG_FILTER_PAETH   0x80
1533 #define PNG_FAST_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP)
1534 #define PNG_ALL_FILTERS (PNG_FAST_FILTERS | PNG_FILTER_AVG | PNG_FILTER_PAETH)
1535 
1536 /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
1537  * These defines should NOT be changed.
1538  */
1539 #define PNG_FILTER_VALUE_NONE  0
1540 #define PNG_FILTER_VALUE_SUB   1
1541 #define PNG_FILTER_VALUE_UP    2
1542 #define PNG_FILTER_VALUE_AVG   3
1543 #define PNG_FILTER_VALUE_PAETH 4
1544 #define PNG_FILTER_VALUE_LAST  5
1545 
1546 #ifdef PNG_WRITE_SUPPORTED
1547 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* DEPRECATED */
1548 PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr,
1549     int heuristic_method, int num_weights, png_const_doublep filter_weights,
1550     png_const_doublep filter_costs))
1551 PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
1552     (png_structrp png_ptr, int heuristic_method, int num_weights,
1553     png_const_fixed_point_p filter_weights,
1554     png_const_fixed_point_p filter_costs))
1555 #endif /* WRITE_WEIGHTED_FILTER */
1556 
1557 /* The following are no longer used and will be removed from libpng-1.7: */
1558 #define PNG_FILTER_HEURISTIC_DEFAULT    0  /* Currently "UNWEIGHTED" */
1559 #define PNG_FILTER_HEURISTIC_UNWEIGHTED 1  /* Used by libpng < 0.95 */
1560 #define PNG_FILTER_HEURISTIC_WEIGHTED   2  /* Experimental feature */
1561 #define PNG_FILTER_HEURISTIC_LAST       3  /* Not a valid value */
1562 
1563 /* Set the library compression level.  Currently, valid values range from
1564  * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
1565  * (0 - no compression, 9 - "maximal" compression).  Note that tests have
1566  * shown that zlib compression levels 3-6 usually perform as well as level 9
1567  * for PNG images, and do considerably fewer caclulations.  In the future,
1568  * these values may not correspond directly to the zlib compression levels.
1569  */
1570 #ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
1571 PNG_EXPORT(69, void, png_set_compression_level, (png_structrp png_ptr,
1572     int level));
1573 
1574 PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structrp png_ptr,
1575     int mem_level));
1576 
1577 PNG_EXPORT(71, void, png_set_compression_strategy, (png_structrp png_ptr,
1578     int strategy));
1579 
1580 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1581  * smaller value of window_bits if it can do so safely.
1582  */
1583 PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
1584     int window_bits));
1585 
1586 PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr,
1587     int method));
1588 #endif /* WRITE_CUSTOMIZE_COMPRESSION */
1589 
1590 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
1591 /* Also set zlib parameters for compressing non-IDAT chunks */
1592 PNG_EXPORT(222, void, png_set_text_compression_level, (png_structrp png_ptr,
1593     int level));
1594 
1595 PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structrp png_ptr,
1596     int mem_level));
1597 
1598 PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structrp png_ptr,
1599     int strategy));
1600 
1601 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1602  * smaller value of window_bits if it can do so safely.
1603  */
1604 PNG_EXPORT(225, void, png_set_text_compression_window_bits,
1605     (png_structrp png_ptr, int window_bits));
1606 
1607 PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr,
1608     int method));
1609 #endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
1610 #endif /* WRITE */
1611 
1612 /* These next functions are called for input/output, memory, and error
1613  * handling.  They are in the file pngrio.c, pngwio.c, and pngerror.c,
1614  * and call standard C I/O routines such as fread(), fwrite(), and
1615  * fprintf().  These functions can be made to use other I/O routines
1616  * at run time for those applications that need to handle I/O in a
1617  * different manner by calling png_set_???_fn().  See libpng-manual.txt for
1618  * more information.
1619  */
1620 
1621 #ifdef PNG_STDIO_SUPPORTED
1622 /* Initialize the input/output for the PNG file to the default functions. */
1623 PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp));
1624 #endif
1625 
1626 /* Replace the (error and abort), and warning functions with user
1627  * supplied functions.  If no messages are to be printed you must still
1628  * write and use replacement functions. The replacement error_fn should
1629  * still do a longjmp to the last setjmp location if you are using this
1630  * method of error handling.  If error_fn or warning_fn is NULL, the
1631  * default function will be used.
1632  */
1633 
1634 PNG_EXPORT(75, void, png_set_error_fn, (png_structrp png_ptr,
1635     png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
1636 
1637 /* Return the user pointer associated with the error functions */
1638 PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structrp png_ptr));
1639 
1640 /* Replace the default data output functions with a user supplied one(s).
1641  * If buffered output is not used, then output_flush_fn can be set to NULL.
1642  * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
1643  * output_flush_fn will be ignored (and thus can be NULL).
1644  * It is probably a mistake to use NULL for output_flush_fn if
1645  * write_data_fn is not also NULL unless you have built libpng with
1646  * PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's
1647  * default flush function, which uses the standard *FILE structure, will
1648  * be used.
1649  */
1650 PNG_EXPORT(77, void, png_set_write_fn, (png_structrp png_ptr, png_voidp io_ptr,
1651     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
1652 
1653 /* Replace the default data input function with a user supplied one. */
1654 PNG_EXPORT(78, void, png_set_read_fn, (png_structrp png_ptr, png_voidp io_ptr,
1655     png_rw_ptr read_data_fn));
1656 
1657 /* Return the user pointer associated with the I/O functions */
1658 PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_const_structrp png_ptr));
1659 
1660 PNG_EXPORT(80, void, png_set_read_status_fn, (png_structrp png_ptr,
1661     png_read_status_ptr read_row_fn));
1662 
1663 PNG_EXPORT(81, void, png_set_write_status_fn, (png_structrp png_ptr,
1664     png_write_status_ptr write_row_fn));
1665 
1666 #ifdef PNG_USER_MEM_SUPPORTED
1667 /* Replace the default memory allocation functions with user supplied one(s). */
1668 PNG_EXPORT(82, void, png_set_mem_fn, (png_structrp png_ptr, png_voidp mem_ptr,
1669     png_malloc_ptr malloc_fn, png_free_ptr free_fn));
1670 /* Return the user pointer associated with the memory functions */
1671 PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structrp png_ptr));
1672 #endif
1673 
1674 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1675 PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr,
1676     png_user_transform_ptr read_user_transform_fn));
1677 #endif
1678 
1679 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
1680 PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr,
1681     png_user_transform_ptr write_user_transform_fn));
1682 #endif
1683 
1684 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
1685 PNG_EXPORT(86, void, png_set_user_transform_info, (png_structrp png_ptr,
1686     png_voidp user_transform_ptr, int user_transform_depth,
1687     int user_transform_channels));
1688 /* Return the user pointer associated with the user transform functions */
1689 PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr,
1690     (png_const_structrp png_ptr));
1691 #endif
1692 
1693 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
1694 /* Return information about the row currently being processed.  Note that these
1695  * APIs do not fail but will return unexpected results if called outside a user
1696  * transform callback.  Also note that when transforming an interlaced image the
1697  * row number is the row number within the sub-image of the interlace pass, so
1698  * the value will increase to the height of the sub-image (not the full image)
1699  * then reset to 0 for the next pass.
1700  *
1701  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
1702  * find the output pixel (x,y) given an interlaced sub-image pixel
1703  * (row,col,pass).  (See below for these macros.)
1704  */
1705 PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structrp));
1706 PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
1707 #endif
1708 
1709 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
1710 /* This callback is called only for *unknown* chunks.  If
1711  * PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
1712  * chunks to be treated as unknown, however in this case the callback must do
1713  * any processing required by the chunk (e.g. by calling the appropriate
1714  * png_set_ APIs.)
1715  *
1716  * There is no write support - on write, by default, all the chunks in the
1717  * 'unknown' list are written in the specified position.
1718  *
1719  * The integer return from the callback function is interpreted thus:
1720  *
1721  * negative: An error occurred; png_chunk_error will be called.
1722  *     zero: The chunk was not handled, the chunk will be saved. A critical
1723  *           chunk will cause an error at this point unless it is to be saved.
1724  * positive: The chunk was handled, libpng will ignore/discard it.
1725  *
1726  * See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
1727  * how this behavior will change in libpng 1.7
1728  */
1729 PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
1730     png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
1731 #endif
1732 
1733 #ifdef PNG_USER_CHUNKS_SUPPORTED
1734 PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr));
1735 #endif
1736 
1737 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1738 /* Sets the function callbacks for the push reader, and a pointer to a
1739  * user-defined structure available to the callback functions.
1740  */
1741 PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structrp png_ptr,
1742     png_voidp progressive_ptr, png_progressive_info_ptr info_fn,
1743     png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn));
1744 
1745 /* Returns the user pointer associated with the push read functions */
1746 PNG_EXPORT(91, png_voidp, png_get_progressive_ptr,
1747     (png_const_structrp png_ptr));
1748 
1749 /* Function to be called when data becomes available */
1750 PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
1751     png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size));
1752 
1753 /* A function which may be called *only* within png_process_data to stop the
1754  * processing of any more data.  The function returns the number of bytes
1755  * remaining, excluding any that libpng has cached internally.  A subsequent
1756  * call to png_process_data must supply these bytes again.  If the argument
1757  * 'save' is set to true the routine will first save all the pending data and
1758  * will always return 0.
1759  */
1760 PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save));
1761 
1762 /* A function which may be called *only* outside (after) a call to
1763  * png_process_data.  It returns the number of bytes of data to skip in the
1764  * input.  Normally it will return 0, but if it returns a non-zero value the
1765  * application must skip than number of bytes of input data and pass the
1766  * following data to the next call to png_process_data.
1767  */
1768 PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structrp));
1769 
1770 /* Function that combines rows.  'new_row' is a flag that should come from
1771  * the callback and be non-NULL if anything needs to be done; the library
1772  * stores its own version of the new data internally and ignores the passed
1773  * in value.
