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1 
2 /* png.h - header file for PNG reference library
3  *
4  * libpng version 1.6.22, May 26, 2016
5  *
6  * Copyright (c) 1998-2002,2004,2006-2016 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 1.6.22, May 26, 2016:
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  * Some files in the "contrib" directory and some configure-generated
29  * files that are distributed with libpng have other copyright owners and
30  * are released under other open source licenses.
31  *
32  * libpng versions 1.0.7, July 1, 2000 through 1.6.22, May 26, 2016 are
33  * Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
34  * derived from libpng-1.0.6, and are distributed according to the same
35  * disclaimer and license as libpng-1.0.6 with the following individuals
36  * added to the list of Contributing Authors:
37  *
38  *    Simon-Pierre Cadieux
39  *    Eric S. Raymond
40  *    Mans Rullgard
41  *    Cosmin Truta
42  *    Gilles Vollant
43  *    James Yu
44  *
45  * and with the following additions to the disclaimer:
46  *
47  *    There is no warranty against interference with your enjoyment of the
48  *    library or against infringement.  There is no warranty that our
49  *    efforts or the library will fulfill any of your particular purposes
50  *    or needs.  This library is provided with all faults, and the entire
51  *    risk of satisfactory quality, performance, accuracy, and effort is with
52  *    the user.
53  *
54  * Some files in the "contrib" directory have other copyright owners and
55  * are released under other open source licenses.
56  *
57  *
58  * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
59  * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
60  * libpng-0.96, and are distributed according to the same disclaimer and
61  * license as libpng-0.96, with the following individuals added to the list
62  * of Contributing Authors:
63  *
64  *    Tom Lane
65  *    Glenn Randers-Pehrson
66  *    Willem van Schaik
67  *
68  * Some files in the "scripts" directory have different copyright owners
69  * but are also released under this license.
70  *
71  * libpng versions 0.89, June 1996, through 0.96, May 1997, are
72  * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
73  * and are distributed according to the same disclaimer and license as
74  * libpng-0.88, with the following individuals added to the list of
75  * Contributing Authors:
76  *
77  *    John Bowler
78  *    Kevin Bracey
79  *    Sam Bushell
80  *    Magnus Holmgren
81  *    Greg Roelofs
82  *    Tom Tanner
83  *
84  * Some files in the "scripts" directory have other copyright owners
85  * but are released under this license.
86  *
87  * libpng versions 0.5, May 1995, through 0.88, January 1996, are
88  * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
89  *
90  * For the purposes of this copyright and license, "Contributing Authors"
91  * is defined as the following set of individuals:
92  *
93  *    Andreas Dilger
94  *    Dave Martindale
95  *    Guy Eric Schalnat
96  *    Paul Schmidt
97  *    Tim Wegner
98  *
99  * The PNG Reference Library is supplied "AS IS".  The Contributing Authors
100  * and Group 42, Inc. disclaim all warranties, expressed or implied,
101  * including, without limitation, the warranties of merchantability and of
102  * fitness for any purpose.  The Contributing Authors and Group 42, Inc.
103  * assume no liability for direct, indirect, incidental, special, exemplary,
104  * or consequential damages, which may result from the use of the PNG
105  * Reference Library, even if advised of the possibility of such damage.
106  *
107  * Permission is hereby granted to use, copy, modify, and distribute this
108  * source code, or portions hereof, for any purpose, without fee, subject
109  * to the following restrictions:
110  *
111  *   1. The origin of this source code must not be misrepresented.
112  *
113  *   2. Altered versions must be plainly marked as such and must not
114  *      be misrepresented as being the original source.
115  *
116  *   3. This Copyright notice may not be removed or altered from any
117  *      source or altered source distribution.
118  *
119  * The Contributing Authors and Group 42, Inc. specifically permit, without
120  * fee, and encourage the use of this source code as a component to
121  * supporting the PNG file format in commercial products.  If you use this
122  * source code in a product, acknowledgment is not required but would be
123  * appreciated.
124  *
125  * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
126  *
127  * TRADEMARK:
128  *
129  * The name "libpng" has not been registered by the Copyright owner
130  * as a trademark in any jurisdiction.  However, because libpng has
131  * been distributed and maintained world-wide, continually since 1995,
132  * the Copyright owner claims "common-law trademark protection" in any
133  * jurisdiction where common-law trademark is recognized.
134  *
135  * OSI CERTIFICATION:
136  *
137  * Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is
138  * a certification mark of the Open Source Initiative. OSI has not addressed
139  * the additional disclaimers inserted at version 1.0.7.
140  *
141  * EXPORT CONTROL:
142  *
143  * The Copyright owner believes that the Export Control Classification
144  * Number (ECCN) for libpng is EAR99, which means not subject to export
145  * controls or International Traffic in Arms Regulations (ITAR) because
146  * it is open source, publicly available software, that does not contain
147  * any encryption software.  See the EAR, paragraphs 734.3(b)(3) and
148  * 734.7(b).
149  */
150 
151 /*
152  * A "png_get_copyright" function is available, for convenient use in "about"
153  * boxes and the like:
154  *
155  *    printf("%s", png_get_copyright(NULL));
156  *
157  * Also, the PNG logo (in PNG format, of course) is supplied in the
158  * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
159  */
160 
161 /*
162  * The contributing authors would like to thank all those who helped
163  * with testing, bug fixes, and patience.  This wouldn't have been
164  * possible without all of you.
165  *
166  * Thanks to Frank J. T. Wojcik for helping with the documentation.
167  */
168 
169 /* Note about libpng version numbers:
170  *
171  *    Due to various miscommunications, unforeseen code incompatibilities
172  *    and occasional factors outside the authors' control, version numbering
173  *    on the library has not always been consistent and straightforward.
174  *    The following table summarizes matters since version 0.89c, which was
175  *    the first widely used release:
176  *
177  *    source                 png.h  png.h  shared-lib
178  *    version                string   int  version
179  *    -------                ------ -----  ----------
180  *    0.89c "1.0 beta 3"     0.89      89  1.0.89
181  *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
182  *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
183  *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
184  *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
185  *    0.97c                  0.97      97  2.0.97
186  *    0.98                   0.98      98  2.0.98
187  *    0.99                   0.99      98  2.0.99
188  *    0.99a-m                0.99      99  2.0.99
189  *    1.00                   1.00     100  2.1.0 [100 should be 10000]
190  *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
191  *    1.0.1       png.h string is   10001  2.1.0
192  *    1.0.1a-e    identical to the  10002  from here on, the shared library
193  *    1.0.2       source version)   10002  is 2.V where V is the source code
194  *    1.0.2a-b                      10003  version, except as noted.
195  *    1.0.3                         10003
196  *    1.0.3a-d                      10004
197  *    1.0.4                         10004
198  *    1.0.4a-f                      10005
199  *    1.0.5 (+ 2 patches)           10005
200  *    1.0.5a-d                      10006
201  *    1.0.5e-r                      10100 (not source compatible)
202  *    1.0.5s-v                      10006 (not binary compatible)
203  *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)
204  *    1.0.6d-f                      10007 (still binary incompatible)
205  *    1.0.6g                        10007
206  *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)
207  *    1.0.6i                        10007  10.6i
208  *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
209  *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
210  *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
211  *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
212  *    1.0.7                    1    10007  (still compatible)
213  *    ...
214  *    1.0.19                  10    10019  10.so.0.19[.0]
215  *    ...
216  *    1.2.56                  13    10256  12.so.0.56[.0]
217  *    ...
218  *    1.5.27                  15    10527  15.so.15.27[.0]
219  *    ...
220  *    1.6.22                  16    10622  16.so.16.22[.0]
221  *
222  *    Henceforth the source version will match the shared-library major
223  *    and minor numbers; the shared-library major version number will be
224  *    used for changes in backward compatibility, as it is intended.  The
225  *    PNG_LIBPNG_VER macro, which is not used within libpng but is available
226  *    for applications, is an unsigned integer of the form xyyzz corresponding
227  *    to the source version x.y.z (leading zeros in y and z).  Beta versions
228  *    were given the previous public release number plus a letter, until
229  *    version 1.0.6j; from then on they were given the upcoming public
230  *    release number plus "betaNN" or "rcNN".
231  *
232  *    Binary incompatibility exists only when applications make direct access
233  *    to the info_ptr or png_ptr members through png.h, and the compiled
234  *    application is loaded with a different version of the library.
235  *
236  *    DLLNUM will change each time there are forward or backward changes
237  *    in binary compatibility (e.g., when a new feature is added).
238  *
239  * See libpng.txt or libpng.3 for more information.  The PNG specification
240  * is available as a W3C Recommendation and as an ISO Specification,
241  * <http://www.w3.org/TR/2003/REC-PNG-20031110/
242  */
243 
244 /*
245  * Y2K compliance in libpng:
246  * =========================
247  *
248  *    May 26, 2016
249  *
250  *    Since the PNG Development group is an ad-hoc body, we can't make
251  *    an official declaration.
252  *
253  *    This is your unofficial assurance that libpng from version 0.71 and
254  *    upward through 1.6.22 are Y2K compliant.  It is my belief that
255  *    earlier versions were also Y2K compliant.
256  *
257  *    Libpng only has two year fields.  One is a 2-byte unsigned integer
258  *    that will hold years up to 65535.  The other, which is deprecated,
259  *    holds the date in text format, and will hold years up to 9999.
260  *
261  *    The integer is
262  *        "png_uint_16 year" in png_time_struct.
263  *
264  *    The string is
265  *        "char time_buffer[29]" in png_struct.  This is no longer used
266  *    in libpng-1.6.x and will be removed from libpng-1.7.0.
267  *
268  *    There are seven time-related functions:
269  *        png.c: png_convert_to_rfc_1123_buffer() in png.c
270  *          (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
271  *          png_convert_to_rfc_1152() in error prior to libpng-0.98)
272  *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
273  *        png_convert_from_time_t() in pngwrite.c
274  *        png_get_tIME() in pngget.c
275  *        png_handle_tIME() in pngrutil.c, called in pngread.c
276  *        png_set_tIME() in pngset.c
277  *        png_write_tIME() in pngwutil.c, called in pngwrite.c
278  *
279  *    All handle dates properly in a Y2K environment.  The
280  *    png_convert_from_time_t() function calls gmtime() to convert from system
281  *    clock time, which returns (year - 1900), which we properly convert to
282  *    the full 4-digit year.  There is a possibility that libpng applications
283  *    are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
284  *    function, or that they are incorrectly passing only a 2-digit year
285  *    instead of "year - 1900" into the png_convert_from_struct_tm() function,
286  *    but this is not under our control.  The libpng documentation has always
287  *    stated that it works with 4-digit years, and the APIs have been
288  *    documented as such.
289  *
290  *    The tIME chunk itself is also Y2K compliant.  It uses a 2-byte unsigned
291  *    integer to hold the year, and can hold years as large as 65535.
292  *
293  *    zlib, upon which libpng depends, is also Y2K compliant.  It contains
294  *    no date-related code.
295  *
296  *       Glenn Randers-Pehrson
297  *       libpng maintainer
298  *       PNG Development Group
299  */
300 
301 #ifndef PNG_H
302 #define PNG_H
303 
304 /* This is not the place to learn how to use libpng. The file libpng-manual.txt
305  * describes how to use libpng, and the file example.c summarizes it
306  * with some code on which to build.  This file is useful for looking
307  * at the actual function definitions and structure components.  If that
308  * file has been stripped from your copy of libpng, you can find it at
309  * <http://www.libpng.org/pub/png/libpng-manual.txt>
310  *
311  * If you just need to read a PNG file and don't want to read the documentation
312  * skip to the end of this file and read the section entitled 'simplified API'.
313  */
314 
315 /* Version information for png.h - this should match the version in png.c */
316 #define PNG_LIBPNG_VER_STRING "1.6.22"
317 #define PNG_HEADER_VERSION_STRING \
318      " libpng version 1.6.22 - May 26, 2016\n"
319 
320 #define PNG_LIBPNG_VER_SONUM   16
321 #define PNG_LIBPNG_VER_DLLNUM  16
322 
323 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
324 #define PNG_LIBPNG_VER_MAJOR   1
325 #define PNG_LIBPNG_VER_MINOR   6
326 #define PNG_LIBPNG_VER_RELEASE 22
327 
328 /* This should match the numeric part of the final component of
329  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
330  */
331 
332 #define PNG_LIBPNG_VER_BUILD  0
333 
334 /* Release Status */
335 #define PNG_LIBPNG_BUILD_ALPHA    1
336 #define PNG_LIBPNG_BUILD_BETA     2
337 #define PNG_LIBPNG_BUILD_RC       3
338 #define PNG_LIBPNG_BUILD_STABLE   4
339 #define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7
340 
341 /* Release-Specific Flags */
342 #define PNG_LIBPNG_BUILD_PATCH    8 /* Can be OR'ed with
343                                        PNG_LIBPNG_BUILD_STABLE only */
344 #define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with
345                                        PNG_LIBPNG_BUILD_SPECIAL */
346 #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
347                                        PNG_LIBPNG_BUILD_PRIVATE */
348 
349 #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
350 
351 /* Careful here.  At one time, Guy wanted to use 082, but that would be octal.
352  * We must not include leading zeros.
353  * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
354  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
355  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
356  */
357 #define PNG_LIBPNG_VER 10622 /* 1.6.22 */
358 
359 /* Library configuration: these options cannot be changed after
360  * the library has been built.
361  */
362 #ifndef PNGLCONF_H
363     /* If pnglibconf.h is missing, you can
364      * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
365      */
366 #   include "pnglibconf.h"
367 #endif
368 
369 #ifndef PNG_VERSION_INFO_ONLY
370    /* Machine specific configuration. */
371 #  include "pngconf.h"
372 #endif
373 
374 /*
375  * Added at libpng-1.2.8
376  *
377  * Ref MSDN: Private as priority over Special
378  * VS_FF_PRIVATEBUILD File *was not* built using standard release
379  * procedures. If this value is given, the StringFileInfo block must
380  * contain a PrivateBuild string.
381  *
382  * VS_FF_SPECIALBUILD File *was* built by the original company using
383  * standard release procedures but is a variation of the standard
384  * file of the same version number. If this value is given, the
385  * StringFileInfo block must contain a SpecialBuild string.
386  */
387 
388 #ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */
389 #  define PNG_LIBPNG_BUILD_TYPE \
390        (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
391 #else
392 #  ifdef PNG_LIBPNG_SPECIALBUILD
393 #    define PNG_LIBPNG_BUILD_TYPE \
394          (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
395 #  else
396 #    define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)
397 #  endif
398 #endif
399 
400 #ifndef PNG_VERSION_INFO_ONLY
401 
402 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
403 #ifdef __cplusplus
404 extern "C" {
405 #endif /* __cplusplus */
406 
407 /* Version information for C files, stored in png.c.  This had better match
408  * the version above.
409  */
410 #define png_libpng_ver png_get_header_ver(NULL)
411 
412 /* This file is arranged in several sections:
413  *
414  * 1. [omitted]
415  * 2. Any configuration options that can be specified by for the application
416  *    code when it is built.  (Build time configuration is in pnglibconf.h)
417  * 3. Type definitions (base types are defined in pngconf.h), structure
418  *    definitions.
419  * 4. Exported library functions.
420  * 5. Simplified API.
421  * 6. Implementation options.
422  *
423  * The library source code has additional files (principally pngpriv.h) that
424  * allow configuration of the library.
425  */
426 
427 /* Section 1: [omitted] */
428 
429 /* Section 2: run time configuration
430  * See pnglibconf.h for build time configuration
431  *
432  * Run time configuration allows the application to choose between
433  * implementations of certain arithmetic APIs.  The default is set
434  * at build time and recorded in pnglibconf.h, but it is safe to
435  * override these (and only these) settings.  Note that this won't
436  * change what the library does, only application code, and the
437  * settings can (and probably should) be made on a per-file basis
438  * by setting the #defines before including png.h
439  *
440  * Use macros to read integers from PNG data or use the exported
441  * functions?
442  *   PNG_USE_READ_MACROS: use the macros (see below)  Note that
443  *     the macros evaluate their argument multiple times.
444  *   PNG_NO_USE_READ_MACROS: call the relevant library function.
445  *
446  * Use the alternative algorithm for compositing alpha samples that
447  * does not use division?
448  *   PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division'
449  *      algorithm.
450  *   PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm.
451  *
452  * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is
453  * false?
454  *   PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error
455  *      APIs to png_warning.
456  * Otherwise the calls are mapped to png_error.
457  */
458 
459 /* Section 3: type definitions, including structures and compile time
460  * constants.
461  * See pngconf.h for base types that vary by machine/system
462  */
463 
464 /* This triggers a compiler error in png.c, if png.c and png.h
465  * do not agree upon the version number.
466  */
467 typedef char* png_libpng_version_1_6_22;
468 
469 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
470  *
471  * png_struct is the cache of information used while reading or writing a single
472  * PNG file.  One of these is always required, although the simplified API
473  * (below) hides the creation and destruction of it.
474  */
475 typedef struct png_struct_def png_struct;
476 typedef const png_struct * png_const_structp;
477 typedef png_struct * png_structp;
478 typedef png_struct * * png_structpp;
479 
480 /* png_info contains information read from or to be written to a PNG file.  One
481  * or more of these must exist while reading or creating a PNG file.  The
482  * information is not used by libpng during read but is used to control what
483  * gets written when a PNG file is created.  "png_get_" function calls read
484  * information during read and "png_set_" functions calls write information
485  * when creating a PNG.
