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1 
2 /* png.h - header file for PNG reference library
3  *
4  * libpng version 1.6.34, September 29, 2017
5  *
6  * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
7  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
8  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
9  *
10  * This code is released under the libpng license (See LICENSE, below)
11  *
12  * Authors and maintainers:
13  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
14  *   libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
15  *   libpng versions 0.97, January 1998, through 1.6.34, September 29, 2017:
16  *     Glenn Randers-Pehrson.
17  *   See also "Contributing Authors", below.
18  */
19 
20 /*
21  * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
22  *
23  * If you modify libpng you may insert additional notices immediately following
24  * this sentence.
25  *
26  * This code is released under the libpng license.
27  *
28  * libpng versions 1.0.7, July 1, 2000 through 1.6.34, September 29, 2017 are
29  * Copyright (c) 2000-2002, 2004, 2006-2017 Glenn Randers-Pehrson, are
30  * derived from libpng-1.0.6, and are distributed according to the same
31  * disclaimer and license as libpng-1.0.6 with the following individuals
32  * added to the list of Contributing Authors:
33  *
34  *    Simon-Pierre Cadieux
35  *    Eric S. Raymond
36  *    Mans Rullgard
37  *    Cosmin Truta
38  *    Gilles Vollant
39  *    James Yu
40  *    Mandar Sahastrabuddhe
41  *    Google Inc.
42  *    Vadim Barkov
43  *
44  * and with the following additions to the disclaimer:
45  *
46  *    There is no warranty against interference with your enjoyment of the
47  *    library or against infringement.  There is no warranty that our
48  *    efforts or the library will fulfill any of your particular purposes
49  *    or needs.  This library is provided with all faults, and the entire
50  *    risk of satisfactory quality, performance, accuracy, and effort is with
51  *    the user.
52  *
53  * Some files in the "contrib" directory and some configure-generated
54  * files that are distributed with libpng have other copyright owners and
55  * are released under other open source licenses.
56  *
57  * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
58  * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
59  * libpng-0.96, and are distributed according to the same disclaimer and
60  * license as libpng-0.96, with the following individuals added to the list
61  * of Contributing Authors:
62  *
63  *    Tom Lane
64  *    Glenn Randers-Pehrson
65  *    Willem van Schaik
66  *
67  * libpng versions 0.89, June 1996, through 0.96, May 1997, are
68  * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
69  * and are distributed according to the same disclaimer and license as
70  * libpng-0.88, with the following individuals added to the list of
71  * Contributing Authors:
72  *
73  *    John Bowler
74  *    Kevin Bracey
75  *    Sam Bushell
76  *    Magnus Holmgren
77  *    Greg Roelofs
78  *    Tom Tanner
79  *
80  * Some files in the "scripts" directory have other copyright owners
81  * but are released under this license.
82  *
83  * libpng versions 0.5, May 1995, through 0.88, January 1996, are
84  * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
85  *
86  * For the purposes of this copyright and license, "Contributing Authors"
87  * is defined as the following set of individuals:
88  *
89  *    Andreas Dilger
90  *    Dave Martindale
91  *    Guy Eric Schalnat
92  *    Paul Schmidt
93  *    Tim Wegner
94  *
95  * The PNG Reference Library is supplied "AS IS".  The Contributing Authors
96  * and Group 42, Inc. disclaim all warranties, expressed or implied,
97  * including, without limitation, the warranties of merchantability and of
98  * fitness for any purpose.  The Contributing Authors and Group 42, Inc.
99  * assume no liability for direct, indirect, incidental, special, exemplary,
100  * or consequential damages, which may result from the use of the PNG
101  * Reference Library, even if advised of the possibility of such damage.
102  *
103  * Permission is hereby granted to use, copy, modify, and distribute this
104  * source code, or portions hereof, for any purpose, without fee, subject
105  * to the following restrictions:
106  *
107  *   1. The origin of this source code must not be misrepresented.
108  *
109  *   2. Altered versions must be plainly marked as such and must not
110  *      be misrepresented as being the original source.
111  *
112  *   3. This Copyright notice may not be removed or altered from any
113  *      source or altered source distribution.
114  *
115  * The Contributing Authors and Group 42, Inc. specifically permit, without
116  * fee, and encourage the use of this source code as a component to
117  * supporting the PNG file format in commercial products.  If you use this
118  * source code in a product, acknowledgment is not required but would be
119  * appreciated.
120  *
121  * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
122  *
123  * TRADEMARK:
124  *
125  * The name "libpng" has not been registered by the Copyright owner
126  * as a trademark in any jurisdiction.  However, because libpng has
127  * been distributed and maintained world-wide, continually since 1995,
128  * the Copyright owner claims "common-law trademark protection" in any
129  * jurisdiction where common-law trademark is recognized.
130  *
131  * OSI CERTIFICATION:
132  *
133  * Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
134  * a certification mark of the Open Source Initiative. OSI has not addressed
135  * the additional disclaimers inserted at version 1.0.7.
136  *
137  * EXPORT CONTROL:
138  *
139  * The Copyright owner believes that the Export Control Classification
140  * Number (ECCN) for libpng is EAR99, which means not subject to export
141  * controls or International Traffic in Arms Regulations (ITAR) because
142  * it is open source, publicly available software, that does not contain
143  * any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
144  * 734.7(b).
145  */
146 
147 /*
148  * A "png_get_copyright" function is available, for convenient use in "about"
149  * boxes and the like:
150  *
151  *    printf("%s", png_get_copyright(NULL));
152  *
153  * Also, the PNG logo (in PNG format, of course) is supplied in the
154  * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
155  */
156 
157 /*
158  * The contributing authors would like to thank all those who helped
159  * with testing, bug fixes, and patience.  This wouldn't have been
160  * possible without all of you.
161  *
162  * Thanks to Frank J. T. Wojcik for helping with the documentation.
163  */
164 
165 /* Note about libpng version numbers:
166  *
167  *    Due to various miscommunications, unforeseen code incompatibilities
168  *    and occasional factors outside the authors' control, version numbering
169  *    on the library has not always been consistent and straightforward.
170  *    The following table summarizes matters since version 0.89c, which was
171  *    the first widely used release:
172  *
173  *    source                 png.h  png.h  shared-lib
174  *    version                string   int  version
175  *    -------                ------ -----  ----------
176  *    0.89c "1.0 beta 3"     0.89      89  1.0.89
177  *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
178  *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
179  *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
180  *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
181  *    0.97c                  0.97      97  2.0.97
182  *    0.98                   0.98      98  2.0.98
183  *    0.99                   0.99      98  2.0.99
184  *    0.99a-m                0.99      99  2.0.99
185  *    1.00                   1.00     100  2.1.0 [100 should be 10000]
186  *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
187  *    1.0.1       png.h string is   10001  2.1.0
188  *    1.0.1a-e    identical to the  10002  from here on, the shared library
189  *    1.0.2       source version)   10002  is 2.V where V is the source code
190  *    1.0.2a-b                      10003  version, except as noted.
191  *    1.0.3                         10003
192  *    1.0.3a-d                      10004
193  *    1.0.4                         10004
194  *    1.0.4a-f                      10005
195  *    1.0.5 (+ 2 patches)           10005
196  *    1.0.5a-d                      10006
197  *    1.0.5e-r                      10100 (not source compatible)
198  *    1.0.5s-v                      10006 (not binary compatible)
199  *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)
200  *    1.0.6d-f                      10007 (still binary incompatible)
201  *    1.0.6g                        10007
202  *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)
203  *    1.0.6i                        10007  10.6i
204  *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
205  *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
206  *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
207  *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
208  *    1.0.7                    1    10007  (still compatible)
209  *    ...
210  *    1.0.19                  10    10019  10.so.0.19[.0]
211  *    ...
212  *    1.2.59                  13    10257  12.so.0.59[.0]
213  *    ...
214  *    1.5.30                  15    10527  15.so.15.30[.0]
215  *    ...
216  *    1.6.34                  16    10633  16.so.16.34[.0]
217  *
218  *    Henceforth the source version will match the shared-library major
219  *    and minor numbers; the shared-library major version number will be
220  *    used for changes in backward compatibility, as it is intended.  The
221  *    PNG_LIBPNG_VER macro, which is not used within libpng but is available
222  *    for applications, is an unsigned integer of the form xyyzz corresponding
223  *    to the source version x.y.z (leading zeros in y and z).  Beta versions
224  *    were given the previous public release number plus a letter, until
225  *    version 1.0.6j; from then on they were given the upcoming public
226  *    release number plus "betaNN" or "rcNN".
227  *
228  *    Binary incompatibility exists only when applications make direct access
229  *    to the info_ptr or png_ptr members through png.h, and the compiled
230  *    application is loaded with a different version of the library.
231  *
232  *    DLLNUM will change each time there are forward or backward changes
233  *    in binary compatibility (e.g., when a new feature is added).
234  *
235  * See libpng.txt or libpng.3 for more information.  The PNG specification
236  * is available as a W3C Recommendation and as an ISO Specification,
237  * <https://www.w3.org/TR/2003/REC-PNG-20031110/
238  */
239 
240 /*
241  * Y2K compliance in libpng:
242  * =========================
243  *
244  *    September 29, 2017
245  *
246  *    Since the PNG Development group is an ad-hoc body, we can't make
247  *    an official declaration.
248  *
249  *    This is your unofficial assurance that libpng from version 0.71 and
250  *    upward through 1.6.34 are Y2K compliant.  It is my belief that
251  *    earlier versions were also Y2K compliant.
252  *
253  *    Libpng only has two year fields.  One is a 2-byte unsigned integer
254  *    that will hold years up to 65535.  The other, which is deprecated,
255  *    holds the date in text format, and will hold years up to 9999.
256  *
257  *    The integer is
258  *        "png_uint_16 year" in png_time_struct.
259  *
260  *    The string is
261  *        "char time_buffer[29]" in png_struct.  This is no longer used
262  *    in libpng-1.6.x and will be removed from libpng-1.7.0.
263  *
264  *    There are seven time-related functions:
265  *        png.c: png_convert_to_rfc_1123_buffer() in png.c
266  *          (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
267  *          png_convert_to_rfc_1152() in error prior to libpng-0.98)
268  *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
269  *        png_convert_from_time_t() in pngwrite.c
270  *        png_get_tIME() in pngget.c
271  *        png_handle_tIME() in pngrutil.c, called in pngread.c
272  *        png_set_tIME() in pngset.c
273  *        png_write_tIME() in pngwutil.c, called in pngwrite.c
274  *
275  *    All handle dates properly in a Y2K environment.  The
276  *    png_convert_from_time_t() function calls gmtime() to convert from system
277  *    clock time, which returns (year - 1900), which we properly convert to
278  *    the full 4-digit year.  There is a possibility that libpng applications
279  *    are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
280  *    function, or that they are incorrectly passing only a 2-digit year
281  *    instead of "year - 1900" into the png_convert_from_struct_tm() function,
282  *    but this is not under our control.  The libpng documentation has always
283  *    stated that it works with 4-digit years, and the APIs have been
284  *    documented as such.
285  *
286  *    The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
287  *    integer to hold the year, and can hold years as large as 65535.
288  *
289  *    zlib, upon which libpng depends, is also Y2K compliant.  It contains
290  *    no date-related code.
291  *
292  *       Glenn Randers-Pehrson
293  *       libpng maintainer
294  *       PNG Development Group
295  */
296 
297 #ifndef PNG_H
298 #define PNG_H
299 
300 /* This is not the place to learn how to use libpng. The file libpng-manual.txt
301  * describes how to use libpng, and the file example.c summarizes it
302  * with some code on which to build.  This file is useful for looking
303  * at the actual function definitions and structure components.  If that
304  * file has been stripped from your copy of libpng, you can find it at
305  * <http://www.libpng.org/pub/png/libpng-manual.txt>
306  *
307  * If you just need to read a PNG file and don't want to read the documentation
308  * skip to the end of this file and read the section entitled 'simplified API'.
309  */
310 
311 /* Version information for png.h - this should match the version in png.c */
312 #define PNG_LIBPNG_VER_STRING "1.6.34"
313 #define PNG_HEADER_VERSION_STRING " libpng version 1.6.34 - September 29, 2017\n"
314 
315 #define PNG_LIBPNG_VER_SONUM   16
316 #define PNG_LIBPNG_VER_DLLNUM  16
317 
318 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
319 #define PNG_LIBPNG_VER_MAJOR   1
320 #define PNG_LIBPNG_VER_MINOR   6
321 #define PNG_LIBPNG_VER_RELEASE 34
322 
323 /* This should match the numeric part of the final component of
324  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
325  */
326 
327 #define PNG_LIBPNG_VER_BUILD  0
328 
329 /* Release Status */
330 #define PNG_LIBPNG_BUILD_ALPHA    1
331 #define PNG_LIBPNG_BUILD_BETA     2
332 #define PNG_LIBPNG_BUILD_RC       3
333 #define PNG_LIBPNG_BUILD_STABLE   4
334 #define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7
335 
336 /* Release-Specific Flags */
337 #define PNG_LIBPNG_BUILD_PATCH    8 /* Can be OR'ed with
338                                        PNG_LIBPNG_BUILD_STABLE only */
339 #define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with
340                                        PNG_LIBPNG_BUILD_SPECIAL */
341 #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
342                                        PNG_LIBPNG_BUILD_PRIVATE */
343 
344 #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
345 
346 /* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
347  * We must not include leading zeros.
348  * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
349  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
350  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
351  */
352 #define PNG_LIBPNG_VER 10634 /* 1.6.34 */
353 
354 /* Library configuration: these options cannot be changed after
355  * the library has been built.
356  */
357 #ifndef PNGLCONF_H
358 /* If pnglibconf.h is missing, you can
359  * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
360  */
361 #   include "pnglibconf.h"
362 #endif
363 
364 #ifndef PNG_VERSION_INFO_ONLY
365 /* Machine specific configuration. */
366 #  include "pngconf.h"
367 #endif
368 
369 /*
370  * Added at libpng-1.2.8
371  *
372  * Ref MSDN: Private as priority over Special
373  * VS_FF_PRIVATEBUILD File *was not* built using standard release
374  * procedures. If this value is given, the StringFileInfo block must
375  * contain a PrivateBuild string.
376  *
377  * VS_FF_SPECIALBUILD File *was* built by the original company using
378  * standard release procedures but is a variation of the standard
379  * file of the same version number. If this value is given, the
380  * StringFileInfo block must contain a SpecialBuild string.
381  */
382 
383 #ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */
384 #  define PNG_LIBPNG_BUILD_TYPE \
385        (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
386 #else
387 #  ifdef PNG_LIBPNG_SPECIALBUILD
388 #    define PNG_LIBPNG_BUILD_TYPE \
389          (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
390 #  else
391 #    define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)
392 #  endif
393 #endif
394 
395 #ifndef PNG_VERSION_INFO_ONLY
396 
397 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
398 #ifdef __cplusplus
399 extern "C" {
400 #endif /* __cplusplus */
401 
402 /* Version information for C files, stored in png.c.  This had better match
403  * the version above.
404  */
405 #define png_libpng_ver png_get_header_ver(NULL)
406 
407 /* This file is arranged in several sections:
408  *
409  * 1. [omitted]
410  * 2. Any configuration options that can be specified by for the application
411  *    code when it is built.  (Build time configuration is in pnglibconf.h)
412  * 3. Type definitions (base types are defined in pngconf.h), structure
413  *    definitions.
414  * 4. Exported library functions.
415  * 5. Simplified API.
416  * 6. Implementation options.
417  *
418  * The library source code has additional files (principally pngpriv.h) that
419  * allow configuration of the library.
420  */
421 
422 /* Section 1: [omitted] */
423 
424 /* Section 2: run time configuration
425  * See pnglibconf.h for build time configuration
426  *
427  * Run time configuration allows the application to choose between
428  * implementations of certain arithmetic APIs.  The default is set
429  * at build time and recorded in pnglibconf.h, but it is safe to
430  * override these (and only these) settings.  Note that this won't
431  * change what the library does, only application code, and the
432  * settings can (and probably should) be made on a per-file basis
433  * by setting the #defines before including png.h
434  *
435  * Use macros to read integers from PNG data or use the exported
436  * functions?
437  *   PNG_USE_READ_MACROS: use the macros (see below)  Note that
438  *     the macros evaluate their argument multiple times.
439  *   PNG_NO_USE_READ_MACROS: call the relevant library function.
440  *
441  * Use the alternative algorithm for compositing alpha samples that
442  * does not use division?
443  *   PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division'
444  *      algorithm.
445  *   PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm.
446  *
447  * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is
448  * false?
449  *   PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error
450  *      APIs to png_warning.
451  * Otherwise the calls are mapped to png_error.
452  */
453 
454 /* Section 3: type definitions, including structures and compile time
455  * constants.
456  * See pngconf.h for base types that vary by machine/system
457  */
458 
459 /* This triggers a compiler error in png.c, if png.c and png.h
460  * do not agree upon the version number.
461  */
462 typedef char* png_libpng_version_1_6_34;
463 
464 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
465  *
466  * png_struct is the cache of information used while reading or writing a single
467  * PNG file.  One of these is always required, although the simplified API
468  * (below) hides the creation and destruction of it.
469  */
470 typedef struct png_struct_def png_struct;
471 typedef const png_struct * png_const_structp;
472 typedef png_struct * png_structp;
473 typedef png_struct * * png_structpp;
474 
475 /* png_info contains information read from or to be written to a PNG file.  One
476  * or more of these must exist while reading or creating a PNG file.  The
477  * information is not used by libpng during read but is used to control what
478  * gets written when a PNG file is created.  "png_get_" function calls read
479  * information during read and "png_set_" functions calls write information
480  * when creating a PNG.