1774  */
1775 PNG_EXPORT(93, void, png_progressive_combine_row, (png_const_structrp png_ptr,
1776     png_bytep old_row, png_const_bytep new_row));
1777 #endif /* PROGRESSIVE_READ */
1778 
1779 PNG_EXPORTA(94, png_voidp, png_malloc, (png_const_structrp png_ptr,
1780     png_alloc_size_t size), PNG_ALLOCATED);
1781 /* Added at libpng version 1.4.0 */
1782 PNG_EXPORTA(95, png_voidp, png_calloc, (png_const_structrp png_ptr,
1783     png_alloc_size_t size), PNG_ALLOCATED);
1784 
1785 /* Added at libpng version 1.2.4 */
1786 PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_const_structrp png_ptr,
1787     png_alloc_size_t size), PNG_ALLOCATED);
1788 
1789 /* Frees a pointer allocated by png_malloc() */
1790 PNG_EXPORT(97, void, png_free, (png_const_structrp png_ptr, png_voidp ptr));
1791 
1792 /* Free data that was allocated internally */
1793 PNG_EXPORT(98, void, png_free_data, (png_const_structrp png_ptr,
1794     png_inforp info_ptr, png_uint_32 free_me, int num));
1795 
1796 /* Reassign responsibility for freeing existing data, whether allocated
1797  * by libpng or by the application; this works on the png_info structure passed
1798  * in, it does not change the state for other png_info structures.
1799  *
1800  * It is unlikely that this function works correctly as of 1.6.0 and using it
1801  * may result either in memory leaks or double free of allocated data.
1802  */
1803 PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
1804     png_inforp info_ptr, int freer, png_uint_32 mask));
1805 
1806 /* Assignments for png_data_freer */
1807 #define PNG_DESTROY_WILL_FREE_DATA 1
1808 #define PNG_SET_WILL_FREE_DATA 1
1809 #define PNG_USER_WILL_FREE_DATA 2
1810 /* Flags for png_ptr->free_me and info_ptr->free_me */
1811 #define PNG_FREE_HIST 0x0008U
1812 #define PNG_FREE_ICCP 0x0010U
1813 #define PNG_FREE_SPLT 0x0020U
1814 #define PNG_FREE_ROWS 0x0040U
1815 #define PNG_FREE_PCAL 0x0080U
1816 #define PNG_FREE_SCAL 0x0100U
1817 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
1818 #  define PNG_FREE_UNKN 0x0200U
1819 #endif
1820 /*      PNG_FREE_LIST 0x0400U   removed in 1.6.0 because it is ignored */
1821 #define PNG_FREE_PLTE 0x1000U
1822 #define PNG_FREE_TRNS 0x2000U
1823 #define PNG_FREE_TEXT 0x4000U
1824 #define PNG_FREE_ALL  0x7fffU
1825 #define PNG_FREE_MUL  0x4220U /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
1826 
1827 #ifdef PNG_USER_MEM_SUPPORTED
1828 PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
1829     png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED);
1830 PNG_EXPORTA(101, void, png_free_default, (png_const_structrp png_ptr,
1831     png_voidp ptr), PNG_DEPRECATED);
1832 #endif
1833 
1834 #ifdef PNG_ERROR_TEXT_SUPPORTED
1835 /* Fatal error in PNG image of libpng - can't continue */
1836 PNG_EXPORTA(102, void, png_error, (png_const_structrp png_ptr,
1837     png_const_charp error_message), PNG_NORETURN);
1838 
1839 /* The same, but the chunk name is prepended to the error string. */
1840 PNG_EXPORTA(103, void, png_chunk_error, (png_const_structrp png_ptr,
1841     png_const_charp error_message), PNG_NORETURN);
1842 
1843 #else
1844 /* Fatal error in PNG image of libpng - can't continue */
1845 PNG_EXPORTA(104, void, png_err, (png_const_structrp png_ptr), PNG_NORETURN);
1846 #  define png_error(s1,s2) png_err(s1)
1847 #  define png_chunk_error(s1,s2) png_err(s1)
1848 #endif
1849 
1850 #ifdef PNG_WARNINGS_SUPPORTED
1851 /* Non-fatal error in libpng.  Can continue, but may have a problem. */
1852 PNG_EXPORT(105, void, png_warning, (png_const_structrp png_ptr,
1853     png_const_charp warning_message));
1854 
1855 /* Non-fatal error in libpng, chunk name is prepended to message. */
1856 PNG_EXPORT(106, void, png_chunk_warning, (png_const_structrp png_ptr,
1857     png_const_charp warning_message));
1858 #else
1859 #  define png_warning(s1,s2) ((void)(s1))
1860 #  define png_chunk_warning(s1,s2) ((void)(s1))
1861 #endif
1862 
1863 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
1864 /* Benign error in libpng.  Can continue, but may have a problem.
1865  * User can choose whether to handle as a fatal error or as a warning. */
1866 PNG_EXPORT(107, void, png_benign_error, (png_const_structrp png_ptr,
1867     png_const_charp warning_message));
1868 
1869 #ifdef PNG_READ_SUPPORTED
1870 /* Same, chunk name is prepended to message (only during read) */
1871 PNG_EXPORT(108, void, png_chunk_benign_error, (png_const_structrp png_ptr,
1872     png_const_charp warning_message));
1873 #endif
1874 
1875 PNG_EXPORT(109, void, png_set_benign_errors,
1876     (png_structrp png_ptr, int allowed));
1877 #else
1878 #  ifdef PNG_ALLOW_BENIGN_ERRORS
1879 #    define png_benign_error png_warning
1880 #    define png_chunk_benign_error png_chunk_warning
1881 #  else
1882 #    define png_benign_error png_error
1883 #    define png_chunk_benign_error png_chunk_error
1884 #  endif
1885 #endif
1886 
1887 /* The png_set_<chunk> functions are for storing values in the png_info_struct.
1888  * Similarly, the png_get_<chunk> calls are used to read values from the
1889  * png_info_struct, either storing the parameters in the passed variables, or
1890  * setting pointers into the png_info_struct where the data is stored.  The
1891  * png_get_<chunk> functions return a non-zero value if the data was available
1892  * in info_ptr, or return zero and do not change any of the parameters if the
1893  * data was not available.
1894  *
1895  * These functions should be used instead of directly accessing png_info
1896  * to avoid problems with future changes in the size and internal layout of
1897  * png_info_struct.
1898  */
1899 /* Returns "flag" if chunk data is valid in info_ptr. */
1900 PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr,
1901     png_const_inforp info_ptr, png_uint_32 flag));
1902 
1903 /* Returns number of bytes needed to hold a transformed row. */
1904 PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
1905     png_const_inforp info_ptr));
1906 
1907 #ifdef PNG_INFO_IMAGE_SUPPORTED
1908 /* Returns row_pointers, which is an array of pointers to scanlines that was
1909  * returned from png_read_png().
1910  */
1911 PNG_EXPORT(112, png_bytepp, png_get_rows, (png_const_structrp png_ptr,
1912     png_const_inforp info_ptr));
1913 
1914 /* Set row_pointers, which is an array of pointers to scanlines for use
1915  * by png_write_png().