486  * been moved into a separate header file that is not accessible to
487  * applications.  Read libpng-manual.txt or libpng.3 for more info.
488  */
489 typedef struct png_info_def png_info;
490 typedef png_info * png_infop;
491 typedef const png_info * png_const_infop;
492 typedef png_info * * png_infopp;
493 
494 /* Types with names ending 'p' are pointer types.  The corresponding types with
495  * names ending 'rp' are identical pointer types except that the pointer is
496  * marked 'restrict', which means that it is the only pointer to the object
497  * passed to the function.  Applications should not use the 'restrict' types;
498  * it is always valid to pass 'p' to a pointer with a function argument of the
499  * corresponding 'rp' type.  Different compilers have different rules with
500  * regard to type matching in the presence of 'restrict'.  For backward
501  * compatibility libpng callbacks never have 'restrict' in their parameters and,
502  * consequentially, writing portable application code is extremely difficult if
503  * an attempt is made to use 'restrict'.
504  */
505 typedef png_struct * PNG_RESTRICT png_structrp;
506 typedef const png_struct * PNG_RESTRICT png_const_structrp;
507 typedef png_info * PNG_RESTRICT png_inforp;
508 typedef const png_info * PNG_RESTRICT png_const_inforp;
509 
510 /* Three color definitions.  The order of the red, green, and blue, (and the
511  * exact size) is not important, although the size of the fields need to
512  * be png_byte or png_uint_16 (as defined below).
513  */
514 typedef struct png_color_struct
515 {
516    png_byte red;
517    png_byte green;
518    png_byte blue;
519 } png_color;
520 typedef png_color * png_colorp;
521 typedef const png_color * png_const_colorp;
522 typedef png_color * * png_colorpp;
523 
524 typedef struct png_color_16_struct
525 {
526    png_byte index;    /* used for palette files */
527    png_uint_16 red;   /* for use in red green blue files */
528    png_uint_16 green;
529    png_uint_16 blue;
530    png_uint_16 gray;  /* for use in grayscale files */
531 } png_color_16;
532 typedef png_color_16 * png_color_16p;
533 typedef const png_color_16 * png_const_color_16p;
534 typedef png_color_16 * * png_color_16pp;
535 
536 typedef struct png_color_8_struct
537 {
538    png_byte red;   /* for use in red green blue files */
539    png_byte green;
540    png_byte blue;
541    png_byte gray;  /* for use in grayscale files */
542    png_byte alpha; /* for alpha channel files */
543 } png_color_8;
544 typedef png_color_8 * png_color_8p;
545 typedef const png_color_8 * png_const_color_8p;
546 typedef png_color_8 * * png_color_8pp;
547 
548 /*
549  * The following two structures are used for the in-core representation
550  * of sPLT chunks.
551  */
552 typedef struct png_sPLT_entry_struct
553 {
554    png_uint_16 red;
555    png_uint_16 green;
556    png_uint_16 blue;
557    png_uint_16 alpha;
558    png_uint_16 frequency;
559 } png_sPLT_entry;
560 typedef png_sPLT_entry * png_sPLT_entryp;
561 typedef const png_sPLT_entry * png_const_sPLT_entryp;
562 typedef png_sPLT_entry * * png_sPLT_entrypp;
563 
564 /*  When the depth of the sPLT palette is 8 bits, the color and alpha samples
565  *  occupy the LSB of their respective members, and the MSB of each member
566  *  is zero-filled.  The frequency member always occupies the full 16 bits.
567  */
568 
569 typedef struct png_sPLT_struct
570 {
571    png_charp name;           /* palette name */
572    png_byte depth;           /* depth of palette samples */
573    png_sPLT_entryp entries;  /* palette entries */
574    png_int_32 nentries;      /* number of palette entries */
575 } png_sPLT_t;
576 typedef png_sPLT_t * png_sPLT_tp;
577 typedef const png_sPLT_t * png_const_sPLT_tp;
578 typedef png_sPLT_t * * png_sPLT_tpp;
579 
580 #ifdef PNG_TEXT_SUPPORTED
581 /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
582  * and whether that contents is compressed or not.  The "key" field
583  * points to a regular zero-terminated C string.  The "text" fields can be a
584  * regular C string, an empty string, or a NULL pointer.
585  * However, the structure returned by png_get_text() will always contain
586  * the "text" field as a regular zero-terminated C string (possibly
587  * empty), never a NULL pointer, so it can be safely used in printf() and
588  * other string-handling functions.  Note that the "itxt_length", "lang", and
589  * "lang_key" members of the structure only exist when the library is built
590  * with iTXt chunk support.  Prior to libpng-1.4.0 the library was built by
591  * default without iTXt support. Also note that when iTXt *is* supported,
592  * the "lang" and "lang_key" fields contain NULL pointers when the
593  * "compression" field contains * PNG_TEXT_COMPRESSION_NONE or
594  * PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the
595  * same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag"
596  * which is always 0 or 1, or its "compression method" which is always 0.
597  */
598 typedef struct png_text_struct
599 {
600    int  compression;       /* compression value:
601                              -1: tEXt, none
602                               0: zTXt, deflate
603                               1: iTXt, none
604                               2: iTXt, deflate  */
605    png_charp key;          /* keyword, 1-79 character description of "text" */
606    png_charp text;         /* comment, may be an empty string (ie "")
607                               or a NULL pointer */
608    png_size_t text_length; /* length of the text string */
609    png_size_t itxt_length; /* length of the itxt string */
610    png_charp lang;         /* language code, 0-79 characters
611                               or a NULL pointer */
612    png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more
613                               chars or a NULL pointer */
614 } png_text;
615 typedef png_text * png_textp;
616 typedef const png_text * png_const_textp;
617 typedef png_text * * png_textpp;
618 #endif
619 
620 /* Supported compression types for text in PNG files (tEXt, and zTXt).
621  * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
622 #define PNG_TEXT_COMPRESSION_NONE_WR -3
623 #define PNG_TEXT_COMPRESSION_zTXt_WR -2
624 #define PNG_TEXT_COMPRESSION_NONE    -1
625 #define PNG_TEXT_COMPRESSION_zTXt     0
626 #define PNG_ITXT_COMPRESSION_NONE     1
627 #define PNG_ITXT_COMPRESSION_zTXt     2
628 #define PNG_TEXT_COMPRESSION_LAST     3  /* Not a valid value */
629 
630 /* png_time is a way to hold the time in an machine independent way.
631  * Two conversions are provided, both from time_t and struct tm.  There
632  * is no portable way to convert to either of these structures, as far
633  * as I know.  If you know of a portable way, send it to me.  As a side
634  * note - PNG has always been Year 2000 compliant!
635  */
636 typedef struct png_time_struct
637 {
638    png_uint_16 year; /* full year, as in, 1995 */
639    png_byte month;   /* month of year, 1 - 12 */
640    png_byte day;     /* day of month, 1 - 31 */
641    png_byte hour;    /* hour of day, 0 - 23 */
642    png_byte minute;  /* minute of hour, 0 - 59 */
643    png_byte second;  /* second of minute, 0 - 60 (for leap seconds) */
644 } png_time;
645 typedef png_time * png_timep;
646 typedef const png_time * png_const_timep;
647 typedef png_time * * png_timepp;
648 
649 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) ||\
650    defined(PNG_USER_CHUNKS_SUPPORTED)
651 /* png_unknown_chunk is a structure to hold queued chunks for which there is
652  * no specific support.  The idea is that we can use this to queue
653  * up private chunks for output even though the library doesn't actually
654  * know about their semantics.
655  *
656  * The data in the structure is set by libpng on read and used on write.
657  */
658 typedef struct png_unknown_chunk_t
659 {
660     png_byte name[5]; /* Textual chunk name with '\0' terminator */
661     png_byte *data;   /* Data, should not be modified on read! */
662     png_size_t size;
663 
664     /* On write 'location' must be set using the flag values listed below.
665      * Notice that on read it is set by libpng however the values stored have
666      * more bits set than are listed below.  Always treat the value as a
667      * bitmask.  On write set only one bit - setting multiple bits may cause the
668      * chunk to be written in multiple places.
669      */
670     png_byte location; /* mode of operation at read time */
671 }
672 png_unknown_chunk;
673 
674 typedef png_unknown_chunk * png_unknown_chunkp;
675 typedef const png_unknown_chunk * png_const_unknown_chunkp;
676 typedef png_unknown_chunk * * png_unknown_chunkpp;
677 #endif
678 
679 /* Flag values for the unknown chunk location byte. */
680 #define PNG_HAVE_IHDR  0x01
681 #define PNG_HAVE_PLTE  0x02
682 #define PNG_AFTER_IDAT 0x08
683 
684 /* Maximum positive integer used in PNG is (2^31)-1 */
685 #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
686 #define PNG_UINT_32_MAX ((png_uint_32)(-1))
687 #define PNG_SIZE_MAX ((png_size_t)(-1))
688 
689 /* These are constants for fixed point values encoded in the
690  * PNG specification manner (x100000)
691  */
692 #define PNG_FP_1    100000
693 #define PNG_FP_HALF  50000
694 #define PNG_FP_MAX  ((png_fixed_point)0x7fffffffL)
695 #define PNG_FP_MIN  (-PNG_FP_MAX)
696 
697 /* These describe the color_type field in png_info. */
698 /* color type masks */
699 #define PNG_COLOR_MASK_PALETTE    1
700 #define PNG_COLOR_MASK_COLOR      2
701 #define PNG_COLOR_MASK_ALPHA      4
702 
703 /* color types.  Note that not all combinations are legal */
704 #define PNG_COLOR_TYPE_GRAY 0
705 #define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
706 #define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)
707 #define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
708 #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
709 /* aliases */
710 #define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA
711 #define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA
712 
713 /* This is for compression type. PNG 1.0-1.2 only define the single type. */
714 #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
715 #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE
716 
717 /* This is for filter type. PNG 1.0-1.2 only define the single type. */
718 #define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */
719 #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
720 #define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE
721 
722 /* These are for the interlacing type.  These values should NOT be changed. */
723 #define PNG_INTERLACE_NONE        0 /* Non-interlaced image */
724 #define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */
725 #define PNG_INTERLACE_LAST        2 /* Not a valid value */
726 
727 /* These are for the oFFs chunk.  These values should NOT be changed. */
728 #define PNG_OFFSET_PIXEL          0 /* Offset in pixels */
729 #define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */
730 #define PNG_OFFSET_LAST           2 /* Not a valid value */
731 
732 /* These are for the pCAL chunk.  These values should NOT be changed. */
733 #define PNG_EQUATION_LINEAR       0 /* Linear transformation */
734 #define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */
735 #define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */
736 #define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */
737 #define PNG_EQUATION_LAST         4 /* Not a valid value */
738 
739 /* These are for the sCAL chunk.  These values should NOT be changed. */
740 #define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */
741 #define PNG_SCALE_METER           1 /* meters per pixel */
742 #define PNG_SCALE_RADIAN          2 /* radians per pixel */
743 #define PNG_SCALE_LAST            3 /* Not a valid value */
744 
745 /* These are for the pHYs chunk.  These values should NOT be changed. */
746 #define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */
747 #define PNG_RESOLUTION_METER      1 /* pixels/meter */
748 #define PNG_RESOLUTION_LAST       2 /* Not a valid value */
749 
750 /* These are for the sRGB chunk.  These values should NOT be changed. */
751 #define PNG_sRGB_INTENT_PERCEPTUAL 0
752 #define PNG_sRGB_INTENT_RELATIVE   1
753 #define PNG_sRGB_INTENT_SATURATION 2
754 #define PNG_sRGB_INTENT_ABSOLUTE   3
755 #define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */
756 
757 /* This is for text chunks */
758 #define PNG_KEYWORD_MAX_LENGTH     79
759 
760 /* Maximum number of entries in PLTE/sPLT/tRNS arrays */
761 #define PNG_MAX_PALETTE_LENGTH    256
762 
763 /* These determine if an ancillary chunk's data has been successfully read
764  * from the PNG header, or if the application has filled in the corresponding
765  * data in the info_struct to be written into the output file.  The values
766  * of the PNG_INFO_<chunk> defines should NOT be changed.
767  */
768 #define PNG_INFO_gAMA 0x0001U
769 #define PNG_INFO_sBIT 0x0002U
770 #define PNG_INFO_cHRM 0x0004U
771 #define PNG_INFO_PLTE 0x0008U
772 #define PNG_INFO_tRNS 0x0010U
773 #define PNG_INFO_bKGD 0x0020U
774 #define PNG_INFO_hIST 0x0040U
775 #define PNG_INFO_pHYs 0x0080U
776 #define PNG_INFO_oFFs 0x0100U
777 #define PNG_INFO_tIME 0x0200U
778 #define PNG_INFO_pCAL 0x0400U
779 #define PNG_INFO_sRGB 0x0800U  /* GR-P, 0.96a */
780 #define PNG_INFO_iCCP 0x1000U  /* ESR, 1.0.6 */
781 #define PNG_INFO_sPLT 0x2000U  /* ESR, 1.0.6 */
782 #define PNG_INFO_sCAL 0x4000U  /* ESR, 1.0.6 */
783 #define PNG_INFO_IDAT 0x8000U  /* ESR, 1.0.6 */
784 
785 /* This is used for the transformation routines, as some of them
786  * change these values for the row.  It also should enable using
787  * the routines for other purposes.
788  */
789 typedef struct png_row_info_struct
790 {
791    png_uint_32 width;    /* width of row */
792    png_size_t rowbytes;  /* number of bytes in row */
793    png_byte color_type;  /* color type of row */
794    png_byte bit_depth;   /* bit depth of row */
795    png_byte channels;    /* number of channels (1, 2, 3, or 4) */
796    png_byte pixel_depth; /* bits per pixel (depth * channels) */
797 } png_row_info;
798 
799 typedef png_row_info * png_row_infop;
800 typedef png_row_info * * png_row_infopp;
801 
802 /* These are the function types for the I/O functions and for the functions
803  * that allow the user to override the default I/O functions with his or her
804  * own.  The png_error_ptr type should match that of user-supplied warning
805  * and error functions, while the png_rw_ptr type should match that of the
806  * user read/write data functions.  Note that the 'write' function must not
807  * modify the buffer it is passed. The 'read' function, on the other hand, is
808  * expected to return the read data in the buffer.
809  */
810 typedef PNG_CALLBACK(void, *png_error_ptr, (png_structp, png_const_charp));
811 typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, png_size_t));
812 typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp));
813 typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32,
814     int));
815 typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32,
816     int));
817 
818 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
819 typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
820 typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
821 
822 /* The following callback receives png_uint_32 row_number, int pass for the
823  * png_bytep data of the row.  When transforming an interlaced image the
824  * row number is the row number within the sub-image of the interlace pass, so
825  * the value will increase to the height of the sub-image (not the full image)
826  * then reset to 0 for the next pass.
827  *
828  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
829  * find the output pixel (x,y) given an interlaced sub-image pixel
830  * (row,col,pass).  (See below for these macros.)
831  */
832 typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp, png_bytep,
833     png_uint_32, int));
834 #endif
835 
836 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
837     defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
838 typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop,
839     png_bytep));
840 #endif
841 
842 #ifdef PNG_USER_CHUNKS_SUPPORTED
843 typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,
844     png_unknown_chunkp));
845 #endif
846 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
847 /* not used anywhere */
848 /* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
849 #endif
850 
851 #ifdef PNG_SETJMP_SUPPORTED
852 /* This must match the function definition in <setjmp.h>, and the application
853  * must include this before png.h to obtain the definition of jmp_buf.  The
854  * function is required to be PNG_NORETURN, but this is not checked.  If the
855  * function does return the application will crash via an abort() or similar
856  * system level call.
857  *
858  * If you get a warning here while building the library you may need to make
859  * changes to ensure that pnglibconf.h records the calling convention used by
860  * your compiler.  This may be very difficult - try using a different compiler
861  * to build the library!
862  */
863 PNG_FUNCTION(void, (PNGCAPI *png_longjmp_ptr), PNGARG((jmp_buf, int)), typedef);
864 #endif
865 
866 /* Transform masks for the high-level interface */
867 #define PNG_TRANSFORM_IDENTITY       0x0000    /* read and write */
868 #define PNG_TRANSFORM_STRIP_16       0x0001    /* read only */
869 #define PNG_TRANSFORM_STRIP_ALPHA    0x0002    /* read only */
870 #define PNG_TRANSFORM_PACKING        0x0004    /* read and write */
871 #define PNG_TRANSFORM_PACKSWAP       0x0008    /* read and write */
872 #define PNG_TRANSFORM_EXPAND         0x0010    /* read only */
873 #define PNG_TRANSFORM_INVERT_MONO    0x0020    /* read and write */
874 #define PNG_TRANSFORM_SHIFT          0x0040    /* read and write */
875 #define PNG_TRANSFORM_BGR            0x0080    /* read and write */
876 #define PNG_TRANSFORM_SWAP_ALPHA     0x0100    /* read and write */
877 #define PNG_TRANSFORM_SWAP_ENDIAN    0x0200    /* read and write */
878 #define PNG_TRANSFORM_INVERT_ALPHA   0x0400    /* read and write */
879 #define PNG_TRANSFORM_STRIP_FILLER   0x0800    /* write only */
880 /* Added to libpng-1.2.34 */
881 #define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER
882 #define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */
883 /* Added to libpng-1.4.0 */
884 #define PNG_TRANSFORM_GRAY_TO_RGB   0x2000      /* read only */
885 /* Added to libpng-1.5.4 */
886 #define PNG_TRANSFORM_EXPAND_16     0x4000      /* read only */
887 #if INT_MAX >= 0x8000 /* else this might break */
888 #define PNG_TRANSFORM_SCALE_16      0x8000      /* read only */
889 #endif
890 
891 /* Flags for MNG supported features */
892 #define PNG_FLAG_MNG_EMPTY_PLTE     0x01
893 #define PNG_FLAG_MNG_FILTER_64      0x04
894 #define PNG_ALL_MNG_FEATURES        0x05
895 
896 /* NOTE: prior to 1.5 these functions had no 'API' style declaration,
897  * this allowed the zlib default functions to be used on Windows
898  * platforms.  In 1.5 the zlib default malloc (which just calls malloc and
899  * ignores the first argument) should be completely compatible with the
900  * following.