481  * been moved into a separate header file that is not accessible to
482  * applications.  Read libpng-manual.txt or libpng.3 for more info.
483  */
484 typedef struct png_info_def png_info;
485 typedef png_info * png_infop;
486 typedef const png_info * png_const_infop;
487 typedef png_info * * png_infopp;
488 
489 /* Types with names ending 'p' are pointer types.  The corresponding types with
490  * names ending 'rp' are identical pointer types except that the pointer is
491  * marked 'restrict', which means that it is the only pointer to the object
492  * passed to the function.  Applications should not use the 'restrict' types;
493  * it is always valid to pass 'p' to a pointer with a function argument of the
494  * corresponding 'rp' type.  Different compilers have different rules with
495  * regard to type matching in the presence of 'restrict'.  For backward
496  * compatibility libpng callbacks never have 'restrict' in their parameters and,
497  * consequentially, writing portable application code is extremely difficult if
498  * an attempt is made to use 'restrict'.
499  */
500 typedef png_struct * PNG_RESTRICT png_structrp;
501 typedef const png_struct * PNG_RESTRICT png_const_structrp;
502 typedef png_info * PNG_RESTRICT png_inforp;
503 typedef const png_info * PNG_RESTRICT png_const_inforp;
504 
505 /* Three color definitions.  The order of the red, green, and blue, (and the
506  * exact size) is not important, although the size of the fields need to
507  * be png_byte or png_uint_16 (as defined below).
508  */
509 typedef struct png_color_struct
510 {
511    png_byte red;
512    png_byte green;
513    png_byte blue;
514 } png_color;
515 typedef png_color * png_colorp;
516 typedef const png_color * png_const_colorp;
517 typedef png_color * * png_colorpp;
518 
519 typedef struct png_color_16_struct
520 {
521    png_byte index;    /* used for palette files */
522    png_uint_16 red;   /* for use in red green blue files */
523    png_uint_16 green;
524    png_uint_16 blue;
525    png_uint_16 gray;  /* for use in grayscale files */
526 } png_color_16;
527 typedef png_color_16 * png_color_16p;
528 typedef const png_color_16 * png_const_color_16p;
529 typedef png_color_16 * * png_color_16pp;
530 
531 typedef struct png_color_8_struct
532 {
533    png_byte red;   /* for use in red green blue files */
534    png_byte green;
535    png_byte blue;
536    png_byte gray;  /* for use in grayscale files */
537    png_byte alpha; /* for alpha channel files */
538 } png_color_8;
539 typedef png_color_8 * png_color_8p;
540 typedef const png_color_8 * png_const_color_8p;
541 typedef png_color_8 * * png_color_8pp;
542 
543 /*
544  * The following two structures are used for the in-core representation
545  * of sPLT chunks.
546  */
547 typedef struct png_sPLT_entry_struct
548 {
549    png_uint_16 red;
550    png_uint_16 green;
551    png_uint_16 blue;
552    png_uint_16 alpha;
553    png_uint_16 frequency;
554 } png_sPLT_entry;
555 typedef png_sPLT_entry * png_sPLT_entryp;
556 typedef const png_sPLT_entry * png_const_sPLT_entryp;
557 typedef png_sPLT_entry * * png_sPLT_entrypp;
558 
559 /*  When the depth of the sPLT palette is 8 bits, the color and alpha samples
560  *  occupy the LSB of their respective members, and the MSB of each member
561  *  is zero-filled.  The frequency member always occupies the full 16 bits.
562  */
563 
564 typedef struct png_sPLT_struct
565 {
566    png_charp name;           /* palette name */
567    png_byte depth;           /* depth of palette samples */
568    png_sPLT_entryp entries;  /* palette entries */
569    png_int_32 nentries;      /* number of palette entries */
570 } png_sPLT_t;
571 typedef png_sPLT_t * png_sPLT_tp;
572 typedef const png_sPLT_t * png_const_sPLT_tp;
573 typedef png_sPLT_t * * png_sPLT_tpp;
574 
575 #ifdef PNG_TEXT_SUPPORTED
576 /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
577  * and whether that contents is compressed or not.  The "key" field
578  * points to a regular zero-terminated C string.  The "text" fields can be a
579  * regular C string, an empty string, or a NULL pointer.
580  * However, the structure returned by png_get_text() will always contain
581  * the "text" field as a regular zero-terminated C string (possibly
582  * empty), never a NULL pointer, so it can be safely used in printf() and
583  * other string-handling functions.  Note that the "itxt_length", "lang", and
584  * "lang_key" members of the structure only exist when the library is built
585  * with iTXt chunk support.  Prior to libpng-1.4.0 the library was built by
586  * default without iTXt support. Also note that when iTXt *is* supported,
587  * the "lang" and "lang_key" fields contain NULL pointers when the
588  * "compression" field contains * PNG_TEXT_COMPRESSION_NONE or
589  * PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the
590  * same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag"
591  * which is always 0 or 1, or its "compression method" which is always 0.
592  */
593 typedef struct png_text_struct
594 {
595    int  compression;       /* compression value:
596                              -1: tEXt, none
597                               0: zTXt, deflate
598                               1: iTXt, none
599                               2: iTXt, deflate  */
600    png_charp key;          /* keyword, 1-79 character description of "text" */
601    png_charp text;         /* comment, may be an empty string (ie "")
602                               or a NULL pointer */
603    png_size_t text_length; /* length of the text string */
604    png_size_t itxt_length; /* length of the itxt string */
605    png_charp lang;         /* language code, 0-79 characters
606                               or a NULL pointer */
607    png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more
608                               chars or a NULL pointer */
609 } png_text;
610 typedef png_text * png_textp;
611 typedef const png_text * png_const_textp;
612 typedef png_text * * png_textpp;
613 #endif
614 
615 /* Supported compression types for text in PNG files (tEXt, and zTXt).
616  * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
617 #define PNG_TEXT_COMPRESSION_NONE_WR -3
618 #define PNG_TEXT_COMPRESSION_zTXt_WR -2
619 #define PNG_TEXT_COMPRESSION_NONE    -1
620 #define PNG_TEXT_COMPRESSION_zTXt     0
621 #define PNG_ITXT_COMPRESSION_NONE     1
622 #define PNG_ITXT_COMPRESSION_zTXt     2
623 #define PNG_TEXT_COMPRESSION_LAST     3  /* Not a valid value */
624 
625 /* png_time is a way to hold the time in an machine independent way.
626  * Two conversions are provided, both from time_t and struct tm.  There
627  * is no portable way to convert to either of these structures, as far
628  * as I know.  If you know of a portable way, send it to me.  As a side
629  * note - PNG has always been Year 2000 compliant!
630  */
631 typedef struct png_time_struct
632 {
633    png_uint_16 year; /* full year, as in, 1995 */
634    png_byte month;   /* month of year, 1 - 12 */
635    png_byte day;     /* day of month, 1 - 31 */
636    png_byte hour;    /* hour of day, 0 - 23 */
637    png_byte minute;  /* minute of hour, 0 - 59 */
638    png_byte second;  /* second of minute, 0 - 60 (for leap seconds) */
639 } png_time;
640 typedef png_time * png_timep;
641 typedef const png_time * png_const_timep;
642 typedef png_time * * png_timepp;
643 
644 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) ||\
645    defined(PNG_USER_CHUNKS_SUPPORTED)
646 /* png_unknown_chunk is a structure to hold queued chunks for which there is
647  * no specific support.  The idea is that we can use this to queue
648  * up private chunks for output even though the library doesn't actually
649  * know about their semantics.
650  *
651  * The data in the structure is set by libpng on read and used on write.
652  */
653 typedef struct png_unknown_chunk_t
654 {
655    png_byte name[5]; /* Textual chunk name with '\0' terminator */
656    png_byte *data;   /* Data, should not be modified on read! */
657    png_size_t size;
658 
659    /* On write 'location' must be set using the flag values listed below.
660     * Notice that on read it is set by libpng however the values stored have
661     * more bits set than are listed below.  Always treat the value as a
662     * bitmask.  On write set only one bit - setting multiple bits may cause the
663     * chunk to be written in multiple places.
664     */
665    png_byte location; /* mode of operation at read time */
666 }
667 png_unknown_chunk;
668 
669 typedef png_unknown_chunk * png_unknown_chunkp;
670 typedef const png_unknown_chunk * png_const_unknown_chunkp;
671 typedef png_unknown_chunk * * png_unknown_chunkpp;
672 #endif
673 
674 /* Flag values for the unknown chunk location byte. */
675 #define PNG_HAVE_IHDR  0x01
676 #define PNG_HAVE_PLTE  0x02
677 #define PNG_AFTER_IDAT 0x08
678 
679 /* Maximum positive integer used in PNG is (2^31)-1 */
680 #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
681 #define PNG_UINT_32_MAX ((png_uint_32)(-1))
682 #define PNG_SIZE_MAX ((png_size_t)(-1))
683 
684 /* These are constants for fixed point values encoded in the
685  * PNG specification manner (x100000)
686  */
687 #define PNG_FP_1    100000
688 #define PNG_FP_HALF  50000
689 #define PNG_FP_MAX  ((png_fixed_point)0x7fffffffL)
690 #define PNG_FP_MIN  (-PNG_FP_MAX)
691 
692 /* These describe the color_type field in png_info. */
693 /* color type masks */
694 #define PNG_COLOR_MASK_PALETTE    1
695 #define PNG_COLOR_MASK_COLOR      2
696 #define PNG_COLOR_MASK_ALPHA      4
697 
698 /* color types.  Note that not all combinations are legal */
699 #define PNG_COLOR_TYPE_GRAY 0
700 #define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
701 #define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)
702 #define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
703 #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
704 /* aliases */
705 #define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA
706 #define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA
707 
708 /* This is for compression type. PNG 1.0-1.2 only define the single type. */
709 #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
710 #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE
711 
712 /* This is for filter type. PNG 1.0-1.2 only define the single type. */
713 #define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */
714 #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
715 #define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE
716 
717 /* These are for the interlacing type.  These values should NOT be changed. */
718 #define PNG_INTERLACE_NONE        0 /* Non-interlaced image */
719 #define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */
720 #define PNG_INTERLACE_LAST        2 /* Not a valid value */
721 
722 /* These are for the oFFs chunk.  These values should NOT be changed. */
723 #define PNG_OFFSET_PIXEL          0 /* Offset in pixels */
724 #define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */
725 #define PNG_OFFSET_LAST           2 /* Not a valid value */
726 
727 /* These are for the pCAL chunk.  These values should NOT be changed. */
728 #define PNG_EQUATION_LINEAR       0 /* Linear transformation */
729 #define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */
730 #define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */
731 #define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */
732 #define PNG_EQUATION_LAST         4 /* Not a valid value */
733 
734 /* These are for the sCAL chunk.  These values should NOT be changed. */
735 #define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */
736 #define PNG_SCALE_METER           1 /* meters per pixel */
737 #define PNG_SCALE_RADIAN          2 /* radians per pixel */
738 #define PNG_SCALE_LAST            3 /* Not a valid value */
739 
740 /* These are for the pHYs chunk.  These values should NOT be changed. */
741 #define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */
742 #define PNG_RESOLUTION_METER      1 /* pixels/meter */
743 #define PNG_RESOLUTION_LAST       2 /* Not a valid value */
744 
745 /* These are for the sRGB chunk.  These values should NOT be changed. */
746 #define PNG_sRGB_INTENT_PERCEPTUAL 0
747 #define PNG_sRGB_INTENT_RELATIVE   1
748 #define PNG_sRGB_INTENT_SATURATION 2
749 #define PNG_sRGB_INTENT_ABSOLUTE   3
750 #define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */
751 
752 /* This is for text chunks */
753 #define PNG_KEYWORD_MAX_LENGTH     79
754 
755 /* Maximum number of entries in PLTE/sPLT/tRNS arrays */
756 #define PNG_MAX_PALETTE_LENGTH    256
757 
758 /* These determine if an ancillary chunk's data has been successfully read
759  * from the PNG header, or if the application has filled in the corresponding
760  * data in the info_struct to be written into the output file.  The values
761  * of the PNG_INFO_<chunk> defines should NOT be changed.
762  */
763 #define PNG_INFO_gAMA 0x0001U
764 #define PNG_INFO_sBIT 0x0002U
765 #define PNG_INFO_cHRM 0x0004U
766 #define PNG_INFO_PLTE 0x0008U
767 #define PNG_INFO_tRNS 0x0010U
768 #define PNG_INFO_bKGD 0x0020U
769 #define PNG_INFO_hIST 0x0040U
770 #define PNG_INFO_pHYs 0x0080U
771 #define PNG_INFO_oFFs 0x0100U
772 #define PNG_INFO_tIME 0x0200U
773 #define PNG_INFO_pCAL 0x0400U
774 #define PNG_INFO_sRGB 0x0800U  /* GR-P, 0.96a */
775 #define PNG_INFO_iCCP 0x1000U  /* ESR, 1.0.6 */
776 #define PNG_INFO_sPLT 0x2000U  /* ESR, 1.0.6 */
777 #define PNG_INFO_sCAL 0x4000U  /* ESR, 1.0.6 */
778 #define PNG_INFO_IDAT 0x8000U  /* ESR, 1.0.6 */
779 #define PNG_INFO_eXIf 0x10000U /* GR-P, 1.6.31 */
780 
781 /* This is used for the transformation routines, as some of them
782  * change these values for the row.  It also should enable using
783  * the routines for other purposes.
784  */
785 typedef struct png_row_info_struct
786 {
787    png_uint_32 width;    /* width of row */
788    png_size_t rowbytes;  /* number of bytes in row */
789    png_byte color_type;  /* color type of row */
790    png_byte bit_depth;   /* bit depth of row */
791    png_byte channels;    /* number of channels (1, 2, 3, or 4) */
792    png_byte pixel_depth; /* bits per pixel (depth * channels) */
793 } png_row_info;
794 
795 typedef png_row_info * png_row_infop;
796 typedef png_row_info * * png_row_infopp;
797 
798 /* These are the function types for the I/O functions and for the functions
799  * that allow the user to override the default I/O functions with his or her
800  * own.  The png_error_ptr type should match that of user-supplied warning
801  * and error functions, while the png_rw_ptr type should match that of the
802  * user read/write data functions.  Note that the 'write' function must not
803  * modify the buffer it is passed. The 'read' function, on the other hand, is
804  * expected to return the read data in the buffer.
805  */
806 typedef PNG_CALLBACK(void, *png_error_ptr, (png_structp, png_const_charp));
807 typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, png_size_t));
808 typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp));
809 typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32,
810     int));
811 typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32,
812     int));
813 
814 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
815 typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
816 typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
817 
818 /* The following callback receives png_uint_32 row_number, int pass for the
819  * png_bytep data of the row.  When transforming an interlaced image the
820  * row number is the row number within the sub-image of the interlace pass, so
821  * the value will increase to the height of the sub-image (not the full image)
822  * then reset to 0 for the next pass.
823  *
824  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
825  * find the output pixel (x,y) given an interlaced sub-image pixel
826  * (row,col,pass).  (See below for these macros.)
827  */
828 typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp, png_bytep,
829     png_uint_32, int));
830 #endif
831 
832 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
833     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
834 typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop,
835     png_bytep));
836 #endif
837 
838 #ifdef PNG_USER_CHUNKS_SUPPORTED
839 typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,
840     png_unknown_chunkp));
841 #endif
842 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
843 /* not used anywhere */
844 /* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
845 #endif
846 
847 #ifdef PNG_SETJMP_SUPPORTED
848 /* This must match the function definition in <setjmp.h>, and the application
849  * must include this before png.h to obtain the definition of jmp_buf.  The
850  * function is required to be PNG_NORETURN, but this is not checked.  If the
851  * function does return the application will crash via an abort() or similar
852  * system level call.
853  *
854  * If you get a warning here while building the library you may need to make
855  * changes to ensure that pnglibconf.h records the calling convention used by
856  * your compiler.  This may be very difficult - try using a different compiler
857  * to build the library!
858  */
859 PNG_FUNCTION(void, (PNGCAPI *png_longjmp_ptr), PNGARG((jmp_buf, int)), typedef);
860 #endif
861 
862 /* Transform masks for the high-level interface */
863 #define PNG_TRANSFORM_IDENTITY       0x0000    /* read and write */
864 #define PNG_TRANSFORM_STRIP_16       0x0001    /* read only */
865 #define PNG_TRANSFORM_STRIP_ALPHA    0x0002    /* read only */
866 #define PNG_TRANSFORM_PACKING        0x0004    /* read and write */
867 #define PNG_TRANSFORM_PACKSWAP       0x0008    /* read and write */
868 #define PNG_TRANSFORM_EXPAND         0x0010    /* read only */
869 #define PNG_TRANSFORM_INVERT_MONO    0x0020    /* read and write */
870 #define PNG_TRANSFORM_SHIFT          0x0040    /* read and write */
871 #define PNG_TRANSFORM_BGR            0x0080    /* read and write */
872 #define PNG_TRANSFORM_SWAP_ALPHA     0x0100    /* read and write */
873 #define PNG_TRANSFORM_SWAP_ENDIAN    0x0200    /* read and write */
874 #define PNG_TRANSFORM_INVERT_ALPHA   0x0400    /* read and write */
875 #define PNG_TRANSFORM_STRIP_FILLER   0x0800    /* write only */
876 /* Added to libpng-1.2.34 */
877 #define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER
878 #define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */
879 /* Added to libpng-1.4.0 */
880 #define PNG_TRANSFORM_GRAY_TO_RGB   0x2000      /* read only */
881 /* Added to libpng-1.5.4 */
882 #define PNG_TRANSFORM_EXPAND_16     0x4000      /* read only */
883 #if INT_MAX >= 0x8000 /* else this might break */
884 #define PNG_TRANSFORM_SCALE_16      0x8000      /* read only */
885 #endif
886 
887 /* Flags for MNG supported features */
888 #define PNG_FLAG_MNG_EMPTY_PLTE     0x01
889 #define PNG_FLAG_MNG_FILTER_64      0x04
890 #define PNG_ALL_MNG_FEATURES        0x05
891 
892 /* NOTE: prior to 1.5 these functions had no 'API' style declaration,
893  * this allowed the zlib default functions to be used on Windows
894  * platforms.  In 1.5 the zlib default malloc (which just calls malloc and
895  * ignores the first argument) should be completely compatible with the
896  * following.