1916  */
1917 PNG_EXPORT(113, void, png_set_rows, (png_const_structrp png_ptr,
1918     png_inforp info_ptr, png_bytepp row_pointers));
1919 #endif
1920 
1921 /* Returns number of color channels in image. */
1922 PNG_EXPORT(114, png_byte, png_get_channels, (png_const_structrp png_ptr,
1923     png_const_inforp info_ptr));
1924 
1925 #ifdef PNG_EASY_ACCESS_SUPPORTED
1926 /* Returns image width in pixels. */
1927 PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structrp png_ptr,
1928     png_const_inforp info_ptr));
1929 
1930 /* Returns image height in pixels. */
1931 PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structrp png_ptr,
1932     png_const_inforp info_ptr));
1933 
1934 /* Returns image bit_depth. */
1935 PNG_EXPORT(117, png_byte, png_get_bit_depth, (png_const_structrp png_ptr,
1936     png_const_inforp info_ptr));
1937 
1938 /* Returns image color_type. */
1939 PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structrp png_ptr,
1940     png_const_inforp info_ptr));
1941 
1942 /* Returns image filter_type. */
1943 PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structrp png_ptr,
1944     png_const_inforp info_ptr));
1945 
1946 /* Returns image interlace_type. */
1947 PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structrp png_ptr,
1948     png_const_inforp info_ptr));
1949 
1950 /* Returns image compression_type. */
1951 PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structrp png_ptr,
1952     png_const_inforp info_ptr));
1953 
1954 /* Returns image resolution in pixels per meter, from pHYs chunk data. */
1955 PNG_EXPORT(122, png_uint_32, png_get_pixels_per_meter,
1956     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1957 PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter,
1958     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1959 PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter,
1960     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1961 
1962 /* Returns pixel aspect ratio, computed from pHYs chunk data.  */
1963 PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio,
1964     (png_const_structrp png_ptr, png_const_inforp info_ptr))
1965 PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed,
1966     (png_const_structrp png_ptr, png_const_inforp info_ptr))
1967 
1968 /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
1969 PNG_EXPORT(126, png_int_32, png_get_x_offset_pixels,
1970     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1971 PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels,
1972     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1973 PNG_EXPORT(128, png_int_32, png_get_x_offset_microns,
1974     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1975 PNG_EXPORT(129, png_int_32, png_get_y_offset_microns,
1976     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1977 
1978 #endif /* EASY_ACCESS */
1979 
1980 #ifdef PNG_READ_SUPPORTED
1981 /* Returns pointer to signature string read from PNG header */
1982 PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr,
1983     png_const_inforp info_ptr));
1984 #endif
1985 
1986 #ifdef PNG_bKGD_SUPPORTED
1987 PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
1988     png_inforp info_ptr, png_color_16p *background));
1989 #endif
1990 
1991 #ifdef PNG_bKGD_SUPPORTED
1992 PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
1993     png_inforp info_ptr, png_const_color_16p background));
1994 #endif
1995 
1996 #ifdef PNG_cHRM_SUPPORTED
1997 PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr,
1998     png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x,
1999     double *red_y, double *green_x, double *green_y, double *blue_x,
2000     double *blue_y))
2001 PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr,
2002     png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z,
2003     double *green_X, double *green_Y, double *green_Z, double *blue_X,
2004     double *blue_Y, double *blue_Z))
2005 PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed,
2006     (png_const_structrp png_ptr, png_const_inforp info_ptr,
2007     png_fixed_point *int_white_x, png_fixed_point *int_white_y,
2008     png_fixed_point *int_red_x, png_fixed_point *int_red_y,
2009     png_fixed_point *int_green_x, png_fixed_point *int_green_y,
2010     png_fixed_point *int_blue_x, png_fixed_point *int_blue_y))
2011 PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed,
2012     (png_const_structrp png_ptr, png_const_inforp info_ptr,
2013     png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
2014     png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
2015     png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
2016     png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
2017     png_fixed_point *int_blue_Z))
2018 #endif
2019 
2020 #ifdef PNG_cHRM_SUPPORTED
2021 PNG_FP_EXPORT(135, void, png_set_cHRM, (png_const_structrp png_ptr,
2022     png_inforp info_ptr,
2023     double white_x, double white_y, double red_x, double red_y, double green_x,
2024     double green_y, double blue_x, double blue_y))
2025 PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_const_structrp png_ptr,
2026     png_inforp info_ptr, double red_X, double red_Y, double red_Z,
2027     double green_X, double green_Y, double green_Z, double blue_X,
2028     double blue_Y, double blue_Z))
2029 PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_const_structrp png_ptr,
2030     png_inforp info_ptr, png_fixed_point int_white_x,
2031     png_fixed_point int_white_y, png_fixed_point int_red_x,
2032     png_fixed_point int_red_y, png_fixed_point int_green_x,
2033     png_fixed_point int_green_y, png_fixed_point int_blue_x,
2034     png_fixed_point int_blue_y))
2035 PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
2036     png_inforp info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y,
2037     png_fixed_point int_red_Z, png_fixed_point int_green_X,
2038     png_fixed_point int_green_Y, png_fixed_point int_green_Z,
2039     png_fixed_point int_blue_X, png_fixed_point int_blue_Y,
2040     png_fixed_point int_blue_Z))
2041 #endif
2042 
2043 #ifdef PNG_gAMA_SUPPORTED
2044 PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
2045     png_const_inforp info_ptr, double *file_gamma))
2046 PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed,
2047     (png_const_structrp png_ptr, png_const_inforp info_ptr,
2048     png_fixed_point *int_file_gamma))
2049 #endif
2050 
2051 #ifdef PNG_gAMA_SUPPORTED
2052 PNG_FP_EXPORT(139, void, png_set_gAMA, (png_const_structrp png_ptr,
2053     png_inforp info_ptr, double file_gamma))
2054 PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
2055     png_inforp info_ptr, png_fixed_point int_file_gamma))
2056 #endif
2057 
2058 #ifdef PNG_hIST_SUPPORTED
2059 PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
2060     png_inforp info_ptr, png_uint_16p *hist));
2061 #endif
2062 
2063 #ifdef PNG_hIST_SUPPORTED
2064 PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
2065     png_inforp info_ptr, png_const_uint_16p hist));
2066 #endif
2067 
2068 PNG_EXPORT(143, png_uint_32, png_get_IHDR, (png_const_structrp png_ptr,
2069     png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height,
2070     int *bit_depth, int *color_type, int *interlace_method,
2071     int *compression_method, int *filter_method));
2072 
2073 PNG_EXPORT(144, void, png_set_IHDR, (png_const_structrp png_ptr,
2074     png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
2075     int color_type, int interlace_method, int compression_method,
2076     int filter_method));
2077 
2078 #ifdef PNG_oFFs_SUPPORTED
2079 PNG_EXPORT(145, png_uint_32, png_get_oFFs, (png_const_structrp png_ptr,
2080    png_const_inforp info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
2081    int *unit_type));
2082 #endif
2083 
2084 #ifdef PNG_oFFs_SUPPORTED
2085 PNG_EXPORT(146, void, png_set_oFFs, (png_const_structrp png_ptr,
2086     png_inforp info_ptr, png_int_32 offset_x, png_int_32 offset_y,
2087     int unit_type));
2088 #endif
2089 
2090 #ifdef PNG_pCAL_SUPPORTED
2091 PNG_EXPORT(147, png_uint_32, png_get_pCAL, (png_const_structrp png_ptr,
2092     png_inforp info_ptr, png_charp *purpose, png_int_32 *X0,
2093     png_int_32 *X1, int *type, int *nparams, png_charp *units,
2094     png_charpp *params));
2095 #endif
2096 
2097 #ifdef PNG_pCAL_SUPPORTED
2098 PNG_EXPORT(148, void, png_set_pCAL, (png_const_structrp png_ptr,
2099     png_inforp info_ptr, png_const_charp purpose, png_int_32 X0, png_int_32 X1,
2100     int type, int nparams, png_const_charp units, png_charpp params));
2101 #endif
2102 
2103 #ifdef PNG_pHYs_SUPPORTED
2104 PNG_EXPORT(149, png_uint_32, png_get_pHYs, (png_const_structrp png_ptr,
2105     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
2106     int *unit_type));
2107 #endif
2108 
2109 #ifdef PNG_pHYs_SUPPORTED
2110 PNG_EXPORT(150, void, png_set_pHYs, (png_const_structrp png_ptr,
2111     png_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
2112 #endif
2113 
2114 PNG_EXPORT(151, png_uint_32, png_get_PLTE, (png_const_structrp png_ptr,
2115    png_inforp info_ptr, png_colorp *palette, int *num_palette));
2116 
2117 PNG_EXPORT(152, void, png_set_PLTE, (png_structrp png_ptr,
2118     png_inforp info_ptr, png_const_colorp palette, int num_palette));
2119 
2120 #ifdef PNG_sBIT_SUPPORTED
2121 PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr,
2122     png_inforp info_ptr, png_color_8p *sig_bit));
2123 #endif
2124 
2125 #ifdef PNG_sBIT_SUPPORTED
2126 PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr,
2127     png_inforp info_ptr, png_const_color_8p sig_bit));
2128 #endif
2129 
2130 #ifdef PNG_sRGB_SUPPORTED
2131 PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr,
2132     png_const_inforp info_ptr, int *file_srgb_intent));
2133 #endif
2134 
2135 #ifdef PNG_sRGB_SUPPORTED
2136 PNG_EXPORT(156, void, png_set_sRGB, (png_const_structrp png_ptr,
2137     png_inforp info_ptr, int srgb_intent));
2138 PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_const_structrp png_ptr,
2139     png_inforp info_ptr, int srgb_intent));
2140 #endif
2141 
2142 #ifdef PNG_iCCP_SUPPORTED
2143 PNG_EXPORT(158, png_uint_32, png_get_iCCP, (png_const_structrp png_ptr,
2144     png_inforp info_ptr, png_charpp name, int *compression_type,
2145     png_bytepp profile, png_uint_32 *proflen));
2146 #endif
2147 
2148 #ifdef PNG_iCCP_SUPPORTED
2149 PNG_EXPORT(159, void, png_set_iCCP, (png_const_structrp png_ptr,
2150     png_inforp info_ptr, png_const_charp name, int compression_type,
2151     png_const_bytep profile, png_uint_32 proflen));
2152 #endif
2153 
2154 #ifdef PNG_sPLT_SUPPORTED
2155 PNG_EXPORT(160, int, png_get_sPLT, (png_const_structrp png_ptr,
2156     png_inforp info_ptr, png_sPLT_tpp entries));
2157 #endif
2158 
2159 #ifdef PNG_sPLT_SUPPORTED
2160 PNG_EXPORT(161, void, png_set_sPLT, (png_const_structrp png_ptr,
2161     png_inforp info_ptr, png_const_sPLT_tp entries, int nentries));
2162 #endif
2163 
2164 #ifdef PNG_TEXT_SUPPORTED
2165 /* png_get_text also returns the number of text chunks in *num_text */
2166 PNG_EXPORT(162, int, png_get_text, (png_const_structrp png_ptr,
2167     png_inforp info_ptr, png_textp *text_ptr, int *num_text));
2168 #endif
2169 
2170 /* Note while png_set_text() will accept a structure whose text,
2171  * language, and  translated keywords are NULL pointers, the structure
2172  * returned by png_get_text will always contain regular
2173  * zero-terminated C strings.  They might be empty strings but
2174  * they will never be NULL pointers.
2175  */
2176 
2177 #ifdef PNG_TEXT_SUPPORTED
2178 PNG_EXPORT(163, void, png_set_text, (png_const_structrp png_ptr,
2179     png_inforp info_ptr, png_const_textp text_ptr, int num_text));
2180 #endif
2181 
2182 #ifdef PNG_tIME_SUPPORTED
2183 PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr,
2184     png_inforp info_ptr, png_timep *mod_time));
2185 #endif
2186 
2187 #ifdef PNG_tIME_SUPPORTED
2188 PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr,
2189     png_inforp info_ptr, png_const_timep mod_time));
2190 #endif
2191 
2192 #ifdef PNG_tRNS_SUPPORTED
2193 PNG_EXPORT(166, png_uint_32, png_get_tRNS, (png_const_structrp png_ptr,
2194     png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans,
2195     png_color_16p *trans_color));
2196 #endif
2197 
2198 #ifdef PNG_tRNS_SUPPORTED
2199 PNG_EXPORT(167, void, png_set_tRNS, (png_structrp png_ptr,
2200     png_inforp info_ptr, png_const_bytep trans_alpha, int num_trans,
2201     png_const_color_16p trans_color));
2202 #endif
2203 
2204 #ifdef PNG_sCAL_SUPPORTED
2205 PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL, (png_const_structrp png_ptr,
2206     png_const_inforp info_ptr, int *unit, double *width, double *height))
2207 #if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
2208    defined(PNG_FLOATING_POINT_SUPPORTED)
2209 /* NOTE: this API is currently implemented using floating point arithmetic,
2210  * consequently it can only be used on systems with floating point support.