901  */
902 typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,
903     png_alloc_size_t));
904 typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));
905 
906 /* Section 4: exported functions
907  * Here are the function definitions most commonly used.  This is not
908  * the place to find out how to use libpng.  See libpng-manual.txt for the
909  * full explanation, see example.c for the summary.  This just provides
910  * a simple one line description of the use of each function.
911  *
912  * The PNG_EXPORT() and PNG_EXPORTA() macros used below are defined in
913  * pngconf.h and in the *.dfn files in the scripts directory.
914  *
915  *   PNG_EXPORT(ordinal, type, name, (args));
916  *
917  *       ordinal:    ordinal that is used while building
918  *                   *.def files. The ordinal value is only
919  *                   relevant when preprocessing png.h with
920  *                   the *.dfn files for building symbol table
921  *                   entries, and are removed by pngconf.h.
922  *       type:       return type of the function
923  *       name:       function name
924  *       args:       function arguments, with types
925  *
926  * When we wish to append attributes to a function prototype we use
927  * the PNG_EXPORTA() macro instead.
928  *
929  *   PNG_EXPORTA(ordinal, type, name, (args), attributes);
930  *
931  *       ordinal, type, name, and args: same as in PNG_EXPORT().
932  *       attributes: function attributes
933  */
934 
935 /* Returns the version number of the library */
936 PNG_EXPORT(1, png_uint_32, png_access_version_number, (void));
937 
938 /* Tell lib we have already handled the first <num_bytes> magic bytes.
939  * Handling more than 8 bytes from the beginning of the file is an error.
940  */
941 PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
942 
943 /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
944  * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG
945  * signature, and non-zero otherwise.  Having num_to_check == 0 or
946  * start > 7 will always fail (ie return non-zero).
947  */
948 PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, png_size_t start,
949     png_size_t num_to_check));
950 
951 /* Simple signature checking function.  This is the same as calling
952  * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
953  */
954 #define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
955 
956 /* Allocate and initialize png_ptr struct for reading, and any other memory. */
957 PNG_EXPORTA(4, png_structp, png_create_read_struct,
958     (png_const_charp user_png_ver, png_voidp error_ptr,
959     png_error_ptr error_fn, png_error_ptr warn_fn),
960     PNG_ALLOCATED);
961 
962 /* Allocate and initialize png_ptr struct for writing, and any other memory */
963 PNG_EXPORTA(5, png_structp, png_create_write_struct,
964     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
965     png_error_ptr warn_fn),
966     PNG_ALLOCATED);
967 
968 PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
969     (png_const_structrp png_ptr));
970 
971 PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
972     png_size_t size));
973 
974 /* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
975  * match up.
976  */
977 #ifdef PNG_SETJMP_SUPPORTED
978 /* This function returns the jmp_buf built in to *png_ptr.  It must be
979  * supplied with an appropriate 'longjmp' function to use on that jmp_buf
980  * unless the default error function is overridden in which case NULL is
981  * acceptable.  The size of the jmp_buf is checked against the actual size
982  * allocated by the library - the call will return NULL on a mismatch
983  * indicating an ABI mismatch.
984  */
985 PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structrp png_ptr,
986     png_longjmp_ptr longjmp_fn, size_t jmp_buf_size));
987 #  define png_jmpbuf(png_ptr) \
988       (*png_set_longjmp_fn((png_ptr), longjmp, (sizeof (jmp_buf))))
989 #else
990 #  define png_jmpbuf(png_ptr) \
991       (LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP)
992 #endif
993 /* This function should be used by libpng applications in place of
994  * longjmp(png_ptr->jmpbuf, val).  If longjmp_fn() has been set, it
995  * will use it; otherwise it will call PNG_ABORT().  This function was
996  * added in libpng-1.5.0.
997  */
998 PNG_EXPORTA(9, void, png_longjmp, (png_const_structrp png_ptr, int val),
999     PNG_NORETURN);
1000 
1001 #ifdef PNG_READ_SUPPORTED
1002 /* Reset the compression stream */
1003 PNG_EXPORTA(10, int, png_reset_zstream, (png_structrp png_ptr), PNG_DEPRECATED);
1004 #endif
1005 
1006 /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
1007 #ifdef PNG_USER_MEM_SUPPORTED
1008 PNG_EXPORTA(11, png_structp, png_create_read_struct_2,
1009     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
1010     png_error_ptr warn_fn,
1011     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
1012     PNG_ALLOCATED);
1013 PNG_EXPORTA(12, png_structp, png_create_write_struct_2,
1014     (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
1015     png_error_ptr warn_fn,
1016     png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
1017     PNG_ALLOCATED);
1018 #endif
1019 
1020 /* Write the PNG file signature. */
1021 PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr));
1022 
1023 /* Write a PNG chunk - size, type, (optional) data, CRC. */
1024 PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep
1025     chunk_name, png_const_bytep data, png_size_t length));
1026 
1027 /* Write the start of a PNG chunk - length and chunk name. */
1028 PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
1029     png_const_bytep chunk_name, png_uint_32 length));
1030 
1031 /* Write the data of a PNG chunk started with png_write_chunk_start(). */
1032 PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr,
1033     png_const_bytep data, png_size_t length));
1034 
1035 /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
1036 PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr));
1037 
1038 /* Allocate and initialize the info structure */
1039 PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr),
1040     PNG_ALLOCATED);
1041 
1042 /* DEPRECATED: this function allowed init structures to be created using the
1043  * default allocation method (typically malloc).  Use is deprecated in 1.6.0 and
1044  * the API will be removed in the future.
1045  */
1046 PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr,
1047     png_size_t png_info_struct_size), PNG_DEPRECATED);
1048 
1049 /* Writes all the PNG information before the image. */
1050 PNG_EXPORT(20, void, png_write_info_before_PLTE,
1051     (png_structrp png_ptr, png_const_inforp info_ptr));
1052 PNG_EXPORT(21, void, png_write_info,
1053     (png_structrp png_ptr, png_const_inforp info_ptr));
1054 
1055 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1056 /* Read the information before the actual image data. */
1057 PNG_EXPORT(22, void, png_read_info,
1058     (png_structrp png_ptr, png_inforp info_ptr));
1059 #endif
1060 
1061 #ifdef PNG_TIME_RFC1123_SUPPORTED
1062    /* Convert to a US string format: there is no localization support in this
1063     * routine.  The original implementation used a 29 character buffer in
1064     * png_struct, this will be removed in future versions.
1065     */
1066 #if PNG_LIBPNG_VER < 10700
1067 /* To do: remove this from libpng17 (and from libpng17/png.c and pngstruct.h) */
1068 PNG_EXPORTA(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr,
1069     png_const_timep ptime),PNG_DEPRECATED);
1070 #endif
1071 PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29],
1072     png_const_timep ptime));
1073 #endif
1074 
1075 #ifdef PNG_CONVERT_tIME_SUPPORTED
1076 /* Convert from a struct tm to png_time */
1077 PNG_EXPORT(24, void, png_convert_from_struct_tm, (png_timep ptime,
1078     const struct tm * ttime));
1079 
1080 /* Convert from time_t to png_time.  Uses gmtime() */
1081 PNG_EXPORT(25, void, png_convert_from_time_t, (png_timep ptime, time_t ttime));
1082 #endif /* CONVERT_tIME */
1083 
1084 #ifdef PNG_READ_EXPAND_SUPPORTED
1085 /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
1086 PNG_EXPORT(26, void, png_set_expand, (png_structrp png_ptr));
1087 PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structrp png_ptr));
1088 PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structrp png_ptr));
1089 PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structrp png_ptr));
1090 #endif
1091 
1092 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1093 /* Expand to 16-bit channels, forces conversion of palette to RGB and expansion
1094  * of a tRNS chunk if present.
1095  */
1096 PNG_EXPORT(221, void, png_set_expand_16, (png_structrp png_ptr));
1097 #endif
1098 
1099 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
1100 /* Use blue, green, red order for pixels. */
1101 PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr));
1102 #endif
1103 
1104 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1105 /* Expand the grayscale to 24-bit RGB if necessary. */
1106 PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr));
1107 #endif
1108 
1109 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1110 /* Reduce RGB to grayscale. */
1111 #define PNG_ERROR_ACTION_NONE  1
1112 #define PNG_ERROR_ACTION_WARN  2
1113 #define PNG_ERROR_ACTION_ERROR 3
1114 #define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/
1115 
1116 PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structrp png_ptr,
1117     int error_action, double red, double green))
1118 PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structrp png_ptr,
1119     int error_action, png_fixed_point red, png_fixed_point green))
1120 
1121 PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp
1122     png_ptr));
1123 #endif
1124 
1125 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
1126 PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
1127     png_colorp palette));
1128 #endif
1129 
1130 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1131 /* How the alpha channel is interpreted - this affects how the color channels
1132  * of a PNG file are returned to the calling application when an alpha channel,
1133  * or a tRNS chunk in a palette file, is present.
1134  *
1135  * This has no effect on the way pixels are written into a PNG output
1136  * datastream. The color samples in a PNG datastream are never premultiplied
1137  * with the alpha samples.
1138  *
1139  * The default is to return data according to the PNG specification: the alpha
1140  * channel is a linear measure of the contribution of the pixel to the
1141  * corresponding composited pixel, and the color channels are unassociated
1142  * (not premultiplied).  The gamma encoded color channels must be scaled
1143  * according to the contribution and to do this it is necessary to undo
1144  * the encoding, scale the color values, perform the composition and reencode
1145  * the values.  This is the 'PNG' mode.
1146  *
1147  * The alternative is to 'associate' the alpha with the color information by
1148  * storing color channel values that have been scaled by the alpha.
1149  * image.  These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
1150  * (the latter being the two common names for associated alpha color channels).
1151  *
1152  * For the 'OPTIMIZED' mode, a pixel is treated as opaque only if the alpha
1153  * value is equal to the maximum value.
1154  *
1155  * The final choice is to gamma encode the alpha channel as well.  This is
1156  * broken because, in practice, no implementation that uses this choice
1157  * correctly undoes the encoding before handling alpha composition.  Use this
1158  * choice only if other serious errors in the software or hardware you use
1159  * mandate it; the typical serious error is for dark halos to appear around
1160  * opaque areas of the composited PNG image because of arithmetic overflow.
1161  *
1162  * The API function png_set_alpha_mode specifies which of these choices to use
1163  * with an enumerated 'mode' value and the gamma of the required output:
1164  */
1165 #define PNG_ALPHA_PNG           0 /* according to the PNG standard */
1166 #define PNG_ALPHA_STANDARD      1 /* according to Porter/Duff */
1167 #define PNG_ALPHA_ASSOCIATED    1 /* as above; this is the normal practice */
1168 #define PNG_ALPHA_PREMULTIPLIED 1 /* as above */
1169 #define PNG_ALPHA_OPTIMIZED     2 /* 'PNG' for opaque pixels, else 'STANDARD' */
1170 #define PNG_ALPHA_BROKEN        3 /* the alpha channel is gamma encoded */
1171 
1172 PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structrp png_ptr, int mode,
1173     double output_gamma))
1174 PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
1175     int mode, png_fixed_point output_gamma))
1176 #endif
1177 
1178 #if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1179 /* The output_gamma value is a screen gamma in libpng terminology: it expresses
1180  * how to decode the output values, not how they are encoded.
1181  */
1182 #define PNG_DEFAULT_sRGB -1       /* sRGB gamma and color space */
1183 #define PNG_GAMMA_MAC_18 -2       /* Old Mac '1.8' gamma and color space */
1184 #define PNG_GAMMA_sRGB   220000   /* Television standards--matches sRGB gamma */
1185 #define PNG_GAMMA_LINEAR PNG_FP_1 /* Linear */
1186 #endif
1187 
1188 /* The following are examples of calls to png_set_alpha_mode to achieve the
1189  * required overall gamma correction and, where necessary, alpha
1190  * premultiplication.
1191  *
1192  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1193  *    This is the default libpng handling of the alpha channel - it is not
1194  *    pre-multiplied into the color components.  In addition the call states
1195  *    that the output is for a sRGB system and causes all PNG files without gAMA
1196  *    chunks to be assumed to be encoded using sRGB.
1197  *
1198  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1199  *    In this case the output is assumed to be something like an sRGB conformant
1200  *    display preceeded by a power-law lookup table of power 1.45.  This is how
1201  *    early Mac systems behaved.
1202  *
1203  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
1204  *    This is the classic Jim Blinn approach and will work in academic
1205  *    environments where everything is done by the book.  It has the shortcoming
1206  *    of assuming that input PNG data with no gamma information is linear - this
1207  *    is unlikely to be correct unless the PNG files where generated locally.
1208  *    Most of the time the output precision will be so low as to show
1209  *    significant banding in dark areas of the image.
1210  *
1211  * png_set_expand_16(pp);
1212  * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
1213  *    This is a somewhat more realistic Jim Blinn inspired approach.  PNG files
1214  *    are assumed to have the sRGB encoding if not marked with a gamma value and
1215  *    the output is always 16 bits per component.  This permits accurate scaling
1216  *    and processing of the data.  If you know that your input PNG files were
1217  *    generated locally you might need to replace PNG_DEFAULT_sRGB with the
1218  *    correct value for your system.
1219  *
1220  * png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
1221  *    If you just need to composite the PNG image onto an existing background
1222  *    and if you control the code that does this you can use the optimization
1223  *    setting.  In this case you just copy completely opaque pixels to the
1224  *    output.  For pixels that are not completely transparent (you just skip
1225  *    those) you do the composition math using png_composite or png_composite_16
1226  *    below then encode the resultant 8-bit or 16-bit values to match the output
1227  *    encoding.
1228  *
1229  * Other cases
1230  *    If neither the PNG nor the standard linear encoding work for you because
1231  *    of the software or hardware you use then you have a big problem.  The PNG
1232  *    case will probably result in halos around the image.  The linear encoding
1233  *    will probably result in a washed out, too bright, image (it's actually too
1234  *    contrasty.)  Try the ALPHA_OPTIMIZED mode above - this will probably
1235  *    substantially reduce the halos.  Alternatively try:
1236  *
1237  * png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
1238  *    This option will also reduce the halos, but there will be slight dark
1239  *    halos round the opaque parts of the image where the background is light.
1240  *    In the OPTIMIZED mode the halos will be light halos where the background
1241  *    is dark.  Take your pick - the halos are unavoidable unless you can get
1242  *    your hardware/software fixed!  (The OPTIMIZED approach is slightly
1243  *    faster.)
1244  *
1245  * When the default gamma of PNG files doesn't match the output gamma.
1246  *    If you have PNG files with no gamma information png_set_alpha_mode allows
1247  *    you to provide a default gamma, but it also sets the ouput gamma to the
1248  *    matching value.  If you know your PNG files have a gamma that doesn't
1249  *    match the output you can take advantage of the fact that
1250  *    png_set_alpha_mode always sets the output gamma but only sets the PNG
1251  *    default if it is not already set:
1252  *
1253  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1254  * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1255  *    The first call sets both the default and the output gamma values, the
1256  *    second call overrides the output gamma without changing the default.  This
1257  *    is easier than achieving the same effect with png_set_gamma.  You must use
1258  *    PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
1259  *    fire if more than one call to png_set_alpha_mode and png_set_background is
1260  *    made in the same read operation, however multiple calls with PNG_ALPHA_PNG
1261  *    are ignored.
1262  */
1263 
1264 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1265 PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
1266 #endif
1267 
1268 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
1269     defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
1270 PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr));
1271 #endif
1272 
1273 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
1274     defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
1275 PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
1276 #endif
1277 
1278 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
1279 /* Add a filler byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
1280 PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler,
1281     int flags));
1282 /* The values of the PNG_FILLER_ defines should NOT be changed */
1283 #  define PNG_FILLER_BEFORE 0
1284 #  define PNG_FILLER_AFTER 1
1285 /* Add an alpha byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
1286 PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
1287     png_uint_32 filler, int flags));
1288 #endif /* READ_FILLER || WRITE_FILLER */
1289 
1290 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
1291 /* Swap bytes in 16-bit depth files. */
1292 PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr));
1293 #endif
1294 
1295 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
1296 /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
1297 PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr));
1298 #endif
1299 
1300 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
1301     defined(PNG_WRITE_PACKSWAP_SUPPORTED)
1302 /* Swap packing order of pixels in bytes. */
1303 PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr));
1304 #endif
1305 
1306 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
1307 /* Converts files to legal bit depths. */
1308 PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p
1309     true_bits));
1310 #endif
1311 
1312 #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
1313     defined(PNG_WRITE_INTERLACING_SUPPORTED)
1314 /* Have the code handle the interlacing.  Returns the number of passes.
