1
2/* pngwrite.c - general routines to write a PNG file
3 *
4 * Copyright (c) 2018-2023 Cosmin Truta
5 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6 * Copyright (c) 1996-1997 Andreas Dilger
7 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
8 *
9 * This code is released under the libpng license.
10 * For conditions of distribution and use, see the disclaimer
11 * and license in png.h
12 */
13
14#include "pngpriv.h"
15#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
16# include <errno.h>
17#endif /* SIMPLIFIED_WRITE_STDIO */
18
19#ifdef PNG_WRITE_SUPPORTED
20
21#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
22/* Write out all the unknown chunks for the current given location */
23static void
24write_unknown_chunks(png_structrp png_ptr, png_const_inforp info_ptr,
25 unsigned int where)
26{
27 if (info_ptr->unknown_chunks_num != 0)
28 {
29 png_const_unknown_chunkp up;
30
31 png_debug(5, "writing extra chunks");
32
33 for (up = info_ptr->unknown_chunks;
34 up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
35 ++up)
36 if ((up->location & where) != 0)
37 {
38 /* If per-chunk unknown chunk handling is enabled use it, otherwise
39 * just write the chunks the application has set.
40 */
41#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
42 int keep = png_handle_as_unknown(png_ptr, up->name);
43
44 /* NOTE: this code is radically different from the read side in the
45 * matter of handling an ancillary unknown chunk. In the read side
46 * the default behavior is to discard it, in the code below the default
47 * behavior is to write it. Critical chunks are, however, only
48 * written if explicitly listed or if the default is set to write all
49 * unknown chunks.
50 *
51 * The default handling is also slightly weird - it is not possible to
52 * stop the writing of all unsafe-to-copy chunks!
53 *
54 * TODO: REVIEW: this would seem to be a bug.
55 */
56 if (keep != PNG_HANDLE_CHUNK_NEVER &&
57 ((up->name[3] & 0x20) /* safe-to-copy overrides everything */ ||
58 keep == PNG_HANDLE_CHUNK_ALWAYS ||
59 (keep == PNG_HANDLE_CHUNK_AS_DEFAULT &&
60 png_ptr->unknown_default == PNG_HANDLE_CHUNK_ALWAYS)))
61#endif
62 {
63 /* TODO: review, what is wrong with a zero length unknown chunk? */
64 if (up->size == 0)
65 png_warning(png_ptr, "Writing zero-length unknown chunk");
66
67 png_write_chunk(png_ptr, up->name, up->data, up->size);
68 }
69 }
70 }
71}
72#endif /* WRITE_UNKNOWN_CHUNKS */
73
74/* Writes all the PNG information. This is the suggested way to use the
75 * library. If you have a new chunk to add, make a function to write it,
76 * and put it in the correct location here. If you want the chunk written
77 * after the image data, put it in png_write_end(). I strongly encourage
78 * you to supply a PNG_INFO_<chunk> flag, and check info_ptr->valid before
79 * writing the chunk, as that will keep the code from breaking if you want
80 * to just write a plain PNG file. If you have long comments, I suggest
81 * writing them in png_write_end(), and compressing them.
82 */
83void PNGAPI
84png_write_info_before_PLTE(png_structrp png_ptr, png_const_inforp info_ptr)
85{
86 png_debug(1, "in png_write_info_before_PLTE");
87
88 if (png_ptr == NULL || info_ptr == NULL)
89 return;
90
91 if ((png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE) == 0)
92 {
93 /* Write PNG signature */
94 png_write_sig(png_ptr);
95
96#ifdef PNG_MNG_FEATURES_SUPPORTED
97 if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 && \
98 png_ptr->mng_features_permitted != 0)
99 {
100 png_warning(png_ptr,
101 "MNG features are not allowed in a PNG datastream");
102 png_ptr->mng_features_permitted = 0;
103 }
104#endif
105
106 /* Write IHDR information. */
107 png_write_IHDR(png_ptr, info_ptr->width, info_ptr->height,
108 info_ptr->bit_depth, info_ptr->color_type, info_ptr->compression_type,
109 info_ptr->filter_type,
110#ifdef PNG_WRITE_INTERLACING_SUPPORTED
111 info_ptr->interlace_type
112#else
113 0
114#endif
115 );
116
117 /* The rest of these check to see if the valid field has the appropriate
118 * flag set, and if it does, writes the chunk.
119 *
120 * 1.6.0: COLORSPACE support controls the writing of these chunks too, and
121 * the chunks will be written if the WRITE routine is there and
122 * information * is available in the COLORSPACE. (See
123 * png_colorspace_sync_info in png.c for where the valid flags get set.)
124 *
125 * Under certain circumstances the colorspace can be invalidated without
126 * syncing the info_struct 'valid' flags; this happens if libpng detects
127 * an error and calls png_error while the color space is being set, yet
128 * the application continues writing the PNG. So check the 'invalid'
129 * flag here too.
130 */
131#ifdef PNG_GAMMA_SUPPORTED
132# ifdef PNG_WRITE_gAMA_SUPPORTED
133 if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
134 (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_gAMA) != 0 &&
135 (info_ptr->valid & PNG_INFO_gAMA) != 0)
136 png_write_gAMA_fixed(png_ptr, info_ptr->colorspace.gamma);
137# endif
138#endif
139
140#ifdef PNG_COLORSPACE_SUPPORTED
141 /* Write only one of sRGB or an ICC profile. If a profile was supplied
142 * and it matches one of the known sRGB ones issue a warning.