2211  * In any case the range of values supported by png_fixed_point is small and it
2212  * is highly recommended that png_get_sCAL_s be used instead.
2213  */
2214 PNG_FIXED_EXPORT(214, png_uint_32, png_get_sCAL_fixed,
2215     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
2216     png_fixed_point *width, png_fixed_point *height))
2217 #endif
2218 PNG_EXPORT(169, png_uint_32, png_get_sCAL_s,
2219     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
2220     png_charpp swidth, png_charpp sheight));
2221 
2222 PNG_FP_EXPORT(170, void, png_set_sCAL, (png_const_structrp png_ptr,
2223     png_inforp info_ptr, int unit, double width, double height))
2224 PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_const_structrp png_ptr,
2225    png_inforp info_ptr, int unit, png_fixed_point width,
2226    png_fixed_point height))
2227 PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
2228     png_inforp info_ptr, int unit,
2229     png_const_charp swidth, png_const_charp sheight));
2230 #endif /* sCAL */
2231 
2232 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2233 /* Provide the default handling for all unknown chunks or, optionally, for
2234  * specific unknown chunks.
2235  *
2236  * NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
2237  * ignored and the default was used, the per-chunk setting only had an effect on
2238  * write.  If you wish to have chunk-specific handling on read in code that must
2239  * work on earlier versions you must use a user chunk callback to specify the
2240  * desired handling (keep or discard.)
2241  *
2242  * The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below.  The
2243  * parameter is interpreted as follows:
2244  *
2245  * READ:
2246  *    PNG_HANDLE_CHUNK_AS_DEFAULT:
2247  *       Known chunks: do normal libpng processing, do not keep the chunk (but
2248  *          see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
2249  *       Unknown chunks: for a specific chunk use the global default, when used
2250  *          as the default discard the chunk data.
2251  *    PNG_HANDLE_CHUNK_NEVER:
2252  *       Discard the chunk data.
2253  *    PNG_HANDLE_CHUNK_IF_SAFE:
2254  *       Keep the chunk data if the chunk is not critical else raise a chunk
2255  *       error.
2256  *    PNG_HANDLE_CHUNK_ALWAYS:
2257  *       Keep the chunk data.
2258  *
2259  * If the chunk data is saved it can be retrieved using png_get_unknown_chunks,
2260  * below.  Notice that specifying "AS_DEFAULT" as a global default is equivalent
2261  * to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
2262  * it simply resets the behavior to the libpng default.
2263  *
2264  * INTERACTION WTIH USER CHUNK CALLBACKS:
2265  * The per-chunk handling is always used when there is a png_user_chunk_ptr
2266  * callback and the callback returns 0; the chunk is then always stored *unless*
2267  * it is critical and the per-chunk setting is other than ALWAYS.  Notice that
2268  * the global default is *not* used in this case.  (In effect the per-chunk
2269  * value is incremented to at least IF_SAFE.)
2270  *
2271  * IMPORTANT NOTE: this behavior will change in libpng 1.7 - the global and
2272  * per-chunk defaults will be honored.  If you want to preserve the current
2273  * behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE
2274  * as the default - if you don't do this libpng 1.6 will issue a warning.
2275  *
2276  * If you want unhandled unknown chunks to be discarded in libpng 1.6 and
2277  * earlier simply return '1' (handled).
2278  *
2279  * PNG_HANDLE_AS_UNKNOWN_SUPPORTED:
2280  *    If this is *not* set known chunks will always be handled by libpng and
2281  *    will never be stored in the unknown chunk list.  Known chunks listed to
2282  *    png_set_keep_unknown_chunks will have no effect.  If it is set then known
2283  *    chunks listed with a keep other than AS_DEFAULT will *never* be processed
2284  *    by libpng, in addition critical chunks must either be processed by the
2285  *    callback or saved.
2286  *
2287  *    The IHDR and IEND chunks must not be listed.  Because this turns off the
2288  *    default handling for chunks that would otherwise be recognized the
2289  *    behavior of libpng transformations may well become incorrect!
2290  *
2291  * WRITE:
2292  *    When writing chunks the options only apply to the chunks specified by
2293  *    png_set_unknown_chunks (below), libpng will *always* write known chunks
2294  *    required by png_set_ calls and will always write the core critical chunks
2295  *    (as required for PLTE).
2296  *
2297  *    Each chunk in the png_set_unknown_chunks list is looked up in the
2298  *    png_set_keep_unknown_chunks list to find the keep setting, this is then
2299  *    interpreted as follows:
2300  *
2301  *    PNG_HANDLE_CHUNK_AS_DEFAULT:
2302  *       Write safe-to-copy chunks and write other chunks if the global
2303  *       default is set to _ALWAYS, otherwise don't write this chunk.
2304  *    PNG_HANDLE_CHUNK_NEVER:
2305  *       Do not write the chunk.
2306  *    PNG_HANDLE_CHUNK_IF_SAFE:
2307  *       Write the chunk if it is safe-to-copy, otherwise do not write it.
2308  *    PNG_HANDLE_CHUNK_ALWAYS:
2309  *       Write the chunk.
2310  *
2311  * Note that the default behavior is effectively the opposite of the read case -
2312  * in read unknown chunks are not stored by default, in write they are written
2313  * by default.  Also the behavior of PNG_HANDLE_CHUNK_IF_SAFE is very different
2314  * - on write the safe-to-copy bit is checked, on read the critical bit is
2315  * checked and on read if the chunk is critical an error will be raised.
2316  *
2317  * num_chunks:
2318  * ===========
2319  *    If num_chunks is positive, then the "keep" parameter specifies the manner
2320  *    for handling only those chunks appearing in the chunk_list array,
2321  *    otherwise the chunk list array is ignored.
2322  *
2323  *    If num_chunks is 0 the "keep" parameter specifies the default behavior for
2324  *    unknown chunks, as described above.
2325  *
2326  *    If num_chunks is negative, then the "keep" parameter specifies the manner
2327  *    for handling all unknown chunks plus all chunks recognized by libpng
2328  *    except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
2329  *    be processed by libpng.
2330  */
2331 PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
2332     int keep, png_const_bytep chunk_list, int num_chunks));
2333 
2334 /* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
2335  * the result is therefore true (non-zero) if special handling is required,
2336  * false for the default handling.
2337  */
2338 PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
2339     png_const_bytep chunk_name));
2340 #endif
2341 
2342 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
2343 PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
2344     png_inforp info_ptr, png_const_unknown_chunkp unknowns,
2345     int num_unknowns));
2346    /* NOTE: prior to 1.6.0 this routine set the 'location' field of the added
2347     * unknowns to the location currently stored in the png_struct.  This is
2348     * invariably the wrong value on write.  To fix this call the following API
2349     * for each chunk in the list with the correct location.  If you know your
2350     * code won't be compiled on earlier versions you can rely on
2351     * png_set_unknown_chunks(write-ptr, png_get_unknown_chunks(read-ptr)) doing
2352     * the correct thing.
2353     */
2354 
2355 PNG_EXPORT(175, void, png_set_unknown_chunk_location,
2356     (png_const_structrp png_ptr, png_inforp info_ptr, int chunk, int location));
2357 
2358 PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structrp png_ptr,
2359     png_inforp info_ptr, png_unknown_chunkpp entries));
2360 #endif
2361 
2362 /* Png_free_data() will turn off the "valid" flag for anything it frees.
2363  * If you need to turn it off for a chunk that your application has freed,
2364  * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
2365  */
2366 PNG_EXPORT(177, void, png_set_invalid, (png_const_structrp png_ptr,
2367     png_inforp info_ptr, int mask));
2368 
2369 #ifdef PNG_INFO_IMAGE_SUPPORTED
2370 /* The "params" pointer is currently not used and is for future expansion. */
2371 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
2372 PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr,
2373     int transforms, png_voidp params));
2374 #endif
2375 #ifdef PNG_WRITE_SUPPORTED
2376 PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr,
2377     int transforms, png_voidp params));
2378 #endif
2379 #endif
2380 
2381 PNG_EXPORT(180, png_const_charp, png_get_copyright,
2382     (png_const_structrp png_ptr));
2383 PNG_EXPORT(181, png_const_charp, png_get_header_ver,
2384     (png_const_structrp png_ptr));
2385 PNG_EXPORT(182, png_const_charp, png_get_header_version,
2386     (png_const_structrp png_ptr));
2387 PNG_EXPORT(183, png_const_charp, png_get_libpng_ver,
2388     (png_const_structrp png_ptr));
2389 
2390 #ifdef PNG_MNG_FEATURES_SUPPORTED
2391 PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr,
2392     png_uint_32 mng_features_permitted));
2393 #endif
2394 
2395 /* For use in png_set_keep_unknown, added to version 1.2.6 */
2396 #define PNG_HANDLE_CHUNK_AS_DEFAULT   0
2397 #define PNG_HANDLE_CHUNK_NEVER        1
2398 #define PNG_HANDLE_CHUNK_IF_SAFE      2
2399 #define PNG_HANDLE_CHUNK_ALWAYS       3
2400 #define PNG_HANDLE_CHUNK_LAST         4
2401 
2402 /* Strip the prepended error numbers ("#nnn ") from error and warning
2403  * messages before passing them to the error or warning handler.