1315  * MUST be called before png_read_update_info or png_start_read_image,
1316  * otherwise it will not have the desired effect.  Note that it is still
1317  * necessary to call png_read_row or png_read_rows png_get_image_height
1318  * times for each pass.
1319 */
1320 PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr));
1321 #endif
1322 
1323 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
1324 /* Invert monochrome files */
1325 PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
1326 #endif
1327 
1328 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1329 /* Handle alpha and tRNS by replacing with a background color.  Prior to
1330  * libpng-1.5.4 this API must not be called before the PNG file header has been
1331  * read.  Doing so will result in unexpected behavior and possible warnings or
1332  * errors if the PNG file contains a bKGD chunk.
1333  */
1334 PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr,
1335     png_const_color_16p background_color, int background_gamma_code,
1336     int need_expand, double background_gamma))
1337 PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr,
1338     png_const_color_16p background_color, int background_gamma_code,
1339     int need_expand, png_fixed_point background_gamma))
1340 #endif
1341 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1342 #  define PNG_BACKGROUND_GAMMA_UNKNOWN 0
1343 #  define PNG_BACKGROUND_GAMMA_SCREEN  1
1344 #  define PNG_BACKGROUND_GAMMA_FILE    2
1345 #  define PNG_BACKGROUND_GAMMA_UNIQUE  3
1346 #endif
1347 
1348 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1349 /* Scale a 16-bit depth file down to 8-bit, accurately. */
1350 PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
1351 #endif
1352 
1353 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1354 #define PNG_READ_16_TO_8_SUPPORTED /* Name prior to 1.5.4 */
1355 /* Strip the second byte of information from a 16-bit depth file. */
1356 PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
1357 #endif
1358 
1359 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1360 /* Turn on quantizing, and reduce the palette to the number of colors
1361  * available.
1362  */
1363 PNG_EXPORT(49, void, png_set_quantize, (png_structrp png_ptr,
1364     png_colorp palette, int num_palette, int maximum_colors,
1365     png_const_uint_16p histogram, int full_quantize));
1366 #endif
1367 
1368 #ifdef PNG_READ_GAMMA_SUPPORTED
1369 /* The threshold on gamma processing is configurable but hard-wired into the
1370  * library.  The following is the floating point variant.
1371  */
1372 #define PNG_GAMMA_THRESHOLD (PNG_GAMMA_THRESHOLD_FIXED*.00001)
1373 
1374 /* Handle gamma correction. Screen_gamma=(display_exponent).
1375  * NOTE: this API simply sets the screen and file gamma values. It will
1376  * therefore override the value for gamma in a PNG file if it is called after
1377  * the file header has been read - use with care  - call before reading the PNG
1378  * file for best results!
1379  *
1380  * These routines accept the same gamma values as png_set_alpha_mode (described
1381  * above).  The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either
1382  * API (floating point or fixed.)  Notice, however, that the 'file_gamma' value
1383  * is the inverse of a 'screen gamma' value.
1384  */
1385 PNG_FP_EXPORT(50, void, png_set_gamma, (png_structrp png_ptr,
1386     double screen_gamma, double override_file_gamma))
1387 PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structrp png_ptr,
1388     png_fixed_point screen_gamma, png_fixed_point override_file_gamma))
1389 #endif
1390 
1391 #ifdef PNG_WRITE_FLUSH_SUPPORTED
1392 /* Set how many lines between output flushes - 0 for no flushing */
1393 PNG_EXPORT(51, void, png_set_flush, (png_structrp png_ptr, int nrows));
1394 /* Flush the current PNG output buffer */
1395 PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr));
1396 #endif
1397 
1398 /* Optional update palette with requested transformations */
1399 PNG_EXPORT(53, void, png_start_read_image, (png_structrp png_ptr));
1400 
1401 /* Optional call to update the users info structure */
1402 PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr,
1403     png_inforp info_ptr));
1404 
1405 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1406 /* Read one or more rows of image data. */
1407 PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row,
1408     png_bytepp display_row, png_uint_32 num_rows));
1409 #endif
1410 
1411 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1412 /* Read a row of data. */
1413 PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
1414     png_bytep display_row));
1415 #endif
1416 
1417 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1418 /* Read the whole image into memory at once. */
1419 PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
1420 #endif
1421 
1422 /* Write a row of image data */
1423 PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr,
1424     png_const_bytep row));
1425 
1426 /* Write a few rows of image data: (*row) is not written; however, the type
1427  * is declared as writeable to maintain compatibility with previous versions
1428  * of libpng and to allow the 'display_row' array from read_rows to be passed
1429  * unchanged to write_rows.
1430  */
1431 PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row,
1432     png_uint_32 num_rows));
1433 
1434 /* Write the image data */
1435 PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image));
1436 
1437 /* Write the end of the PNG file. */
1438 PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr,
1439     png_inforp info_ptr));
1440 
1441 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1442 /* Read the end of the PNG file. */
1443 PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
1444 #endif
1445 
1446 /* Free any memory associated with the png_info_struct */
1447 PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr,
1448     png_infopp info_ptr_ptr));
1449 
1450 /* Free any memory associated with the png_struct and the png_info_structs */
1451 PNG_EXPORT(64, void, png_destroy_read_struct, (png_structpp png_ptr_ptr,
1452     png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));
1453 
1454 /* Free any memory associated with the png_struct and the png_info_structs */
1455 PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr,
1456     png_infopp info_ptr_ptr));
1457 
1458 /* Set the libpng method of handling chunk CRC errors */
1459 PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
1460     int ancil_action));
1461 
1462 /* Values for png_set_crc_action() say how to handle CRC errors in
1463  * ancillary and critical chunks, and whether to use the data contained
1464  * therein.  Note that it is impossible to "discard" data in a critical
1465  * chunk.  For versions prior to 0.90, the action was always error/quit,
1466  * whereas in version 0.90 and later, the action for CRC errors in ancillary
1467  * chunks is warn/discard.  These values should NOT be changed.
1468  *
1469  *      value                       action:critical     action:ancillary
1470  */
1471 #define PNG_CRC_DEFAULT       0  /* error/quit          warn/discard data */
1472 #define PNG_CRC_ERROR_QUIT    1  /* error/quit          error/quit        */
1473 #define PNG_CRC_WARN_DISCARD  2  /* (INVALID)           warn/discard data */
1474 #define PNG_CRC_WARN_USE      3  /* warn/use data       warn/use data     */
1475 #define PNG_CRC_QUIET_USE     4  /* quiet/use data      quiet/use data    */
1476 #define PNG_CRC_NO_CHANGE     5  /* use current value   use current value */
1477 
1478 #ifdef PNG_WRITE_SUPPORTED
1479 /* These functions give the user control over the scan-line filtering in
1480  * libpng and the compression methods used by zlib.  These functions are
1481  * mainly useful for testing, as the defaults should work with most users.
1482  * Those users who are tight on memory or want faster performance at the
1483  * expense of compression can modify them.  See the compression library
1484  * header file (zlib.h) for an explination of the compression functions.
1485  */
1486 
1487 /* Set the filtering method(s) used by libpng.  Currently, the only valid
1488  * value for "method" is 0.
1489  */
1490 PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
1491     int filters));
1492 #endif /* WRITE */
1493 
1494 /* Flags for png_set_filter() to say which filters to use.  The flags
1495  * are chosen so that they don't conflict with real filter types
1496  * below, in case they are supplied instead of the #defined constants.
1497  * These values should NOT be changed.
1498  */
1499 #define PNG_NO_FILTERS     0x00
1500 #define PNG_FILTER_NONE    0x08
1501 #define PNG_FILTER_SUB     0x10
1502 #define PNG_FILTER_UP      0x20
1503 #define PNG_FILTER_AVG     0x40
1504 #define PNG_FILTER_PAETH   0x80
1505 #define PNG_FAST_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP)
1506 #define PNG_ALL_FILTERS (PNG_FAST_FILTERS | PNG_FILTER_AVG | PNG_FILTER_PAETH)
1507 
1508 /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
1509  * These defines should NOT be changed.
1510  */
1511 #define PNG_FILTER_VALUE_NONE  0
1512 #define PNG_FILTER_VALUE_SUB   1
1513 #define PNG_FILTER_VALUE_UP    2
1514 #define PNG_FILTER_VALUE_AVG   3
1515 #define PNG_FILTER_VALUE_PAETH 4
1516 #define PNG_FILTER_VALUE_LAST  5
1517 
1518 #ifdef PNG_WRITE_SUPPORTED
1519 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* DEPRECATED */
1520 PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr,
1521     int heuristic_method, int num_weights, png_const_doublep filter_weights,
1522     png_const_doublep filter_costs))
1523 PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
1524     (png_structrp png_ptr, int heuristic_method, int num_weights,
1525     png_const_fixed_point_p filter_weights,
1526     png_const_fixed_point_p filter_costs))
1527 #endif /* WRITE_WEIGHTED_FILTER */
1528 
1529 /* The following are no longer used and will be removed from libpng-1.7: */
1530 #define PNG_FILTER_HEURISTIC_DEFAULT    0  /* Currently "UNWEIGHTED" */
1531 #define PNG_FILTER_HEURISTIC_UNWEIGHTED 1  /* Used by libpng < 0.95 */
1532 #define PNG_FILTER_HEURISTIC_WEIGHTED   2  /* Experimental feature */
1533 #define PNG_FILTER_HEURISTIC_LAST       3  /* Not a valid value */
1534 
1535 /* Set the library compression level.  Currently, valid values range from
1536  * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
1537  * (0 - no compression, 9 - "maximal" compression).  Note that tests have
1538  * shown that zlib compression levels 3-6 usually perform as well as level 9
1539  * for PNG images, and do considerably fewer caclulations.  In the future,
1540  * these values may not correspond directly to the zlib compression levels.
1541  */
1542 #ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
1543 PNG_EXPORT(69, void, png_set_compression_level, (png_structrp png_ptr,
1544     int level));
1545 
1546 PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structrp png_ptr,
1547     int mem_level));
1548 
1549 PNG_EXPORT(71, void, png_set_compression_strategy, (png_structrp png_ptr,
1550     int strategy));
1551 
1552 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1553  * smaller value of window_bits if it can do so safely.
1554  */
1555 PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
1556     int window_bits));
1557 
1558 PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr,
1559     int method));
1560 #endif /* WRITE_CUSTOMIZE_COMPRESSION */
1561 
1562 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
1563 /* Also set zlib parameters for compressing non-IDAT chunks */
1564 PNG_EXPORT(222, void, png_set_text_compression_level, (png_structrp png_ptr,
1565     int level));
1566 
1567 PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structrp png_ptr,
1568     int mem_level));
1569 
1570 PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structrp png_ptr,
1571     int strategy));
1572 
1573 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1574  * smaller value of window_bits if it can do so safely.
1575  */
1576 PNG_EXPORT(225, void, png_set_text_compression_window_bits,
1577     (png_structrp png_ptr, int window_bits));
1578 
1579 PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr,
1580     int method));
1581 #endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
1582 #endif /* WRITE */
1583 
1584 /* These next functions are called for input/output, memory, and error
1585  * handling.  They are in the file pngrio.c, pngwio.c, and pngerror.c,
1586  * and call standard C I/O routines such as fread(), fwrite(), and
1587  * fprintf().  These functions can be made to use other I/O routines
1588  * at run time for those applications that need to handle I/O in a
1589  * different manner by calling png_set_???_fn().  See libpng-manual.txt for
1590  * more information.
1591  */
1592 
1593 #ifdef PNG_STDIO_SUPPORTED
1594 /* Initialize the input/output for the PNG file to the default functions. */
1595 PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp));
1596 #endif
1597 
1598 /* Replace the (error and abort), and warning functions with user
1599  * supplied functions.  If no messages are to be printed you must still
1600  * write and use replacement functions. The replacement error_fn should
1601  * still do a longjmp to the last setjmp location if you are using this
1602  * method of error handling.  If error_fn or warning_fn is NULL, the
1603  * default function will be used.
1604  */
1605 
1606 PNG_EXPORT(75, void, png_set_error_fn, (png_structrp png_ptr,
1607     png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
1608 
1609 /* Return the user pointer associated with the error functions */
1610 PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structrp png_ptr));
1611 
1612 /* Replace the default data output functions with a user supplied one(s).
1613  * If buffered output is not used, then output_flush_fn can be set to NULL.
1614  * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
1615  * output_flush_fn will be ignored (and thus can be NULL).
1616  * It is probably a mistake to use NULL for output_flush_fn if
1617  * write_data_fn is not also NULL unless you have built libpng with
1618  * PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's
1619  * default flush function, which uses the standard *FILE structure, will
1620  * be used.
1621  */
1622 PNG_EXPORT(77, void, png_set_write_fn, (png_structrp png_ptr, png_voidp io_ptr,
1623     png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
1624 
1625 /* Replace the default data input function with a user supplied one. */
1626 PNG_EXPORT(78, void, png_set_read_fn, (png_structrp png_ptr, png_voidp io_ptr,
1627     png_rw_ptr read_data_fn));
1628 
1629 /* Return the user pointer associated with the I/O functions */
1630 PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_const_structrp png_ptr));
1631 
1632 PNG_EXPORT(80, void, png_set_read_status_fn, (png_structrp png_ptr,
1633     png_read_status_ptr read_row_fn));
1634 
1635 PNG_EXPORT(81, void, png_set_write_status_fn, (png_structrp png_ptr,
1636     png_write_status_ptr write_row_fn));
1637 
1638 #ifdef PNG_USER_MEM_SUPPORTED
1639 /* Replace the default memory allocation functions with user supplied one(s). */
1640 PNG_EXPORT(82, void, png_set_mem_fn, (png_structrp png_ptr, png_voidp mem_ptr,
1641     png_malloc_ptr malloc_fn, png_free_ptr free_fn));
1642 /* Return the user pointer associated with the memory functions */
1643 PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structrp png_ptr));
1644 #endif
1645 
1646 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1647 PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr,
1648     png_user_transform_ptr read_user_transform_fn));
1649 #endif
1650 
1651 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
1652 PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr,
1653     png_user_transform_ptr write_user_transform_fn));
1654 #endif
1655 
1656 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
1657 PNG_EXPORT(86, void, png_set_user_transform_info, (png_structrp png_ptr,
1658     png_voidp user_transform_ptr, int user_transform_depth,
1659     int user_transform_channels));
1660 /* Return the user pointer associated with the user transform functions */
1661 PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr,
1662     (png_const_structrp png_ptr));
1663 #endif
1664 
1665 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
1666 /* Return information about the row currently being processed.  Note that these
1667  * APIs do not fail but will return unexpected results if called outside a user
1668  * transform callback.  Also note that when transforming an interlaced image the
1669  * row number is the row number within the sub-image of the interlace pass, so
1670  * the value will increase to the height of the sub-image (not the full image)
1671  * then reset to 0 for the next pass.
1672  *
1673  * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
1674  * find the output pixel (x,y) given an interlaced sub-image pixel
1675  * (row,col,pass).  (See below for these macros.)
1676  */
1677 PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structrp));
1678 PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
1679 #endif
1680 
1681 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
1682 /* This callback is called only for *unknown* chunks.  If
1683  * PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
1684  * chunks to be treated as unknown, however in this case the callback must do
1685  * any processing required by the chunk (e.g. by calling the appropriate
1686  * png_set_ APIs.)
1687  *
1688  * There is no write support - on write, by default, all the chunks in the
1689  * 'unknown' list are written in the specified position.
1690  *
1691  * The integer return from the callback function is interpreted thus:
1692  *
1693  * negative: An error occurred; png_chunk_error will be called.
1694  *     zero: The chunk was not handled, the chunk will be saved. A critical
1695  *           chunk will cause an error at this point unless it is to be saved.
1696  * positive: The chunk was handled, libpng will ignore/discard it.
1697  *
1698  * See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
1699  * how this behavior will change in libpng 1.7
1700  */
1701 PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
1702     png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
1703 #endif
1704 
1705 #ifdef PNG_USER_CHUNKS_SUPPORTED
1706 PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr));
1707 #endif
1708 
1709 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1710 /* Sets the function callbacks for the push reader, and a pointer to a
1711  * user-defined structure available to the callback functions.
1712  */
1713 PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structrp png_ptr,
1714     png_voidp progressive_ptr, png_progressive_info_ptr info_fn,
1715     png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn));
1716 
1717 /* Returns the user pointer associated with the push read functions */
1718 PNG_EXPORT(91, png_voidp, png_get_progressive_ptr,
1719     (png_const_structrp png_ptr));
1720 
1721 /* Function to be called when data becomes available */
1722 PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
1723     png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size));
1724 
1725 /* A function which may be called *only* within png_process_data to stop the
1726  * processing of any more data.  The function returns the number of bytes
1727  * remaining, excluding any that libpng has cached internally.  A subsequent
1728  * call to png_process_data must supply these bytes again.  If the argument
1729  * 'save' is set to true the routine will first save all the pending data and
1730  * will always return 0.