143 */
144# ifdef PNG_WRITE_iCCP_SUPPORTED
145 if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
146 (info_ptr->valid & PNG_INFO_iCCP) != 0)
147 {
148# ifdef PNG_WRITE_sRGB_SUPPORTED
149 if ((info_ptr->valid & PNG_INFO_sRGB) != 0)
150 png_app_warning(png_ptr,
151 "profile matches sRGB but writing iCCP instead");
152# endif
153
154 png_write_iCCP(png_ptr, info_ptr->iccp_name,
155 info_ptr->iccp_profile);
156 }
157# ifdef PNG_WRITE_sRGB_SUPPORTED
158 else
159# endif
160# endif
161
162# ifdef PNG_WRITE_sRGB_SUPPORTED
163 if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
164 (info_ptr->valid & PNG_INFO_sRGB) != 0)
165 png_write_sRGB(png_ptr, info_ptr->colorspace.rendering_intent);
166# endif /* WRITE_sRGB */
167#endif /* COLORSPACE */
168
169#ifdef PNG_WRITE_sBIT_SUPPORTED
170 if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
171 png_write_sBIT(png_ptr, &(info_ptr->sig_bit), info_ptr->color_type);
172#endif
173
174#ifdef PNG_COLORSPACE_SUPPORTED
175# ifdef PNG_WRITE_cHRM_SUPPORTED
176 if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) == 0 &&
177 (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) != 0 &&
178 (info_ptr->valid & PNG_INFO_cHRM) != 0)
179 png_write_cHRM_fixed(png_ptr, &info_ptr->colorspace.end_points_xy);
180# endif
181#endif
182
183#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
184 write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_IHDR);
185#endif
186
187 png_ptr->mode |= PNG_WROTE_INFO_BEFORE_PLTE;
188 }
189}
190
191void PNGAPI
192png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
193{
194#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
195 int i;
196#endif
197
198 png_debug(1, "in png_write_info");
199
200 if (png_ptr == NULL || info_ptr == NULL)
201 return;
202
203 png_write_info_before_PLTE(png_ptr, info_ptr);
204
205 if ((info_ptr->valid & PNG_INFO_PLTE) != 0)
206 png_write_PLTE(png_ptr, info_ptr->palette,
207 (png_uint_32)info_ptr->num_palette);
208
209 else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
210 png_error(png_ptr, "Valid palette required for paletted images");
211
212#ifdef PNG_WRITE_tRNS_SUPPORTED
213 if ((info_ptr->valid & PNG_INFO_tRNS) !=0)
214 {
215#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
216 /* Invert the alpha channel (in tRNS) */
217 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0 &&
218 info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
219 {
220 int j, jend;
221
222 jend = info_ptr->num_trans;
223 if (jend > PNG_MAX_PALETTE_LENGTH)
224 jend = PNG_MAX_PALETTE_LENGTH;
225
226 for (j = 0; j<jend; ++j)
227 info_ptr->trans_alpha[j] =
228 (png_byte)(255 - info_ptr->trans_alpha[j]);
229 }
230#endif
231 png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color),
232 info_ptr->num_trans, info_ptr->color_type);
233 }
234#endif
235#ifdef PNG_WRITE_bKGD_SUPPORTED
236 if ((info_ptr->valid & PNG_INFO_bKGD) != 0)
237 png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
238#endif
239
240#ifdef PNG_WRITE_eXIf_SUPPORTED
241 if ((info_ptr->valid & PNG_INFO_eXIf) != 0)
242 {
243 png_write_eXIf(png_ptr, info_ptr->exif, info_ptr->num_exif);
244 png_ptr->mode |= PNG_WROTE_eXIf;
245 }
246#endif
247
248#ifdef PNG_WRITE_hIST_SUPPORTED
249 if ((info_ptr->valid & PNG_INFO_hIST) != 0)
250 png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
251#endif
252
253#ifdef PNG_WRITE_oFFs_SUPPORTED
254 if ((info_ptr->valid & PNG_INFO_oFFs) != 0)
255 png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
256 info_ptr->offset_unit_type);
257#endif
258
259#ifdef PNG_WRITE_pCAL_SUPPORTED
260 if ((info_ptr->valid & PNG_INFO_pCAL) != 0)
261 png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0,
262 info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams,
263 info_ptr->pcal_units, info_ptr->pcal_params);
264#endif
265
266#ifdef PNG_WRITE_sCAL_SUPPORTED
267 if ((info_ptr->valid & PNG_INFO_sCAL) != 0)
268 png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit,
269 info_ptr->scal_s_width, info_ptr->scal_s_height);
270#endif /* sCAL */
271
272#ifdef PNG_WRITE_pHYs_SUPPORTED
273 if ((info_ptr->valid & PNG_INFO_pHYs) != 0)
274 png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
275 info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
276#endif /* pHYs */
277
278#ifdef PNG_WRITE_tIME_SUPPORTED
279 if ((info_ptr->valid & PNG_INFO_tIME) != 0)
280 {
281 png_write_tIME(png_ptr, &(info_ptr->mod_time));
282 png_ptr->mode |= PNG_WROTE_tIME;
283 }
284#endif /* tIME */
285
286#ifdef PNG_WRITE_sPLT_SUPPORTED
287 if ((info_ptr->valid & PNG_INFO_sPLT) != 0)
288 for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
289 png_write_sPLT(png_ptr, info_ptr->splt_palettes + i);
290#endif /* sPLT */
291
292#ifdef PNG_WRITE_TEXT_SUPPORTED
293 /* Check to see if we need to write text chunks */
294 for (i = 0; i < info_ptr->num_text; i++)
295 {
296 png_debug2(2, "Writing header text chunk %d, type %d", i,
297 info_ptr->text[i].compression);
298 /* An internationalized chunk? */
299 if (info_ptr->text[i].compression > 0)
300 {
301#ifdef PNG_WRITE_iTXt_SUPPORTED
302 /* Write international chunk */
303 png_write_iTXt(png_ptr,
304 info_ptr->text[i].compression,
305 info_ptr->text[i].key,
306 info_ptr->text[i].lang,
307 info_ptr->text[i].lang_key,
308 info_ptr->text[i].text);
309 /* Mark this chunk as written */
310 if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
311 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
312 else
313 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
314#else
315 png_warning(png_ptr, "Unable to write international text");
316#endif
317 }
318
319 /* If we want a compressed text chunk */
320 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_zTXt)
321 {
322#ifdef PNG_WRITE_zTXt_SUPPORTED
323 /* Write compressed chunk */
324 png_write_zTXt(png_ptr, info_ptr->text[i].key,
325 info_ptr->text[i].text, info_ptr->text[i].compression);
326 /* Mark this chunk as written */
327 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
328#else
329 png_warning(png_ptr, "Unable to write compressed text");
330#endif
331 }
332
333 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
334 {
335#ifdef PNG_WRITE_tEXt_SUPPORTED
336 /* Write uncompressed chunk */
337 png_write_tEXt(png_ptr, info_ptr->text[i].key,
338 info_ptr->text[i].text,
339 0);
340 /* Mark this chunk as written */
341 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
342#else
343 /* Can't get here */
344 png_warning(png_ptr, "Unable to write uncompressed text");
345#endif
346 }
347 }
348#endif /* tEXt */
349
350#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
351 write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_PLTE);
352#endif
353}
354
355/* Writes the end of the PNG file. If you don't want to write comments or
356 * time information, you can pass NULL for info. If you already wrote these
357 * in png_write_info(), do not write them again here. If you have long
358 * comments, I suggest writing them here, and compressing them.