897  */
898 typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,
899     png_alloc_size_t));
900 typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));
901 
902 /* Section 4: exported functions
903  * Here are the function definitions most commonly used.  This is not
904  * the place to find out how to use libpng.  See libpng-manual.txt for the
905  * full explanation, see example.c for the summary.  This just provides
906  * a simple one line description of the use of each function.
907  *
908  * The PNG_EXPORT() and PNG_EXPORTA() macros used below are defined in
909  * pngconf.h and in the *.dfn files in the scripts directory.
910  *
911  *   PNG_EXPORT(ordinal, type, name, (args));
912  *
913  *       ordinal:    ordinal that is used while building
914  *                   *.def files. The ordinal value is only
915  *                   relevant when preprocessing png.h with
916  *                   the *.dfn files for building symbol table
917  *                   entries, and are removed by pngconf.h.
918  *       type:       return type of the function
919  *       name:       function name
920  *       args:       function arguments, with types
921  *
922  * When we wish to append attributes to a function prototype we use
923  * the PNG_EXPORTA() macro instead.
924  *
925  *   PNG_EXPORTA(ordinal, type, name, (args), attributes);
926  *
927  *       ordinal, type, name, and args: same as in PNG_EXPORT().
928  *       attributes: function attributes
929  */
930 
931 /* Returns the version number of the library */
932 PNG_EXPORT(1, png_uint_32, png_access_version_number, (void));
933 
934 /* Tell lib we have already handled the first <num_bytes> magic bytes.
935  * Handling more than 8 bytes from the beginning of the file is an error.
936  */
937 PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
938 
939 /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
940  * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG
941  * signature, and non-zero otherwise.  Having num_to_check == 0 or
942  * start > 7 will always fail (ie return non-zero).
943  */
944 PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, png_size_t start,
945     png_size_t num_to_check));
946 
947 /* Simple signature checking function.  This is the same as calling
948  * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
949  */
950 #define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
951 
952 /* Allocate and initialize png_ptr struct for reading, and any other memory. */
953 PNG_EXPORTA(4, png_structp, png_create_read_struct,
954     (png_const_charp user_png_ver, png_voidp error_ptr,
955     png_error_ptr error_fn, png_error_ptr warn_fn),
956     PNG_ALLOCATED);
957 
958 /* Allocate and initialize png_ptr struct for writing, and any other memory */
959 PNG_EXPORTA(5, png_structp, png_create_write_struct,
960     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
961     png_error_ptr warn_fn),
962     PNG_ALLOCATED);
963 
964 PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
965     (png_const_structrp png_ptr));
966 
967 PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
968     png_size_t size));
969 
970 /* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
971  * match up.
972  */
973 #ifdef PNG_SETJMP_SUPPORTED
974 /* This function returns the jmp_buf built in to *png_ptr.  It must be
975  * supplied with an appropriate 'longjmp' function to use on that jmp_buf
976  * unless the default error function is overridden in which case NULL is
977  * acceptable.  The size of the jmp_buf is checked against the actual size
978  * allocated by the library - the call will return NULL on a mismatch
979  * indicating an ABI mismatch.
980  */
981 PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structrp png_ptr,
982     png_longjmp_ptr longjmp_fn, size_t jmp_buf_size));
983 #  define png_jmpbuf(png_ptr) \
984       (*png_set_longjmp_fn((png_ptr), longjmp, (sizeof (jmp_buf))))
985 #else
986 #  define png_jmpbuf(png_ptr) \
987       (LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP)
988 #endif
989 /* This function should be used by libpng applications in place of
990  * longjmp(png_ptr->jmpbuf, val).  If longjmp_fn() has been set, it
991  * will use it; otherwise it will call PNG_ABORT().  This function was
992  * added in libpng-1.5.0.
993  */
994 PNG_EXPORTA(9, void, png_longjmp, (png_const_structrp png_ptr, int val),
995     PNG_NORETURN);
996 
997 #ifdef PNG_READ_SUPPORTED
998 /* Reset the compression stream */
999 PNG_EXPORTA(10, int, png_reset_zstream, (png_structrp png_ptr), PNG_DEPRECATED);
1000 #endif
1001 
1002 /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
1003 #ifdef PNG_USER_MEM_SUPPORTED
1004 PNG_EXPORTA(11, png_structp, png_create_read_struct_2,
1005     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
1006     png_error_ptr warn_fn,
1007     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
1008     PNG_ALLOCATED);
1009 PNG_EXPORTA(12, png_structp, png_create_write_struct_2,
1010     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
1011     png_error_ptr warn_fn,
1012     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
1013     PNG_ALLOCATED);
1014 #endif
1015 
1016 /* Write the PNG file signature. */
1017 PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr));
1018 
1019 /* Write a PNG chunk - size, type, (optional) data, CRC. */
1020 PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep
1021     chunk_name, png_const_bytep data, png_size_t length));
1022 
1023 /* Write the start of a PNG chunk - length and chunk name. */
1024 PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
1025     png_const_bytep chunk_name, png_uint_32 length));
1026 
1027 /* Write the data of a PNG chunk started with png_write_chunk_start(). */
1028 PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr,
1029     png_const_bytep data, png_size_t length));
1030 
1031 /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
1032 PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr));
1033 
1034 /* Allocate and initialize the info structure */
1035 PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr),
1036     PNG_ALLOCATED);
1037 
1038 /* DEPRECATED: this function allowed init structures to be created using the
1039  * default allocation method (typically malloc).  Use is deprecated in 1.6.0 and
1040  * the API will be removed in the future.
1041  */
1042 PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr,
1043     png_size_t png_info_struct_size), PNG_DEPRECATED);
1044 
1045 /* Writes all the PNG information before the image. */
1046 PNG_EXPORT(20, void, png_write_info_before_PLTE,
1047     (png_structrp png_ptr, png_const_inforp info_ptr));
1048 PNG_EXPORT(21, void, png_write_info,
1049     (png_structrp png_ptr, png_const_inforp info_ptr));
1050 
1051 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1052 /* Read the information before the actual image data. */
1053 PNG_EXPORT(22, void, png_read_info,
1054     (png_structrp png_ptr, png_inforp info_ptr));
1055 #endif
1056 
1057 #ifdef PNG_TIME_RFC1123_SUPPORTED
1058    /* Convert to a US string format: there is no localization support in this
1059     * routine.  The original implementation used a 29 character buffer in
1060     * png_struct, this will be removed in future versions.
1061     */
1062 #if PNG_LIBPNG_VER < 10700
1063 /* To do: remove this from libpng17 (and from libpng17/png.c and pngstruct.h) */
1064 PNG_EXPORTA(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr,
1065     png_const_timep ptime),PNG_DEPRECATED);
1066 #endif
1067 PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29],
1068     png_const_timep ptime));
1069 #endif
1070 
1071 #ifdef PNG_CONVERT_tIME_SUPPORTED
1072 /* Convert from a struct tm to png_time */
1073 PNG_EXPORT(24, void, png_convert_from_struct_tm, (png_timep ptime,
1074     const struct tm * ttime));
1075 
1076 /* Convert from time_t to png_time.  Uses gmtime() */
1077 PNG_EXPORT(25, void, png_convert_from_time_t, (png_timep ptime, time_t ttime));
1078 #endif /* CONVERT_tIME */
1079 
1080 #ifdef PNG_READ_EXPAND_SUPPORTED
1081 /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
1082 PNG_EXPORT(26, void, png_set_expand, (png_structrp png_ptr));
1083 PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structrp png_ptr));
1084 PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structrp png_ptr));
1085 PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structrp png_ptr));
1086 #endif
1087 
1088 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1089 /* Expand to 16-bit channels, forces conversion of palette to RGB and expansion
1090  * of a tRNS chunk if present.
1091  */
1092 PNG_EXPORT(221, void, png_set_expand_16, (png_structrp png_ptr));
1093 #endif
1094 
1095 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
1096 /* Use blue, green, red order for pixels. */
1097 PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr));
1098 #endif
1099 
1100 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1101 /* Expand the grayscale to 24-bit RGB if necessary. */
1102 PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr));
1103 #endif
1104 
1105 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1106 /* Reduce RGB to grayscale. */
1107 #define PNG_ERROR_ACTION_NONE  1
1108 #define PNG_ERROR_ACTION_WARN  2
1109 #define PNG_ERROR_ACTION_ERROR 3
1110 #define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/
1111 
1112 PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structrp png_ptr,
1113     int error_action, double red, double green))
1114 PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structrp png_ptr,
1115     int error_action, png_fixed_point red, png_fixed_point green))
1116 
1117 PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp
1118     png_ptr));
1119 #endif
1120 
1121 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
1122 PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
1123     png_colorp palette));
1124 #endif
1125 
1126 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1127 /* How the alpha channel is interpreted - this affects how the color channels
1128  * of a PNG file are returned to the calling application when an alpha channel,
1129  * or a tRNS chunk in a palette file, is present.
1130  *
1131  * This has no effect on the way pixels are written into a PNG output
1132  * datastream. The color samples in a PNG datastream are never premultiplied
1133  * with the alpha samples.
1134  *
1135  * The default is to return data according to the PNG specification: the alpha
1136  * channel is a linear measure of the contribution of the pixel to the
1137  * corresponding composited pixel, and the color channels are unassociated
1138  * (not premultiplied).  The gamma encoded color channels must be scaled
1139  * according to the contribution and to do this it is necessary to undo
1140  * the encoding, scale the color values, perform the composition and reencode
1141  * the values.  This is the 'PNG' mode.
1142  *
1143  * The alternative is to 'associate' the alpha with the color information by
1144  * storing color channel values that have been scaled by the alpha.
1145  * image.  These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
1146  * (the latter being the two common names for associated alpha color channels).
1147  *
1148  * For the 'OPTIMIZED' mode, a pixel is treated as opaque only if the alpha
1149  * value is equal to the maximum value.
1150  *
1151  * The final choice is to gamma encode the alpha channel as well.  This is
1152  * broken because, in practice, no implementation that uses this choice
1153  * correctly undoes the encoding before handling alpha composition.  Use this
1154  * choice only if other serious errors in the software or hardware you use
1155  * mandate it; the typical serious error is for dark halos to appear around
1156  * opaque areas of the composited PNG image because of arithmetic overflow.
1157  *
1158  * The API function png_set_alpha_mode specifies which of these choices to use
1159  * with an enumerated 'mode' value and the gamma of the required output:
1160  */
1161 #define PNG_ALPHA_PNG           0 /* according to the PNG standard */
1162 #define PNG_ALPHA_STANDARD      1 /* according to Porter/Duff */
1163 #define PNG_ALPHA_ASSOCIATED    1 /* as above; this is the normal practice */
1164 #define PNG_ALPHA_PREMULTIPLIED 1 /* as above */
1165 #define PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */
1166 #define PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */
1167 
1168 PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structrp png_ptr, int mode,
1169     double output_gamma))
1170 PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
1171     int mode, png_fixed_point output_gamma))
1172 #endif
1173 
1174 #if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1175 /* The output_gamma value is a screen gamma in libpng terminology: it expresses
1176  * how to decode the output values, not how they are encoded.
1177  */
1178 #define PNG_DEFAULT_sRGB -1       /* sRGB gamma and color space */
1179 #define PNG_GAMMA_MAC_18 -2       /* Old Mac '1.8' gamma and color space */
1180 #define PNG_GAMMA_sRGB   220000   /* Television standards--matches sRGB gamma */
1181 #define PNG_GAMMA_LINEAR PNG_FP_1 /* Linear */
1182 #endif
1183 
1184 /* The following are examples of calls to png_set_alpha_mode to achieve the
1185  * required overall gamma correction and, where necessary, alpha
1186  * premultiplication.
1187  *
1188  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1189  *    This is the default libpng handling of the alpha channel - it is not
1190  *    pre-multiplied into the color components.  In addition the call states
1191  *    that the output is for a sRGB system and causes all PNG files without gAMA
1192  *    chunks to be assumed to be encoded using sRGB.
1193  *
1194  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1195  *    In this case the output is assumed to be something like an sRGB conformant
1196  *    display preceeded by a power-law lookup table of power 1.45.  This is how
1197  *    early Mac systems behaved.
1198  *
1199  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
1200  *    This is the classic Jim Blinn approach and will work in academic
1201  *    environments where everything is done by the book.  It has the shortcoming
1202  *    of assuming that input PNG data with no gamma information is linear - this
1203  *    is unlikely to be correct unless the PNG files where generated locally.
1204  *    Most of the time the output precision will be so low as to show
1205  *    significant banding in dark areas of the image.
1206  *
1207  * png_set_expand_16(pp);
1208  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
1209  *    This is a somewhat more realistic Jim Blinn inspired approach.  PNG files
1210  *    are assumed to have the sRGB encoding if not marked with a gamma value and
1211  *    the output is always 16 bits per component.  This permits accurate scaling
1212  *    and processing of the data.  If you know that your input PNG files were
1213  *    generated locally you might need to replace PNG_DEFAULT_sRGB with the
1214  *    correct value for your system.
1215  *
1216  * png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
1217  *    If you just need to composite the PNG image onto an existing background
1218  *    and if you control the code that does this you can use the optimization
1219  *    setting.  In this case you just copy completely opaque pixels to the
1220  *    output.  For pixels that are not completely transparent (you just skip
1221  *    those) you do the composition math using png_composite or png_composite_16
1222  *    below then encode the resultant 8-bit or 16-bit values to match the output
1223  *    encoding.
1224  *
1225  * Other cases
1226  *    If neither the PNG nor the standard linear encoding work for you because
1227  *    of the software or hardware you use then you have a big problem.  The PNG
1228  *    case will probably result in halos around the image.  The linear encoding
1229  *    will probably result in a washed out, too bright, image (it's actually too
1230  *    contrasty.)  Try the ALPHA_OPTIMIZED mode above - this will probably
1231  *    substantially reduce the halos.  Alternatively try:
1232  *
1233  * png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
1234  *    This option will also reduce the halos, but there will be slight dark
1235  *    halos round the opaque parts of the image where the background is light.
1236  *    In the OPTIMIZED mode the halos will be light halos where the background
1237  *    is dark.  Take your pick - the halos are unavoidable unless you can get
1238  *    your hardware/software fixed!  (The OPTIMIZED approach is slightly
1239  *    faster.)
1240  *
1241  * When the default gamma of PNG files doesn't match the output gamma.
1242  *    If you have PNG files with no gamma information png_set_alpha_mode allows
1243  *    you to provide a default gamma, but it also sets the ouput gamma to the
1244  *    matching value.  If you know your PNG files have a gamma that doesn't
1245  *    match the output you can take advantage of the fact that
1246  *    png_set_alpha_mode always sets the output gamma but only sets the PNG
1247  *    default if it is not already set:
1248  *
1249  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1250  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1251  *    The first call sets both the default and the output gamma values, the
1252  *    second call overrides the output gamma without changing the default.  This
1253  *    is easier than achieving the same effect with png_set_gamma.  You must use
1254  *    PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
1255  *    fire if more than one call to png_set_alpha_mode and png_set_background is
1256  *    made in the same read operation, however multiple calls with PNG_ALPHA_PNG
1257  *    are ignored.
1258  */
1259 
1260 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1261 PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
1262 #endif
1263 
1264 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
1265     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
1266 PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr));
1267 #endif
1268 
1269 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
1270     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
1271 PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
1272 #endif
1273 
1274 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
1275 /* Add a filler byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
1276 PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler,
1277     int flags));
1278 /* The values of the PNG_FILLER_ defines should NOT be changed */
1279 #  define PNG_FILLER_BEFORE 0
1280 #  define PNG_FILLER_AFTER 1
1281 /* Add an alpha byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
1282 PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
1283     png_uint_32 filler, int flags));
1284 #endif /* READ_FILLER || WRITE_FILLER */
1285 
1286 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
1287 /* Swap bytes in 16-bit depth files. */
1288 PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr));
1289 #endif
1290 
1291 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
1292 /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
1293 PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr));
1294 #endif
1295 
1296 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
1297     defined(PNG_WRITE_PACKSWAP_SUPPORTED)
1298 /* Swap packing order of pixels in bytes. */
1299 PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr));
1300 #endif
1301 
1302 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
1303 /* Converts files to legal bit depths. */
1304 PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p
1305     true_bits));
1306 #endif
1307 
1308 #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
1309     defined(PNG_WRITE_INTERLACING_SUPPORTED)
1310 /* Have the code handle the interlacing.  Returns the number of passes.