1731  */
1732 PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save));
1733 
1734 /* A function which may be called *only* outside (after) a call to
1735  * png_process_data.  It returns the number of bytes of data to skip in the
1736  * input.  Normally it will return 0, but if it returns a non-zero value the
1737  * application must skip than number of bytes of input data and pass the
1738  * following data to the next call to png_process_data.
1739  */
1740 PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structrp));
1741 
1742 /* Function that combines rows.  'new_row' is a flag that should come from
1743  * the callback and be non-NULL if anything needs to be done; the library
1744  * stores its own version of the new data internally and ignores the passed
1745  * in value.
1746  */
1747 PNG_EXPORT(93, void, png_progressive_combine_row, (png_const_structrp png_ptr,
1748     png_bytep old_row, png_const_bytep new_row));
1749 #endif /* PROGRESSIVE_READ */
1750 
1751 PNG_EXPORTA(94, png_voidp, png_malloc, (png_const_structrp png_ptr,
1752     png_alloc_size_t size), PNG_ALLOCATED);
1753 /* Added at libpng version 1.4.0 */
1754 PNG_EXPORTA(95, png_voidp, png_calloc, (png_const_structrp png_ptr,
1755     png_alloc_size_t size), PNG_ALLOCATED);
1756 
1757 /* Added at libpng version 1.2.4 */
1758 PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_const_structrp png_ptr,
1759     png_alloc_size_t size), PNG_ALLOCATED);
1760 
1761 /* Frees a pointer allocated by png_malloc() */
1762 PNG_EXPORT(97, void, png_free, (png_const_structrp png_ptr, png_voidp ptr));
1763 
1764 /* Free data that was allocated internally */
1765 PNG_EXPORT(98, void, png_free_data, (png_const_structrp png_ptr,
1766     png_inforp info_ptr, png_uint_32 free_me, int num));
1767 
1768 /* Reassign responsibility for freeing existing data, whether allocated
1769  * by libpng or by the application; this works on the png_info structure passed
1770  * in, it does not change the state for other png_info structures.
1771  *
1772  * It is unlikely that this function works correctly as of 1.6.0 and using it
1773  * may result either in memory leaks or double free of allocated data.
1774  */
1775 PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
1776     png_inforp info_ptr, int freer, png_uint_32 mask));
1777 
1778 /* Assignments for png_data_freer */
1779 #define PNG_DESTROY_WILL_FREE_DATA 1
1780 #define PNG_SET_WILL_FREE_DATA 1
1781 #define PNG_USER_WILL_FREE_DATA 2
1782 /* Flags for png_ptr->free_me and info_ptr->free_me */
1783 #define PNG_FREE_HIST 0x0008U
1784 #define PNG_FREE_ICCP 0x0010U
1785 #define PNG_FREE_SPLT 0x0020U
1786 #define PNG_FREE_ROWS 0x0040U
1787 #define PNG_FREE_PCAL 0x0080U
1788 #define PNG_FREE_SCAL 0x0100U
1789 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
1790 #  define PNG_FREE_UNKN 0x0200U
1791 #endif
1792 /*      PNG_FREE_LIST 0x0400U   removed in 1.6.0 because it is ignored */
1793 #define PNG_FREE_PLTE 0x1000U
1794 #define PNG_FREE_TRNS 0x2000U
1795 #define PNG_FREE_TEXT 0x4000U
1796 #define PNG_FREE_ALL  0x7fffU
1797 #define PNG_FREE_MUL  0x4220U /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
1798 
1799 #ifdef PNG_USER_MEM_SUPPORTED
1800 PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
1801     png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED);
1802 PNG_EXPORTA(101, void, png_free_default, (png_const_structrp png_ptr,
1803     png_voidp ptr), PNG_DEPRECATED);
1804 #endif
1805 
1806 #ifdef PNG_ERROR_TEXT_SUPPORTED
1807 /* Fatal error in PNG image of libpng - can't continue */
1808 PNG_EXPORTA(102, void, png_error, (png_const_structrp png_ptr,
1809     png_const_charp error_message), PNG_NORETURN);
1810 
1811 /* The same, but the chunk name is prepended to the error string. */
1812 PNG_EXPORTA(103, void, png_chunk_error, (png_const_structrp png_ptr,
1813     png_const_charp error_message), PNG_NORETURN);
1814 
1815 #else
1816 /* Fatal error in PNG image of libpng - can't continue */
1817 PNG_EXPORTA(104, void, png_err, (png_const_structrp png_ptr), PNG_NORETURN);
1818 #  define png_error(s1,s2) png_err(s1)
1819 #  define png_chunk_error(s1,s2) png_err(s1)
1820 #endif
1821 
1822 #ifdef PNG_WARNINGS_SUPPORTED
1823 /* Non-fatal error in libpng.  Can continue, but may have a problem. */
1824 PNG_EXPORT(105, void, png_warning, (png_const_structrp png_ptr,
1825     png_const_charp warning_message));
1826 
1827 /* Non-fatal error in libpng, chunk name is prepended to message. */
1828 PNG_EXPORT(106, void, png_chunk_warning, (png_const_structrp png_ptr,
1829     png_const_charp warning_message));
1830 #else
1831 #  define png_warning(s1,s2) ((void)(s1))
1832 #  define png_chunk_warning(s1,s2) ((void)(s1))
1833 #endif
1834 
1835 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
1836 /* Benign error in libpng.  Can continue, but may have a problem.
1837  * User can choose whether to handle as a fatal error or as a warning. */
1838 PNG_EXPORT(107, void, png_benign_error, (png_const_structrp png_ptr,
1839     png_const_charp warning_message));
1840 
1841 #ifdef PNG_READ_SUPPORTED
1842 /* Same, chunk name is prepended to message (only during read) */
1843 PNG_EXPORT(108, void, png_chunk_benign_error, (png_const_structrp png_ptr,
1844     png_const_charp warning_message));
1845 #endif
1846 
1847 PNG_EXPORT(109, void, png_set_benign_errors,
1848     (png_structrp png_ptr, int allowed));
1849 #else
1850 #  ifdef PNG_ALLOW_BENIGN_ERRORS
1851 #    define png_benign_error png_warning
1852 #    define png_chunk_benign_error png_chunk_warning
1853 #  else
1854 #    define png_benign_error png_error
1855 #    define png_chunk_benign_error png_chunk_error
1856 #  endif
1857 #endif
1858 
1859 /* The png_set_<chunk> functions are for storing values in the png_info_struct.
1860  * Similarly, the png_get_<chunk> calls are used to read values from the
1861  * png_info_struct, either storing the parameters in the passed variables, or
1862  * setting pointers into the png_info_struct where the data is stored.  The
1863  * png_get_<chunk> functions return a non-zero value if the data was available
1864  * in info_ptr, or return zero and do not change any of the parameters if the
1865  * data was not available.
1866  *
1867  * These functions should be used instead of directly accessing png_info
1868  * to avoid problems with future changes in the size and internal layout of
1869  * png_info_struct.
1870  */
1871 /* Returns "flag" if chunk data is valid in info_ptr. */
1872 PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr,
1873     png_const_inforp info_ptr, png_uint_32 flag));
1874 
1875 /* Returns number of bytes needed to hold a transformed row. */
1876 PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
1877     png_const_inforp info_ptr));
1878 
1879 #ifdef PNG_INFO_IMAGE_SUPPORTED
1880 /* Returns row_pointers, which is an array of pointers to scanlines that was
1881  * returned from png_read_png().
1882  */
1883 PNG_EXPORT(112, png_bytepp, png_get_rows, (png_const_structrp png_ptr,
1884     png_const_inforp info_ptr));
1885 
1886 /* Set row_pointers, which is an array of pointers to scanlines for use
1887  * by png_write_png().
1888  */
1889 PNG_EXPORT(113, void, png_set_rows, (png_const_structrp png_ptr,
1890     png_inforp info_ptr, png_bytepp row_pointers));
1891 #endif
1892 
1893 /* Returns number of color channels in image. */
1894 PNG_EXPORT(114, png_byte, png_get_channels, (png_const_structrp png_ptr,
1895     png_const_inforp info_ptr));
1896 
1897 #ifdef PNG_EASY_ACCESS_SUPPORTED
1898 /* Returns image width in pixels. */
1899 PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structrp png_ptr,
1900     png_const_inforp info_ptr));
1901 
1902 /* Returns image height in pixels. */
1903 PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structrp png_ptr,
1904     png_const_inforp info_ptr));
1905 
1906 /* Returns image bit_depth. */
1907 PNG_EXPORT(117, png_byte, png_get_bit_depth, (png_const_structrp png_ptr,
1908     png_const_inforp info_ptr));
1909 
1910 /* Returns image color_type. */
1911 PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structrp png_ptr,
1912     png_const_inforp info_ptr));
1913 
1914 /* Returns image filter_type. */
1915 PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structrp png_ptr,
1916     png_const_inforp info_ptr));
1917 
1918 /* Returns image interlace_type. */
1919 PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structrp png_ptr,
1920     png_const_inforp info_ptr));
1921 
1922 /* Returns image compression_type. */
1923 PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structrp png_ptr,
1924     png_const_inforp info_ptr));
1925 
1926 /* Returns image resolution in pixels per meter, from pHYs chunk data. */
1927 PNG_EXPORT(122, png_uint_32, png_get_pixels_per_meter,
1928     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1929 PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter,
1930     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1931 PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter,
1932     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1933 
1934 /* Returns pixel aspect ratio, computed from pHYs chunk data.  */
1935 PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio,
1936     (png_const_structrp png_ptr, png_const_inforp info_ptr))
1937 PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed,
1938     (png_const_structrp png_ptr, png_const_inforp info_ptr))
1939 
1940 /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
1941 PNG_EXPORT(126, png_int_32, png_get_x_offset_pixels,
1942     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1943 PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels,
1944     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1945 PNG_EXPORT(128, png_int_32, png_get_x_offset_microns,
1946     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1947 PNG_EXPORT(129, png_int_32, png_get_y_offset_microns,
1948     (png_const_structrp png_ptr, png_const_inforp info_ptr));
1949 
1950 #endif /* EASY_ACCESS */
1951 
1952 #ifdef PNG_READ_SUPPORTED
1953 /* Returns pointer to signature string read from PNG header */
1954 PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr,
1955     png_const_inforp info_ptr));
1956 #endif
1957 
1958 #ifdef PNG_bKGD_SUPPORTED
1959 PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
1960     png_inforp info_ptr, png_color_16p *background));
1961 #endif
1962 
1963 #ifdef PNG_bKGD_SUPPORTED
1964 PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
1965     png_inforp info_ptr, png_const_color_16p background));
1966 #endif
1967 
1968 #ifdef PNG_cHRM_SUPPORTED
1969 PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr,
1970     png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x,
1971     double *red_y, double *green_x, double *green_y, double *blue_x,
1972     double *blue_y))
1973 PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr,
1974     png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z,
1975     double *green_X, double *green_Y, double *green_Z, double *blue_X,
1976     double *blue_Y, double *blue_Z))
1977 PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed,
1978     (png_const_structrp png_ptr, png_const_inforp info_ptr,
1979     png_fixed_point *int_white_x, png_fixed_point *int_white_y,
1980     png_fixed_point *int_red_x, png_fixed_point *int_red_y,
1981     png_fixed_point *int_green_x, png_fixed_point *int_green_y,
1982     png_fixed_point *int_blue_x, png_fixed_point *int_blue_y))
1983 PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed,
1984     (png_const_structrp png_ptr, png_const_inforp info_ptr,
1985     png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
1986     png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
1987     png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
1988     png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
1989     png_fixed_point *int_blue_Z))
1990 #endif
1991 
1992 #ifdef PNG_cHRM_SUPPORTED
1993 PNG_FP_EXPORT(135, void, png_set_cHRM, (png_const_structrp png_ptr,
1994     png_inforp info_ptr,
1995     double white_x, double white_y, double red_x, double red_y, double green_x,
1996     double green_y, double blue_x, double blue_y))
1997 PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_const_structrp png_ptr,
1998     png_inforp info_ptr, double red_X, double red_Y, double red_Z,
1999     double green_X, double green_Y, double green_Z, double blue_X,
2000     double blue_Y, double blue_Z))
2001 PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_const_structrp png_ptr,
2002     png_inforp info_ptr, png_fixed_point int_white_x,
2003     png_fixed_point int_white_y, png_fixed_point int_red_x,
2004     png_fixed_point int_red_y, png_fixed_point int_green_x,
2005     png_fixed_point int_green_y, png_fixed_point int_blue_x,
2006     png_fixed_point int_blue_y))
2007 PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
2008     png_inforp info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y,
2009     png_fixed_point int_red_Z, png_fixed_point int_green_X,
2010     png_fixed_point int_green_Y, png_fixed_point int_green_Z,
2011     png_fixed_point int_blue_X, png_fixed_point int_blue_Y,
2012     png_fixed_point int_blue_Z))
2013 #endif
2014 
2015 #ifdef PNG_gAMA_SUPPORTED
2016 PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
2017     png_const_inforp info_ptr, double *file_gamma))
2018 PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed,
2019     (png_const_structrp png_ptr, png_const_inforp info_ptr,
2020     png_fixed_point *int_file_gamma))
2021 #endif
2022 
2023 #ifdef PNG_gAMA_SUPPORTED
2024 PNG_FP_EXPORT(139, void, png_set_gAMA, (png_const_structrp png_ptr,
2025     png_inforp info_ptr, double file_gamma))
2026 PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
2027     png_inforp info_ptr, png_fixed_point int_file_gamma))
2028 #endif
2029 
2030 #ifdef PNG_hIST_SUPPORTED
2031 PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
2032     png_inforp info_ptr, png_uint_16p *hist));
2033 #endif
2034 
2035 #ifdef PNG_hIST_SUPPORTED
2036 PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
2037     png_inforp info_ptr, png_const_uint_16p hist));
2038 #endif
2039 
2040 PNG_EXPORT(143, png_uint_32, png_get_IHDR, (png_const_structrp png_ptr,
2041     png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height,
2042     int *bit_depth, int *color_type, int *interlace_method,
2043     int *compression_method, int *filter_method));
2044 
2045 PNG_EXPORT(144, void, png_set_IHDR, (png_const_structrp png_ptr,
2046     png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
2047     int color_type, int interlace_method, int compression_method,
2048     int filter_method));
2049 
2050 #ifdef PNG_oFFs_SUPPORTED
2051 PNG_EXPORT(145, png_uint_32, png_get_oFFs, (png_const_structrp png_ptr,
2052    png_const_inforp info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
2053    int *unit_type));
2054 #endif
2055 
2056 #ifdef PNG_oFFs_SUPPORTED
2057 PNG_EXPORT(146, void, png_set_oFFs, (png_const_structrp png_ptr,
2058     png_inforp info_ptr, png_int_32 offset_x, png_int_32 offset_y,
2059     int unit_type));
2060 #endif
2061 
2062 #ifdef PNG_pCAL_SUPPORTED
2063 PNG_EXPORT(147, png_uint_32, png_get_pCAL, (png_const_structrp png_ptr,
2064     png_inforp info_ptr, png_charp *purpose, png_int_32 *X0,
2065     png_int_32 *X1, int *type, int *nparams, png_charp *units,
2066     png_charpp *params));
2067 #endif
2068 
2069 #ifdef PNG_pCAL_SUPPORTED
2070 PNG_EXPORT(148, void, png_set_pCAL, (png_const_structrp png_ptr,
2071     png_inforp info_ptr, png_const_charp purpose, png_int_32 X0, png_int_32 X1,
2072     int type, int nparams, png_const_charp units, png_charpp params));
2073 #endif
2074 
2075 #ifdef PNG_pHYs_SUPPORTED
2076 PNG_EXPORT(149, png_uint_32, png_get_pHYs, (png_const_structrp png_ptr,
2077     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
2078     int *unit_type));
2079 #endif
2080 
2081 #ifdef PNG_pHYs_SUPPORTED
2082 PNG_EXPORT(150, void, png_set_pHYs, (png_const_structrp png_ptr,
2083     png_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
2084 #endif
2085 
2086 PNG_EXPORT(151, png_uint_32, png_get_PLTE, (png_const_structrp png_ptr,
2087    png_inforp info_ptr, png_colorp *palette, int *num_palette));
2088 
2089 PNG_EXPORT(152, void, png_set_PLTE, (png_structrp png_ptr,
2090     png_inforp info_ptr, png_const_colorp palette, int num_palette));
2091 
2092 #ifdef PNG_sBIT_SUPPORTED
2093 PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr,
2094     png_inforp info_ptr, png_color_8p *sig_bit));
2095 #endif
2096 
2097 #ifdef PNG_sBIT_SUPPORTED
2098 PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr,
2099     png_inforp info_ptr, png_const_color_8p sig_bit));
2100 #endif
2101 
2102 #ifdef PNG_sRGB_SUPPORTED
2103 PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr,
2104     png_const_inforp info_ptr, int *file_srgb_intent));
2105 #endif
2106 
2107 #ifdef PNG_sRGB_SUPPORTED
2108 PNG_EXPORT(156, void, png_set_sRGB, (png_const_structrp png_ptr,
2109     png_inforp info_ptr, int srgb_intent));
2110 PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_const_structrp png_ptr,
2111     png_inforp info_ptr, int srgb_intent));
2112 #endif
2113 
2114 #ifdef PNG_iCCP_SUPPORTED
2115 PNG_EXPORT(158, png_uint_32, png_get_iCCP, (png_const_structrp png_ptr,
2116     png_inforp info_ptr, png_charpp name, int *compression_type,
2117     png_bytepp profile, png_uint_32 *proflen));
2118 #endif
2119 
2120 #ifdef PNG_iCCP_SUPPORTED
2121 PNG_EXPORT(159, void, png_set_iCCP, (png_const_structrp png_ptr,
2122     png_inforp info_ptr, png_const_charp name, int compression_type,
2123     png_const_bytep profile, png_uint_32 proflen));
2124 #endif
2125 
2126 #ifdef PNG_sPLT_SUPPORTED
2127 PNG_EXPORT(160, int, png_get_sPLT, (png_const_structrp png_ptr,
2128     png_inforp info_ptr, png_sPLT_tpp entries));
2129 #endif
2130 
2131 #ifdef PNG_sPLT_SUPPORTED
2132 PNG_EXPORT(161, void, png_set_sPLT, (png_const_structrp png_ptr,
2133     png_inforp info_ptr, png_const_sPLT_tp entries, int nentries));
2134 #endif
2135 
2136 #ifdef PNG_TEXT_SUPPORTED
2137 /* png_get_text also returns the number of text chunks in *num_text */
2138 PNG_EXPORT(162, int, png_get_text, (png_const_structrp png_ptr,
2139     png_inforp info_ptr, png_textp *text_ptr, int *num_text));
2140 #endif
2141 
2142 /* Note while png_set_text() will accept a structure whose text,
2143  * language, and  translated keywords are NULL pointers, the structure
2144  * returned by png_get_text will always contain regular
2145  * zero-terminated C strings.  They might be empty strings but
2146  * they will never be NULL pointers.