2404  */
2405 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
2406 PNG_EXPORT(185, void, png_set_strip_error_numbers, (png_structrp png_ptr,
2407     png_uint_32 strip_mode));
2408 #endif
2409 
2410 /* Added in libpng-1.2.6 */
2411 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
2412 PNG_EXPORT(186, void, png_set_user_limits, (png_structrp png_ptr,
2413     png_uint_32 user_width_max, png_uint_32 user_height_max));
2414 PNG_EXPORT(187, png_uint_32, png_get_user_width_max,
2415     (png_const_structrp png_ptr));
2416 PNG_EXPORT(188, png_uint_32, png_get_user_height_max,
2417     (png_const_structrp png_ptr));
2418 /* Added in libpng-1.4.0 */
2419 PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structrp png_ptr,
2420     png_uint_32 user_chunk_cache_max));
2421 PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max,
2422     (png_const_structrp png_ptr));
2423 /* Added in libpng-1.4.1 */
2424 PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structrp png_ptr,
2425     png_alloc_size_t user_chunk_cache_max));
2426 PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max,
2427     (png_const_structrp png_ptr));
2428 #endif
2429 
2430 #if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
2431 PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch,
2432     (png_const_structrp png_ptr, png_const_inforp info_ptr));
2433 
2434 PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch,
2435     (png_const_structrp png_ptr, png_const_inforp info_ptr));
2436 
2437 PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch,
2438     (png_const_structrp png_ptr, png_const_inforp info_ptr));
2439 
2440 PNG_FP_EXPORT(196, float, png_get_x_offset_inches,
2441     (png_const_structrp png_ptr, png_const_inforp info_ptr))
2442 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2443 PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed,
2444     (png_const_structrp png_ptr, png_const_inforp info_ptr))
2445 #endif
2446 
2447 PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structrp png_ptr,
2448     png_const_inforp info_ptr))
2449 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2450 PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed,
2451     (png_const_structrp png_ptr, png_const_inforp info_ptr))
2452 #endif
2453 
2454 #  ifdef PNG_pHYs_SUPPORTED
2455 PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structrp png_ptr,
2456     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
2457     int *unit_type));
2458 #  endif /* pHYs */
2459 #endif  /* INCH_CONVERSIONS */
2460 
2461 /* Added in libpng-1.4.0 */
2462 #ifdef PNG_IO_STATE_SUPPORTED
2463 PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_const_structrp png_ptr));
2464 
2465 /* Removed from libpng 1.6; use png_get_io_chunk_type. */
2466 PNG_REMOVED(200, png_const_bytep, png_get_io_chunk_name, (png_structrp png_ptr),
2467     PNG_DEPRECATED)
2468 
2469 PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
2470     (png_const_structrp png_ptr));
2471 
2472 /* The flags returned by png_get_io_state() are the following: */
2473 #  define PNG_IO_NONE        0x0000   /* no I/O at this moment */
2474 #  define PNG_IO_READING     0x0001   /* currently reading */
2475 #  define PNG_IO_WRITING     0x0002   /* currently writing */
2476 #  define PNG_IO_SIGNATURE   0x0010   /* currently at the file signature */
2477 #  define PNG_IO_CHUNK_HDR   0x0020   /* currently at the chunk header */
2478 #  define PNG_IO_CHUNK_DATA  0x0040   /* currently at the chunk data */
2479 #  define PNG_IO_CHUNK_CRC   0x0080   /* currently at the chunk crc */
2480 #  define PNG_IO_MASK_OP     0x000f   /* current operation: reading/writing */
2481 #  define PNG_IO_MASK_LOC    0x00f0   /* current location: sig/hdr/data/crc */
2482 #endif /* IO_STATE */
2483 
2484 /* Interlace support.  The following macros are always defined so that if
2485  * libpng interlace handling is turned off the macros may be used to handle
2486  * interlaced images within the application.
2487  */
2488 #define PNG_INTERLACE_ADAM7_PASSES 7
2489 
2490 /* Two macros to return the first row and first column of the original,
2491  * full, image which appears in a given pass.  'pass' is in the range 0
2492  * to 6 and the result is in the range 0 to 7.
2493  */
2494 #define PNG_PASS_START_ROW(pass) (((1&~(pass))<<(3-((pass)>>1)))&7)
2495 #define PNG_PASS_START_COL(pass) (((1& (pass))<<(3-(((pass)+1)>>1)))&7)
2496 
2497 /* A macro to return the offset between pixels in the output row for a pair of
2498  * pixels in the input - effectively the inverse of the 'COL_SHIFT' macro that
2499  * follows.  Note that ROW_OFFSET is the offset from one row to the next whereas
2500  * COL_OFFSET is from one column to the next, within a row.
2501  */
2502 #define PNG_PASS_ROW_OFFSET(pass) ((pass)>2?(8>>(((pass)-1)>>1)):8)
2503 #define PNG_PASS_COL_OFFSET(pass) (1<<((7-(pass))>>1))
2504 
2505 /* Two macros to help evaluate the number of rows or columns in each
2506  * pass.  This is expressed as a shift - effectively log2 of the number or
2507  * rows or columns in each 8x8 tile of the original image.
2508  */
2509 #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
2510 #define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
2511 
2512 /* Hence two macros to determine the number of rows or columns in a given
2513  * pass of an image given its height or width.  In fact these macros may
2514  * return non-zero even though the sub-image is empty, because the other
2515  * dimension may be empty for a small image.
2516  */
2517 #define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
2518    -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
2519 #define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
2520    -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
2521 
2522 /* For the reader row callbacks (both progressive and sequential) it is
2523  * necessary to find the row in the output image given a row in an interlaced
2524  * image, so two more macros:
2525  */
2526 #define PNG_ROW_FROM_PASS_ROW(y_in, pass) \
2527    (((y_in)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
2528 #define PNG_COL_FROM_PASS_COL(x_in, pass) \
2529    (((x_in)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
2530 
2531 /* Two macros which return a boolean (0 or 1) saying whether the given row
2532  * or column is in a particular pass.  These use a common utility macro that
2533  * returns a mask for a given pass - the offset 'off' selects the row or
2534  * column version.  The mask has the appropriate bit set for each column in
2535  * the tile.
2536  */
2537 #define PNG_PASS_MASK(pass,off) ( \
2538    ((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \
2539    ((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0))
2540 
2541 #define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
2542    ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
2543 #define PNG_COL_IN_INTERLACE_PASS(x, pass) \
2544    ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
2545 
2546 #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
2547 /* With these routines we avoid an integer divide, which will be slower on
2548  * most machines.  However, it does take more operations than the corresponding
2549  * divide method, so it may be slower on a few RISC systems.  There are two
2550  * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
2551  *
2552  * Note that the rounding factors are NOT supposed to be the same!  128 and
2553  * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
2554  * standard method.
2555  *
2556  * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
2557  */
2558 
2559  /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
2560 
2561 #  define png_composite(composite, fg, alpha, bg)         \
2562      { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
2563            * (png_uint_16)(alpha)                         \
2564            + (png_uint_16)(bg)*(png_uint_16)(255          \
2565            - (png_uint_16)(alpha)) + 128);                \
2566        (composite) = (png_byte)(((temp + (temp >> 8)) >> 8) & 0xff); }
2567 
2568 #  define png_composite_16(composite, fg, alpha, bg)       \
2569      { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg)  \
2570            * (png_uint_32)(alpha)                          \
2571            + (png_uint_32)(bg)*(65535                      \
2572            - (png_uint_32)(alpha)) + 32768);               \
2573        (composite) = (png_uint_16)(0xffff & ((temp + (temp >> 16)) >> 16)); }
2574 
2575 #else  /* Standard method using integer division */
2576 
2577 #  define png_composite(composite, fg, alpha, bg)                        \
2578      (composite) =                                                       \
2579          (png_byte)(0xff & (((png_uint_16)(fg) * (png_uint_16)(alpha) +  \
2580          (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
2581          127) / 255))
2582 
2583 #  define png_composite_16(composite, fg, alpha, bg)                         \
2584      (composite) =                                                           \
2585          (png_uint_16)(0xffff & (((png_uint_32)(fg) * (png_uint_32)(alpha) + \
2586          (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) +     \
2587          32767) / 65535))
2588 #endif /* READ_COMPOSITE_NODIV */
2589 
2590 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
2591 PNG_EXPORT(201, png_uint_32, png_get_uint_32, (png_const_bytep buf));
2592 PNG_EXPORT(202, png_uint_16, png_get_uint_16, (png_const_bytep buf));
2593 PNG_EXPORT(203, png_int_32, png_get_int_32, (png_const_bytep buf));
2594 #endif
2595 
2596 PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_const_structrp png_ptr,
2597     png_const_bytep buf));
2598 /* No png_get_int_16 -- may be added if there's a real need for it. */
2599 
2600 /* Place a 32-bit number into a buffer in PNG byte order (big-endian). */
2601 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2602 PNG_EXPORT(205, void, png_save_uint_32, (png_bytep buf, png_uint_32 i));
2603 #endif
2604 #ifdef PNG_SAVE_INT_32_SUPPORTED
2605 PNG_EXPORT(206, void, png_save_int_32, (png_bytep buf, png_int_32 i));
2606 #endif
2607 
2608 /* Place a 16-bit number into a buffer in PNG byte order.
2609  * The parameter is declared unsigned int, not png_uint_16,
2610  * just to avoid potential problems on pre-ANSI C compilers.
2611  */
2612 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2613 PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
2614 /* No png_save_int_16 -- may be added if there's a real need for it. */
2615 #endif
2616 
2617 #ifdef PNG_USE_READ_MACROS
2618 /* Inline macros to do direct reads of bytes from the input buffer.
2619  * The png_get_int_32() routine assumes we are using two's complement
2620  * format for negative values, which is almost certainly true.