1311  * MUST be called before png_read_update_info or png_start_read_image,
1312  * otherwise it will not have the desired effect.  Note that it is still
1313  * necessary to call png_read_row or png_read_rows png_get_image_height
1314  * times for each pass.
1315 */
1316 PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr));
1317 #endif
1318 
1319 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
1320 /* Invert monochrome files */
1321 PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
1322 #endif
1323 
1324 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1325 /* Handle alpha and tRNS by replacing with a background color.  Prior to
1326  * libpng-1.5.4 this API must not be called before the PNG file header has been
1327  * read.  Doing so will result in unexpected behavior and possible warnings or
1328  * errors if the PNG file contains a bKGD chunk.
1329  */
1330 PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr,
1331     png_const_color_16p background_color, int background_gamma_code,
1332     int need_expand, double background_gamma))
1333 PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr,
1334     png_const_color_16p background_color, int background_gamma_code,
1335     int need_expand, png_fixed_point background_gamma))
1336 #endif
1337 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1338 #  define PNG_BACKGROUND_GAMMA_UNKNOWN 0
1339 #  define PNG_BACKGROUND_GAMMA_SCREEN  1
1340 #  define PNG_BACKGROUND_GAMMA_FILE    2
1341 #  define PNG_BACKGROUND_GAMMA_UNIQUE  3
1342 #endif
1343 
1344 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1345 /* Scale a 16-bit depth file down to 8-bit, accurately. */
1346 PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
1347 #endif
1348 
1349 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1350 #define PNG_READ_16_TO_8_SUPPORTED /* Name prior to 1.5.4 */
1351 /* Strip the second byte of information from a 16-bit depth file. */
1352 PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
1353 #endif
1354 
1355 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1356 /* Turn on quantizing, and reduce the palette to the number of colors
1357  * available.
1358  */
1359 PNG_EXPORT(49, void, png_set_quantize, (png_structrp png_ptr,
1360     png_colorp palette, int num_palette, int maximum_colors,
1361     png_const_uint_16p histogram, int full_quantize));
1362 #endif
1363 
1364 #ifdef PNG_READ_GAMMA_SUPPORTED
1365 /* The threshold on gamma processing is configurable but hard-wired into the
1366  * library.  The following is the floating point variant.
1367  */
1368 #define PNG_GAMMA_THRESHOLD (PNG_GAMMA_THRESHOLD_FIXED*.00001)
1369 
1370 /* Handle gamma correction. Screen_gamma=(display_exponent).
1371  * NOTE: this API simply sets the screen and file gamma values. It will
1372  * therefore override the value for gamma in a PNG file if it is called after
1373  * the file header has been read - use with care  - call before reading the PNG
1374  * file for best results!
1375  *
1376  * These routines accept the same gamma values as png_set_alpha_mode (described
1377  * above).  The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either
1378  * API (floating point or fixed.)  Notice, however, that the 'file_gamma' value
1379  * is the inverse of a 'screen gamma' value.
1380  */
1381 PNG_FP_EXPORT(50, void, png_set_gamma, (png_structrp png_ptr,
1382     double screen_gamma, double override_file_gamma))
1383 PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structrp png_ptr,
1384     png_fixed_point screen_gamma, png_fixed_point override_file_gamma))
1385 #endif
1386 
1387 #ifdef PNG_WRITE_FLUSH_SUPPORTED
1388 /* Set how many lines between output flushes - 0 for no flushing */
1389 PNG_EXPORT(51, void, png_set_flush, (png_structrp png_ptr, int nrows));
1390 /* Flush the current PNG output buffer */
1391 PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr));
1392 #endif
1393 
1394 /* Optional update palette with requested transformations */
1395 PNG_EXPORT(53, void, png_start_read_image, (png_structrp png_ptr));
1396 
1397 /* Optional call to update the users info structure */
1398 PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr,
1399     png_inforp info_ptr));
1400 
1401 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1402 /* Read one or more rows of image data. */
1403 PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row,
1404     png_bytepp display_row, png_uint_32 num_rows));
1405 #endif
1406 
1407 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1408 /* Read a row of data. */
1409 PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
1410     png_bytep display_row));
1411 #endif
1412 
1413 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1414 /* Read the whole image into memory at once. */
1415 PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
1416 #endif
1417 
1418 /* Write a row of image data */
1419 PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr,
1420     png_const_bytep row));
1421 
1422 /* Write a few rows of image data: (*row) is not written; however, the type
1423  * is declared as writeable to maintain compatibility with previous versions
1424  * of libpng and to allow the 'display_row' array from read_rows to be passed
1425  * unchanged to write_rows.
1426  */
1427 PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row,
1428     png_uint_32 num_rows));
1429 
1430 /* Write the image data */
1431 PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image));
1432 
1433 /* Write the end of the PNG file. */
1434 PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr,
1435     png_inforp info_ptr));
1436 
1437 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1438 /* Read the end of the PNG file. */
1439 PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
1440 #endif
1441 
1442 /* Free any memory associated with the png_info_struct */
1443 PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr,
1444     png_infopp info_ptr_ptr));
1445 
1446 /* Free any memory associated with the png_struct and the png_info_structs */
1447 PNG_EXPORT(64, void, png_destroy_read_struct, (png_structpp png_ptr_ptr,
1448     png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));
1449 
1450 /* Free any memory associated with the png_struct and the png_info_structs */
1451 PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr,
1452     png_infopp info_ptr_ptr));
1453 
1454 /* Set the libpng method of handling chunk CRC errors */
1455 PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
1456     int ancil_action));
1457 
1458 /* Values for png_set_crc_action() say how to handle CRC errors in
1459  * ancillary and critical chunks, and whether to use the data contained
1460  * therein.  Note that it is impossible to "discard" data in a critical
1461  * chunk.  For versions prior to 0.90, the action was always error/quit,
1462  * whereas in version 0.90 and later, the action for CRC errors in ancillary
1463  * chunks is warn/discard.  These values should NOT be changed.
1464  *
1465  *      value                       action:critical     action:ancillary
1466  */
1467 #define PNG_CRC_DEFAULT       0  /* error/quit          warn/discard data */
1468 #define PNG_CRC_ERROR_QUIT    1  /* error/quit          error/quit        */
1469 #define PNG_CRC_WARN_DISCARD  2  /* (INVALID)           warn/discard data */
1470 #define PNG_CRC_WARN_USE      3  /* warn/use data       warn/use data     */
1471 #define PNG_CRC_QUIET_USE     4  /* quiet/use data      quiet/use data    */
1472 #define PNG_CRC_NO_CHANGE     5  /* use current value   use current value */
1473 
1474 #ifdef PNG_WRITE_SUPPORTED
1475 /* These functions give the user control over the scan-line filtering in
1476  * libpng and the compression methods used by zlib.  These functions are
1477  * mainly useful for testing, as the defaults should work with most users.
1478  * Those users who are tight on memory or want faster performance at the
1479  * expense of compression can modify them.  See the compression library
1480  * header file (zlib.h) for an explination of the compression functions.
1481  */
1482 
1483 /* Set the filtering method(s) used by libpng.  Currently, the only valid
1484  * value for "method" is 0.
1485  */
1486 PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
1487     int filters));
1488 #endif /* WRITE */
1489 
1490 /* Flags for png_set_filter() to say which filters to use.  The flags
1491  * are chosen so that they don't conflict with real filter types
1492  * below, in case they are supplied instead of the #defined constants.
1493  * These values should NOT be changed.
1494  */
1495 #define PNG_NO_FILTERS     0x00
1496 #define PNG_FILTER_NONE    0x08
1497 #define PNG_FILTER_SUB     0x10
1498 #define PNG_FILTER_UP      0x20
1499 #define PNG_FILTER_AVG     0x40
1500 #define PNG_FILTER_PAETH   0x80
1501 #define PNG_FAST_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP)
1502 #define PNG_ALL_FILTERS (PNG_FAST_FILTERS | PNG_FILTER_AVG | PNG_FILTER_PAETH)
1503 
1504 /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
1505  * These defines should NOT be changed.
1506  */
1507 #define PNG_FILTER_VALUE_NONE  0
1508 #define PNG_FILTER_VALUE_SUB   1
1509 #define PNG_FILTER_VALUE_UP    2
1510 #define PNG_FILTER_VALUE_AVG   3
1511 #define PNG_FILTER_VALUE_PAETH 4
1512 #define PNG_FILTER_VALUE_LAST  5
1513 
1514 #ifdef PNG_WRITE_SUPPORTED
1515 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* DEPRECATED */
1516 PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr,
1517     int heuristic_method, int num_weights, png_const_doublep filter_weights,
1518     png_const_doublep filter_costs))
1519 PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
1520     (png_structrp png_ptr, int heuristic_method, int num_weights,
1521     png_const_fixed_point_p filter_weights,
1522     png_const_fixed_point_p filter_costs))
1523 #endif /* WRITE_WEIGHTED_FILTER */
1524 
1525 /* The following are no longer used and will be removed from libpng-1.7: */
1526 #define PNG_FILTER_HEURISTIC_DEFAULT    0  /* Currently "UNWEIGHTED" */
1527 #define PNG_FILTER_HEURISTIC_UNWEIGHTED 1  /* Used by libpng < 0.95 */
1528 #define PNG_FILTER_HEURISTIC_WEIGHTED   2  /* Experimental feature */
1529 #define PNG_FILTER_HEURISTIC_LAST       3  /* Not a valid value */
1530 
1531 /* Set the library compression level.  Currently, valid values range from
1532  * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
1533  * (0 - no compression, 9 - "maximal" compression).  Note that tests have
1534  * shown that zlib compression levels 3-6 usually perform as well as level 9
1535  * for PNG images, and do considerably fewer caclulations.  In the future,
1536  * these values may not correspond directly to the zlib compression levels.
1537  */
1538 #ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
1539 PNG_EXPORT(69, void, png_set_compression_level, (png_structrp png_ptr,
1540     int level));
1541 
1542 PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structrp png_ptr,
1543     int mem_level));
1544 
1545 PNG_EXPORT(71, void, png_set_compression_strategy, (png_structrp png_ptr,
1546     int strategy));
1547 
1548 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1549  * smaller value of window_bits if it can do so safely.
1550  */
1551 PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
1552     int window_bits));
1553 
1554 PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr,
1555     int method));
1556 #endif /* WRITE_CUSTOMIZE_COMPRESSION */
1557 
1558 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
1559 /* Also set zlib parameters for compressing non-IDAT chunks */
1560 PNG_EXPORT(222, void, png_set_text_compression_level, (png_structrp png_ptr,
1561     int level));
1562 
1563 PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structrp png_ptr,
1564     int mem_level));
1565 
1566 PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structrp png_ptr,
1567     int strategy));
1568 
1569 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1570  * smaller value of window_bits if it can do so safely.
1571  */
1572 PNG_EXPORT(225, void, png_set_text_compression_window_bits,
1573     (png_structrp png_ptr, int window_bits));
1574 
1575 PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr,
1576     int method));
1577 #endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
1578 #endif /* WRITE */
1579 
1580 /* These next functions are called for input/output, memory, and error
1581  * handling.  They are in the file pngrio.c, pngwio.c, and pngerror.c,
1582  * and call standard C I/O routines such as fread(), fwrite(), and
1583  * fprintf().  These functions can be made to use other I/O routines
1584  * at run time for those applications that need to handle I/O in a
1585  * different manner by calling png_set_???_fn().  See libpng-manual.txt for
1586  * more information.
1587  */
1588 
1589 #ifdef PNG_STDIO_SUPPORTED
1590 /* Initialize the input/output for the PNG file to the default functions. */
1591 PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp));
1592 #endif
1593 
1594 /* Replace the (error and abort), and warning functions with user
1595  * supplied functions.  If no messages are to be printed you must still
1596  * write and use replacement functions. The replacement error_fn should
1597  * still do a longjmp to the last setjmp location if you are using this
1598  * method of error handling.  If error_fn or warning_fn is NULL, the
1599  * default function will be used.
1600  */
1601 
1602 PNG_EXPORT(75, void, png_set_error_fn, (png_structrp png_ptr,
1603     png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
1604 
1605 /* Return the user pointer associated with the error functions */
1606 PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structrp png_ptr));
1607 
1608 /* Replace the default data output functions with a user supplied one(s).
1609  * If buffered output is not used, then output_flush_fn can be set to NULL.
1610  * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
1611  * output_flush_fn will be ignored (and thus can be NULL).
1612  * It is probably a mistake to use NULL for output_flush_fn if
1613  * write_data_fn is not also NULL unless you have built libpng with
1614  * PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's
1615  * default flush function, which uses the standard *FILE structure, will
1616  * be used.
1617  */
1618 PNG_EXPORT(77, void, png_set_write_fn, (png_structrp png_ptr, png_voidp io_ptr,
1619     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
1620 
1621 /* Replace the default data input function with a user supplied one. */
1622 PNG_EXPORT(78, void, png_set_read_fn, (png_structrp png_ptr, png_voidp io_ptr,
1623     png_rw_ptr read_data_fn));
1624 
1625 /* Return the user pointer associated with the I/O functions */
1626 PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_const_structrp png_ptr));
1627 
1628 PNG_EXPORT(80, void, png_set_read_status_fn, (png_structrp png_ptr,
1629     png_read_status_ptr read_row_fn));
1630 
1631 PNG_EXPORT(81, void, png_set_write_status_fn, (png_structrp png_ptr,
1632     png_write_status_ptr write_row_fn));
1633 
1634 #ifdef PNG_USER_MEM_SUPPORTED
1635 /* Replace the default memory allocation functions with user supplied one(s). */
1636 PNG_EXPORT(82, void, png_set_mem_fn, (png_structrp png_ptr, png_voidp mem_ptr,
1637     png_malloc_ptr malloc_fn, png_free_ptr free_fn));
1638 /* Return the user pointer associated with the memory functions */
1639 PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structrp png_ptr));
1640 #endif
1641 
1642 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1643 PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr,
1644     png_user_transform_ptr read_user_transform_fn));
1645 #endif
1646 
1647 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
1648 PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr,
1649     png_user_transform_ptr write_user_transform_fn));
1650 #endif
1651 
1652 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
1653 PNG_EXPORT(86, void, png_set_user_transform_info, (png_structrp png_ptr,
1654     png_voidp user_transform_ptr, int user_transform_depth,
1655     int user_transform_channels));
1656 /* Return the user pointer associated with the user transform functions */
1657 PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr,
1658     (png_const_structrp png_ptr));
1659 #endif
1660 
1661 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
1662 /* Return information about the row currently being processed.  Note that these
1663  * APIs do not fail but will return unexpected results if called outside a user
1664  * transform callback.  Also note that when transforming an interlaced image the
1665  * row number is the row number within the sub-image of the interlace pass, so
1666  * the value will increase to the height of the sub-image (not the full image)
1667  * then reset to 0 for the next pass.
1668  *
1669  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
1670  * find the output pixel (x,y) given an interlaced sub-image pixel
1671  * (row,col,pass).  (See below for these macros.)
1672  */
1673 PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structrp));
1674 PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
1675 #endif
1676 
1677 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
1678 /* This callback is called only for *unknown* chunks.  If
1679  * PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
1680  * chunks to be treated as unknown, however in this case the callback must do
1681  * any processing required by the chunk (e.g. by calling the appropriate
1682  * png_set_ APIs.)
1683  *
1684  * There is no write support - on write, by default, all the chunks in the
1685  * 'unknown' list are written in the specified position.
1686  *
1687  * The integer return from the callback function is interpreted thus:
1688  *
1689  * negative: An error occurred; png_chunk_error will be called.
1690  *     zero: The chunk was not handled, the chunk will be saved. A critical
1691  *           chunk will cause an error at this point unless it is to be saved.
1692  * positive: The chunk was handled, libpng will ignore/discard it.
1693  *
1694  * See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
1695  * how this behavior will change in libpng 1.7
1696  */
1697 PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
1698     png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
1699 #endif
1700 
1701 #ifdef PNG_USER_CHUNKS_SUPPORTED
1702 PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr));
1703 #endif
1704 
1705 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1706 /* Sets the function callbacks for the push reader, and a pointer to a
1707  * user-defined structure available to the callback functions.
1708  */
1709 PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structrp png_ptr,
1710     png_voidp progressive_ptr, png_progressive_info_ptr info_fn,
1711     png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn));
1712 
1713 /* Returns the user pointer associated with the push read functions */
1714 PNG_EXPORT(91, png_voidp, png_get_progressive_ptr,
1715     (png_const_structrp png_ptr));
1716 
1717 /* Function to be called when data becomes available */
1718 PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
1719     png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size));
1720 
1721 /* A function which may be called *only* within png_process_data to stop the
1722  * processing of any more data.  The function returns the number of bytes
1723  * remaining, excluding any that libpng has cached internally.  A subsequent
1724  * call to png_process_data must supply these bytes again.  If the argument
1725  * 'save' is set to true the routine will first save all the pending data and
1726  * will always return 0.
1727  */
1728 PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save));
1729 
1730 /* A function which may be called *only* outside (after) a call to
1731  * png_process_data.  It returns the number of bytes of data to skip in the
1732  * input.  Normally it will return 0, but if it returns a non-zero value the
1733  * application must skip than number of bytes of input data and pass the
1734  * following data to the next call to png_process_data.
1735  */
1736 PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structrp));
1737 
1738 /* Function that combines rows.  'new_row' is a flag that should come from
1739  * the callback and be non-NULL if anything needs to be done; the library
1740  * stores its own version of the new data internally and ignores the passed
1741  * in value.