2147  */
2148 
2149 #ifdef PNG_TEXT_SUPPORTED
2150 PNG_EXPORT(163, void, png_set_text, (png_const_structrp png_ptr,
2151     png_inforp info_ptr, png_const_textp text_ptr, int num_text));
2152 #endif
2153 
2154 #ifdef PNG_tIME_SUPPORTED
2155 PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr,
2156     png_inforp info_ptr, png_timep *mod_time));
2157 #endif
2158 
2159 #ifdef PNG_tIME_SUPPORTED
2160 PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr,
2161     png_inforp info_ptr, png_const_timep mod_time));
2162 #endif
2163 
2164 #ifdef PNG_tRNS_SUPPORTED
2165 PNG_EXPORT(166, png_uint_32, png_get_tRNS, (png_const_structrp png_ptr,
2166     png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans,
2167     png_color_16p *trans_color));
2168 #endif
2169 
2170 #ifdef PNG_tRNS_SUPPORTED
2171 PNG_EXPORT(167, void, png_set_tRNS, (png_structrp png_ptr,
2172     png_inforp info_ptr, png_const_bytep trans_alpha, int num_trans,
2173     png_const_color_16p trans_color));
2174 #endif
2175 
2176 #ifdef PNG_sCAL_SUPPORTED
2177 PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL, (png_const_structrp png_ptr,
2178     png_const_inforp info_ptr, int *unit, double *width, double *height))
2179 #if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
2180    defined(PNG_FLOATING_POINT_SUPPORTED)
2181 /* NOTE: this API is currently implemented using floating point arithmetic,
2182  * consequently it can only be used on systems with floating point support.
2183  * In any case the range of values supported by png_fixed_point is small and it
2184  * is highly recommended that png_get_sCAL_s be used instead.
2185  */
2186 PNG_FIXED_EXPORT(214, png_uint_32, png_get_sCAL_fixed,
2187     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
2188     png_fixed_point *width, png_fixed_point *height))
2189 #endif
2190 PNG_EXPORT(169, png_uint_32, png_get_sCAL_s,
2191     (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
2192     png_charpp swidth, png_charpp sheight));
2193 
2194 PNG_FP_EXPORT(170, void, png_set_sCAL, (png_const_structrp png_ptr,
2195     png_inforp info_ptr, int unit, double width, double height))
2196 PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_const_structrp png_ptr,
2197    png_inforp info_ptr, int unit, png_fixed_point width,
2198    png_fixed_point height))
2199 PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
2200     png_inforp info_ptr, int unit,
2201     png_const_charp swidth, png_const_charp sheight));
2202 #endif /* sCAL */
2203 
2204 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2205 /* Provide the default handling for all unknown chunks or, optionally, for
2206  * specific unknown chunks.
2207  *
2208  * NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
2209  * ignored and the default was used, the per-chunk setting only had an effect on
2210  * write.  If you wish to have chunk-specific handling on read in code that must
2211  * work on earlier versions you must use a user chunk callback to specify the
2212  * desired handling (keep or discard.)
2213  *
2214  * The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below.  The
2215  * parameter is interpreted as follows:
2216  *
2217  * READ:
2218  *    PNG_HANDLE_CHUNK_AS_DEFAULT:
2219  *       Known chunks: do normal libpng processing, do not keep the chunk (but
2220  *          see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
2221  *       Unknown chunks: for a specific chunk use the global default, when used
2222  *          as the default discard the chunk data.
2223  *    PNG_HANDLE_CHUNK_NEVER:
2224  *       Discard the chunk data.
2225  *    PNG_HANDLE_CHUNK_IF_SAFE:
2226  *       Keep the chunk data if the chunk is not critical else raise a chunk
2227  *       error.
2228  *    PNG_HANDLE_CHUNK_ALWAYS:
2229  *       Keep the chunk data.
2230  *
2231  * If the chunk data is saved it can be retrieved using png_get_unknown_chunks,
2232  * below.  Notice that specifying "AS_DEFAULT" as a global default is equivalent
2233  * to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
2234  * it simply resets the behavior to the libpng default.
2235  *
2236  * INTERACTION WTIH USER CHUNK CALLBACKS:
2237  * The per-chunk handling is always used when there is a png_user_chunk_ptr
2238  * callback and the callback returns 0; the chunk is then always stored *unless*
2239  * it is critical and the per-chunk setting is other than ALWAYS.  Notice that
2240  * the global default is *not* used in this case.  (In effect the per-chunk
2241  * value is incremented to at least IF_SAFE.)
2242  *
2243  * IMPORTANT NOTE: this behavior will change in libpng 1.7 - the global and
2244  * per-chunk defaults will be honored.  If you want to preserve the current
2245  * behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE
2246  * as the default - if you don't do this libpng 1.6 will issue a warning.
2247  *
2248  * If you want unhandled unknown chunks to be discarded in libpng 1.6 and
2249  * earlier simply return '1' (handled).
2250  *
2251  * PNG_HANDLE_AS_UNKNOWN_SUPPORTED:
2252  *    If this is *not* set known chunks will always be handled by libpng and
2253  *    will never be stored in the unknown chunk list.  Known chunks listed to
2254  *    png_set_keep_unknown_chunks will have no effect.  If it is set then known
2255  *    chunks listed with a keep other than AS_DEFAULT will *never* be processed
2256  *    by libpng, in addition critical chunks must either be processed by the
2257  *    callback or saved.
2258  *
2259  *    The IHDR and IEND chunks must not be listed.  Because this turns off the
2260  *    default handling for chunks that would otherwise be recognized the
2261  *    behavior of libpng transformations may well become incorrect!
2262  *
2263  * WRITE:
2264  *    When writing chunks the options only apply to the chunks specified by
2265  *    png_set_unknown_chunks (below), libpng will *always* write known chunks
2266  *    required by png_set_ calls and will always write the core critical chunks
2267  *    (as required for PLTE).
2268  *
2269  *    Each chunk in the png_set_unknown_chunks list is looked up in the
2270  *    png_set_keep_unknown_chunks list to find the keep setting, this is then
2271  *    interpreted as follows:
2272  *
2273  *    PNG_HANDLE_CHUNK_AS_DEFAULT:
2274  *       Write safe-to-copy chunks and write other chunks if the global
2275  *       default is set to _ALWAYS, otherwise don't write this chunk.
2276  *    PNG_HANDLE_CHUNK_NEVER:
2277  *       Do not write the chunk.
2278  *    PNG_HANDLE_CHUNK_IF_SAFE:
2279  *       Write the chunk if it is safe-to-copy, otherwise do not write it.
2280  *    PNG_HANDLE_CHUNK_ALWAYS:
2281  *       Write the chunk.
2282  *
2283  * Note that the default behavior is effectively the opposite of the read case -
2284  * in read unknown chunks are not stored by default, in write they are written
2285  * by default.  Also the behavior of PNG_HANDLE_CHUNK_IF_SAFE is very different
2286  * - on write the safe-to-copy bit is checked, on read the critical bit is
2287  * checked and on read if the chunk is critical an error will be raised.
2288  *
2289  * num_chunks:
2290  * ===========
2291  *    If num_chunks is positive, then the "keep" parameter specifies the manner
2292  *    for handling only those chunks appearing in the chunk_list array,
2293  *    otherwise the chunk list array is ignored.
2294  *
2295  *    If num_chunks is 0 the "keep" parameter specifies the default behavior for
2296  *    unknown chunks, as described above.
2297  *
2298  *    If num_chunks is negative, then the "keep" parameter specifies the manner
2299  *    for handling all unknown chunks plus all chunks recognized by libpng
2300  *    except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
2301  *    be processed by libpng.
2302  */
2303 PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
2304     int keep, png_const_bytep chunk_list, int num_chunks));
2305 
2306 /* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
2307  * the result is therefore true (non-zero) if special handling is required,
2308  * false for the default handling.
2309  */
2310 PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
2311     png_const_bytep chunk_name));
2312 #endif
2313 
2314 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
2315 PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
2316     png_inforp info_ptr, png_const_unknown_chunkp unknowns,
2317     int num_unknowns));
2318    /* NOTE: prior to 1.6.0 this routine set the 'location' field of the added
2319     * unknowns to the location currently stored in the png_struct.  This is
2320     * invariably the wrong value on write.  To fix this call the following API
2321     * for each chunk in the list with the correct location.  If you know your
2322     * code won't be compiled on earlier versions you can rely on
2323     * png_set_unknown_chunks(write-ptr, png_get_unknown_chunks(read-ptr)) doing
2324     * the correct thing.
2325     */
2326 
2327 PNG_EXPORT(175, void, png_set_unknown_chunk_location,
2328     (png_const_structrp png_ptr, png_inforp info_ptr, int chunk, int location));
2329 
2330 PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structrp png_ptr,
2331     png_inforp info_ptr, png_unknown_chunkpp entries));
2332 #endif
2333 
2334 /* Png_free_data() will turn off the "valid" flag for anything it frees.
2335  * If you need to turn it off for a chunk that your application has freed,
2336  * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
2337  */
2338 PNG_EXPORT(177, void, png_set_invalid, (png_const_structrp png_ptr,
2339     png_inforp info_ptr, int mask));
2340 
2341 #ifdef PNG_INFO_IMAGE_SUPPORTED
2342 /* The "params" pointer is currently not used and is for future expansion. */
2343 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
2344 PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr,
2345     int transforms, png_voidp params));
2346 #endif
2347 #ifdef PNG_WRITE_SUPPORTED
2348 PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr,
2349     int transforms, png_voidp params));
2350 #endif
2351 #endif
2352 
2353 PNG_EXPORT(180, png_const_charp, png_get_copyright,
2354     (png_const_structrp png_ptr));
2355 PNG_EXPORT(181, png_const_charp, png_get_header_ver,
2356     (png_const_structrp png_ptr));
2357 PNG_EXPORT(182, png_const_charp, png_get_header_version,
2358     (png_const_structrp png_ptr));
2359 PNG_EXPORT(183, png_const_charp, png_get_libpng_ver,
2360     (png_const_structrp png_ptr));
2361 
2362 #ifdef PNG_MNG_FEATURES_SUPPORTED
2363 PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr,
2364     png_uint_32 mng_features_permitted));
2365 #endif
2366 
2367 /* For use in png_set_keep_unknown, added to version 1.2.6 */
2368 #define PNG_HANDLE_CHUNK_AS_DEFAULT   0
2369 #define PNG_HANDLE_CHUNK_NEVER        1
2370 #define PNG_HANDLE_CHUNK_IF_SAFE      2
2371 #define PNG_HANDLE_CHUNK_ALWAYS       3
2372 #define PNG_HANDLE_CHUNK_LAST         4
2373 
2374 /* Strip the prepended error numbers ("#nnn ") from error and warning
2375  * messages before passing them to the error or warning handler.
2376  */
2377 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
2378 PNG_EXPORT(185, void, png_set_strip_error_numbers, (png_structrp png_ptr,
2379     png_uint_32 strip_mode));
2380 #endif
2381 
2382 /* Added in libpng-1.2.6 */
2383 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
2384 PNG_EXPORT(186, void, png_set_user_limits, (png_structrp png_ptr,
2385     png_uint_32 user_width_max, png_uint_32 user_height_max));
2386 PNG_EXPORT(187, png_uint_32, png_get_user_width_max,
2387     (png_const_structrp png_ptr));
2388 PNG_EXPORT(188, png_uint_32, png_get_user_height_max,
2389     (png_const_structrp png_ptr));
2390 /* Added in libpng-1.4.0 */
2391 PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structrp png_ptr,
2392     png_uint_32 user_chunk_cache_max));
2393 PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max,
2394     (png_const_structrp png_ptr));
2395 /* Added in libpng-1.4.1 */
2396 PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structrp png_ptr,
2397     png_alloc_size_t user_chunk_cache_max));
2398 PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max,
2399     (png_const_structrp png_ptr));
2400 #endif
2401 
2402 #if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
2403 PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch,
2404     (png_const_structrp png_ptr, png_const_inforp info_ptr));
2405 
2406 PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch,
2407     (png_const_structrp png_ptr, png_const_inforp info_ptr));
2408 
2409 PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch,
2410     (png_const_structrp png_ptr, png_const_inforp info_ptr));
2411 
2412 PNG_FP_EXPORT(196, float, png_get_x_offset_inches,
2413     (png_const_structrp png_ptr, png_const_inforp info_ptr))
2414 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2415 PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed,
2416     (png_const_structrp png_ptr, png_const_inforp info_ptr))
2417 #endif
2418 
2419 PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structrp png_ptr,
2420     png_const_inforp info_ptr))
2421 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2422 PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed,
2423     (png_const_structrp png_ptr, png_const_inforp info_ptr))
2424 #endif
2425 
2426 #  ifdef PNG_pHYs_SUPPORTED
2427 PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structrp png_ptr,
2428     png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
2429     int *unit_type));
2430 #  endif /* pHYs */
2431 #endif  /* INCH_CONVERSIONS */
2432 
2433 /* Added in libpng-1.4.0 */
2434 #ifdef PNG_IO_STATE_SUPPORTED
2435 PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_const_structrp png_ptr));
2436 
2437 /* Removed from libpng 1.6; use png_get_io_chunk_type. */
2438 PNG_REMOVED(200, png_const_bytep, png_get_io_chunk_name, (png_structrp png_ptr),
2439     PNG_DEPRECATED)
2440 
2441 PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
2442     (png_const_structrp png_ptr));
2443 
2444 /* The flags returned by png_get_io_state() are the following: */
2445 #  define PNG_IO_NONE        0x0000   /* no I/O at this moment */
2446 #  define PNG_IO_READING     0x0001   /* currently reading */
2447 #  define PNG_IO_WRITING     0x0002   /* currently writing */
2448 #  define PNG_IO_SIGNATURE   0x0010   /* currently at the file signature */
2449 #  define PNG_IO_CHUNK_HDR   0x0020   /* currently at the chunk header */
2450 #  define PNG_IO_CHUNK_DATA  0x0040   /* currently at the chunk data */
2451 #  define PNG_IO_CHUNK_CRC   0x0080   /* currently at the chunk crc */
2452 #  define PNG_IO_MASK_OP     0x000f   /* current operation: reading/writing */
2453 #  define PNG_IO_MASK_LOC    0x00f0   /* current location: sig/hdr/data/crc */
2454 #endif /* IO_STATE */
2455 
2456 /* Interlace support.  The following macros are always defined so that if
2457  * libpng interlace handling is turned off the macros may be used to handle
2458  * interlaced images within the application.
2459  */
2460 #define PNG_INTERLACE_ADAM7_PASSES 7
2461 
2462 /* Two macros to return the first row and first column of the original,
2463  * full, image which appears in a given pass.  'pass' is in the range 0
2464  * to 6 and the result is in the range 0 to 7.
2465  */
2466 #define PNG_PASS_START_ROW(pass) (((1&~(pass))<<(3-((pass)>>1)))&7)
2467 #define PNG_PASS_START_COL(pass) (((1& (pass))<<(3-(((pass)+1)>>1)))&7)
2468 
2469 /* A macro to return the offset between pixels in the output row for a pair of
2470  * pixels in the input - effectively the inverse of the 'COL_SHIFT' macro that
2471  * follows.  Note that ROW_OFFSET is the offset from one row to the next whereas
2472  * COL_OFFSET is from one column to the next, within a row.