2621  */
2622 #  define PNG_get_uint_32(buf) \
2623      (((png_uint_32)(*(buf)) << 24) + \
2624       ((png_uint_32)(*((buf) + 1)) << 16) + \
2625       ((png_uint_32)(*((buf) + 2)) << 8) + \
2626       ((png_uint_32)(*((buf) + 3))))
2627 
2628    /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
2629     * function) incorrectly returned a value of type png_uint_32.
2630     */
2631 #  define PNG_get_uint_16(buf) \
2632      ((png_uint_16) \
2633       (((unsigned int)(*(buf)) << 8) + \
2634        ((unsigned int)(*((buf) + 1)))))
2635 
2636 #  define PNG_get_int_32(buf) \
2637      ((png_int_32)((*(buf) & 0x80) \
2638       ? -((png_int_32)(((png_get_uint_32(buf)^0xffffffffU)+1U)&0x7fffffffU)) \
2639       : (png_int_32)png_get_uint_32(buf)))
2640 
2641    /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
2642     * but defining a macro name prefixed with PNG_PREFIX.
2643     */
2644 #  ifndef PNG_PREFIX
2645 #     define png_get_uint_32(buf) PNG_get_uint_32(buf)
2646 #     define png_get_uint_16(buf) PNG_get_uint_16(buf)
2647 #     define png_get_int_32(buf)  PNG_get_int_32(buf)
2648 #  endif
2649 #else
2650 #  ifdef PNG_PREFIX
2651       /* No macros; revert to the (redefined) function */
2652 #     define PNG_get_uint_32 (png_get_uint_32)
2653 #     define PNG_get_uint_16 (png_get_uint_16)
2654 #     define PNG_get_int_32  (png_get_int_32)
2655 #  endif
2656 #endif
2657 
2658 #ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
2659 PNG_EXPORT(242, void, png_set_check_for_invalid_index,
2660     (png_structrp png_ptr, int allowed));
2661 #  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
2662 PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
2663     png_const_infop info_ptr));
2664 #  endif
2665 #endif /* CHECK_FOR_INVALID_INDEX */
2666 
2667 /*******************************************************************************
2668  * Section 5: SIMPLIFIED API
2669  *******************************************************************************
2670  *
2671  * Please read the documentation in libpng-manual.txt (TODO: write said
2672  * documentation) if you don't understand what follows.
2673  *
2674  * The simplified API hides the details of both libpng and the PNG file format
2675  * itself.  It allows PNG files to be read into a very limited number of
2676  * in-memory bitmap formats or to be written from the same formats.  If these
2677  * formats do not accomodate your needs then you can, and should, use the more
2678  * sophisticated APIs above - these support a wide variety of in-memory formats
2679  * and a wide variety of sophisticated transformations to those formats as well
2680  * as a wide variety of APIs to manipulate ancillary information.
2681  *
2682  * To read a PNG file using the simplified API:
2683  *
2684  * 1) Declare a 'png_image' structure (see below) on the stack, set the
2685  *    version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
2686  *    (this is REQUIRED, your program may crash if you don't do it.)
2687  * 2) Call the appropriate png_image_begin_read... function.
2688  * 3) Set the png_image 'format' member to the required sample format.
2689  * 4) Allocate a buffer for the image and, if required, the color-map.
2690  * 5) Call png_image_finish_read to read the image and, if required, the
2691  *    color-map into your buffers.
2692  *
2693  * There are no restrictions on the format of the PNG input itself; all valid
2694  * color types, bit depths, and interlace methods are acceptable, and the
2695  * input image is transformed as necessary to the requested in-memory format
2696  * during the png_image_finish_read() step.  The only caveat is that if you
2697  * request a color-mapped image from a PNG that is full-color or makes
2698  * complex use of an alpha channel the transformation is extremely lossy and the
2699  * result may look terrible.
2700  *
2701  * To write a PNG file using the simplified API:
2702  *
2703  * 1) Declare a 'png_image' structure on the stack and memset() it to all zero.
2704  * 2) Initialize the members of the structure that describe the image, setting
2705  *    the 'format' member to the format of the image samples.
2706  * 3) Call the appropriate png_image_write... function with a pointer to the
2707  *    image and, if necessary, the color-map to write the PNG data.
2708  *
2709  * png_image is a structure that describes the in-memory format of an image
2710  * when it is being read or defines the in-memory format of an image that you
2711  * need to write:
2712  */
2713 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) || \
2714     defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
2715 
2716 #define PNG_IMAGE_VERSION 1
2717 
2718 typedef struct png_control *png_controlp;
2719 typedef struct
2720 {
2721    png_controlp opaque;    /* Initialize to NULL, free with png_image_free */
2722    png_uint_32  version;   /* Set to PNG_IMAGE_VERSION */
2723    png_uint_32  width;     /* Image width in pixels (columns) */
2724    png_uint_32  height;    /* Image height in pixels (rows) */
2725    png_uint_32  format;    /* Image format as defined below */
2726    png_uint_32  flags;     /* A bit mask containing informational flags */
2727    png_uint_32  colormap_entries;
2728                            /* Number of entries in the color-map */
2729 
2730    /* In the event of an error or warning the following field will be set to a
2731     * non-zero value and the 'message' field will contain a '\0' terminated
2732     * string with the libpng error or warning message.  If both warnings and
2733     * an error were encountered, only the error is recorded.  If there
2734     * are multiple warnings, only the first one is recorded.
2735     *
2736     * The upper 30 bits of this value are reserved, the low two bits contain
2737     * a value as follows:
2738     */
2739 #  define PNG_IMAGE_WARNING 1
2740 #  define PNG_IMAGE_ERROR 2
2741    /*
2742     * The result is a two-bit code such that a value more than 1 indicates
2743     * a failure in the API just called:
2744     *
2745     *    0 - no warning or error
2746     *    1 - warning
2747     *    2 - error
2748     *    3 - error preceded by warning
2749     */
2750 #  define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1)
2751 
2752    png_uint_32  warning_or_error;
2753 
2754    char         message[64];
2755 } png_image, *png_imagep;
2756 
2757 /* The samples of the image have one to four channels whose components have
2758  * original values in the range 0 to 1.0:
2759  *
2760  * 1: A single gray or luminance channel (G).
2761  * 2: A gray/luminance channel and an alpha channel (GA).
2762  * 3: Three red, green, blue color channels (RGB).
2763  * 4: Three color channels and an alpha channel (RGBA).
2764  *
2765  * The components are encoded in one of two ways:
2766  *
2767  * a) As a small integer, value 0..255, contained in a single byte.  For the
2768  * alpha channel the original value is simply value/255.  For the color or
2769  * luminance channels the value is encoded according to the sRGB specification
2770  * and matches the 8-bit format expected by typical display devices.
2771  *
2772  * The color/gray channels are not scaled (pre-multiplied) by the alpha
2773  * channel and are suitable for passing to color management software.
2774  *
2775  * b) As a value in the range 0..65535, contained in a 2-byte integer.  All
2776  * channels can be converted to the original value by dividing by 65535; all
2777  * channels are linear.  Color channels use the RGB encoding (RGB end-points) of
2778  * the sRGB specification.  This encoding is identified by the
2779  * PNG_FORMAT_FLAG_LINEAR flag below.
2780  *
2781  * When the simplified API needs to convert between sRGB and linear colorspaces,
2782  * the actual sRGB transfer curve defined in the sRGB specification (see the
2783  * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
2784  * approximation used elsewhere in libpng.
2785  *
2786  * When an alpha channel is present it is expected to denote pixel coverage
2787  * of the color or luminance channels and is returned as an associated alpha
2788  * channel: the color/gray channels are scaled (pre-multiplied) by the alpha
2789  * value.
2790  *
2791  * The samples are either contained directly in the image data, between 1 and 8
2792  * bytes per pixel according to the encoding, or are held in a color-map indexed
2793  * by bytes in the image data.  In the case of a color-map the color-map entries
2794  * are individual samples, encoded as above, and the image data has one byte per
2795  * pixel to select the relevant sample from the color-map.
2796  */
2797 
2798 /* PNG_FORMAT_*
2799  *
2800  * #defines to be used in png_image::format.  Each #define identifies a
2801  * particular layout of sample data and, if present, alpha values.  There are
2802  * separate defines for each of the two component encodings.
2803  *
2804  * A format is built up using single bit flag values.  All combinations are
2805  * valid.  Formats can be built up from the flag values or you can use one of
2806  * the predefined values below.  When testing formats always use the FORMAT_FLAG
2807  * macros to test for individual features - future versions of the library may
2808  * add new flags.
2809  *
2810  * When reading or writing color-mapped images the format should be set to the
2811  * format of the entries in the color-map then png_image_{read,write}_colormap
2812  * called to read or write the color-map and set the format correctly for the
2813  * image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
2814  *
2815  * NOTE: libpng can be built with particular features disabled. If you see
2816  * compiler errors because the definition of one of the following flags has been
2817  * compiled out it is because libpng does not have the required support.  It is
2818  * possible, however, for the libpng configuration to enable the format on just
2819  * read or just write; in that case you may see an error at run time.  You can
2820  * guard against this by checking for the definition of the appropriate
2821  * "_SUPPORTED" macro, one of:
2822  *
2823  *    PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
2824  */
2825 #define PNG_FORMAT_FLAG_ALPHA    0x01U /* format with an alpha channel */
2826 #define PNG_FORMAT_FLAG_COLOR    0x02U /* color format: otherwise grayscale */
2827 #define PNG_FORMAT_FLAG_LINEAR   0x04U /* 2-byte channels else 1-byte */
2828 #define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
2829 
2830 #ifdef PNG_FORMAT_BGR_SUPPORTED
2831 #  define PNG_FORMAT_FLAG_BGR    0x10U /* BGR colors, else order is RGB */
2832 #endif
2833 
2834 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
2835 #  define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
2836 #endif
2837 
2838 /* Commonly used formats have predefined macros.