359 */
360void PNGAPI
361png_write_end(png_structrp png_ptr, png_inforp info_ptr)
362{
363 png_debug(1, "in png_write_end");
364
365 if (png_ptr == NULL)
366 return;
367
368 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
369 png_error(png_ptr, "No IDATs written into file");
370
371#ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
372 if (png_ptr->num_palette_max > png_ptr->num_palette)
373 png_benign_error(png_ptr, "Wrote palette index exceeding num_palette");
374#endif
375
376 /* See if user wants us to write information chunks */
377 if (info_ptr != NULL)
378 {
379#ifdef PNG_WRITE_TEXT_SUPPORTED
380 int i; /* local index variable */
381#endif
382#ifdef PNG_WRITE_tIME_SUPPORTED
383 /* Check to see if user has supplied a time chunk */
384 if ((info_ptr->valid & PNG_INFO_tIME) != 0 &&
385 (png_ptr->mode & PNG_WROTE_tIME) == 0)
386 png_write_tIME(png_ptr, &(info_ptr->mod_time));
387
388#endif
389#ifdef PNG_WRITE_TEXT_SUPPORTED
390 /* Loop through comment chunks */
391 for (i = 0; i < info_ptr->num_text; i++)
392 {
393 png_debug2(2, "Writing trailer text chunk %d, type %d", i,
394 info_ptr->text[i].compression);
395 /* An internationalized chunk? */
396 if (info_ptr->text[i].compression > 0)
397 {
398#ifdef PNG_WRITE_iTXt_SUPPORTED
399 /* Write international chunk */
400 png_write_iTXt(png_ptr,
401 info_ptr->text[i].compression,
402 info_ptr->text[i].key,
403 info_ptr->text[i].lang,
404 info_ptr->text[i].lang_key,
405 info_ptr->text[i].text);
406 /* Mark this chunk as written */
407 if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
408 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
409 else
410 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
411#else
412 png_warning(png_ptr, "Unable to write international text");
413#endif
414 }
415
416 else if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
417 {
418#ifdef PNG_WRITE_zTXt_SUPPORTED
419 /* Write compressed chunk */
420 png_write_zTXt(png_ptr, info_ptr->text[i].key,
421 info_ptr->text[i].text, info_ptr->text[i].compression);
422 /* Mark this chunk as written */
423 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
424#else
425 png_warning(png_ptr, "Unable to write compressed text");
426#endif
427 }
428
429 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
430 {
431#ifdef PNG_WRITE_tEXt_SUPPORTED
432 /* Write uncompressed chunk */
433 png_write_tEXt(png_ptr, info_ptr->text[i].key,
434 info_ptr->text[i].text, 0);
435 /* Mark this chunk as written */
436 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
437#else
438 png_warning(png_ptr, "Unable to write uncompressed text");
439#endif
440 }
441 }
442#endif
443
444#ifdef PNG_WRITE_eXIf_SUPPORTED
445 if ((info_ptr->valid & PNG_INFO_eXIf) != 0 &&
446 (png_ptr->mode & PNG_WROTE_eXIf) == 0)
447 png_write_eXIf(png_ptr, info_ptr->exif, info_ptr->num_exif);
448#endif
449
450#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
451 write_unknown_chunks(png_ptr, info_ptr, PNG_AFTER_IDAT);
452#endif
453 }
454
455 png_ptr->mode |= PNG_AFTER_IDAT;
456
457 /* Write end of PNG file */
458 png_write_IEND(png_ptr);
459
460 /* This flush, added in libpng-1.0.8, removed from libpng-1.0.9beta03,
461 * and restored again in libpng-1.2.30, may cause some applications that
462 * do not set png_ptr->output_flush_fn to crash. If your application
463 * experiences a problem, please try building libpng with
464 * PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED defined, and report the event to
465 * png-mng-implement at lists.sf.net .
466 */
467#ifdef PNG_WRITE_FLUSH_SUPPORTED
468# ifdef PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED
469 png_flush(png_ptr);
470# endif
471#endif
472}
473
474#ifdef PNG_CONVERT_tIME_SUPPORTED
475void PNGAPI
476png_convert_from_struct_tm(png_timep ptime, const struct tm * ttime)
477{
478 png_debug(1, "in png_convert_from_struct_tm");
479
480 ptime->year = (png_uint_16)(1900 + ttime->tm_year);
481 ptime->month = (png_byte)(ttime->tm_mon + 1);
482 ptime->day = (png_byte)ttime->tm_mday;
483 ptime->hour = (png_byte)ttime->tm_hour;
484 ptime->minute = (png_byte)ttime->tm_min;
485 ptime->second = (png_byte)ttime->tm_sec;
486}
487
488void PNGAPI
489png_convert_from_time_t(png_timep ptime, time_t ttime)
490{
491 struct tm *tbuf;
492
493 png_debug(1, "in png_convert_from_time_t");
494
495 tbuf = gmtime(&ttime);
496 if (tbuf == NULL)
497 {
498 /* TODO: add a safe function which takes a png_ptr argument and raises
499 * a png_error if the ttime argument is invalid and the call to gmtime
500 * fails as a consequence.
501 */
502 memset(ptime, 0, sizeof(*ptime));
503 return;
504 }
505
506 png_convert_from_struct_tm(ptime, tbuf);
507}
508#endif
509
510/* Initialize png_ptr structure, and allocate any memory needed */
511PNG_FUNCTION(png_structp,PNGAPI
512png_create_write_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
513 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
514{
515#ifndef PNG_USER_MEM_SUPPORTED
516 png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
517 error_fn, warn_fn, NULL, NULL, NULL);
518#else
519 return png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
520 warn_fn, NULL, NULL, NULL);
521}
522
523/* Alternate initialize png_ptr structure, and allocate any memory needed */
524PNG_FUNCTION(png_structp,PNGAPI
525png_create_write_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
526 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
527 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
528{
529 png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
530 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
531#endif /* USER_MEM */
532 if (png_ptr != NULL)
533 {
534 /* Set the zlib control values to defaults; they can be overridden by the
535 * application after the struct has been created.
536 */
537 png_ptr->zbuffer_size = PNG_ZBUF_SIZE;
538
539 /* The 'zlib_strategy' setting is irrelevant because png_default_claim in
540 * pngwutil.c defaults it according to whether or not filters will be
541 * used, and ignores this setting.
542 */
543 png_ptr->zlib_strategy = PNG_Z_DEFAULT_STRATEGY;
544 png_ptr->zlib_level = PNG_Z_DEFAULT_COMPRESSION;
545 png_ptr->zlib_mem_level = 8;
546 png_ptr->zlib_window_bits = 15;
547 png_ptr->zlib_method = 8;
548
549#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
550 png_ptr->zlib_text_strategy = PNG_TEXT_Z_DEFAULT_STRATEGY;
551 png_ptr->zlib_text_level = PNG_TEXT_Z_DEFAULT_COMPRESSION;
552 png_ptr->zlib_text_mem_level = 8;
553 png_ptr->zlib_text_window_bits = 15;
554 png_ptr->zlib_text_method = 8;
555#endif /* WRITE_COMPRESSED_TEXT */
556
557 /* This is a highly dubious configuration option; by default it is off,
558 * but it may be appropriate for private builds that are testing
559 * extensions not conformant to the current specification, or of
560 * applications that must not fail to write at all costs!
561 */
562#ifdef PNG_BENIGN_WRITE_ERRORS_SUPPORTED
563 /* In stable builds only warn if an application error can be completely
564 * handled.
565 */
566 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
567#endif
568
569 /* App warnings are warnings in release (or release candidate) builds but
570 * are errors during development.
571 */
572#if PNG_RELEASE_BUILD
573 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
574#endif
575
576 /* TODO: delay this, it can be done in png_init_io() (if the app doesn't
577 * do it itself) avoiding setting the default function if it is not
578 * required.