1742  */
1743 PNG_EXPORT(93, void, png_progressive_combine_row, (png_const_structrp png_ptr,
1744     png_bytep old_row, png_const_bytep new_row));
1745 #endif /* PROGRESSIVE_READ */
1746 
1747 PNG_EXPORTA(94, png_voidp, png_malloc, (png_const_structrp png_ptr,
1748     png_alloc_size_t size), PNG_ALLOCATED);
1749 /* Added at libpng version 1.4.0 */
1750 PNG_EXPORTA(95, png_voidp, png_calloc, (png_const_structrp png_ptr,
1751     png_alloc_size_t size), PNG_ALLOCATED);
1752 
1753 /* Added at libpng version 1.2.4 */
1754 PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_const_structrp png_ptr,
1755     png_alloc_size_t size), PNG_ALLOCATED);
1756 
1757 /* Frees a pointer allocated by png_malloc() */
1758 PNG_EXPORT(97, void, png_free, (png_const_structrp png_ptr, png_voidp ptr));
1759 
1760 /* Free data that was allocated internally */
1761 PNG_EXPORT(98, void, png_free_data, (png_const_structrp png_ptr,
1762     png_inforp info_ptr, png_uint_32 free_me, int num));
1763 
1764 /* Reassign responsibility for freeing existing data, whether allocated
1765  * by libpng or by the application; this works on the png_info structure passed
1766  * in, it does not change the state for other png_info structures.
1767  *
1768  * It is unlikely that this function works correctly as of 1.6.0 and using it
1769  * may result either in memory leaks or double free of allocated data.
1770  */
1771 PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
1772     png_inforp info_ptr, int freer, png_uint_32 mask));
1773 
1774 /* Assignments for png_data_freer */
1775 #define PNG_DESTROY_WILL_FREE_DATA 1
1776 #define PNG_SET_WILL_FREE_DATA 1
1777 #define PNG_USER_WILL_FREE_DATA 2
1778 /* Flags for png_ptr->free_me and info_ptr->free_me */
1779 #define PNG_FREE_HIST 0x0008U
1780 #define PNG_FREE_ICCP 0x0010U
1781 #define PNG_FREE_SPLT 0x0020U
1782 #define PNG_FREE_ROWS 0x0040U
1783 #define PNG_FREE_PCAL 0x0080U
1784 #define PNG_FREE_SCAL 0x0100U
1785 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
1786 #  define PNG_FREE_UNKN 0x0200U
1787 #endif
1788 /*      PNG_FREE_LIST 0x0400U   removed in 1.6.0 because it is ignored */
1789 #define PNG_FREE_PLTE 0x1000U
1790 #define PNG_FREE_TRNS 0x2000U
1791 #define PNG_FREE_TEXT 0x4000U
1792 #define PNG_FREE_EXIF 0x8000U /* Added at libpng-1.6.31 */
1793 #define PNG_FREE_ALL  0xffffU
1794 #define PNG_FREE_MUL  0x4220U /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
1795 
1796 #ifdef PNG_USER_MEM_SUPPORTED
1797 PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
1798     png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED);
1799 PNG_EXPORTA(101, void, png_free_default, (png_const_structrp png_ptr,
1800     png_voidp ptr), PNG_DEPRECATED);
1801 #endif
1802 
1803 #ifdef PNG_ERROR_TEXT_SUPPORTED
1804 /* Fatal error in PNG image of libpng - can't continue */
1805 PNG_EXPORTA(102, void, png_error, (png_const_structrp png_ptr,
1806     png_const_charp error_message), PNG_NORETURN);
1807 
1808 /* The same, but the chunk name is prepended to the error string. */
1809 PNG_EXPORTA(103, void, png_chunk_error, (png_const_structrp png_ptr,
1810     png_const_charp error_message), PNG_NORETURN);
1811 
1812 #else
1813 /* Fatal error in PNG image of libpng - can't continue */
1814 PNG_EXPORTA(104, void, png_err, (png_const_structrp png_ptr), PNG_NORETURN);
1815 #  define png_error(s1,s2) png_err(s1)
1816 #  define png_chunk_error(s1,s2) png_err(s1)
1817 #endif
1818 
1819 #ifdef PNG_WARNINGS_SUPPORTED
1820 /* Non-fatal error in libpng.  Can continue, but may have a problem. */
1821 PNG_EXPORT(105, void, png_warning, (png_const_structrp png_ptr,
1822     png_const_charp warning_message));
1823 
1824 /* Non-fatal error in libpng, chunk name is prepended to message. */
1825 PNG_EXPORT(106, void, png_chunk_warning, (png_const_structrp png_ptr,
1826     png_const_charp warning_message));
1827 #else
1828 #  define png_warning(s1,s2) ((void)(s1))
1829 #  define png_chunk_warning(s1,s2) ((void)(s1))
1830 #endif
1831 
1832 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
1833 /* Benign error in libpng.  Can continue, but may have a problem.
1834  * User can choose whether to handle as a fatal error or as a warning. */
1835 PNG_EXPORT(107, void, png_benign_error, (png_const_structrp png_ptr,
1836     png_const_charp warning_message));
1837 
1838 #ifdef PNG_READ_SUPPORTED
1839 /* Same, chunk name is prepended to message (only during read) */
1840 PNG_EXPORT(108, void, png_chunk_benign_error, (png_const_structrp png_ptr,
1841     png_const_charp warning_message));
1842 #endif
1843 
1844 PNG_EXPORT(109, void, png_set_benign_errors,
1845     (png_structrp png_ptr, int allowed));
1846 #else
1847 #  ifdef PNG_ALLOW_BENIGN_ERRORS
1848 #    define png_benign_error png_warning
1849 #    define png_chunk_benign_error png_chunk_warning
1850 #  else
1851 #    define png_benign_error png_error
1852 #    define png_chunk_benign_error png_chunk_error
1853 #  endif
1854 #endif
1855 
1856 /* The png_set_<chunk> functions are for storing values in the png_info_struct.
1857  * Similarly, the png_get_<chunk> calls are used to read values from the
1858  * png_info_struct, either storing the parameters in the passed variables, or
1859  * setting pointers into the png_info_struct where the data is stored.  The
1860  * png_get_<chunk> functions return a non-zero value if the data was available
1861  * in info_ptr, or return zero and do not change any of the parameters if the
1862  * data was not available.
1863  *
1864  * These functions should be used instead of directly accessing png_info
1865  * to avoid problems with future changes in the size and internal layout of
1866  * png_info_struct.
1867  */
1868 /* Returns "flag" if chunk data is valid in info_ptr. */
1869 PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr,
1870     png_const_inforp info_ptr, png_uint_32 flag));
1871 
1872 /* Returns number of bytes needed to hold a transformed row. */
1873 PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
1874     png_const_inforp info_ptr));
1875 
1876 #ifdef PNG_INFO_IMAGE_SUPPORTED
1877 /* Returns row_pointers, which is an array of pointers to scanlines that was
1878  * returned from png_read_png().
1879  */
1880 PNG_EXPORT(112, png_bytepp, png_get_rows, (png_const_structrp png_ptr,
1881     png_const_inforp info_ptr));
1882 
1883 /* Set row_pointers, which is an array of pointers to scanlines for use
1884  * by png_write_png().
1885  */
1886 PNG_EXPORT(113, void, png_set_rows, (png_const_structrp png_ptr,
1887     png_inforp info_ptr, png_bytepp row_pointers));
1888 #endif
1889 
1890 /* Returns number of color channels in image. */
1891 PNG_EXPORT(114, png_byte, png_get_channels, (png_const_structrp png_ptr,
1892     png_const_inforp info_ptr));
1893 
1894 #ifdef PNG_EASY_ACCESS_SUPPORTED
1895 /* Returns image width in pixels. */
1896 PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structrp png_ptr,
1897     png_const_inforp info_ptr));
1898 
1899 /* Returns image height in pixels. */
1900 PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structrp png_ptr,
1901     png_const_inforp info_ptr));
1902 
1903 /* Returns image bit_depth. */
1904 PNG_EXPORT(117, png_byte, png_get_bit_depth, (png_const_structrp png_ptr,
1905     png_const_inforp info_ptr));
1906 
1907 /* Returns image color_type. */
1908 PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structrp png_ptr,
1909     png_const_inforp info_ptr));
1910 
1911 /* Returns image filter_type. */
1912 PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structrp png_ptr,
1913     png_const_inforp info_ptr));
1914 
1915 /* Returns image interlace_type. */
1916 PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structrp png_ptr,
1917     png_const_inforp info_ptr));
1918 
1919 /* Returns image compression_type. */
1920 PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structrp png_ptr,
1921     png_const_inforp info_ptr));
1922 
1923 /* Returns image resolution in pixels per meter, from pHYs chunk data. */
1924 PNG_EXPORT(122, png_uint_32, png_get_pixels_per_meter,
1925     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1926 PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter,
1927     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1928 PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter,
1929     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1930 
1931 /* Returns pixel aspect ratio, computed from pHYs chunk data.  */
1932 PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio,
1933     (png_const_structrp png_ptr, png_const_inforp info_ptr))
1934 PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed,
1935     (png_const_structrp png_ptr, png_const_inforp info_ptr))
1936 
1937 /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
1938 PNG_EXPORT(126, png_int_32, png_get_x_offset_pixels,
1939     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1940 PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels,
1941     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1942 PNG_EXPORT(128, png_int_32, png_get_x_offset_microns,
1943     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1944 PNG_EXPORT(129, png_int_32, png_get_y_offset_microns,
1945     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1946 
1947 #endif /* EASY_ACCESS */
1948 
1949 #ifdef PNG_READ_SUPPORTED
1950 /* Returns pointer to signature string read from PNG header */
1951 PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr,
1952     png_const_inforp info_ptr));
1953 #endif
1954 
1955 #ifdef PNG_bKGD_SUPPORTED
1956 PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
1957     png_inforp info_ptr, png_color_16p *background));
1958 #endif
1959 
1960 #ifdef PNG_bKGD_SUPPORTED
1961 PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
1962     png_inforp info_ptr, png_const_color_16p background));
1963 #endif
1964 
1965 #ifdef PNG_cHRM_SUPPORTED
1966 PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr,
1967     png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x,
1968     double *red_y, double *green_x, double *green_y, double *blue_x,
1969     double *blue_y))
1970 PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr,
1971     png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z,
1972     double *green_X, double *green_Y, double *green_Z, double *blue_X,
1973     double *blue_Y, double *blue_Z))
1974 PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed,
1975     (png_const_structrp png_ptr, png_const_inforp info_ptr,
1976     png_fixed_point *int_white_x, png_fixed_point *int_white_y,
1977     png_fixed_point *int_red_x, png_fixed_point *int_red_y,
1978     png_fixed_point *int_green_x, png_fixed_point *int_green_y,
1979     png_fixed_point *int_blue_x, png_fixed_point *int_blue_y))
1980 PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed,
1981     (png_const_structrp png_ptr, png_const_inforp info_ptr,
1982     png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
1983     png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
1984     png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
1985     png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
1986     png_fixed_point *int_blue_Z))
1987 #endif
1988 
1989 #ifdef PNG_cHRM_SUPPORTED
1990 PNG_FP_EXPORT(135, void, png_set_cHRM, (png_const_structrp png_ptr,
1991     png_inforp info_ptr,
1992     double white_x, double white_y, double red_x, double red_y, double green_x,
1993     double green_y, double blue_x, double blue_y))
1994 PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_const_structrp png_ptr,
1995     png_inforp info_ptr, double red_X, double red_Y, double red_Z,
1996     double green_X, double green_Y, double green_Z, double blue_X,
1997     double blue_Y, double blue_Z))
1998 PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_const_structrp png_ptr,
1999     png_inforp info_ptr, png_fixed_point int_white_x,
2000     png_fixed_point int_white_y, png_fixed_point int_red_x,
2001     png_fixed_point int_red_y, png_fixed_point int_green_x,
2002     png_fixed_point int_green_y, png_fixed_point int_blue_x,
2003     png_fixed_point int_blue_y))
2004 PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
2005     png_inforp info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y,
2006     png_fixed_point int_red_Z, png_fixed_point int_green_X,
2007     png_fixed_point int_green_Y, png_fixed_point int_green_Z,
2008     png_fixed_point int_blue_X, png_fixed_point int_blue_Y,
2009     png_fixed_point int_blue_Z))
2010 #endif
2011 
2012 #ifdef PNG_eXIf_SUPPORTED
2013 PNG_EXPORT(246, png_uint_32, png_get_eXIf, (png_const_structrp png_ptr,
2014     png_inforp info_ptr, png_bytep *exif));
2015 PNG_EXPORT(247, void, png_set_eXIf, (png_const_structrp png_ptr,
2016     png_inforp info_ptr, const png_bytep exif));
2017 
2018 PNG_EXPORT(248, png_uint_32, png_get_eXIf_1, (png_const_structrp png_ptr,
2019     png_const_inforp info_ptr, png_uint_32 *num_exif, png_bytep *exif));
2020 PNG_EXPORT(249, void, png_set_eXIf_1, (png_const_structrp png_ptr,
2021     png_inforp info_ptr, const png_uint_32 num_exif, const png_bytep exif));
2022 #endif
2023 
2024 #ifdef PNG_gAMA_SUPPORTED
2025 PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
2026     png_const_inforp info_ptr, double *file_gamma))
2027 PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed,
2028     (png_const_structrp png_ptr, png_const_inforp info_ptr,
2029     png_fixed_point *int_file_gamma))
2030 #endif
2031 
2032 #ifdef PNG_gAMA_SUPPORTED
2033 PNG_FP_EXPORT(139, void, png_set_gAMA, (png_const_structrp png_ptr,
2034     png_inforp info_ptr, double file_gamma))
2035 PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
2036     png_inforp info_ptr, png_fixed_point int_file_gamma))
2037 #endif
2038 
2039 #ifdef PNG_hIST_SUPPORTED
2040 PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
2041     png_inforp info_ptr, png_uint_16p *hist));
2042 PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
2043     png_inforp info_ptr, png_const_uint_16p hist));
2044 #endif
2045 
2046 PNG_EXPORT(143, png_uint_32, png_get_IHDR, (png_const_structrp png_ptr,
2047     png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height,
2048     int *bit_depth, int *color_type, int *interlace_method,
2049     int *compression_method, int *filter_method));
2050 
2051 PNG_EXPORT(144, void, png_set_IHDR, (png_const_structrp png_ptr,
2052     png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
2053     int color_type, int interlace_method, int compression_method,
2054     int filter_method));
2055 
2056 #ifdef PNG_oFFs_SUPPORTED
2057 PNG_EXPORT(145, png_uint_32, png_get_oFFs, (png_const_structrp png_ptr,
2058    png_const_inforp info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
2059    int *unit_type));
2060 #endif
2061 
2062 #ifdef PNG_oFFs_SUPPORTED
2063 PNG_EXPORT(146, void, png_set_oFFs, (png_const_structrp png_ptr,
2064     png_inforp info_ptr, png_int_32 offset_x, png_int_32 offset_y,
2065     int unit_type));
2066 #endif
2067 
2068 #ifdef PNG_pCAL_SUPPORTED
2069 PNG_EXPORT(147, png_uint_32, png_get_pCAL, (png_const_structrp png_ptr,
2070     png_inforp info_ptr, png_charp *purpose, png_int_32 *X0,
2071     png_int_32 *X1, int *type, int *nparams, png_charp *units,
2072     png_charpp *params));
2073 #endif
2074 
2075 #ifdef PNG_pCAL_SUPPORTED
2076 PNG_EXPORT(148, void, png_set_pCAL, (png_const_structrp png_ptr,
2077     png_inforp info_ptr, png_const_charp purpose, png_int_32 X0, png_int_32 X1,
2078     int type, int nparams, png_const_charp units, png_charpp params));
2079 #endif
2080 
2081 #ifdef PNG_pHYs_SUPPORTED
2082 PNG_EXPORT(149, png_uint_32, png_get_pHYs, (png_const_structrp png_ptr,
2083     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
2084     int *unit_type));
2085 #endif
2086 
2087 #ifdef PNG_pHYs_SUPPORTED
2088 PNG_EXPORT(150, void, png_set_pHYs, (png_const_structrp png_ptr,
2089     png_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
2090 #endif
2091 
2092 PNG_EXPORT(151, png_uint_32, png_get_PLTE, (png_const_structrp png_ptr,
2093    png_inforp info_ptr, png_colorp *palette, int *num_palette));
2094 
2095 PNG_EXPORT(152, void, png_set_PLTE, (png_structrp png_ptr,
2096     png_inforp info_ptr, png_const_colorp palette, int num_palette));
2097 
2098 #ifdef PNG_sBIT_SUPPORTED
2099 PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr,
2100     png_inforp info_ptr, png_color_8p *sig_bit));
2101 #endif
2102 
2103 #ifdef PNG_sBIT_SUPPORTED
2104 PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr,
2105     png_inforp info_ptr, png_const_color_8p sig_bit));
2106 #endif
2107 
2108 #ifdef PNG_sRGB_SUPPORTED
2109 PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr,
2110     png_const_inforp info_ptr, int *file_srgb_intent));
2111 #endif
2112 
2113 #ifdef PNG_sRGB_SUPPORTED
2114 PNG_EXPORT(156, void, png_set_sRGB, (png_const_structrp png_ptr,
2115     png_inforp info_ptr, int srgb_intent));
2116 PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_const_structrp png_ptr,
2117     png_inforp info_ptr, int srgb_intent));
2118 #endif
2119 
2120 #ifdef PNG_iCCP_SUPPORTED
2121 PNG_EXPORT(158, png_uint_32, png_get_iCCP, (png_const_structrp png_ptr,
2122     png_inforp info_ptr, png_charpp name, int *compression_type,
2123     png_bytepp profile, png_uint_32 *proflen));
2124 #endif
2125 
2126 #ifdef PNG_iCCP_SUPPORTED
2127 PNG_EXPORT(159, void, png_set_iCCP, (png_const_structrp png_ptr,
2128     png_inforp info_ptr, png_const_charp name, int compression_type,
2129     png_const_bytep profile, png_uint_32 proflen));
2130 #endif
2131 
2132 #ifdef PNG_sPLT_SUPPORTED
2133 PNG_EXPORT(160, int, png_get_sPLT, (png_const_structrp png_ptr,
2134     png_inforp info_ptr, png_sPLT_tpp entries));
2135 #endif
2136 
2137 #ifdef PNG_sPLT_SUPPORTED
2138 PNG_EXPORT(161, void, png_set_sPLT, (png_const_structrp png_ptr,
2139     png_inforp info_ptr, png_const_sPLT_tp entries, int nentries));
2140 #endif
2141 
2142 #ifdef PNG_TEXT_SUPPORTED
2143 /* png_get_text also returns the number of text chunks in *num_text */
2144 PNG_EXPORT(162, int, png_get_text, (png_const_structrp png_ptr,
2145     png_inforp info_ptr, png_textp *text_ptr, int *num_text));
2146 #endif
2147 
2148 /* Note while png_set_text() will accept a structure whose text,
2149  * language, and  translated keywords are NULL pointers, the structure
2150  * returned by png_get_text will always contain regular
2151  * zero-terminated C strings.  They might be empty strings but
2152  * they will never be NULL pointers.