2839  *
2840  * First the single byte (sRGB) formats:
2841  */
2842 #define PNG_FORMAT_GRAY 0
2843 #define PNG_FORMAT_GA   PNG_FORMAT_FLAG_ALPHA
2844 #define PNG_FORMAT_AG   (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
2845 #define PNG_FORMAT_RGB  PNG_FORMAT_FLAG_COLOR
2846 #define PNG_FORMAT_BGR  (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
2847 #define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
2848 #define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
2849 #define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
2850 #define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
2851 
2852 /* Then the linear 2-byte formats.  When naming these "Y" is used to
2853  * indicate a luminance (gray) channel.
2854  */
2855 #define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
2856 #define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
2857 #define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
2858 #define PNG_FORMAT_LINEAR_RGB_ALPHA \
2859    (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA)
2860 
2861 /* With color-mapped formats the image data is one byte for each pixel, the byte
2862  * is an index into the color-map which is formatted as above.  To obtain a
2863  * color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
2864  * to one of the above definitions, or you can use one of the definitions below.
2865  */
2866 #define PNG_FORMAT_RGB_COLORMAP  (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP)
2867 #define PNG_FORMAT_BGR_COLORMAP  (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP)
2868 #define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP)
2869 #define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP)
2870 #define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP)
2871 #define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP)
2872 
2873 /* PNG_IMAGE macros
2874  *
2875  * These are convenience macros to derive information from a png_image
2876  * structure.  The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
2877  * actual image sample values - either the entries in the color-map or the
2878  * pixels in the image.  The PNG_IMAGE_PIXEL_ macros return corresponding values
2879  * for the pixels and will always return 1 for color-mapped formats.  The
2880  * remaining macros return information about the rows in the image and the
2881  * complete image.
2882  *
2883  * NOTE: All the macros that take a png_image::format parameter are compile time
2884  * constants if the format parameter is, itself, a constant.  Therefore these
2885  * macros can be used in array declarations and case labels where required.
2886  * Similarly the macros are also pre-processor constants (sizeof is not used) so
2887  * they can be used in #if tests.
2888  *
2889  * First the information about the samples.
2890  */
2891 #define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\
2892    (((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1)
2893    /* Return the total number of channels in a given format: 1..4 */
2894 
2895 #define PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)\
2896    ((((fmt) & PNG_FORMAT_FLAG_LINEAR) >> 2)+1)
2897    /* Return the size in bytes of a single component of a pixel or color-map
2898     * entry (as appropriate) in the image: 1 or 2.
2899     */
2900 
2901 #define PNG_IMAGE_SAMPLE_SIZE(fmt)\
2902    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt))
2903    /* This is the size of the sample data for one sample.  If the image is
2904     * color-mapped it is the size of one color-map entry (and image pixels are
2905     * one byte in size), otherwise it is the size of one image pixel.
2906     */
2907 
2908 #define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
2909    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
2910    /* The maximum size of the color-map required by the format expressed in a
2911     * count of components.  This can be used to compile-time allocate a
2912     * color-map:
2913     *
2914     * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
2915     *
2916     * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
2917     *
2918     * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
2919     * information from one of the png_image_begin_read_ APIs and dynamically
2920     * allocate the required memory.
2921     */
2922 
2923 /* Corresponding information about the pixels */
2924 #define PNG_IMAGE_PIXEL_(test,fmt)\
2925    (((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt))
2926 
2927 #define PNG_IMAGE_PIXEL_CHANNELS(fmt)\
2928    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt)
2929    /* The number of separate channels (components) in a pixel; 1 for a
2930     * color-mapped image.
2931     */
2932 
2933 #define PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
2934    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_COMPONENT_SIZE,fmt)
2935    /* The size, in bytes, of each component in a pixel; 1 for a color-mapped
2936     * image.
2937     */
2938 
2939 #define PNG_IMAGE_PIXEL_SIZE(fmt) PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_SIZE,fmt)
2940    /* The size, in bytes, of a complete pixel; 1 for a color-mapped image. */
2941 
2942 /* Information about the whole row, or whole image */
2943 #define PNG_IMAGE_ROW_STRIDE(image)\
2944    (PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width)
2945    /* Return the total number of components in a single row of the image; this
2946     * is the minimum 'row stride', the minimum count of components between each
2947     * row.  For a color-mapped image this is the minimum number of bytes in a
2948     * row.
2949     *
2950     * WARNING: this macro overflows for some images with more than one component
2951     * and very large image widths.  libpng will refuse to process an image where
2952     * this macro would overflow.
2953     */
2954 
2955 #define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
2956    (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
2957    /* Return the size, in bytes, of an image buffer given a png_image and a row
2958     * stride - the number of components to leave space for in each row.
2959     *
2960     * WARNING: this macro overflows a 32-bit integer for some large PNG images,
2961     * libpng will refuse to process an image where such an overflow would occur.
2962     */
2963 
2964 #define PNG_IMAGE_SIZE(image)\
2965    PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image))
2966    /* Return the size, in bytes, of the image in memory given just a png_image;
2967     * the row stride is the minimum stride required for the image.
2968     */
2969 
2970 #define PNG_IMAGE_COLORMAP_SIZE(image)\
2971    (PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries)
2972    /* Return the size, in bytes, of the color-map of this image.  If the image
2973     * format is not a color-map format this will return a size sufficient for
2974     * 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
2975     * you don't want to allocate a color-map in this case.
2976     */
2977 
2978 /* PNG_IMAGE_FLAG_*
2979  *
2980  * Flags containing additional information about the image are held in the
2981  * 'flags' field of png_image.
2982  */
2983 #define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
2984    /* This indicates the the RGB values of the in-memory bitmap do not
2985     * correspond to the red, green and blue end-points defined by sRGB.
2986     */
2987 
2988 #define PNG_IMAGE_FLAG_FAST 0x02
2989    /* On write emphasise speed over compression; the resultant PNG file will be
2990     * larger but will be produced significantly faster, particular for large
2991     * images.  Do not use this option for images which will be distributed, only
2992     * used it when producing intermediate files that will be read back in
2993     * repeatedly.  For a typical 24-bit image the option will double the read
2994     * speed at the cost of increasing the image size by 25%, however for many
2995     * more compressible images the PNG file can be 10 times larger with only a
2996     * slight speed gain.
2997     */
2998 
2999 #define PNG_IMAGE_FLAG_16BIT_sRGB 0x04
3000    /* On read if the image is a 16-bit per component image and there is no gAMA
3001     * or sRGB chunk assume that the components are sRGB encoded.  Notice that
3002     * images output by the simplified API always have gamma information; setting
3003     * this flag only affects the interpretation of 16-bit images from an
3004     * external source.  It is recommended that the application expose this flag
3005     * to the user; the user can normally easily recognize the difference between
3006     * linear and sRGB encoding.  This flag has no effect on write - the data
3007     * passed to the write APIs must have the correct encoding (as defined
3008     * above.)
3009     *
3010     * If the flag is not set (the default) input 16-bit per component data is
3011     * assumed to be linear.
3012     *
3013     * NOTE: the flag can only be set after the png_image_begin_read_ call,
3014     * because that call initializes the 'flags' field.
3015     */
3016 
3017 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
3018 /* READ APIs
3019  * ---------
3020  *
3021  * The png_image passed to the read APIs must have been initialized by setting
3022  * the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.)
3023  */
3024 #ifdef PNG_STDIO_SUPPORTED
3025 PNG_EXPORT(234, int, png_image_begin_read_from_file, (png_imagep image,
3026    const char *file_name));
3027    /* The named file is opened for read and the image header is filled in
3028     * from the PNG header in the file.
3029     */
3030 
3031 PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
3032    FILE* file));
3033    /* The PNG header is read from the stdio FILE object. */
3034 #endif /* STDIO */
3035 
3036 PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
3037    png_const_voidp memory, png_size_t size));
3038    /* The PNG header is read from the given memory buffer. */
3039 
3040 PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
3041    png_const_colorp background, void *buffer, png_int_32 row_stride,
3042    void *colormap));
3043    /* Finish reading the image into the supplied buffer and clean up the
3044     * png_image structure.
3045     *
3046     * row_stride is the step, in byte or 2-byte units as appropriate,
3047     * between adjacent rows.  A positive stride indicates that the top-most row
3048     * is first in the buffer - the normal top-down arrangement.  A negative
3049     * stride indicates that the bottom-most row is first in the buffer.
3050     *
3051     * background need only be supplied if an alpha channel must be removed from
3052     * a png_byte format and the removal is to be done by compositing on a solid
3053     * color; otherwise it may be NULL and any composition will be done directly
3054     * onto the buffer.  The value is an sRGB color to use for the background,
3055     * for grayscale output the green channel is used.
3056     *
3057     * background must be supplied when an alpha channel must be removed from a
3058     * single byte color-mapped output format, in other words if:
3059     *
3060     * 1) The original format from png_image_begin_read_from_* had
3061     *    PNG_FORMAT_FLAG_ALPHA set.
3062     * 2) The format set by the application does not.
3063     * 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
3064     *    PNG_FORMAT_FLAG_LINEAR *not* set.
3065     *
3066     * For linear output removing the alpha channel is always done by compositing
3067     * on black and background is ignored.
3068     *
3069     * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set.  It must
3070     * be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
3071     * image->colormap_entries will be updated to the actual number of entries
3072     * written to the colormap; this may be less than the original value.
3073     */
3074 
3075 PNG_EXPORT(238, void, png_image_free, (png_imagep image));
3076    /* Free any data allocated by libpng in image->opaque, setting the pointer to
3077     * NULL.  May be called at any time after the structure is initialized.
3078     */
3079 #endif /* SIMPLIFIED_READ */
3080 
3081 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
3082 /* WRITE APIS
3083  * ----------
3084  * For write you must initialize a png_image structure to describe the image to
3085  * be written.  To do this use memset to set the whole structure to 0 then
3086  * initialize fields describing your image.