579 */
580 png_set_write_fn(png_ptr, NULL, NULL, NULL);
581 }
582
583 return png_ptr;
584}
585
586
587/* Write a few rows of image data. If the image is interlaced,
588 * either you will have to write the 7 sub images, or, if you
589 * have called png_set_interlace_handling(), you will have to
590 * "write" the image seven times.
591 */
592void PNGAPI
593png_write_rows(png_structrp png_ptr, png_bytepp row,
594 png_uint_32 num_rows)
595{
596 png_uint_32 i; /* row counter */
597 png_bytepp rp; /* row pointer */
598
599 png_debug(1, "in png_write_rows");
600
601 if (png_ptr == NULL)
602 return;
603
604 /* Loop through the rows */
605 for (i = 0, rp = row; i < num_rows; i++, rp++)
606 {
607 png_write_row(png_ptr, *rp);
608 }
609}
610
611/* Write the image. You only need to call this function once, even
612 * if you are writing an interlaced image.
613 */
614void PNGAPI
615png_write_image(png_structrp png_ptr, png_bytepp image)
616{
617 png_uint_32 i; /* row index */
618 int pass, num_pass; /* pass variables */
619 png_bytepp rp; /* points to current row */
620
621 if (png_ptr == NULL)
622 return;
623
624 png_debug(1, "in png_write_image");
625
626#ifdef PNG_WRITE_INTERLACING_SUPPORTED
627 /* Initialize interlace handling. If image is not interlaced,
628 * this will set pass to 1
629 */
630 num_pass = png_set_interlace_handling(png_ptr);
631#else
632 num_pass = 1;
633#endif
634 /* Loop through passes */
635 for (pass = 0; pass < num_pass; pass++)
636 {
637 /* Loop through image */
638 for (i = 0, rp = image; i < png_ptr->height; i++, rp++)
639 {
640 png_write_row(png_ptr, *rp);
641 }
642 }
643}
644
645#ifdef PNG_MNG_FEATURES_SUPPORTED
646/* Performs intrapixel differencing */
647static void
648png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
649{
650 png_debug(1, "in png_do_write_intrapixel");
651
652 if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
653 {
654 int bytes_per_pixel;
655 png_uint_32 row_width = row_info->width;
656 if (row_info->bit_depth == 8)
657 {
658 png_bytep rp;
659 png_uint_32 i;
660
661 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
662 bytes_per_pixel = 3;
663
664 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
665 bytes_per_pixel = 4;
666
667 else
668 return;
669
670 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
671 {
672 *(rp) = (png_byte)(*rp - *(rp + 1));
673 *(rp + 2) = (png_byte)(*(rp + 2) - *(rp + 1));
674 }
675 }
676
677#ifdef PNG_WRITE_16BIT_SUPPORTED
678 else if (row_info->bit_depth == 16)
679 {
680 png_bytep rp;
681 png_uint_32 i;
682
683 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
684 bytes_per_pixel = 6;
685
686 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
687 bytes_per_pixel = 8;
688
689 else
690 return;
691
692 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
693 {
694 png_uint_32 s0 = (png_uint_32)(*(rp ) << 8) | *(rp + 1);
695 png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
696 png_uint_32 s2 = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
697 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
698 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
699 *(rp ) = (png_byte)(red >> 8);
700 *(rp + 1) = (png_byte)red;
701 *(rp + 4) = (png_byte)(blue >> 8);
702 *(rp + 5) = (png_byte)blue;
703 }
704 }
705#endif /* WRITE_16BIT */
706 }
707}
708#endif /* MNG_FEATURES */
709
710/* Called by user to write a row of image data */
711void PNGAPI
712png_write_row(png_structrp png_ptr, png_const_bytep row)
713{
714 /* 1.5.6: moved from png_struct to be a local structure: */
715 png_row_info row_info;
716
717 if (png_ptr == NULL)
718 return;
719
720 png_debug2(1, "in png_write_row (row %u, pass %d)",
721 png_ptr->row_number, png_ptr->pass);
722
723 /* Initialize transformations and other stuff if first time */
724 if (png_ptr->row_number == 0 && png_ptr->pass == 0)
725 {
726 /* Make sure we wrote the header info */
727 if ((png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE) == 0)
728 png_error(png_ptr,
729 "png_write_info was never called before png_write_row");
730
731 /* Check for transforms that have been set but were defined out */
732#if !defined(PNG_WRITE_INVERT_SUPPORTED) && defined(PNG_READ_INVERT_SUPPORTED)
733 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
734 png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined");
735#endif
736
737#if !defined(PNG_WRITE_FILLER_SUPPORTED) && defined(PNG_READ_FILLER_SUPPORTED)
738 if ((png_ptr->transformations & PNG_FILLER) != 0)
739 png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined");
740#endif
741#if !defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
742 defined(PNG_READ_PACKSWAP_SUPPORTED)
743 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
744 png_warning(png_ptr,
745 "PNG_WRITE_PACKSWAP_SUPPORTED is not defined");
746#endif
747
748#if !defined(PNG_WRITE_PACK_SUPPORTED) && defined(PNG_READ_PACK_SUPPORTED)
749 if ((png_ptr->transformations & PNG_PACK) != 0)
750 png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined");
751#endif
752
753#if !defined(PNG_WRITE_SHIFT_SUPPORTED) && defined(PNG_READ_SHIFT_SUPPORTED)
754 if ((png_ptr->transformations & PNG_SHIFT) != 0)
755 png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined");
756#endif
757
758#if !defined(PNG_WRITE_BGR_SUPPORTED) && defined(PNG_READ_BGR_SUPPORTED)
759 if ((png_ptr->transformations & PNG_BGR) != 0)
760 png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined");
761#endif
762
763#if !defined(PNG_WRITE_SWAP_SUPPORTED) && defined(PNG_READ_SWAP_SUPPORTED)
764 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
765 png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined");
766#endif
767
768 png_write_start_row(png_ptr);
769 }
770
771#ifdef PNG_WRITE_INTERLACING_SUPPORTED
772 /* If interlaced and not interested in row, return */
773 if (png_ptr->interlaced != 0 &&
774 (png_ptr->transformations & PNG_INTERLACE) != 0)
775 {
776 switch (png_ptr->pass)
777 {
778 case 0:
779 if ((png_ptr->row_number & 0x07) != 0)
780 {
781 png_write_finish_row(png_ptr);
782 return;
783 }
784 break;
785
786 case 1:
787 if ((png_ptr->row_number & 0x07) != 0 || png_ptr->width < 5)
788 {
789 png_write_finish_row(png_ptr);
790 return;
791 }
792 break;
793