2153  */
2154 
2155 #ifdef PNG_TEXT_SUPPORTED
2156 PNG_EXPORT(163, void, png_set_text, (png_const_structrp png_ptr,
2157     png_inforp info_ptr, png_const_textp text_ptr, int num_text));
2158 #endif
2159 
2160 #ifdef PNG_tIME_SUPPORTED
2161 PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr,
2162     png_inforp info_ptr, png_timep *mod_time));
2163 #endif
2164 
2165 #ifdef PNG_tIME_SUPPORTED
2166 PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr,
2167     png_inforp info_ptr, png_const_timep mod_time));
2168 #endif
2169 
2170 #ifdef PNG_tRNS_SUPPORTED
2171 PNG_EXPORT(166, png_uint_32, png_get_tRNS, (png_const_structrp png_ptr,
2172     png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans,
2173     png_color_16p *trans_color));
2174 #endif
2175 
2176 #ifdef PNG_tRNS_SUPPORTED
2177 PNG_EXPORT(167, void, png_set_tRNS, (png_structrp png_ptr,
2178     png_inforp info_ptr, png_const_bytep trans_alpha, int num_trans,
2179     png_const_color_16p trans_color));
2180 #endif
2181 
2182 #ifdef PNG_sCAL_SUPPORTED
2183 PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL, (png_const_structrp png_ptr,
2184     png_const_inforp info_ptr, int *unit, double *width, double *height))
2185 #if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
2186    defined(PNG_FLOATING_POINT_SUPPORTED)
2187 /* NOTE: this API is currently implemented using floating point arithmetic,
2188  * consequently it can only be used on systems with floating point support.
2189  * In any case the range of values supported by png_fixed_point is small and it
2190  * is highly recommended that png_get_sCAL_s be used instead.
2191  */
2192 PNG_FIXED_EXPORT(214, png_uint_32, png_get_sCAL_fixed,
2193     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
2194     png_fixed_point *width, png_fixed_point *height))
2195 #endif
2196 PNG_EXPORT(169, png_uint_32, png_get_sCAL_s,
2197     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
2198     png_charpp swidth, png_charpp sheight));
2199 
2200 PNG_FP_EXPORT(170, void, png_set_sCAL, (png_const_structrp png_ptr,
2201     png_inforp info_ptr, int unit, double width, double height))
2202 PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_const_structrp png_ptr,
2203    png_inforp info_ptr, int unit, png_fixed_point width,
2204    png_fixed_point height))
2205 PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
2206     png_inforp info_ptr, int unit,
2207     png_const_charp swidth, png_const_charp sheight));
2208 #endif /* sCAL */
2209 
2210 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2211 /* Provide the default handling for all unknown chunks or, optionally, for
2212  * specific unknown chunks.
2213  *
2214  * NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
2215  * ignored and the default was used, the per-chunk setting only had an effect on
2216  * write.  If you wish to have chunk-specific handling on read in code that must
2217  * work on earlier versions you must use a user chunk callback to specify the
2218  * desired handling (keep or discard.)
2219  *
2220  * The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below.  The
2221  * parameter is interpreted as follows:
2222  *
2223  * READ:
2224  *    PNG_HANDLE_CHUNK_AS_DEFAULT:
2225  *       Known chunks: do normal libpng processing, do not keep the chunk (but
2226  *          see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
2227  *       Unknown chunks: for a specific chunk use the global default, when used
2228  *          as the default discard the chunk data.
2229  *    PNG_HANDLE_CHUNK_NEVER:
2230  *       Discard the chunk data.
2231  *    PNG_HANDLE_CHUNK_IF_SAFE:
2232  *       Keep the chunk data if the chunk is not critical else raise a chunk
2233  *       error.
2234  *    PNG_HANDLE_CHUNK_ALWAYS:
2235  *       Keep the chunk data.
2236  *
2237  * If the chunk data is saved it can be retrieved using png_get_unknown_chunks,
2238  * below.  Notice that specifying "AS_DEFAULT" as a global default is equivalent
2239  * to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
2240  * it simply resets the behavior to the libpng default.
2241  *
2242  * INTERACTION WTIH USER CHUNK CALLBACKS:
2243  * The per-chunk handling is always used when there is a png_user_chunk_ptr
2244  * callback and the callback returns 0; the chunk is then always stored *unless*
2245  * it is critical and the per-chunk setting is other than ALWAYS.  Notice that
2246  * the global default is *not* used in this case.  (In effect the per-chunk
2247  * value is incremented to at least IF_SAFE.)
2248  *
2249  * IMPORTANT NOTE: this behavior will change in libpng 1.7 - the global and
2250  * per-chunk defaults will be honored.  If you want to preserve the current
2251  * behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE
2252  * as the default - if you don't do this libpng 1.6 will issue a warning.
2253  *
2254  * If you want unhandled unknown chunks to be discarded in libpng 1.6 and
2255  * earlier simply return '1' (handled).
2256  *
2257  * PNG_HANDLE_AS_UNKNOWN_SUPPORTED:
2258  *    If this is *not* set known chunks will always be handled by libpng and
2259  *    will never be stored in the unknown chunk list.  Known chunks listed to
2260  *    png_set_keep_unknown_chunks will have no effect.  If it is set then known
2261  *    chunks listed with a keep other than AS_DEFAULT will *never* be processed
2262  *    by libpng, in addition critical chunks must either be processed by the
2263  *    callback or saved.
2264  *
2265  *    The IHDR and IEND chunks must not be listed.  Because this turns off the
2266  *    default handling for chunks that would otherwise be recognized the
2267  *    behavior of libpng transformations may well become incorrect!
2268  *
2269  * WRITE:
2270  *    When writing chunks the options only apply to the chunks specified by
2271  *    png_set_unknown_chunks (below), libpng will *always* write known chunks
2272  *    required by png_set_ calls and will always write the core critical chunks
2273  *    (as required for PLTE).
2274  *
2275  *    Each chunk in the png_set_unknown_chunks list is looked up in the
2276  *    png_set_keep_unknown_chunks list to find the keep setting, this is then
2277  *    interpreted as follows:
2278  *
2279  *    PNG_HANDLE_CHUNK_AS_DEFAULT:
2280  *       Write safe-to-copy chunks and write other chunks if the global
2281  *       default is set to _ALWAYS, otherwise don't write this chunk.
2282  *    PNG_HANDLE_CHUNK_NEVER:
2283  *       Do not write the chunk.
2284  *    PNG_HANDLE_CHUNK_IF_SAFE:
2285  *       Write the chunk if it is safe-to-copy, otherwise do not write it.
2286  *    PNG_HANDLE_CHUNK_ALWAYS:
2287  *       Write the chunk.
2288  *
2289  * Note that the default behavior is effectively the opposite of the read case -
2290  * in read unknown chunks are not stored by default, in write they are written
2291  * by default.  Also the behavior of PNG_HANDLE_CHUNK_IF_SAFE is very different
2292  * - on write the safe-to-copy bit is checked, on read the critical bit is
2293  * checked and on read if the chunk is critical an error will be raised.
2294  *
2295  * num_chunks:
2296  * ===========
2297  *    If num_chunks is positive, then the "keep" parameter specifies the manner
2298  *    for handling only those chunks appearing in the chunk_list array,
2299  *    otherwise the chunk list array is ignored.
2300  *
2301  *    If num_chunks is 0 the "keep" parameter specifies the default behavior for
2302  *    unknown chunks, as described above.
2303  *
2304  *    If num_chunks is negative, then the "keep" parameter specifies the manner
2305  *    for handling all unknown chunks plus all chunks recognized by libpng
2306  *    except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
2307  *    be processed by libpng.
2308  */
2309 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
2310 PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
2311     int keep, png_const_bytep chunk_list, int num_chunks));
2312 #endif /* HANDLE_AS_UNKNOWN */
2313 
2314 /* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
2315  * the result is therefore true (non-zero) if special handling is required,
2316  * false for the default handling.
2317  */
2318 PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
2319     png_const_bytep chunk_name));
2320 #endif /* SET_UNKNOWN_CHUNKS */
2321 
2322 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
2323 PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
2324     png_inforp info_ptr, png_const_unknown_chunkp unknowns,
2325     int num_unknowns));
2326    /* NOTE: prior to 1.6.0 this routine set the 'location' field of the added
2327     * unknowns to the location currently stored in the png_struct.  This is
2328     * invariably the wrong value on write.  To fix this call the following API
2329     * for each chunk in the list with the correct location.  If you know your
2330     * code won't be compiled on earlier versions you can rely on
2331     * png_set_unknown_chunks(write-ptr, png_get_unknown_chunks(read-ptr)) doing
2332     * the correct thing.
2333     */
2334 
2335 PNG_EXPORT(175, void, png_set_unknown_chunk_location,
2336     (png_const_structrp png_ptr, png_inforp info_ptr, int chunk, int location));
2337 
2338 PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structrp png_ptr,
2339     png_inforp info_ptr, png_unknown_chunkpp entries));
2340 #endif
2341 
2342 /* Png_free_data() will turn off the "valid" flag for anything it frees.
2343  * If you need to turn it off for a chunk that your application has freed,
2344  * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
2345  */
2346 PNG_EXPORT(177, void, png_set_invalid, (png_const_structrp png_ptr,
2347     png_inforp info_ptr, int mask));
2348 
2349 #ifdef PNG_INFO_IMAGE_SUPPORTED
2350 /* The "params" pointer is currently not used and is for future expansion. */
2351 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
2352 PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr,
2353     int transforms, png_voidp params));
2354 #endif
2355 #ifdef PNG_WRITE_SUPPORTED
2356 PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr,
2357     int transforms, png_voidp params));
2358 #endif
2359 #endif
2360 
2361 PNG_EXPORT(180, png_const_charp, png_get_copyright,
2362     (png_const_structrp png_ptr));
2363 PNG_EXPORT(181, png_const_charp, png_get_header_ver,
2364     (png_const_structrp png_ptr));
2365 PNG_EXPORT(182, png_const_charp, png_get_header_version,
2366     (png_const_structrp png_ptr));
2367 PNG_EXPORT(183, png_const_charp, png_get_libpng_ver,
2368     (png_const_structrp png_ptr));
2369 
2370 #ifdef PNG_MNG_FEATURES_SUPPORTED
2371 PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr,
2372     png_uint_32 mng_features_permitted));
2373 #endif
2374 
2375 /* For use in png_set_keep_unknown, added to version 1.2.6 */
2376 #define PNG_HANDLE_CHUNK_AS_DEFAULT   0
2377 #define PNG_HANDLE_CHUNK_NEVER        1
2378 #define PNG_HANDLE_CHUNK_IF_SAFE      2
2379 #define PNG_HANDLE_CHUNK_ALWAYS       3
2380 #define PNG_HANDLE_CHUNK_LAST         4
2381 
2382 /* Strip the prepended error numbers ("#nnn ") from error and warning
2383  * messages before passing them to the error or warning handler.
2384  */
2385 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
2386 PNG_EXPORT(185, void, png_set_strip_error_numbers, (png_structrp png_ptr,
2387     png_uint_32 strip_mode));
2388 #endif
2389 
2390 /* Added in libpng-1.2.6 */
2391 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
2392 PNG_EXPORT(186, void, png_set_user_limits, (png_structrp png_ptr,
2393     png_uint_32 user_width_max, png_uint_32 user_height_max));
2394 PNG_EXPORT(187, png_uint_32, png_get_user_width_max,
2395     (png_const_structrp png_ptr));
2396 PNG_EXPORT(188, png_uint_32, png_get_user_height_max,
2397     (png_const_structrp png_ptr));
2398 /* Added in libpng-1.4.0 */
2399 PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structrp png_ptr,
2400     png_uint_32 user_chunk_cache_max));
2401 PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max,
2402     (png_const_structrp png_ptr));
2403 /* Added in libpng-1.4.1 */
2404 PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structrp png_ptr,
2405     png_alloc_size_t user_chunk_cache_max));
2406 PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max,
2407     (png_const_structrp png_ptr));
2408 #endif
2409 
2410 #if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
2411 PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch,
2412     (png_const_structrp png_ptr, png_const_inforp info_ptr));
2413 
2414 PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch,
2415     (png_const_structrp png_ptr, png_const_inforp info_ptr));
2416 
2417 PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch,
2418     (png_const_structrp png_ptr, png_const_inforp info_ptr));
2419 
2420 PNG_FP_EXPORT(196, float, png_get_x_offset_inches,
2421     (png_const_structrp png_ptr, png_const_inforp info_ptr))
2422 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2423 PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed,
2424     (png_const_structrp png_ptr, png_const_inforp info_ptr))
2425 #endif
2426 
2427 PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structrp png_ptr,
2428     png_const_inforp info_ptr))
2429 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2430 PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed,
2431     (png_const_structrp png_ptr, png_const_inforp info_ptr))
2432 #endif
2433 
2434 #  ifdef PNG_pHYs_SUPPORTED
2435 PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structrp png_ptr,
2436     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
2437     int *unit_type));
2438 #  endif /* pHYs */
2439 #endif  /* INCH_CONVERSIONS */
2440 
2441 /* Added in libpng-1.4.0 */
2442 #ifdef PNG_IO_STATE_SUPPORTED
2443 PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_const_structrp png_ptr));
2444 
2445 /* Removed from libpng 1.6; use png_get_io_chunk_type. */
2446 PNG_REMOVED(200, png_const_bytep, png_get_io_chunk_name, (png_structrp png_ptr),
2447     PNG_DEPRECATED)
2448 
2449 PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
2450     (png_const_structrp png_ptr));
2451 
2452 /* The flags returned by png_get_io_state() are the following: */
2453 #  define PNG_IO_NONE        0x0000   /* no I/O at this moment */
2454 #  define PNG_IO_READING     0x0001   /* currently reading */
2455 #  define PNG_IO_WRITING     0x0002   /* currently writing */
2456 #  define PNG_IO_SIGNATURE   0x0010   /* currently at the file signature */
2457 #  define PNG_IO_CHUNK_HDR   0x0020   /* currently at the chunk header */
2458 #  define PNG_IO_CHUNK_DATA  0x0040   /* currently at the chunk data */
2459 #  define PNG_IO_CHUNK_CRC   0x0080   /* currently at the chunk crc */
2460 #  define PNG_IO_MASK_OP     0x000f   /* current operation: reading/writing */
2461 #  define PNG_IO_MASK_LOC    0x00f0   /* current location: sig/hdr/data/crc */
2462 #endif /* IO_STATE */
2463 
2464 /* Interlace support.  The following macros are always defined so that if
2465  * libpng interlace handling is turned off the macros may be used to handle
2466  * interlaced images within the application.
2467  */
2468 #define PNG_INTERLACE_ADAM7_PASSES 7
2469 
2470 /* Two macros to return the first row and first column of the original,
2471  * full, image which appears in a given pass.  'pass' is in the range 0
2472  * to 6 and the result is in the range 0 to 7.
2473  */
2474 #define PNG_PASS_START_ROW(pass) (((1&~(pass))<<(3-((pass)>>1)))&7)
2475 #define PNG_PASS_START_COL(pass) (((1& (pass))<<(3-(((pass)+1)>>1)))&7)
2476 
2477 /* A macro to return the offset between pixels in the output row for a pair of
2478  * pixels in the input - effectively the inverse of the 'COL_SHIFT' macro that
2479  * follows.  Note that ROW_OFFSET is the offset from one row to the next whereas
2480  * COL_OFFSET is from one column to the next, within a row.
2481  */
2482 #define PNG_PASS_ROW_OFFSET(pass) ((pass)>2?(8>>(((pass)-1)>>1)):8)
2483 #define PNG_PASS_COL_OFFSET(pass) (1<<((7-(pass))>>1))
2484 
2485 /* Two macros to help evaluate the number of rows or columns in each
2486  * pass.  This is expressed as a shift - effectively log2 of the number or
2487  * rows or columns in each 8x8 tile of the original image.