2473  */
2474 #define PNG_PASS_ROW_OFFSET(pass) ((pass)>2?(8>>(((pass)-1)>>1)):8)
2475 #define PNG_PASS_COL_OFFSET(pass) (1<<((7-(pass))>>1))
2476 
2477 /* Two macros to help evaluate the number of rows or columns in each
2478  * pass.  This is expressed as a shift - effectively log2 of the number or
2479  * rows or columns in each 8x8 tile of the original image.
2480  */
2481 #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
2482 #define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
2483 
2484 /* Hence two macros to determine the number of rows or columns in a given
2485  * pass of an image given its height or width.  In fact these macros may
2486  * return non-zero even though the sub-image is empty, because the other
2487  * dimension may be empty for a small image.
2488  */
2489 #define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
2490    -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
2491 #define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
2492    -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
2493 
2494 /* For the reader row callbacks (both progressive and sequential) it is
2495  * necessary to find the row in the output image given a row in an interlaced
2496  * image, so two more macros:
2497  */
2498 #define PNG_ROW_FROM_PASS_ROW(y_in, pass) \
2499    (((y_in)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
2500 #define PNG_COL_FROM_PASS_COL(x_in, pass) \
2501    (((x_in)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
2502 
2503 /* Two macros which return a boolean (0 or 1) saying whether the given row
2504  * or column is in a particular pass.  These use a common utility macro that
2505  * returns a mask for a given pass - the offset 'off' selects the row or
2506  * column version.  The mask has the appropriate bit set for each column in
2507  * the tile.
2508  */
2509 #define PNG_PASS_MASK(pass,off) ( \
2510    ((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \
2511    ((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0))
2512 
2513 #define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
2514    ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
2515 #define PNG_COL_IN_INTERLACE_PASS(x, pass) \
2516    ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
2517 
2518 #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
2519 /* With these routines we avoid an integer divide, which will be slower on
2520  * most machines.  However, it does take more operations than the corresponding
2521  * divide method, so it may be slower on a few RISC systems.  There are two
2522  * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
2523  *
2524  * Note that the rounding factors are NOT supposed to be the same!  128 and
2525  * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
2526  * standard method.
2527  *
2528  * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
2529  */
2530 
2531  /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
2532 
2533 #  define png_composite(composite, fg, alpha, bg)         \
2534      { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
2535            * (png_uint_16)(alpha)                         \
2536            + (png_uint_16)(bg)*(png_uint_16)(255          \
2537            - (png_uint_16)(alpha)) + 128);                \
2538        (composite) = (png_byte)(((temp + (temp >> 8)) >> 8) & 0xff); }
2539 
2540 #  define png_composite_16(composite, fg, alpha, bg)       \
2541      { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg)  \
2542            * (png_uint_32)(alpha)                          \
2543            + (png_uint_32)(bg)*(65535                      \
2544            - (png_uint_32)(alpha)) + 32768);               \
2545        (composite) = (png_uint_16)(0xffff & ((temp + (temp >> 16)) >> 16)); }
2546 
2547 #else  /* Standard method using integer division */
2548 
2549 #  define png_composite(composite, fg, alpha, bg)                        \
2550      (composite) =                                                       \
2551          (png_byte)(0xff & (((png_uint_16)(fg) * (png_uint_16)(alpha) +  \
2552          (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
2553          127) / 255))
2554 
2555 #  define png_composite_16(composite, fg, alpha, bg)                         \
2556      (composite) =                                                           \
2557          (png_uint_16)(0xffff & (((png_uint_32)(fg) * (png_uint_32)(alpha) + \
2558          (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) +     \
2559          32767) / 65535))
2560 #endif /* READ_COMPOSITE_NODIV */
2561 
2562 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
2563 PNG_EXPORT(201, png_uint_32, png_get_uint_32, (png_const_bytep buf));
2564 PNG_EXPORT(202, png_uint_16, png_get_uint_16, (png_const_bytep buf));
2565 PNG_EXPORT(203, png_int_32, png_get_int_32, (png_const_bytep buf));
2566 #endif
2567 
2568 PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_const_structrp png_ptr,
2569     png_const_bytep buf));
2570 /* No png_get_int_16 -- may be added if there's a real need for it. */
2571 
2572 /* Place a 32-bit number into a buffer in PNG byte order (big-endian). */
2573 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2574 PNG_EXPORT(205, void, png_save_uint_32, (png_bytep buf, png_uint_32 i));
2575 #endif
2576 #ifdef PNG_SAVE_INT_32_SUPPORTED
2577 PNG_EXPORT(206, void, png_save_int_32, (png_bytep buf, png_int_32 i));
2578 #endif
2579 
2580 /* Place a 16-bit number into a buffer in PNG byte order.
2581  * The parameter is declared unsigned int, not png_uint_16,
2582  * just to avoid potential problems on pre-ANSI C compilers.
2583  */
2584 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2585 PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
2586 /* No png_save_int_16 -- may be added if there's a real need for it. */
2587 #endif
2588 
2589 #ifdef PNG_USE_READ_MACROS
2590 /* Inline macros to do direct reads of bytes from the input buffer.
2591  * The png_get_int_32() routine assumes we are using two's complement
2592  * format for negative values, which is almost certainly true.
2593  */
2594 #  define PNG_get_uint_32(buf) \
2595      (((png_uint_32)(*(buf)) << 24) + \
2596       ((png_uint_32)(*((buf) + 1)) << 16) + \
2597       ((png_uint_32)(*((buf) + 2)) << 8) + \
2598       ((png_uint_32)(*((buf) + 3))))
2599 
2600    /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
2601     * function) incorrectly returned a value of type png_uint_32.
2602     */
2603 #  define PNG_get_uint_16(buf) \
2604      ((png_uint_16) \
2605       (((unsigned int)(*(buf)) << 8) + \
2606        ((unsigned int)(*((buf) + 1)))))
2607 
2608 #  define PNG_get_int_32(buf) \
2609      ((png_int_32)((*(buf) & 0x80) \
2610       ? -((png_int_32)(((png_get_uint_32(buf)^0xffffffffU)+1U)&0x7fffffffU)) \
2611       : (png_int_32)png_get_uint_32(buf)))
2612 
2613    /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
2614     * but defining a macro name prefixed with PNG_PREFIX.
2615     */
2616 #  ifndef PNG_PREFIX
2617 #     define png_get_uint_32(buf) PNG_get_uint_32(buf)
2618 #     define png_get_uint_16(buf) PNG_get_uint_16(buf)
2619 #     define png_get_int_32(buf)  PNG_get_int_32(buf)
2620 #  endif
2621 #else
2622 #  ifdef PNG_PREFIX
2623       /* No macros; revert to the (redefined) function */
2624 #     define PNG_get_uint_32 (png_get_uint_32)
2625 #     define PNG_get_uint_16 (png_get_uint_16)
2626 #     define PNG_get_int_32  (png_get_int_32)
2627 #  endif
2628 #endif
2629 
2630 #ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
2631 PNG_EXPORT(242, void, png_set_check_for_invalid_index,
2632     (png_structrp png_ptr, int allowed));
2633 #  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
2634 PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
2635     png_const_infop info_ptr));
2636 #  endif
2637 #endif /* CHECK_FOR_INVALID_INDEX */
2638 
2639 /*******************************************************************************
2640  * Section 5: SIMPLIFIED API
2641  *******************************************************************************
2642  *
2643  * Please read the documentation in libpng-manual.txt (TODO: write said
2644  * documentation) if you don't understand what follows.
2645  *
2646  * The simplified API hides the details of both libpng and the PNG file format
2647  * itself.  It allows PNG files to be read into a very limited number of
2648  * in-memory bitmap formats or to be written from the same formats.  If these
2649  * formats do not accomodate your needs then you can, and should, use the more
2650  * sophisticated APIs above - these support a wide variety of in-memory formats
2651  * and a wide variety of sophisticated transformations to those formats as well
2652  * as a wide variety of APIs to manipulate ancillary information.
2653  *
2654  * To read a PNG file using the simplified API:
2655  *
2656  * 1) Declare a 'png_image' structure (see below) on the stack, set the
2657  *    version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
2658  *    (this is REQUIRED, your program may crash if you don't do it.)
2659  * 2) Call the appropriate png_image_begin_read... function.
2660  * 3) Set the png_image 'format' member to the required sample format.
2661  * 4) Allocate a buffer for the image and, if required, the color-map.
2662  * 5) Call png_image_finish_read to read the image and, if required, the
2663  *    color-map into your buffers.
2664  *
2665  * There are no restrictions on the format of the PNG input itself; all valid
2666  * color types, bit depths, and interlace methods are acceptable, and the
2667  * input image is transformed as necessary to the requested in-memory format
2668  * during the png_image_finish_read() step.  The only caveat is that if you
2669  * request a color-mapped image from a PNG that is full-color or makes
2670  * complex use of an alpha channel the transformation is extremely lossy and the
2671  * result may look terrible.
2672  *
2673  * To write a PNG file using the simplified API:
2674  *
2675  * 1) Declare a 'png_image' structure on the stack and memset() it to all zero.
2676  * 2) Initialize the members of the structure that describe the image, setting
2677  *    the 'format' member to the format of the image samples.
2678  * 3) Call the appropriate png_image_write... function with a pointer to the
2679  *    image and, if necessary, the color-map to write the PNG data.
2680  *
2681  * png_image is a structure that describes the in-memory format of an image
2682  * when it is being read or defines the in-memory format of an image that you
2683  * need to write:
2684  */
2685 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) || \
2686     defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
2687 
2688 #define PNG_IMAGE_VERSION 1
2689 
2690 typedef struct png_control *png_controlp;
2691 typedef struct
2692 {
2693    png_controlp opaque;    /* Initialize to NULL, free with png_image_free */
2694    png_uint_32  version;   /* Set to PNG_IMAGE_VERSION */
2695    png_uint_32  width;     /* Image width in pixels (columns) */
2696    png_uint_32  height;    /* Image height in pixels (rows) */
2697    png_uint_32  format;    /* Image format as defined below */
2698    png_uint_32  flags;     /* A bit mask containing informational flags */
2699    png_uint_32  colormap_entries;
2700                            /* Number of entries in the color-map */
2701 
2702    /* In the event of an error or warning the following field will be set to a
2703     * non-zero value and the 'message' field will contain a '\0' terminated
2704     * string with the libpng error or warning message.  If both warnings and
2705     * an error were encountered, only the error is recorded.  If there
2706     * are multiple warnings, only the first one is recorded.
2707     *
2708     * The upper 30 bits of this value are reserved, the low two bits contain
2709     * a value as follows:
2710     */
2711 #  define PNG_IMAGE_WARNING 1
2712 #  define PNG_IMAGE_ERROR 2
2713    /*
2714     * The result is a two-bit code such that a value more than 1 indicates
2715     * a failure in the API just called:
2716     *
2717     *    0 - no warning or error
2718     *    1 - warning
2719     *    2 - error
2720     *    3 - error preceded by warning
2721     */
2722 #  define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1)
2723 
2724    png_uint_32  warning_or_error;
2725 
2726    char         message[64];
2727 } png_image, *png_imagep;
2728 
2729 /* The samples of the image have one to four channels whose components have
2730  * original values in the range 0 to 1.0:
2731  *
2732  * 1: A single gray or luminance channel (G).
2733  * 2: A gray/luminance channel and an alpha channel (GA).
2734  * 3: Three red, green, blue color channels (RGB).
2735  * 4: Three color channels and an alpha channel (RGBA).
2736  *
2737  * The components are encoded in one of two ways:
2738  *
2739  * a) As a small integer, value 0..255, contained in a single byte.  For the
2740  * alpha channel the original value is simply value/255.  For the color or
2741  * luminance channels the value is encoded according to the sRGB specification
2742  * and matches the 8-bit format expected by typical display devices.
2743  *
2744  * The color/gray channels are not scaled (pre-multiplied) by the alpha
2745  * channel and are suitable for passing to color management software.
2746  *
2747  * b) As a value in the range 0..65535, contained in a 2-byte integer.  All
2748  * channels can be converted to the original value by dividing by 65535; all
2749  * channels are linear.  Color channels use the RGB encoding (RGB end-points) of
2750  * the sRGB specification.  This encoding is identified by the
2751  * PNG_FORMAT_FLAG_LINEAR flag below.
2752  *
2753  * When the simplified API needs to convert between sRGB and linear colorspaces,
2754  * the actual sRGB transfer curve defined in the sRGB specification (see the
2755  * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
2756  * approximation used elsewhere in libpng.
2757  *
2758  * When an alpha channel is present it is expected to denote pixel coverage
2759  * of the color or luminance channels and is returned as an associated alpha
2760  * channel: the color/gray channels are scaled (pre-multiplied) by the alpha
2761  * value.
2762  *
2763  * The samples are either contained directly in the image data, between 1 and 8
2764  * bytes per pixel according to the encoding, or are held in a color-map indexed
2765  * by bytes in the image data.  In the case of a color-map the color-map entries
2766  * are individual samples, encoded as above, and the image data has one byte per
2767  * pixel to select the relevant sample from the color-map.
2768  */
2769 
2770 /* PNG_FORMAT_*
2771  *
2772  * #defines to be used in png_image::format.  Each #define identifies a
2773  * particular layout of sample data and, if present, alpha values.  There are
2774  * separate defines for each of the two component encodings.
2775  *
2776  * A format is built up using single bit flag values.  All combinations are
2777  * valid.  Formats can be built up from the flag values or you can use one of
2778  * the predefined values below.  When testing formats always use the FORMAT_FLAG
2779  * macros to test for individual features - future versions of the library may
2780  * add new flags.
2781  *
2782  * When reading or writing color-mapped images the format should be set to the
2783  * format of the entries in the color-map then png_image_{read,write}_colormap
2784  * called to read or write the color-map and set the format correctly for the
2785  * image data.  Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
2786  *
2787  * NOTE: libpng can be built with particular features disabled. If you see
2788  * compiler errors because the definition of one of the following flags has been
2789  * compiled out it is because libpng does not have the required support.  It is
2790  * possible, however, for the libpng configuration to enable the format on just
2791  * read or just write; in that case you may see an error at run time.  You can
2792  * guard against this by checking for the definition of the appropriate
2793  * "_SUPPORTED" macro, one of:
2794  *
2795  *    PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
2796  */
2797 #define PNG_FORMAT_FLAG_ALPHA    0x01U /* format with an alpha channel */
2798 #define PNG_FORMAT_FLAG_COLOR    0x02U /* color format: otherwise grayscale */
2799 #define PNG_FORMAT_FLAG_LINEAR   0x04U /* 2-byte channels else 1-byte */
2800 #define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
2801 
2802 #ifdef PNG_FORMAT_BGR_SUPPORTED
2803 #  define PNG_FORMAT_FLAG_BGR    0x10U /* BGR colors, else order is RGB */
2804 #endif
2805 
2806 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
2807 #  define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
2808 #endif
2809 
2810 /* Commonly used formats have predefined macros.
2811  *
2812  * First the single byte (sRGB) formats:
2813  */
2814 #define PNG_FORMAT_GRAY 0
2815 #define PNG_FORMAT_GA   PNG_FORMAT_FLAG_ALPHA
2816 #define PNG_FORMAT_AG   (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
2817 #define PNG_FORMAT_RGB  PNG_FORMAT_FLAG_COLOR
2818 #define PNG_FORMAT_BGR  (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
2819 #define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
2820 #define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
2821 #define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
2822 #define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
2823 
2824 /* Then the linear 2-byte formats.  When naming these "Y" is used to
2825  * indicate a luminance (gray) channel.
2826  */
2827 #define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
2828 #define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
2829 #define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
2830 #define PNG_FORMAT_LINEAR_RGB_ALPHA \
2831    (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA)
2832 
2833 /* With color-mapped formats the image data is one byte for each pixel, the byte
2834  * is an index into the color-map which is formatted as above.  To obtain a
2835  * color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
2836  * to one of the above definitions, or you can use one of the definitions below.
2837  */
2838 #define PNG_FORMAT_RGB_COLORMAP  (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP)
2839 #define PNG_FORMAT_BGR_COLORMAP  (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP)
2840 #define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP)
2841 #define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP)
2842 #define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP)
2843 #define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP)
2844 
2845 /* PNG_IMAGE macros
2846  *
2847  * These are convenience macros to derive information from a png_image
2848  * structure.  The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
2849  * actual image sample values - either the entries in the color-map or the
2850  * pixels in the image.  The PNG_IMAGE_PIXEL_ macros return corresponding values
2851  * for the pixels and will always return 1 for color-mapped formats.  The
2852  * remaining macros return information about the rows in the image and the
2853  * complete image.
2854  *
2855  * NOTE: All the macros that take a png_image::format parameter are compile time
2856  * constants if the format parameter is, itself, a constant.  Therefore these
2857  * macros can be used in array declarations and case labels where required.
2858  * Similarly the macros are also pre-processor constants (sizeof is not used) so
2859  * they can be used in #if tests.
2860  *
2861  * First the information about the samples.
2862  */
2863 #define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\
2864    (((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1)
2865    /* Return the total number of channels in a given format: 1..4 */
2866 
2867 #define PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)\
2868    ((((fmt) & PNG_FORMAT_FLAG_LINEAR) >> 2)+1)
2869    /* Return the size in bytes of a single component of a pixel or color-map
2870     * entry (as appropriate) in the image: 1 or 2.