3087  *
3088  * version: must be set to PNG_IMAGE_VERSION
3089  * opaque: must be initialized to NULL
3090  * width: image width in pixels
3091  * height: image height in rows
3092  * format: the format of the data (image and color-map) you wish to write
3093  * flags: set to 0 unless one of the defined flags applies; set
3094  *    PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB
3095  *    values do not correspond to the colors in sRGB.
3096  * colormap_entries: set to the number of entries in the color-map (0 to 256)
3097  */
3098 #ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
3099 PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
3100    const char *file, int convert_to_8bit, const void *buffer,
3101    png_int_32 row_stride, const void *colormap));
3102    /* Write the image to the named file. */
3103 
3104 PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
3105    int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
3106    const void *colormap));
3107    /* Write the image to the given (FILE*). */
3108 #endif /* SIMPLIFIED_WRITE_STDIO */
3109 
3110 /* With all write APIs if image is in one of the linear formats with 16-bit
3111  * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
3112  * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
3113  * encoded PNG file is written.
3114  *
3115  * With color-mapped data formats the colormap parameter point to a color-map
3116  * with at least image->colormap_entries encoded in the specified format.  If
3117  * the format is linear the written PNG color-map will be converted to sRGB
3118  * regardless of the convert_to_8_bit flag.
3119  *
3120  * With all APIs row_stride is handled as in the read APIs - it is the spacing
3121  * from one row to the next in component sized units (1 or 2 bytes) and if
3122  * negative indicates a bottom-up row layout in the buffer.  If row_stride is
3123  * zero, libpng will calculate it for you from the image width and number of
3124  * channels.
3125  *
3126  * Note that the write API does not support interlacing, sub-8-bit pixels or
3127  * most ancillary chunks.  If you need to write text chunks (e.g. for copyright
3128  * notices) you need to use one of the other APIs.
3129  */
3130 
3131 PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
3132    png_alloc_size_t * PNG_RESTRICT memory_bytes, int convert_to_8_bit,
3133    const void *buffer, png_int_32 row_stride, const void *colormap));
3134    /* Write the image to the given memory buffer.  The function both writes the
3135     * whole PNG data stream to *memory and updates *memory_bytes with the count
3136     * of bytes written.
3137     *
3138     * 'memory' may be NULL.  In this case *memory_bytes is not read however on
3139     * success the number of bytes which would have been written will still be
3140     * stored in *memory_bytes.  On failure *memory_bytes will contain 0.
3141     *
3142     * If 'memory' is not NULL it must point to memory[*memory_bytes] of
3143     * writeable memory.
3144     *
3145     * If the function returns success memory[*memory_bytes] (if 'memory' is not
3146     * NULL) contains the written PNG data.  *memory_bytes will always be less
3147     * than or equal to the original value.
3148     *
3149     * If the function returns false and *memory_bytes was not changed an error
3150     * occured during write.  If *memory_bytes was changed, or is not 0 if
3151     * 'memory' was NULL, the write would have succeeded but for the memory
3152     * buffer being too small.  *memory_bytes contains the required number of
3153     * bytes and will be bigger that the original value.
3154     */
3155 
3156 #define png_image_write_get_memory_size(image, size, convert_to_8_bit, buffer,\
3157    row_stride, colormap)\
3158    png_image_write_to_memory(&(image), 0, &(size), convert_to_8_bit, buffer,\
3159          row_stride, colormap)
3160    /* Return the amount of memory in 'size' required to compress this image.
3161     * The png_image structure 'image' must be filled in as in the above
3162     * function and must not be changed before the actual write call, the buffer
3163     * and all other parameters must also be identical to that in the final
3164     * write call.  The 'size' variable need not be initialized.
3165     *
3166     * NOTE: the macro returns true/false, if false is returned 'size' will be
3167     * set to zero and the write failed and probably will fail if tried again.
3168     */
3169 
3170 /* You can pre-allocate the buffer by making sure it is of sufficient size
3171  * regardless of the amount of compression achieved.  The buffer size will
3172  * always be bigger than the original image and it will never be filled.  The
3173  * following macros are provided to assist in allocating the buffer.
3174  */
3175 #define PNG_IMAGE_DATA_SIZE(image) (PNG_IMAGE_SIZE(image)+(image).height)
3176    /* The number of uncompressed bytes in the PNG byte encoding of the image;
3177     * uncompressing the PNG IDAT data will give this number of bytes.
3178     *
3179     * NOTE: while PNG_IMAGE_SIZE cannot overflow for an image in memory this
3180     * macro can because of the extra bytes used in the PNG byte encoding.  You
3181     * need to avoid this macro if your image size approaches 2^30 in width or
3182     * height.  The same goes for the remainder of these macros; they all produce
3183     * bigger numbers than the actual in-memory image size.
3184     */
3185 #ifndef PNG_ZLIB_MAX_SIZE
3186 #  define PNG_ZLIB_MAX_SIZE(b) ((b)+(((b)+7U)>>3)+(((b)+63U)>>6)+11U)
3187    /* An upper bound on the number of compressed bytes given 'b' uncompressed
3188     * bytes.  This is based on deflateBounds() in zlib; different
3189     * implementations of zlib compression may conceivably produce more data so
3190     * if your zlib implementation is not zlib itself redefine this macro
3191     * appropriately.
3192     */
3193 #endif
3194 
3195 #define PNG_IMAGE_COMPRESSED_SIZE_MAX(image)\
3196    PNG_ZLIB_MAX_SIZE((png_alloc_size_t)PNG_IMAGE_DATA_SIZE(image))
3197    /* An upper bound on the size of the data in the PNG IDAT chunks. */
3198 
3199 #define PNG_IMAGE_PNG_SIZE_MAX_(image, image_size)\
3200    ((8U/*sig*/+25U/*IHDR*/+16U/*gAMA*/+44U/*cHRM*/+12U/*IEND*/+\
3201     (((image).format&PNG_FORMAT_FLAG_COLORMAP)?/*colormap: PLTE, tRNS*/\
3202      12U+3U*(image).colormap_entries/*PLTE data*/+\
3203      (((image).format&PNG_FORMAT_FLAG_ALPHA)?\
3204       12U/*tRNS*/+(image).colormap_entries:0U):0U)+\
3205     12U)+(12U*((image_size)/PNG_ZBUF_SIZE))/*IDAT*/+(image_size))
3206    /* A helper for the following macro; if your compiler cannot handle the
3207     * following macro use this one with the result of
3208     * PNG_IMAGE_COMPRESSED_SIZE_MAX(image) as the second argument (most
3209     * compilers should handle this just fine.)
3210     */
3211 
3212 #define PNG_IMAGE_PNG_SIZE_MAX(image)\
3213    PNG_IMAGE_PNG_SIZE_MAX_(image, PNG_IMAGE_COMPRESSED_SIZE_MAX(image))
3214    /* An upper bound on the total length of the PNG data stream for 'image'.
3215     * The result is of type png_alloc_size_t, on 32-bit systems this may
3216     * overflow even though PNG_IMAGE_DATA_SIZE does not overflow; the write will
3217     * run out of buffer space but return a corrected size which should work.
3218     */
3219 #endif /* SIMPLIFIED_WRITE */
3220 /*******************************************************************************
3221  *  END OF SIMPLIFIED API
3222  ******************************************************************************/
3223 #endif /* SIMPLIFIED_{READ|WRITE} */
3224 
3225 /*******************************************************************************
3226  * Section 6: IMPLEMENTATION OPTIONS
3227  *******************************************************************************
3228  *
3229  * Support for arbitrary implementation-specific optimizations.  The API allows
3230  * particular options to be turned on or off.  'Option' is the number of the
3231  * option and 'onoff' is 0 (off) or non-0 (on).  The value returned is given
3232  * by the PNG_OPTION_ defines below.
3233  *
3234  * HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
3235  *           are detected at run time, however sometimes it may be impossible
3236  *           to do this in user mode, in which case it is necessary to discover
3237  *           the capabilities in an OS specific way.  Such capabilities are
3238  *           listed here when libpng has support for them and must be turned
3239  *           ON by the application if present.
3240  *
3241  * SOFTWARE: sometimes software optimizations actually result in performance
3242  *           decrease on some architectures or systems, or with some sets of
3243  *           PNG images.  'Software' options allow such optimizations to be
3244  *           selected at run time.
3245  */
3246 #ifdef PNG_SET_OPTION_SUPPORTED
3247 #ifdef PNG_ARM_NEON_API_SUPPORTED
3248 #  define PNG_ARM_NEON   0 /* HARDWARE: ARM Neon SIMD instructions supported */
3249 #endif
3250 #define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
3251 #define PNG_SKIP_sRGB_CHECK_PROFILE 4 /* SOFTWARE: Check ICC profile for sRGB */
3252 #define PNG_OPTION_NEXT  6 /* Next option - numbers must be even */
3253 
3254 /* Return values: NOTE: there are four values and 'off' is *not* zero */
3255 #define PNG_OPTION_UNSET   0 /* Unset - defaults to off */
3256 #define PNG_OPTION_INVALID 1 /* Option number out of range */
3257 #define PNG_OPTION_OFF     2
3258 #define PNG_OPTION_ON      3
3259 
3260 PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
3261    int onoff));
3262 #endif /* SET_OPTION */
3263 
3264 /*******************************************************************************
3265  *  END OF HARDWARE AND SOFTWARE OPTIONS
3266  ******************************************************************************/
3267 
3268 /* Maintainer: Put new public prototypes here ^, in libpng.3, in project
3269  * defs, and in scripts/symbols.def.
3270  */
3271 
3272 /* The last ordinal number (this is the *last* one already used; the next
3273  * one to use is one more than this.)
3274  */
3275 #ifdef PNG_EXPORT_LAST_ORDINAL
3276   PNG_EXPORT_LAST_ORDINAL(245);
3277 #endif
3278 
3279 #ifdef __cplusplus
3280 }
3281 #endif
3282 
3283 #endif /* PNG_VERSION_INFO_ONLY */
3284 /* Do not put anything past this line */
3285 #endif /* PNG_H */