2488  */
2489 #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
2490 #define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
2491 
2492 /* Hence two macros to determine the number of rows or columns in a given
2493  * pass of an image given its height or width.  In fact these macros may
2494  * return non-zero even though the sub-image is empty, because the other
2495  * dimension may be empty for a small image.
2496  */
2497 #define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
2498    -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
2499 #define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
2500    -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
2501 
2502 /* For the reader row callbacks (both progressive and sequential) it is
2503  * necessary to find the row in the output image given a row in an interlaced
2504  * image, so two more macros:
2505  */
2506 #define PNG_ROW_FROM_PASS_ROW(y_in, pass) \
2507    (((y_in)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
2508 #define PNG_COL_FROM_PASS_COL(x_in, pass) \
2509    (((x_in)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
2510 
2511 /* Two macros which return a boolean (0 or 1) saying whether the given row
2512  * or column is in a particular pass.  These use a common utility macro that
2513  * returns a mask for a given pass - the offset 'off' selects the row or
2514  * column version.  The mask has the appropriate bit set for each column in
2515  * the tile.
2516  */
2517 #define PNG_PASS_MASK(pass,off) ( \
2518    ((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \
2519    ((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0))
2520 
2521 #define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
2522    ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
2523 #define PNG_COL_IN_INTERLACE_PASS(x, pass) \
2524    ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
2525 
2526 #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
2527 /* With these routines we avoid an integer divide, which will be slower on
2528  * most machines.  However, it does take more operations than the corresponding
2529  * divide method, so it may be slower on a few RISC systems.  There are two
2530  * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
2531  *
2532  * Note that the rounding factors are NOT supposed to be the same!  128 and
2533  * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
2534  * standard method.
2535  *
2536  * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
2537  */
2538 
2539  /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
2540 
2541 #  define png_composite(composite, fg, alpha, bg)        \
2542    {                                                     \
2543       png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
2544           * (png_uint_16)(alpha)                         \
2545           + (png_uint_16)(bg)*(png_uint_16)(255          \
2546           - (png_uint_16)(alpha)) + 128);                \
2547       (composite) = (png_byte)(((temp + (temp >> 8)) >> 8) & 0xff); \
2548    }
2549 
2550 #  define png_composite_16(composite, fg, alpha, bg)     \
2551    {                                                     \
2552       png_uint_32 temp = (png_uint_32)((png_uint_32)(fg) \
2553           * (png_uint_32)(alpha)                         \
2554           + (png_uint_32)(bg)*(65535                     \
2555           - (png_uint_32)(alpha)) + 32768);              \
2556       (composite) = (png_uint_16)(0xffff & ((temp + (temp >> 16)) >> 16)); \
2557    }
2558 
2559 #else  /* Standard method using integer division */
2560 
2561 #  define png_composite(composite, fg, alpha, bg)                      \
2562    (composite) =                                                       \
2563        (png_byte)(0xff & (((png_uint_16)(fg) * (png_uint_16)(alpha) +  \
2564        (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
2565        127) / 255))
2566 
2567 #  define png_composite_16(composite, fg, alpha, bg)                       \
2568    (composite) =                                                           \
2569        (png_uint_16)(0xffff & (((png_uint_32)(fg) * (png_uint_32)(alpha) + \
2570        (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) +     \
2571        32767) / 65535))
2572 #endif /* READ_COMPOSITE_NODIV */
2573 
2574 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
2575 PNG_EXPORT(201, png_uint_32, png_get_uint_32, (png_const_bytep buf));
2576 PNG_EXPORT(202, png_uint_16, png_get_uint_16, (png_const_bytep buf));
2577 PNG_EXPORT(203, png_int_32, png_get_int_32, (png_const_bytep buf));
2578 #endif
2579 
2580 PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_const_structrp png_ptr,
2581     png_const_bytep buf));
2582 /* No png_get_int_16 -- may be added if there's a real need for it. */
2583 
2584 /* Place a 32-bit number into a buffer in PNG byte order (big-endian). */
2585 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2586 PNG_EXPORT(205, void, png_save_uint_32, (png_bytep buf, png_uint_32 i));
2587 #endif
2588 #ifdef PNG_SAVE_INT_32_SUPPORTED
2589 PNG_EXPORT(206, void, png_save_int_32, (png_bytep buf, png_int_32 i));
2590 #endif
2591 
2592 /* Place a 16-bit number into a buffer in PNG byte order.
2593  * The parameter is declared unsigned int, not png_uint_16,
2594  * just to avoid potential problems on pre-ANSI C compilers.
2595  */
2596 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2597 PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
2598 /* No png_save_int_16 -- may be added if there's a real need for it. */
2599 #endif
2600 
2601 #ifdef PNG_USE_READ_MACROS
2602 /* Inline macros to do direct reads of bytes from the input buffer.
2603  * The png_get_int_32() routine assumes we are using two's complement
2604  * format for negative values, which is almost certainly true.
2605  */
2606 #  define PNG_get_uint_32(buf) \
2607    (((png_uint_32)(*(buf)) << 24) + \
2608     ((png_uint_32)(*((buf) + 1)) << 16) + \
2609     ((png_uint_32)(*((buf) + 2)) << 8) + \
2610     ((png_uint_32)(*((buf) + 3))))
2611 
2612    /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
2613     * function) incorrectly returned a value of type png_uint_32.
2614     */
2615 #  define PNG_get_uint_16(buf) \
2616    ((png_uint_16) \
2617     (((unsigned int)(*(buf)) << 8) + \
2618     ((unsigned int)(*((buf) + 1)))))
2619 
2620 #  define PNG_get_int_32(buf) \
2621    ((png_int_32)((*(buf) & 0x80) \
2622     ? -((png_int_32)(((png_get_uint_32(buf)^0xffffffffU)+1U)&0x7fffffffU)) \
2623     : (png_int_32)png_get_uint_32(buf)))
2624 
2625 /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
2626  * but defining a macro name prefixed with PNG_PREFIX.
2627  */
2628 #  ifndef PNG_PREFIX
2629 #    define png_get_uint_32(buf) PNG_get_uint_32(buf)
2630 #    define png_get_uint_16(buf) PNG_get_uint_16(buf)
2631 #    define png_get_int_32(buf)  PNG_get_int_32(buf)
2632 #  endif
2633 #else
2634 #  ifdef PNG_PREFIX
2635    /* No macros; revert to the (redefined) function */
2636 #    define PNG_get_uint_32 (png_get_uint_32)
2637 #    define PNG_get_uint_16 (png_get_uint_16)
2638 #    define PNG_get_int_32  (png_get_int_32)
2639 #  endif
2640 #endif
2641 
2642 #ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
2643 PNG_EXPORT(242, void, png_set_check_for_invalid_index,
2644     (png_structrp png_ptr, int allowed));
2645 #  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
2646 PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
2647     png_const_infop info_ptr));
2648 #  endif
2649 #endif /* CHECK_FOR_INVALID_INDEX */
2650 
2651 /*******************************************************************************
2652  * Section 5: SIMPLIFIED API
2653  *******************************************************************************
2654  *
2655  * Please read the documentation in libpng-manual.txt (TODO: write said
2656  * documentation) if you don't understand what follows.
2657  *
2658  * The simplified API hides the details of both libpng and the PNG file format
2659  * itself.  It allows PNG files to be read into a very limited number of
2660  * in-memory bitmap formats or to be written from the same formats.  If these
2661  * formats do not accomodate your needs then you can, and should, use the more
2662  * sophisticated APIs above - these support a wide variety of in-memory formats
2663  * and a wide variety of sophisticated transformations to those formats as well
2664  * as a wide variety of APIs to manipulate ancillary information.
2665  *
2666  * To read a PNG file using the simplified API:
2667  *
2668  * 1) Declare a 'png_image' structure (see below) on the stack, set the
2669  *    version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
2670  *    (this is REQUIRED, your program may crash if you don't do it.)
2671  * 2) Call the appropriate png_image_begin_read... function.
2672  * 3) Set the png_image 'format' member to the required sample format.
2673  * 4) Allocate a buffer for the image and, if required, the color-map.
2674  * 5) Call png_image_finish_read to read the image and, if required, the
2675  *    color-map into your buffers.
2676  *
2677  * There are no restrictions on the format of the PNG input itself; all valid
2678  * color types, bit depths, and interlace methods are acceptable, and the
2679  * input image is transformed as necessary to the requested in-memory format
2680  * during the png_image_finish_read() step.  The only caveat is that if you
2681  * request a color-mapped image from a PNG that is full-color or makes
2682  * complex use of an alpha channel the transformation is extremely lossy and the
2683  * result may look terrible.
2684  *
2685  * To write a PNG file using the simplified API:
2686  *
2687  * 1) Declare a 'png_image' structure on the stack and memset() it to all zero.
2688  * 2) Initialize the members of the structure that describe the image, setting
2689  *    the 'format' member to the format of the image samples.
2690  * 3) Call the appropriate png_image_write... function with a pointer to the
2691  *    image and, if necessary, the color-map to write the PNG data.
2692  *
2693  * png_image is a structure that describes the in-memory format of an image
2694  * when it is being read or defines the in-memory format of an image that you
2695  * need to write:
2696  */
2697 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) || \
2698     defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
2699 
2700 #define PNG_IMAGE_VERSION 1
2701 
2702 typedef struct png_control *png_controlp;
2703 typedef struct
2704 {
2705    png_controlp opaque;    /* Initialize to NULL, free with png_image_free */
2706    png_uint_32  version;   /* Set to PNG_IMAGE_VERSION */
2707    png_uint_32  width;     /* Image width in pixels (columns) */
2708    png_uint_32  height;    /* Image height in pixels (rows) */
2709    png_uint_32  format;    /* Image format as defined below */
2710    png_uint_32  flags;     /* A bit mask containing informational flags */
2711    png_uint_32  colormap_entries;
2712                            /* Number of entries in the color-map */
2713 
2714    /* In the event of an error or warning the following field will be set to a
2715     * non-zero value and the 'message' field will contain a '\0' terminated
2716     * string with the libpng error or warning message.  If both warnings and
2717     * an error were encountered, only the error is recorded.  If there
2718     * are multiple warnings, only the first one is recorded.
2719     *
2720     * The upper 30 bits of this value are reserved, the low two bits contain
2721     * a value as follows:
2722     */
2723 #  define PNG_IMAGE_WARNING 1
2724 #  define PNG_IMAGE_ERROR 2
2725    /*
2726     * The result is a two-bit code such that a value more than 1 indicates
2727     * a failure in the API just called:
2728     *
2729     *    0 - no warning or error
2730     *    1 - warning
2731     *    2 - error
2732     *    3 - error preceded by warning
2733     */
2734 #  define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1)
2735 
2736    png_uint_32  warning_or_error;
2737 
2738    char         message[64];
2739 } png_image, *png_imagep;
2740 
2741 /* The samples of the image have one to four channels whose components have
2742  * original values in the range 0 to 1.0:
2743  *
2744  * 1: A single gray or luminance channel (G).
2745  * 2: A gray/luminance channel and an alpha channel (GA).
2746  * 3: Three red, green, blue color channels (RGB).
2747  * 4: Three color channels and an alpha channel (RGBA).
2748  *
2749  * The components are encoded in one of two ways:
2750  *
2751  * a) As a small integer, value 0..255, contained in a single byte.  For the
2752  * alpha channel the original value is simply value/255.  For the color or
2753  * luminance channels the value is encoded according to the sRGB specification
2754  * and matches the 8-bit format expected by typical display devices.
2755  *
2756  * The color/gray channels are not scaled (pre-multiplied) by the alpha
2757  * channel and are suitable for passing to color management software.
2758  *
2759  * b) As a value in the range 0..65535, contained in a 2-byte integer.  All
2760  * channels can be converted to the original value by dividing by 65535; all
2761  * channels are linear.  Color channels use the RGB encoding (RGB end-points) of
2762  * the sRGB specification.  This encoding is identified by the
2763  * PNG_FORMAT_FLAG_LINEAR flag below.
2764  *
2765  * When the simplified API needs to convert between sRGB and linear colorspaces,
2766  * the actual sRGB transfer curve defined in the sRGB specification (see the
2767  * article at https://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
2768  * approximation used elsewhere in libpng.
2769  *
2770  * When an alpha channel is present it is expected to denote pixel coverage
2771  * of the color or luminance channels and is returned as an associated alpha
2772  * channel: the color/gray channels are scaled (pre-multiplied) by the alpha
2773  * value.
2774  *
2775  * The samples are either contained directly in the image data, between 1 and 8
2776  * bytes per pixel according to the encoding, or are held in a color-map indexed
2777  * by bytes in the image data.  In the case of a color-map the color-map entries
2778  * are individual samples, encoded as above, and the image data has one byte per
2779  * pixel to select the relevant sample from the color-map.
2780  */
2781 
2782 /* PNG_FORMAT_*
2783  *
2784  * #defines to be used in png_image::format.  Each #define identifies a
2785  * particular layout of sample data and, if present, alpha values.  There are
2786  * separate defines for each of the two component encodings.
2787  *
2788  * A format is built up using single bit flag values.  All combinations are
2789  * valid.  Formats can be built up from the flag values or you can use one of
2790  * the predefined values below.  When testing formats always use the FORMAT_FLAG
2791  * macros to test for individual features - future versions of the library may
2792  * add new flags.
2793  *
2794  * When reading or writing color-mapped images the format should be set to the
2795  * format of the entries in the color-map then png_image_{read,write}_colormap
2796  * called to read or write the color-map and set the format correctly for the
2797  * image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
2798  *
2799  * NOTE: libpng can be built with particular features disabled. If you see
2800  * compiler errors because the definition of one of the following flags has been
2801  * compiled out it is because libpng does not have the required support.  It is
2802  * possible, however, for the libpng configuration to enable the format on just
2803  * read or just write; in that case you may see an error at run time.  You can
2804  * guard against this by checking for the definition of the appropriate
2805  * "_SUPPORTED" macro, one of:
2806  *
2807  *    PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
2808  */
2809 #define PNG_FORMAT_FLAG_ALPHA    0x01U /* format with an alpha channel */
2810 #define PNG_FORMAT_FLAG_COLOR    0x02U /* color format: otherwise grayscale */
2811 #define PNG_FORMAT_FLAG_LINEAR   0x04U /* 2-byte channels else 1-byte */
2812 #define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
2813 
2814 #ifdef PNG_FORMAT_BGR_SUPPORTED
2815 #  define PNG_FORMAT_FLAG_BGR    0x10U /* BGR colors, else order is RGB */
2816 #endif
2817 
2818 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
2819 #  define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
2820 #endif
2821 
2822 #define PNG_FORMAT_FLAG_ASSOCIATED_ALPHA 0x40U /* alpha channel is associated */
2823 
2824 /* Commonly used formats have predefined macros.
2825  *
2826  * First the single byte (sRGB) formats:
2827  */
2828 #define PNG_FORMAT_GRAY 0
2829 #define PNG_FORMAT_GA   PNG_FORMAT_FLAG_ALPHA
2830 #define PNG_FORMAT_AG   (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
2831 #define PNG_FORMAT_RGB  PNG_FORMAT_FLAG_COLOR
2832 #define PNG_FORMAT_BGR  (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
2833 #define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
2834 #define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
2835 #define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
2836 #define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
2837 
2838 /* Then the linear 2-byte formats.  When naming these "Y" is used to
2839  * indicate a luminance (gray) channel.
2840  */
2841 #define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
2842 #define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
2843 #define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
2844 #define PNG_FORMAT_LINEAR_RGB_ALPHA \
2845    (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA)
2846 
2847 /* With color-mapped formats the image data is one byte for each pixel, the byte
2848  * is an index into the color-map which is formatted as above.  To obtain a
2849  * color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
2850  * to one of the above definitions, or you can use one of the definitions below.
2851  */
2852 #define PNG_FORMAT_RGB_COLORMAP  (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP)
2853 #define PNG_FORMAT_BGR_COLORMAP  (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP)
2854 #define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP)
2855 #define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP)
2856 #define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP)
2857 #define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP)
2858 
2859 /* PNG_IMAGE macros
2860  *
2861  * These are convenience macros to derive information from a png_image
2862  * structure.  The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
2863  * actual image sample values - either the entries in the color-map or the
2864  * pixels in the image.  The PNG_IMAGE_PIXEL_ macros return corresponding values
2865  * for the pixels and will always return 1 for color-mapped formats.  The
2866  * remaining macros return information about the rows in the image and the
2867  * complete image.
2868  *
2869  * NOTE: All the macros that take a png_image::format parameter are compile time
2870  * constants if the format parameter is, itself, a constant.  Therefore these
2871  * macros can be used in array declarations and case labels where required.
2872  * Similarly the macros are also pre-processor constants (sizeof is not used) so
2873  * they can be used in #if tests.
2874  *
2875  * First the information about the samples.
2876  */
2877 #define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\
2878    (((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1)
2879    /* Return the total number of channels in a given format: 1..4 */
2880 
2881 #define PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)\
2882    ((((fmt) & PNG_FORMAT_FLAG_LINEAR) >> 2)+1)
2883    /* Return the size in bytes of a single component of a pixel or color-map
2884     * entry (as appropriate) in the image: 1 or 2.
2885     */
2886 
2887 #define PNG_IMAGE_SAMPLE_SIZE(fmt)\
2888    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt))
2889    /* This is the size of the sample data for one sample.  If the image is
2890     * color-mapped it is the size of one color-map entry (and image pixels are
2891     * one byte in size), otherwise it is the size of one image pixel.