794 case 2:
795 if ((png_ptr->row_number & 0x07) != 4)
796 {
797 png_write_finish_row(png_ptr);
798 return;
799 }
800 break;
801
802 case 3:
803 if ((png_ptr->row_number & 0x03) != 0 || png_ptr->width < 3)
804 {
805 png_write_finish_row(png_ptr);
806 return;
807 }
808 break;
809
810 case 4:
811 if ((png_ptr->row_number & 0x03) != 2)
812 {
813 png_write_finish_row(png_ptr);
814 return;
815 }
816 break;
817
818 case 5:
819 if ((png_ptr->row_number & 0x01) != 0 || png_ptr->width < 2)
820 {
821 png_write_finish_row(png_ptr);
822 return;
823 }
824 break;
825
826 case 6:
827 if ((png_ptr->row_number & 0x01) == 0)
828 {
829 png_write_finish_row(png_ptr);
830 return;
831 }
832 break;
833
834 default: /* error: ignore it */
835 break;
836 }
837 }
838#endif
839
840 /* Set up row info for transformations */
841 row_info.color_type = png_ptr->color_type;
842 row_info.width = png_ptr->usr_width;
843 row_info.channels = png_ptr->usr_channels;
844 row_info.bit_depth = png_ptr->usr_bit_depth;
845 row_info.pixel_depth = (png_byte)(row_info.bit_depth * row_info.channels);
846 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
847
848 png_debug1(3, "row_info->color_type = %d", row_info.color_type);
849 png_debug1(3, "row_info->width = %u", row_info.width);
850 png_debug1(3, "row_info->channels = %d", row_info.channels);
851 png_debug1(3, "row_info->bit_depth = %d", row_info.bit_depth);
852 png_debug1(3, "row_info->pixel_depth = %d", row_info.pixel_depth);
853 png_debug1(3, "row_info->rowbytes = %lu", (unsigned long)row_info.rowbytes);
854
855 /* Copy user's row into buffer, leaving room for filter byte. */
856 memcpy(png_ptr->row_buf + 1, row, row_info.rowbytes);
857
858#ifdef PNG_WRITE_INTERLACING_SUPPORTED
859 /* Handle interlacing */
860 if (png_ptr->interlaced && png_ptr->pass < 6 &&
861 (png_ptr->transformations & PNG_INTERLACE) != 0)
862 {
863 png_do_write_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass);
864 /* This should always get caught above, but still ... */
865 if (row_info.width == 0)
866 {
867 png_write_finish_row(png_ptr);
868 return;
869 }
870 }
871#endif
872
873#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
874 /* Handle other transformations */
875 if (png_ptr->transformations != 0)
876 png_do_write_transformations(png_ptr, &row_info);
877#endif
878
879 /* At this point the row_info pixel depth must match the 'transformed' depth,
880 * which is also the output depth.
881 */
882 if (row_info.pixel_depth != png_ptr->pixel_depth ||
883 row_info.pixel_depth != png_ptr->transformed_pixel_depth)
884 png_error(png_ptr, "internal write transform logic error");
885
886#ifdef PNG_MNG_FEATURES_SUPPORTED
887 /* Write filter_method 64 (intrapixel differencing) only if
888 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
889 * 2. Libpng did not write a PNG signature (this filter_method is only
890 * used in PNG datastreams that are embedded in MNG datastreams) and
891 * 3. The application called png_permit_mng_features with a mask that
892 * included PNG_FLAG_MNG_FILTER_64 and
893 * 4. The filter_method is 64 and
894 * 5. The color_type is RGB or RGBA
895 */
896 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
897 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
898 {
899 /* Intrapixel differencing */
900 png_do_write_intrapixel(&row_info, png_ptr->row_buf + 1);
901 }
902#endif
903
904/* Added at libpng-1.5.10 */
905#ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
906 /* Check for out-of-range palette index */
907 if (row_info.color_type == PNG_COLOR_TYPE_PALETTE &&
908 png_ptr->num_palette_max >= 0)
909 png_do_check_palette_indexes(png_ptr, &row_info);
910#endif
911
912 /* Find a filter if necessary, filter the row and write it out. */
913 png_write_find_filter(png_ptr, &row_info);
914
915 if (png_ptr->write_row_fn != NULL)
916 (*(png_ptr->write_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
917}
918
919#ifdef PNG_WRITE_FLUSH_SUPPORTED
920/* Set the automatic flush interval or 0 to turn flushing off */
921void PNGAPI
922png_set_flush(png_structrp png_ptr, int nrows)
923{
924 png_debug(1, "in png_set_flush");
925
926 if (png_ptr == NULL)
927 return;
928
929 png_ptr->flush_dist = (nrows < 0 ? 0 : (png_uint_32)nrows);
930}
931
932/* Flush the current output buffers now */
933void PNGAPI
934png_write_flush(png_structrp png_ptr)
935{
936 png_debug(1, "in png_write_flush");
937
938 if (png_ptr == NULL)
939 return;
940
941 /* We have already written out all of the data */
942 if (png_ptr->row_number >= png_ptr->num_rows)
943 return;
944
945 png_compress_IDAT(png_ptr, NULL, 0, Z_SYNC_FLUSH);
946 png_ptr->flush_rows = 0;
947 png_flush(png_ptr);
948}
949#endif /* WRITE_FLUSH */
950
951/* Free any memory used in png_ptr struct without freeing the struct itself. */
952static void
953png_write_destroy(png_structrp png_ptr)
954{
955 png_debug(1, "in png_write_destroy");
956
957 /* Free any memory zlib uses */
958 if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
959 deflateEnd(&png_ptr->zstream);
960
961 /* Free our memory. png_free checks NULL for us. */
962 png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
963 png_free(png_ptr, png_ptr->row_buf);
964 png_ptr->row_buf = NULL;
965#ifdef PNG_WRITE_FILTER_SUPPORTED
966 png_free(png_ptr, png_ptr->prev_row);
967 png_free(png_ptr, png_ptr->try_row);
968 png_free(png_ptr, png_ptr->tst_row);
969 png_ptr->prev_row = NULL;
970 png_ptr->try_row = NULL;
971 png_ptr->tst_row = NULL;
972#endif
973
974#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
975 png_free(png_ptr, png_ptr->chunk_list);
976 png_ptr->chunk_list = NULL;
977#endif
978
979 /* The error handling and memory handling information is left intact at this
980 * point: the jmp_buf may still have to be freed. See png_destroy_png_struct
981 * for how this happens.
982 */
983}
984
985/* Free all memory used by the write.
986 * In libpng 1.6.0 this API changed quietly to no longer accept a NULL value for
987 * *png_ptr_ptr. Prior to 1.6.0 it would accept such a value and it would free
988 * the passed in info_structs but it would quietly fail to free any of the data
989 * inside them. In 1.6.0 it quietly does nothing (it has to be quiet because it
990 * has no png_ptr.)