2871     */
2872 
2873 #define PNG_IMAGE_SAMPLE_SIZE(fmt)\
2874    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt))
2875    /* This is the size of the sample data for one sample.  If the image is
2876     * color-mapped it is the size of one color-map entry (and image pixels are
2877     * one byte in size), otherwise it is the size of one image pixel.
2878     */
2879 
2880 #define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
2881    (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
2882    /* The maximum size of the color-map required by the format expressed in a
2883     * count of components.  This can be used to compile-time allocate a
2884     * color-map:
2885     *
2886     * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
2887     *
2888     * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
2889     *
2890     * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
2891     * information from one of the png_image_begin_read_ APIs and dynamically
2892     * allocate the required memory.
2893     */
2894 
2895 /* Corresponding information about the pixels */
2896 #define PNG_IMAGE_PIXEL_(test,fmt)\
2897    (((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt))
2898 
2899 #define PNG_IMAGE_PIXEL_CHANNELS(fmt)\
2900    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt)
2901    /* The number of separate channels (components) in a pixel; 1 for a
2902     * color-mapped image.
2903     */
2904 
2905 #define PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
2906    PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_COMPONENT_SIZE,fmt)
2907    /* The size, in bytes, of each component in a pixel; 1 for a color-mapped
2908     * image.
2909     */
2910 
2911 #define PNG_IMAGE_PIXEL_SIZE(fmt) PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_SIZE,fmt)
2912    /* The size, in bytes, of a complete pixel; 1 for a color-mapped image. */
2913 
2914 /* Information about the whole row, or whole image */
2915 #define PNG_IMAGE_ROW_STRIDE(image)\
2916    (PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width)
2917    /* Return the total number of components in a single row of the image; this
2918     * is the minimum 'row stride', the minimum count of components between each
2919     * row.  For a color-mapped image this is the minimum number of bytes in a
2920     * row.
2921     *
2922     * WARNING: this macro overflows for some images with more than one component
2923     * and very large image widths.  libpng will refuse to process an image where
2924     * this macro would overflow.
2925     */
2926 
2927 #define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
2928    (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
2929    /* Return the size, in bytes, of an image buffer given a png_image and a row
2930     * stride - the number of components to leave space for in each row.
2931     *
2932     * WARNING: this macro overflows a 32-bit integer for some large PNG images,
2933     * libpng will refuse to process an image where such an overflow would occur.
2934     */
2935 
2936 #define PNG_IMAGE_SIZE(image)\
2937    PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image))
2938    /* Return the size, in bytes, of the image in memory given just a png_image;
2939     * the row stride is the minimum stride required for the image.
2940     */
2941 
2942 #define PNG_IMAGE_COLORMAP_SIZE(image)\
2943    (PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries)
2944    /* Return the size, in bytes, of the color-map of this image.  If the image
2945     * format is not a color-map format this will return a size sufficient for
2946     * 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
2947     * you don't want to allocate a color-map in this case.
2948     */
2949 
2950 /* PNG_IMAGE_FLAG_*
2951  *
2952  * Flags containing additional information about the image are held in the
2953  * 'flags' field of png_image.
2954  */
2955 #define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
2956    /* This indicates the the RGB values of the in-memory bitmap do not
2957     * correspond to the red, green and blue end-points defined by sRGB.
2958     */
2959 
2960 #define PNG_IMAGE_FLAG_FAST 0x02
2961    /* On write emphasise speed over compression; the resultant PNG file will be
2962     * larger but will be produced significantly faster, particular for large
2963     * images.  Do not use this option for images which will be distributed, only
2964     * used it when producing intermediate files that will be read back in
2965     * repeatedly.  For a typical 24-bit image the option will double the read
2966     * speed at the cost of increasing the image size by 25%, however for many
2967     * more compressible images the PNG file can be 10 times larger with only a
2968     * slight speed gain.
2969     */
2970 
2971 #define PNG_IMAGE_FLAG_16BIT_sRGB 0x04
2972    /* On read if the image is a 16-bit per component image and there is no gAMA
2973     * or sRGB chunk assume that the components are sRGB encoded.  Notice that
2974     * images output by the simplified API always have gamma information; setting
2975     * this flag only affects the interpretation of 16-bit images from an
2976     * external source.  It is recommended that the application expose this flag
2977     * to the user; the user can normally easily recognize the difference between
2978     * linear and sRGB encoding.  This flag has no effect on write - the data
2979     * passed to the write APIs must have the correct encoding (as defined
2980     * above.)
2981     *
2982     * If the flag is not set (the default) input 16-bit per component data is
2983     * assumed to be linear.
2984     *
2985     * NOTE: the flag can only be set after the png_image_begin_read_ call,
2986     * because that call initializes the 'flags' field.
2987     */
2988 
2989 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
2990 /* READ APIs
2991  * ---------
2992  *
2993  * The png_image passed to the read APIs must have been initialized by setting
2994  * the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.)
2995  */
2996 #ifdef PNG_STDIO_SUPPORTED
2997 PNG_EXPORT(234, int, png_image_begin_read_from_file, (png_imagep image,
2998    const char *file_name));
2999    /* The named file is opened for read and the image header is filled in
3000     * from the PNG header in the file.
3001     */
3002 
3003 PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
3004    FILE* file));
3005    /* The PNG header is read from the stdio FILE object. */
3006 #endif /* STDIO */
3007 
3008 PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
3009    png_const_voidp memory, png_size_t size));
3010    /* The PNG header is read from the given memory buffer. */
3011 
3012 PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
3013    png_const_colorp background, void *buffer, png_int_32 row_stride,
3014    void *colormap));
3015    /* Finish reading the image into the supplied buffer and clean up the
3016     * png_image structure.
3017     *
3018     * row_stride is the step, in byte or 2-byte units as appropriate,
3019     * between adjacent rows.  A positive stride indicates that the top-most row
3020     * is first in the buffer - the normal top-down arrangement.  A negative
3021     * stride indicates that the bottom-most row is first in the buffer.
3022     *
3023     * background need only be supplied if an alpha channel must be removed from
3024     * a png_byte format and the removal is to be done by compositing on a solid
3025     * color; otherwise it may be NULL and any composition will be done directly
3026     * onto the buffer.  The value is an sRGB color to use for the background,
3027     * for grayscale output the green channel is used.
3028     *
3029     * background must be supplied when an alpha channel must be removed from a
3030     * single byte color-mapped output format, in other words if:
3031     *
3032     * 1) The original format from png_image_begin_read_from_* had
3033     *    PNG_FORMAT_FLAG_ALPHA set.
3034     * 2) The format set by the application does not.
3035     * 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
3036     *    PNG_FORMAT_FLAG_LINEAR *not* set.
3037     *
3038     * For linear output removing the alpha channel is always done by compositing
3039     * on black and background is ignored.
3040     *
3041     * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set.  It must
3042     * be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
3043     * image->colormap_entries will be updated to the actual number of entries
3044     * written to the colormap; this may be less than the original value.
3045     */
3046 
3047 PNG_EXPORT(238, void, png_image_free, (png_imagep image));
3048    /* Free any data allocated by libpng in image->opaque, setting the pointer to
3049     * NULL.  May be called at any time after the structure is initialized.
3050     */
3051 #endif /* SIMPLIFIED_READ */
3052 
3053 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
3054 /* WRITE APIS
3055  * ----------
3056  * For write you must initialize a png_image structure to describe the image to
3057  * be written.  To do this use memset to set the whole structure to 0 then
3058  * initialize fields describing your image.
3059  *
3060  * version: must be set to PNG_IMAGE_VERSION
3061  * opaque: must be initialized to NULL
3062  * width: image width in pixels
3063  * height: image height in rows
3064  * format: the format of the data (image and color-map) you wish to write
3065  * flags: set to 0 unless one of the defined flags applies; set
3066  *    PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB
3067  *    values do not correspond to the colors in sRGB.
3068  * colormap_entries: set to the number of entries in the color-map (0 to 256)
3069  */
3070 #ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
3071 PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
3072    const char *file, int convert_to_8bit, const void *buffer,
3073    png_int_32 row_stride, const void *colormap));
3074    /* Write the image to the named file. */
3075 
3076 PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
3077    int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
3078    const void *colormap));
3079    /* Write the image to the given (FILE*). */
3080 #endif /* SIMPLIFIED_WRITE_STDIO */
3081 
3082 /* With all write APIs if image is in one of the linear formats with 16-bit
3083  * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
3084  * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
3085  * encoded PNG file is written.
3086  *
3087  * With color-mapped data formats the colormap parameter point to a color-map
3088  * with at least image->colormap_entries encoded in the specified format.  If
3089  * the format is linear the written PNG color-map will be converted to sRGB
3090  * regardless of the convert_to_8_bit flag.
3091  *
3092  * With all APIs row_stride is handled as in the read APIs - it is the spacing
3093  * from one row to the next in component sized units (1 or 2 bytes) and if
3094  * negative indicates a bottom-up row layout in the buffer.  If row_stride is
3095  * zero, libpng will calculate it for you from the image width and number of
3096  * channels.
3097  *
3098  * Note that the write API does not support interlacing, sub-8-bit pixels or
3099  * most ancillary chunks.  If you need to write text chunks (e.g. for copyright
3100  * notices) you need to use one of the other APIs.
3101  */
3102 
3103 PNG_EXPORT(245, int, png_image_write_to_memory, (png_imagep image, void *memory,
3104    png_alloc_size_t * PNG_RESTRICT memory_bytes, int convert_to_8_bit,
3105    const void *buffer, png_int_32 row_stride, const void *colormap));
3106    /* Write the image to the given memory buffer.  The function both writes the
3107     * whole PNG data stream to *memory and updates *memory_bytes with the count
3108     * of bytes written.
3109     *
3110     * 'memory' may be NULL.  In this case *memory_bytes is not read however on
3111     * success the number of bytes which would have been written will still be
3112     * stored in *memory_bytes.  On failure *memory_bytes will contain 0.
3113     *
3114     * If 'memory' is not NULL it must point to memory[*memory_bytes] of
3115     * writeable memory.
3116     *
3117     * If the function returns success memory[*memory_bytes] (if 'memory' is not
3118     * NULL) contains the written PNG data.  *memory_bytes will always be less
3119     * than or equal to the original value.
3120     *
3121     * If the function returns false and *memory_bytes was not changed an error
3122     * occured during write.  If *memory_bytes was changed, or is not 0 if
3123     * 'memory' was NULL, the write would have succeeded but for the memory
3124     * buffer being too small.  *memory_bytes contains the required number of
3125     * bytes and will be bigger that the original value.
3126     */
3127 
3128 #define png_image_write_get_memory_size(image, size, convert_to_8_bit, buffer,\
3129    row_stride, colormap)\
3130    png_image_write_to_memory(&(image), 0, &(size), convert_to_8_bit, buffer,\
3131          row_stride, colormap)
3132    /* Return the amount of memory in 'size' required to compress this image.
3133     * The png_image structure 'image' must be filled in as in the above
3134     * function and must not be changed before the actual write call, the buffer
3135     * and all other parameters must also be identical to that in the final
3136     * write call.  The 'size' variable need not be initialized.
3137     *
3138     * NOTE: the macro returns true/false, if false is returned 'size' will be
3139     * set to zero and the write failed and probably will fail if tried again.
3140     */
3141 
3142 /* You can pre-allocate the buffer by making sure it is of sufficient size
3143  * regardless of the amount of compression achieved.  The buffer size will
3144  * always be bigger than the original image and it will never be filled.  The
3145  * following macros are provided to assist in allocating the buffer.
3146  */
3147 #define PNG_IMAGE_DATA_SIZE(image) (PNG_IMAGE_SIZE(image)+(image).height)
3148    /* The number of uncompressed bytes in the PNG byte encoding of the image;
3149     * uncompressing the PNG IDAT data will give this number of bytes.
3150     *
3151     * NOTE: while PNG_IMAGE_SIZE cannot overflow for an image in memory this
3152     * macro can because of the extra bytes used in the PNG byte encoding.  You
3153     * need to avoid this macro if your image size approaches 2^30 in width or
3154     * height.  The same goes for the remainder of these macros; they all produce
3155     * bigger numbers than the actual in-memory image size.
3156     */
3157 #ifndef PNG_ZLIB_MAX_SIZE
3158 #  define PNG_ZLIB_MAX_SIZE(b) ((b)+(((b)+7U)>>3)+(((b)+63U)>>6)+11U)
3159    /* An upper bound on the number of compressed bytes given 'b' uncompressed
3160     * bytes.  This is based on deflateBounds() in zlib; different
3161     * implementations of zlib compression may conceivably produce more data so
3162     * if your zlib implementation is not zlib itself redefine this macro
3163     * appropriately.
3164     */
3165 #endif
3166 
3167 #define PNG_IMAGE_COMPRESSED_SIZE_MAX(image)\
3168    PNG_ZLIB_MAX_SIZE((png_alloc_size_t)PNG_IMAGE_DATA_SIZE(image))
3169    /* An upper bound on the size of the data in the PNG IDAT chunks. */
3170 
3171 #define PNG_IMAGE_PNG_SIZE_MAX_(image, image_size)\
3172    ((8U/*sig*/+25U/*IHDR*/+16U/*gAMA*/+44U/*cHRM*/+12U/*IEND*/+\
3173     (((image).format&PNG_FORMAT_FLAG_COLORMAP)?/*colormap: PLTE, tRNS*/\
3174      12U+3U*(image).colormap_entries/*PLTE data*/+\
3175      (((image).format&PNG_FORMAT_FLAG_ALPHA)?\
3176       12U/*tRNS*/+(image).colormap_entries:0U):0U)+\
3177     12U)+(12U*((image_size)/PNG_ZBUF_SIZE))/*IDAT*/+(image_size))
3178    /* A helper for the following macro; if your compiler cannot handle the
3179     * following macro use this one with the result of
3180     * PNG_IMAGE_COMPRESSED_SIZE_MAX(image) as the second argument (most
3181     * compilers should handle this just fine.)
3182     */
3183 
3184 #define PNG_IMAGE_PNG_SIZE_MAX(image)\
3185    PNG_IMAGE_PNG_SIZE_MAX_(image, PNG_IMAGE_COMPRESSED_SIZE_MAX(image))
3186    /* An upper bound on the total length of the PNG data stream for 'image'.
3187     * The result is of type png_alloc_size_t, on 32-bit systems this may
3188     * overflow even though PNG_IMAGE_DATA_SIZE does not overflow; the write will
3189     * run out of buffer space but return a corrected size which should work.
3190     */
3191 #endif /* SIMPLIFIED_WRITE */
3192 /*******************************************************************************
3193  *  END OF SIMPLIFIED API
3194  ******************************************************************************/
3195 #endif /* SIMPLIFIED_{READ|WRITE} */
3196 
3197 /*******************************************************************************
3198  * Section 6: IMPLEMENTATION OPTIONS
3199  *******************************************************************************
3200  *
3201  * Support for arbitrary implementation-specific optimizations.  The API allows
3202  * particular options to be turned on or off.  'Option' is the number of the
3203  * option and 'onoff' is 0 (off) or non-0 (on).  The value returned is given
3204  * by the PNG_OPTION_ defines below.
3205  *
3206  * HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
3207  *           are detected at run time, however sometimes it may be impossible
3208  *           to do this in user mode, in which case it is necessary to discover
3209  *           the capabilities in an OS specific way.  Such capabilities are
3210  *           listed here when libpng has support for them and must be turned
3211  *           ON by the application if present.
3212  *
3213  * SOFTWARE: sometimes software optimizations actually result in performance
3214  *           decrease on some architectures or systems, or with some sets of
3215  *           PNG images.  'Software' options allow such optimizations to be
3216  *           selected at run time.
3217  */
3218 #ifdef PNG_SET_OPTION_SUPPORTED
3219 #ifdef PNG_ARM_NEON_API_SUPPORTED
3220 #  define PNG_ARM_NEON   0 /* HARDWARE: ARM Neon SIMD instructions supported */
3221 #endif
3222 #define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
3223 #define PNG_SKIP_sRGB_CHECK_PROFILE 4 /* SOFTWARE: Check ICC profile for sRGB */
3224 #define PNG_OPTION_NEXT  6 /* Next option - numbers must be even */
3225 
3226 /* Return values: NOTE: there are four values and 'off' is *not* zero */
3227 #define PNG_OPTION_UNSET   0 /* Unset - defaults to off */
3228 #define PNG_OPTION_INVALID 1 /* Option number out of range */
3229 #define PNG_OPTION_OFF     2
3230 #define PNG_OPTION_ON      3
3231 
3232 PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
3233    int onoff));
3234 #endif /* SET_OPTION */
3235 
3236 /*******************************************************************************
3237  *  END OF HARDWARE AND SOFTWARE OPTIONS
3238  ******************************************************************************/
3239 
3240 /* Maintainer: Put new public prototypes here ^, in libpng.3, in project
3241  * defs, and in scripts/symbols.def.
3242  */
3243 
3244 /* The last ordinal number (this is the *last* one already used; the next
3245  * one to use is one more than this.)
3246  */
3247 #ifdef PNG_EXPORT_LAST_ORDINAL
3248   PNG_EXPORT_LAST_ORDINAL(245);
3249 #endif
3250 
3251 #ifdef __cplusplus
3252 }
3253 #endif
3254 
3255 #endif /* PNG_VERSION_INFO_ONLY */
3256 /* Do not put anything past this line */
3257 #endif /* PNG_H */
3258