2892     */
2893 
2894 #define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
2895    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
2896    /* The maximum size of the color-map required by the format expressed in a
2897     * count of components.  This can be used to compile-time allocate a
2898     * color-map:
2899     *
2900     * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
2901     *
2902     * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
2903     *
2904     * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
2905     * information from one of the png_image_begin_read_ APIs and dynamically
2906     * allocate the required memory.
2907     */
2908 
2909 /* Corresponding information about the pixels */
2910 #define PNG_IMAGE_PIXEL_(test,fmt)\
2911    (((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt))
2912 
2913 #define PNG_IMAGE_PIXEL_CHANNELS(fmt)\
2914    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt)
2915    /* The number of separate channels (components) in a pixel; 1 for a
2916     * color-mapped image.
2917     */
2918 
2919 #define PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
2920    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_COMPONENT_SIZE,fmt)
2921    /* The size, in bytes, of each component in a pixel; 1 for a color-mapped
2922     * image.
2923     */
2924 
2925 #define PNG_IMAGE_PIXEL_SIZE(fmt) PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_SIZE,fmt)
2926    /* The size, in bytes, of a complete pixel; 1 for a color-mapped image. */
2927 
2928 /* Information about the whole row, or whole image */
2929 #define PNG_IMAGE_ROW_STRIDE(image)\
2930    (PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width)
2931    /* Return the total number of components in a single row of the image; this
2932     * is the minimum 'row stride', the minimum count of components between each
2933     * row.  For a color-mapped image this is the minimum number of bytes in a
2934     * row.
2935     *
2936     * WARNING: this macro overflows for some images with more than one component
2937     * and very large image widths.  libpng will refuse to process an image where
2938     * this macro would overflow.
2939     */
2940 
2941 #define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
2942    (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
2943    /* Return the size, in bytes, of an image buffer given a png_image and a row
2944     * stride - the number of components to leave space for in each row.
2945     *
2946     * WARNING: this macro overflows a 32-bit integer for some large PNG images,
2947     * libpng will refuse to process an image where such an overflow would occur.
2948     */
2949 
2950 #define PNG_IMAGE_SIZE(image)\
2951    PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image))
2952    /* Return the size, in bytes, of the image in memory given just a png_image;
2953     * the row stride is the minimum stride required for the image.
2954     */
2955 
2956 #define PNG_IMAGE_COLORMAP_SIZE(image)\
2957    (PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries)
2958    /* Return the size, in bytes, of the color-map of this image.  If the image
2959     * format is not a color-map format this will return a size sufficient for
2960     * 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
2961     * you don't want to allocate a color-map in this case.
2962     */
2963 
2964 /* PNG_IMAGE_FLAG_*
2965  *
2966  * Flags containing additional information about the image are held in the
2967  * 'flags' field of png_image.
2968  */
2969 #define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
2970    /* This indicates the the RGB values of the in-memory bitmap do not
2971     * correspond to the red, green and blue end-points defined by sRGB.
2972     */
2973 
2974 #define PNG_IMAGE_FLAG_FAST 0x02
2975    /* On write emphasise speed over compression; the resultant PNG file will be
2976     * larger but will be produced significantly faster, particular for large
2977     * images.  Do not use this option for images which will be distributed, only
2978     * used it when producing intermediate files that will be read back in
2979     * repeatedly.  For a typical 24-bit image the option will double the read
2980     * speed at the cost of increasing the image size by 25%, however for many
2981     * more compressible images the PNG file can be 10 times larger with only a
2982     * slight speed gain.
2983     */
2984 
2985 #define PNG_IMAGE_FLAG_16BIT_sRGB 0x04
2986    /* On read if the image is a 16-bit per component image and there is no gAMA
2987     * or sRGB chunk assume that the components are sRGB encoded.  Notice that
2988     * images output by the simplified API always have gamma information; setting
2989     * this flag only affects the interpretation of 16-bit images from an
2990     * external source.  It is recommended that the application expose this flag
2991     * to the user; the user can normally easily recognize the difference between
2992     * linear and sRGB encoding.  This flag has no effect on write - the data
2993     * passed to the write APIs must have the correct encoding (as defined
2994     * above.)
2995     *
2996     * If the flag is not set (the default) input 16-bit per component data is
2997     * assumed to be linear.
2998     *
2999     * NOTE: the flag can only be set after the png_image_begin_read_ call,
3000     * because that call initializes the 'flags' field.
3001     */
3002 
3003 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
3004 /* READ APIs
3005  * ---------
3006  *
3007  * The png_image passed to the read APIs must have been initialized by setting
3008  * the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.)
3009  */
3010 #ifdef PNG_STDIO_SUPPORTED
3011 PNG_EXPORT(234, int, png_image_begin_read_from_file, (png_imagep image,
3012    const char *file_name));
3013    /* The named file is opened for read and the image header is filled in
3014     * from the PNG header in the file.
3015     */
3016 
3017 PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
3018    FILE* file));
3019    /* The PNG header is read from the stdio FILE object. */
3020 #endif /* STDIO */
3021 
3022 PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
3023    png_const_voidp memory, png_size_t size));
3024    /* The PNG header is read from the given memory buffer. */
3025 
3026 PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
3027    png_const_colorp background, void *buffer, png_int_32 row_stride,
3028    void *colormap));
3029    /* Finish reading the image into the supplied buffer and clean up the
3030     * png_image structure.
3031     *
3032     * row_stride is the step, in byte or 2-byte units as appropriate,
3033     * between adjacent rows.  A positive stride indicates that the top-most row
3034     * is first in the buffer - the normal top-down arrangement.  A negative
3035     * stride indicates that the bottom-most row is first in the buffer.
3036     *
3037     * background need only be supplied if an alpha channel must be removed from
3038     * a png_byte format and the removal is to be done by compositing on a solid
3039     * color; otherwise it may be NULL and any composition will be done directly
3040     * onto the buffer.  The value is an sRGB color to use for the background,
3041     * for grayscale output the green channel is used.
3042     *
3043     * background must be supplied when an alpha channel must be removed from a
3044     * single byte color-mapped output format, in other words if:
3045     *
3046     * 1) The original format from png_image_begin_read_from_* had
3047     *    PNG_FORMAT_FLAG_ALPHA set.
3048     * 2) The format set by the application does not.
3049     * 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
3050     *    PNG_FORMAT_FLAG_LINEAR *not* set.
3051     *
3052     * For linear output removing the alpha channel is always done by compositing
3053     * on black and background is ignored.
3054     *
3055     * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set.  It must
3056     * be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
3057     * image->colormap_entries will be updated to the actual number of entries
3058     * written to the colormap; this may be less than the original value.
3059     */
3060 
3061 PNG_EXPORT(238, void, png_image_free, (png_imagep image));
3062    /* Free any data allocated by libpng in image->opaque, setting the pointer to
3063     * NULL.  May be called at any time after the structure is initialized.
3064     */
3065 #endif /* SIMPLIFIED_READ */
3066 
3067 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
3068 /* WRITE APIS
3069  * ----------
3070  * For write you must initialize a png_image structure to describe the image to
3071  * be written.  To do this use memset to set the whole structure to 0 then
3072  * initialize fields describing your image.
3073  *
3074  * version: must be set to PNG_IMAGE_VERSION
3075  * opaque: must be initialized to NULL
3076  * width: image width in pixels
3077  * height: image height in rows
3078  * format: the format of the data (image and color-map) you wish to write
3079  * flags: set to 0 unless one of the defined flags applies; set
3080  *    PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB
3081  *    values do not correspond to the colors in sRGB.
3082  * colormap_entries: set to the number of entries in the color-map (0 to 256)
3083  */
3084 #ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
3085 PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
3086    const char *file, int convert_to_8bit, const void *buffer,
3087    png_int_32 row_stride, const void *colormap));
3088    /* Write the image to the named file. */
3089 
3090 PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
3091    int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
3092    const void *colormap));
3093    /* Write the image to the given (FILE*). */
3094 #endif /* SIMPLIFIED_WRITE_STDIO */
3095 
3096 /* With all write APIs if image is in one of the linear formats with 16-bit
3097  * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
3098  * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
3099  * encoded PNG file is written.
3100  *
3101  * With color-mapped data formats the colormap parameter point to a color-map
3102  * with at least image->colormap_entries encoded in the specified format.  If
3103  * the format is linear the written PNG color-map will be converted to sRGB
3104  * regardless of the convert_to_8_bit flag.
3105  *
3106  * With all APIs row_stride is handled as in the read APIs - it is the spacing
3107  * from one row to the next in component sized units (1 or 2 bytes) and if
3108  * negative indicates a bottom-up row layout in the buffer.  If row_stride is
3109  * zero, libpng will calculate it for you from the image width and number of
3110  * channels.
3111  *
3112  * Note that the write API does not support interlacing, sub-8-bit pixels or
3113  * most ancillary chunks.  If you need to write text chunks (e.g. for copyright
3114  * notices) you need to use one of the other APIs.
3115  */
3116 
3117 PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
3118    png_alloc_size_t * PNG_RESTRICT memory_bytes, int convert_to_8_bit,
3119    const void *buffer, png_int_32 row_stride, const void *colormap));
3120    /* Write the image to the given memory buffer.  The function both writes the
3121     * whole PNG data stream to *memory and updates *memory_bytes with the count
3122     * of bytes written.
3123     *
3124     * 'memory' may be NULL.  In this case *memory_bytes is not read however on
3125     * success the number of bytes which would have been written will still be
3126     * stored in *memory_bytes.  On failure *memory_bytes will contain 0.
3127     *
3128     * If 'memory' is not NULL it must point to memory[*memory_bytes] of
3129     * writeable memory.
3130     *
3131     * If the function returns success memory[*memory_bytes] (if 'memory' is not
3132     * NULL) contains the written PNG data.  *memory_bytes will always be less
3133     * than or equal to the original value.
3134     *
3135     * If the function returns false and *memory_bytes was not changed an error
3136     * occured during write.  If *memory_bytes was changed, or is not 0 if
3137     * 'memory' was NULL, the write would have succeeded but for the memory
3138     * buffer being too small.  *memory_bytes contains the required number of
3139     * bytes and will be bigger that the original value.
3140     */
3141 
3142 #define png_image_write_get_memory_size(image, size, convert_to_8_bit, buffer,\
3143    row_stride, colormap)\
3144    png_image_write_to_memory(&(image), 0, &(size), convert_to_8_bit, buffer,\
3145          row_stride, colormap)
3146    /* Return the amount of memory in 'size' required to compress this image.
3147     * The png_image structure 'image' must be filled in as in the above
3148     * function and must not be changed before the actual write call, the buffer
3149     * and all other parameters must also be identical to that in the final
3150     * write call.  The 'size' variable need not be initialized.
3151     *
3152     * NOTE: the macro returns true/false, if false is returned 'size' will be
3153     * set to zero and the write failed and probably will fail if tried again.
3154     */
3155 
3156 /* You can pre-allocate the buffer by making sure it is of sufficient size
3157  * regardless of the amount of compression achieved.  The buffer size will
3158  * always be bigger than the original image and it will never be filled.  The
3159  * following macros are provided to assist in allocating the buffer.
3160  */
3161 #define PNG_IMAGE_DATA_SIZE(image) (PNG_IMAGE_SIZE(image)+(image).height)
3162    /* The number of uncompressed bytes in the PNG byte encoding of the image;
3163     * uncompressing the PNG IDAT data will give this number of bytes.
3164     *
3165     * NOTE: while PNG_IMAGE_SIZE cannot overflow for an image in memory this
3166     * macro can because of the extra bytes used in the PNG byte encoding.  You
3167     * need to avoid this macro if your image size approaches 2^30 in width or
3168     * height.  The same goes for the remainder of these macros; they all produce
3169     * bigger numbers than the actual in-memory image size.
3170     */
3171 #ifndef PNG_ZLIB_MAX_SIZE
3172 #  define PNG_ZLIB_MAX_SIZE(b) ((b)+(((b)+7U)>>3)+(((b)+63U)>>6)+11U)
3173    /* An upper bound on the number of compressed bytes given 'b' uncompressed
3174     * bytes.  This is based on deflateBounds() in zlib; different
3175     * implementations of zlib compression may conceivably produce more data so
3176     * if your zlib implementation is not zlib itself redefine this macro
3177     * appropriately.
3178     */
3179 #endif
3180 
3181 #define PNG_IMAGE_COMPRESSED_SIZE_MAX(image)\
3182    PNG_ZLIB_MAX_SIZE((png_alloc_size_t)PNG_IMAGE_DATA_SIZE(image))
3183    /* An upper bound on the size of the data in the PNG IDAT chunks. */
3184 
3185 #define PNG_IMAGE_PNG_SIZE_MAX_(image, image_size)\
3186    ((8U/*sig*/+25U/*IHDR*/+16U/*gAMA*/+44U/*cHRM*/+12U/*IEND*/+\
3187     (((image).format&PNG_FORMAT_FLAG_COLORMAP)?/*colormap: PLTE, tRNS*/\
3188     12U+3U*(image).colormap_entries/*PLTE data*/+\
3189     (((image).format&PNG_FORMAT_FLAG_ALPHA)?\
3190     12U/*tRNS*/+(image).colormap_entries:0U):0U)+\
3191     12U)+(12U*((image_size)/PNG_ZBUF_SIZE))/*IDAT*/+(image_size))
3192    /* A helper for the following macro; if your compiler cannot handle the
3193     * following macro use this one with the result of
3194     * PNG_IMAGE_COMPRESSED_SIZE_MAX(image) as the second argument (most
3195     * compilers should handle this just fine.)
3196     */
3197 
3198 #define PNG_IMAGE_PNG_SIZE_MAX(image)\
3199    PNG_IMAGE_PNG_SIZE_MAX_(image, PNG_IMAGE_COMPRESSED_SIZE_MAX(image))
3200    /* An upper bound on the total length of the PNG data stream for 'image'.
3201     * The result is of type png_alloc_size_t, on 32-bit systems this may
3202     * overflow even though PNG_IMAGE_DATA_SIZE does not overflow; the write will
3203     * run out of buffer space but return a corrected size which should work.
3204     */
3205 #endif /* SIMPLIFIED_WRITE */
3206 /*******************************************************************************
3207  *  END OF SIMPLIFIED API
3208  ******************************************************************************/
3209 #endif /* SIMPLIFIED_{READ|WRITE} */
3210 
3211 /*******************************************************************************
3212  * Section 6: IMPLEMENTATION OPTIONS
3213  *******************************************************************************
3214  *
3215  * Support for arbitrary implementation-specific optimizations.  The API allows
3216  * particular options to be turned on or off.  'Option' is the number of the
3217  * option and 'onoff' is 0 (off) or non-0 (on).  The value returned is given
3218  * by the PNG_OPTION_ defines below.
3219  *
3220  * HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
3221  *           are detected at run time, however sometimes it may be impossible
3222  *           to do this in user mode, in which case it is necessary to discover
3223  *           the capabilities in an OS specific way.  Such capabilities are
3224  *           listed here when libpng has support for them and must be turned
3225  *           ON by the application if present.
3226  *
3227  * SOFTWARE: sometimes software optimizations actually result in performance
3228  *           decrease on some architectures or systems, or with some sets of
3229  *           PNG images.  'Software' options allow such optimizations to be
3230  *           selected at run time.
3231  */
3232 #ifdef PNG_SET_OPTION_SUPPORTED
3233 #ifdef PNG_ARM_NEON_API_SUPPORTED
3234 #  define PNG_ARM_NEON   0 /* HARDWARE: ARM Neon SIMD instructions supported */
3235 #endif
3236 #define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
3237 #define PNG_SKIP_sRGB_CHECK_PROFILE 4 /* SOFTWARE: Check ICC profile for sRGB */
3238 #ifdef PNG_MIPS_MSA_API_SUPPORTED
3239 #  define PNG_MIPS_MSA   6 /* HARDWARE: MIPS Msa SIMD instructions supported */
3240 #endif
3241 #define PNG_IGNORE_ADLER32 8
3242 #ifdef PNG_POWERPC_VSX_API_SUPPORTED
3243 #  define PNG_POWERPC_VSX   10 /* HARDWARE: PowerPC VSX SIMD instructions supported */
3244 #endif
3245 #define PNG_OPTION_NEXT  12 /* Next option - numbers must be even */
3246 
3247 /* Return values: NOTE: there are four values and 'off' is *not* zero */
3248 #define PNG_OPTION_UNSET   0 /* Unset - defaults to off */
3249 #define PNG_OPTION_INVALID 1 /* Option number out of range */
3250 #define PNG_OPTION_OFF     2
3251 #define PNG_OPTION_ON      3
3252 
3253 PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
3254    int onoff));
3255 #endif /* SET_OPTION */
3256 
3257 /*******************************************************************************
3258  *  END OF HARDWARE AND SOFTWARE OPTIONS
3259  ******************************************************************************/
3260 
3261 /* Maintainer: Put new public prototypes here ^, in libpng.3, in project
3262  * defs, and in scripts/symbols.def.
3263  */
3264 
3265 /* The last ordinal number (this is the *last* one already used; the next
3266  * one to use is one more than this.)
3267  */
3268 #ifdef PNG_EXPORT_LAST_ORDINAL
3269   PNG_EXPORT_LAST_ORDINAL(249);
3270 #endif
3271 
3272 #ifdef __cplusplus
3273 }
3274 #endif
3275 
3276 #endif /* PNG_VERSION_INFO_ONLY */
3277 /* Do not put anything past this line */
3278 #endif /* PNG_H */
3279