991 */
992void PNGAPI
993png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
994{
995 png_debug(1, "in png_destroy_write_struct");
996
997 if (png_ptr_ptr != NULL)
998 {
999 png_structrp png_ptr = *png_ptr_ptr;
1000
1001 if (png_ptr != NULL) /* added in libpng 1.6.0 */
1002 {
1003 png_destroy_info_struct(png_ptr, info_ptr_ptr);
1004
1005 *png_ptr_ptr = NULL;
1006 png_write_destroy(png_ptr);
1007 png_destroy_png_struct(png_ptr);
1008 }
1009 }
1010}
1011
1012/* Allow the application to select one or more row filters to use. */
1013void PNGAPI
1014png_set_filter(png_structrp png_ptr, int method, int filters)
1015{
1016 png_debug(1, "in png_set_filter");
1017
1018 if (png_ptr == NULL)
1019 return;
1020
1021#ifdef PNG_MNG_FEATURES_SUPPORTED
1022 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
1023 (method == PNG_INTRAPIXEL_DIFFERENCING))
1024 method = PNG_FILTER_TYPE_BASE;
1025
1026#endif
1027 if (method == PNG_FILTER_TYPE_BASE)
1028 {
1029 switch (filters & (PNG_ALL_FILTERS | 0x07))
1030 {
1031#ifdef PNG_WRITE_FILTER_SUPPORTED
1032 case 5:
1033 case 6:
1034 case 7: png_app_error(png_ptr, "Unknown row filter for method 0");
1035#endif /* WRITE_FILTER */
1036 /* FALLTHROUGH */
1037 case PNG_FILTER_VALUE_NONE:
1038 png_ptr->do_filter = PNG_FILTER_NONE; break;
1039
1040#ifdef PNG_WRITE_FILTER_SUPPORTED
1041 case PNG_FILTER_VALUE_SUB:
1042 png_ptr->do_filter = PNG_FILTER_SUB; break;
1043
1044 case PNG_FILTER_VALUE_UP:
1045 png_ptr->do_filter = PNG_FILTER_UP; break;
1046
1047 case PNG_FILTER_VALUE_AVG:
1048 png_ptr->do_filter = PNG_FILTER_AVG; break;
1049
1050 case PNG_FILTER_VALUE_PAETH:
1051 png_ptr->do_filter = PNG_FILTER_PAETH; break;
1052
1053 default:
1054 png_ptr->do_filter = (png_byte)filters; break;
1055#else
1056 default:
1057 png_app_error(png_ptr, "Unknown row filter for method 0");
1058#endif /* WRITE_FILTER */
1059 }
1060
1061#ifdef PNG_WRITE_FILTER_SUPPORTED
1062 /* If we have allocated the row_buf, this means we have already started
1063 * with the image and we should have allocated all of the filter buffers
1064 * that have been selected. If prev_row isn't already allocated, then
1065 * it is too late to start using the filters that need it, since we
1066 * will be missing the data in the previous row. If an application
1067 * wants to start and stop using particular filters during compression,
1068 * it should start out with all of the filters, and then remove them
1069 * or add them back after the start of compression.
1070 *
1071 * NOTE: this is a nasty constraint on the code, because it means that the
1072 * prev_row buffer must be maintained even if there are currently no
1073 * 'prev_row' requiring filters active.
1074 */
1075 if (png_ptr->row_buf != NULL)
1076 {
1077 int num_filters;
1078 png_alloc_size_t buf_size;
1079
1080 /* Repeat the checks in png_write_start_row; 1 pixel high or wide
1081 * images cannot benefit from certain filters. If this isn't done here
1082 * the check below will fire on 1 pixel high images.
1083 */
1084 if (png_ptr->height == 1)
1085 filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1086
1087 if (png_ptr->width == 1)
1088 filters &= ~(PNG_FILTER_SUB|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1089
1090 if ((filters & (PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH)) != 0
1091 && png_ptr->prev_row == NULL)
1092 {
1093 /* This is the error case, however it is benign - the previous row
1094 * is not available so the filter can't be used. Just warn here.
1095 */
1096 png_app_warning(png_ptr,
1097 "png_set_filter: UP/AVG/PAETH cannot be added after start");
1098 filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1099 }
1100
1101 num_filters = 0;
1102
1103 if (filters & PNG_FILTER_SUB)
1104 num_filters++;
1105
1106 if (filters & PNG_FILTER_UP)
1107 num_filters++;
1108
1109 if (filters & PNG_FILTER_AVG)
1110 num_filters++;
1111
1112 if (filters & PNG_FILTER_PAETH)
1113 num_filters++;
1114
1115 /* Allocate needed row buffers if they have not already been
1116 * allocated.
1117 */
1118 buf_size = PNG_ROWBYTES(png_ptr->usr_channels * png_ptr->usr_bit_depth,
1119 png_ptr->width) + 1;
1120
1121 if (png_ptr->try_row == NULL)
1122 png_ptr->try_row = png_voidcast(png_bytep,
1123 png_malloc(png_ptr, buf_size));
1124
1125 if (num_filters > 1)
1126 {
1127 if (png_ptr->tst_row == NULL)
1128 png_ptr->tst_row = png_voidcast(png_bytep,
1129 png_malloc(png_ptr, buf_size));
1130 }
1131 }
1132 png_ptr->do_filter = (png_byte)filters;
1133#endif
1134 }
1135 else
1136 png_error(png_ptr, "Unknown custom filter method");
1137}
1138
1139#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* DEPRECATED */
1140/* Provide floating and fixed point APIs */
1141#ifdef PNG_FLOATING_POINT_SUPPORTED
1142void PNGAPI
1143png_set_filter_heuristics(png_structrp png_ptr, int heuristic_method,
1144 int num_weights, png_const_doublep filter_weights,
1145 png_const_doublep filter_costs)
1146{
1147 PNG_UNUSED(png_ptr)
1148 PNG_UNUSED(heuristic_method)
1149 PNG_UNUSED(num_weights)
1150 PNG_UNUSED(filter_weights)
1151 PNG_UNUSED(filter_costs)
1152}
1153#endif /* FLOATING_POINT */
1154
1155#ifdef PNG_FIXED_POINT_SUPPORTED
1156void PNGAPI
1157png_set_filter_heuristics_fixed(png_structrp png_ptr, int heuristic_method,
1158 int num_weights, png_const_fixed_point_p filter_weights,
1159 png_const_fixed_point_p filter_costs)
1160{
1161 PNG_UNUSED(png_ptr)
1162 PNG_UNUSED(heuristic_method)
1163 PNG_UNUSED(num_weights)
1164 PNG_UNUSED(filter_weights)
1165 PNG_UNUSED(filter_costs)
1166}
1167#endif /* FIXED_POINT */
1168#endif /* WRITE_WEIGHTED_FILTER */
1169
1170#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
1171void PNGAPI
1172png_set_compression_level(png_structrp png_ptr, int level)
1173{
1174 png_debug(1, "in png_set_compression_level");
1175
1176 if (png_ptr == NULL)
1177 return;
1178
1179 png_ptr->zlib_level = level;
1180}
1181
1182void PNGAPI
1183png_set_compression_mem_level(png_structrp png_ptr, int mem_level)
1184{
1185 png_debug(1, "in png_set_compression_mem_level");
1186
1187 if (png_ptr == NULL)
1188 return;
1189
1190 png_ptr->zlib_mem_level = mem_level;
1191}
1192
1193void PNGAPI
1194png_set_compression_strategy(png_structrp png_ptr, int strategy)
1195{
1196 png_debug(1, "in png_set_compression_strategy");
1197
1198 if (png_ptr == NULL)
1199 return;
1200
1201 /* The flag setting here prevents the libpng dynamic selection of strategy.
1202 */
1203 png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
1204 png_ptr->zlib_strategy = strategy;
1205}
1206
1207/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1208 * smaller value of window_bits if it can do so safely.
1209 */
1210void PNGAPI
1211png_set_compression_window_bits(png_structrp png_ptr, int window_bits)
1212{
1213 if (png_ptr == NULL)
1214 return;
1215
1216 /* Prior to 1.6.0 this would warn but then set the window_bits value. This
1217 * meant that negative window bits values could be selected that would cause
1218 * libpng to write a non-standard PNG file with raw deflate or gzip
1219 * compressed IDAT or ancillary chunks. Such files can be read and there is
1220 * no warning on read, so this seems like a very bad idea.
1221 */
1222 if (window_bits > 15)
1223 {
1224 png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
1225 window_bits = 15;
1226 }
1227
1228 else if (window_bits < 8)
1229 {
1230 png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
1231 window_bits = 8;
1232 }
1233
1234 png_ptr->zlib_window_bits = window_bits;
1235}
1236
1237void PNGAPI
1238png_set_compression_method(png_structrp png_ptr, int method)
1239{
1240 png_debug(1, "in png_set_compression_method");
1241
1242 if (png_ptr == NULL)
1243 return;
1244
1245 /* This would produce an invalid PNG file if it worked, but it doesn't and
1246 * deflate will fault it, so it is harmless to just warn here.
1247 */
1248 if (method != 8)
1249 png_warning(png_ptr, "Only compression method 8 is supported by PNG");
1250
1251 png_ptr->zlib_method = method;
1252}
1253#endif /* WRITE_CUSTOMIZE_COMPRESSION */
1254
1255/* The following were added to libpng-1.5.4 */
1256#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
1257void PNGAPI
1258png_set_text_compression_level(png_structrp png_ptr, int level)
1259{
1260 png_debug(1, "in png_set_text_compression_level");
1261
1262 if (png_ptr == NULL)
1263 return;
1264
1265 png_ptr->zlib_text_level = level;
1266}
1267
1268void PNGAPI
1269png_set_text_compression_mem_level(png_structrp png_ptr, int mem_level)
1270{
1271 png_debug(1, "in png_set_text_compression_mem_level");
1272
1273 if (png_ptr == NULL)
1274 return;
1275
1276 png_ptr->zlib_text_mem_level = mem_level;
1277}
1278
1279void PNGAPI
1280png_set_text_compression_strategy(png_structrp png_ptr, int strategy)
1281{
1282 png_debug(1, "in png_set_text_compression_strategy");
1283
1284 if (png_ptr == NULL)
1285 return;
1286
1287 png_ptr->zlib_text_strategy = strategy;
1288}
1289
1290/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1291 * smaller value of window_bits if it can do so safely.
1292 */
1293void PNGAPI
1294png_set_text_compression_window_bits(png_structrp png_ptr, int window_bits)
1295{
1296 if (png_ptr == NULL)
1297 return;
1298
1299 if (window_bits > 15)
1300 {
1301 png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
1302 window_bits = 15;
1303 }
1304
1305 else if (window_bits < 8)
1306 {
1307 png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
1308 window_bits = 8;
1309 }
1310
1311 png_ptr->zlib_text_window_bits = window_bits;
1312}
1313
1314void PNGAPI
1315png_set_text_compression_method(png_structrp png_ptr, int method)
1316{
1317 png_debug(1, "in png_set_text_compression_method");
1318
1319 if (png_ptr == NULL)
1320 return;
1321
1322 if (method != 8)
1323 png_warning(png_ptr, "Only compression method 8 is supported by PNG");
1324
1325 png_ptr->zlib_text_method = method;
1326}
1327#endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
1328/* end of API added to libpng-1.5.4 */
1329
1330void PNGAPI
1331png_set_write_status_fn(png_structrp png_ptr, png_write_status_ptr write_row_fn)
1332{
1333 if (png_ptr == NULL)
1334 return;
1335
1336 png_ptr->write_row_fn = write_row_fn;
1337}
1338
1339#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
1340void PNGAPI
1341png_set_write_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1342 write_user_transform_fn)
1343{
1344 png_debug(1, "in png_set_write_user_transform_fn");
1345
1346 if (png_ptr == NULL)
1347 return;
1348
1349 png_ptr->transformations |= PNG_USER_TRANSFORM;
1350 png_ptr->write_user_transform_fn = write_user_transform_fn;
1351}
1352#endif
1353
1354
1355#ifdef PNG_INFO_IMAGE_SUPPORTED
1356void PNGAPI
1357png_write_png(png_structrp png_ptr, png_inforp info_ptr,
1358 int transforms, voidp params)
1359{
1360 if (png_ptr == NULL || info_ptr == NULL)
1361 return;
1362
1363 if ((info_ptr->valid & PNG_INFO_IDAT) == 0)
1364 {
1365 png_app_error(png_ptr, "no rows for png_write_image to write");
1366 return;
1367 }
1368
1369 /* Write the file header information. */
1370 png_write_info(png_ptr, info_ptr);
1371
1372 /* ------ these transformations don't touch the info structure ------- */
1373
1374 /* Invert monochrome pixels */
1375 if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
1376#ifdef PNG_WRITE_INVERT_SUPPORTED
1377 png_set_invert_mono(png_ptr);
1378#else
1379 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1380#endif
1381
1382 /* Shift the pixels up to a legal bit depth and fill in
1383 * as appropriate to correctly scale the image.
1384 */
1385 if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
1386#ifdef PNG_WRITE_SHIFT_SUPPORTED
1387 if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
1388 png_set_shift(png_ptr, &info_ptr->sig_bit);
1389#else
1390 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1391#endif
1392
1393 /* Pack pixels into bytes */
1394 if ((transforms & PNG_TRANSFORM_PACKING) != 0)
1395#ifdef PNG_WRITE_PACK_SUPPORTED
1396 png_set_packing(png_ptr);
1397#else
1398 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1399#endif
1400
1401 /* Swap location of alpha bytes from ARGB to RGBA */
1402 if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
1403#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
1404 png_set_swap_alpha(png_ptr);
1405#else
1406 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1407#endif
1408
1409 /* Remove a filler (X) from XRGB/RGBX/AG/GA into to convert it into
1410 * RGB, note that the code expects the input color type to be G or RGB; no
1411 * alpha channel.
1412 */
1413 if ((transforms & (PNG_TRANSFORM_STRIP_FILLER_AFTER|
1414 PNG_TRANSFORM_STRIP_FILLER_BEFORE)) != 0)
1415 {
1416#ifdef PNG_WRITE_FILLER_SUPPORTED
1417 if ((transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER) != 0)
1418 {
1419 if ((transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE) != 0)
1420 png_app_error(png_ptr,
1421 "PNG_TRANSFORM_STRIP_FILLER: BEFORE+AFTER not supported");
1422
1423 /* Continue if ignored - this is the pre-1.6.10 behavior */
1424 png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
1425 }
1426
1427 else if ((transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE) != 0)
1428 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
1429#else
1430 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_FILLER not supported");
1431#endif
1432 }
1433
1434 /* Flip BGR pixels to RGB */
1435 if ((transforms & PNG_TRANSFORM_BGR) != 0)
1436#ifdef PNG_WRITE_BGR_SUPPORTED
1437 png_set_bgr(png_ptr);
1438#else
1439 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1440#endif
1441
1442 /* Swap bytes of 16-bit files to most significant byte first */
1443 if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
1444#ifdef PNG_WRITE_SWAP_SUPPORTED
1445 png_set_swap(png_ptr);
1446#else
1447 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1448#endif
1449
1450 /* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats */
1451 if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
1452#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
1453 png_set_packswap(png_ptr);
1454#else
1455 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1456#endif
1457
1458 /* Invert the alpha channel from opacity to transparency */
1459 if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
1460#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
1461 png_set_invert_alpha(png_ptr);
1462#else
1463 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1464#endif
1465
1466 /* ----------------------- end of transformations ------------------- */
1467
1468 /* Write the bits */
1469 png_write_image(png_ptr, info_ptr->row_pointers);
1470
1471 /* It is REQUIRED to call this to finish writing the rest of the file */
1472 png_write_end(png_ptr, info_ptr);
1473
1474 PNG_UNUSED(params)
1475}
1476#endif
1477
1478
1479#ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
1480/* Initialize the write structure - general purpose utility. */
1481static int
1482png_image_write_init(png_imagep image)
1483{
1484 png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, image,
1485 png_safe_error, png_safe_warning);
1486
1487 if (png_ptr != NULL)
1488 {
1489 png_infop info_ptr = png_create_info_struct(png_ptr);
1490
1491 if (info_ptr != NULL)
1492 {
1493 png_controlp control = png_voidcast(png_controlp,
1494 png_malloc_warn(png_ptr, (sizeof *control)));
1495
1496 if (control != NULL)
1497 {
1498 memset(control, 0, (sizeof *control));
1499
1500 control->png_ptr = png_ptr;
1501 control->info_ptr = info_ptr;
1502 control->for_write = 1;
1503
1504 image->opaque = control;
1505 return 1;
1506 }
1507
1508 /* Error clean up */
1509 png_destroy_info_struct(png_ptr, &info_ptr);
1510 }
1511
1512 png_destroy_write_struct(&png_ptr, NULL);
1513 }
1514
1515 return png_image_error(image, "png_image_write_: out of memory");
1516}
1517
1518/* Arguments to png_image_write_main: */
1519typedef struct
1520{
1521 /* Arguments: */
1522 png_imagep image;
1523 png_const_voidp buffer;
1524 png_int_32 row_stride;
1525 png_const_voidp colormap;
1526 int convert_to_8bit;
1527 /* Local variables: */
1528 png_const_voidp first_row;
1529 ptrdiff_t row_bytes;
1530 png_voidp local_row;
1531 /* Byte count for memory writing */
1532 png_bytep memory;
1533 png_alloc_size_t memory_bytes; /* not used for STDIO */
1534 png_alloc_size_t output_bytes; /* running total */
1535} png_image_write_control;
1536
1537/* Write png_uint_16 input to a 16-bit PNG; the png_ptr has already been set to
1538 * do any necessary byte swapping. The component order is defined by the
1539 * png_image format value.
1540 */
1541static int
1542png_write_image_16bit(png_voidp argument)
1543{
1544 png_image_write_control *display = png_voidcast(png_image_write_control*,
1545 argument);
1546 png_imagep image = display->image;
1547 png_structrp png_ptr = image->opaque->png_ptr;
1548
1549 png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
1550 display->first_row);
1551 png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
1552 png_uint_16p row_end;
1553 unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
1554 3 : 1;
1555 int aindex = 0;
1556 png_uint_32 y = image->height;
1557
1558 if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
1559 {
1560# ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
1561 if ((image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
1562 {
1563 aindex = -1;
1564 ++input_row; /* To point to the first component */
1565 ++output_row;
1566 }
1567 else
1568 aindex = (int)channels;
1569# else
1570 aindex = (int)channels;
1571# endif
1572 }
1573
1574 else
1575 png_error(png_ptr, "png_write_image: internal call error");
1576
1577 /* Work out the output row end and count over this, note that the increment
1578 * above to 'row' means that row_end can actually be beyond the end of the
1579 * row; this is correct.
1580 */
1581 row_end = output_row + image->width * (channels+1);
1582
1583 for (; y > 0; --y)
1584 {
1585 png_const_uint_16p in_ptr = input_row;
1586 png_uint_16p out_ptr = output_row;
1587
1588 while (out_ptr < row_end)
1589 {
1590 png_uint_16 alpha = in_ptr[aindex];
1591 png_uint_32 reciprocal = 0;
1592 int c;
1593
1594 out_ptr[aindex] = alpha;
1595
1596 /* Calculate a reciprocal. The correct calculation is simply
1597 * component/alpha*65535 << 15. (I.e. 15 bits of precision); this
1598 * allows correct rounding by adding .5 before the shift. 'reciprocal'
1599 * is only initialized when required.
1600 */
1601 if (alpha > 0 && alpha < 65535)
1602 reciprocal = ((0xffff<<15)+(alpha>>1))/alpha;
1603
1604 c = (int)channels;
1605 do /* always at least one channel */
1606 {
1607 png_uint_16 component = *in_ptr++;
1608
1609 /* The following gives 65535 for an alpha of 0, which is fine,
1610 * otherwise if 0/0 is represented as some other value there is more
1611 * likely to be a discontinuity which will probably damage
1612 * compression when moving from a fully transparent area to a
1613 * nearly transparent one. (The assumption here is that opaque
1614 * areas tend not to be 0 intensity.)
1615 */
1616 if (component >= alpha)
1617 component = 65535;
1618
1619 /* component<alpha, so component/alpha is less than one and
1620 * component*reciprocal is less than 2^31.
1621 */
1622 else if (component > 0 && alpha < 65535)
1623 {
1624 png_uint_32 calc = component * reciprocal;
1625 calc += 16384; /* round to nearest */
1626 component = (png_uint_16)(calc >> 15);
1627 }
1628
1629 *out_ptr++ = component;
1630 }
1631 while (--c > 0);
1632
1633 /* Skip to next component (skip the intervening alpha channel) */
1634 ++in_ptr;
1635 ++out_ptr;
1636 }
1637
1638 png_write_row(png_ptr, png_voidcast(png_const_bytep, display->local_row));
1639 input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
1640 }
1641
1642 return 1;
1643}
1644
1645/* Given 16-bit input (1 to 4 channels) write 8-bit output. If an alpha channel
1646 * is present it must be removed from the components, the components are then
1647 * written in sRGB encoding. No components are added or removed.
1648 *
1649 * Calculate an alpha reciprocal to reverse pre-multiplication. As above the
1650 * calculation can be done to 15 bits of accuracy; however, the output needs to
1651 * be scaled in the range 0..255*65535, so include that scaling here.
1652 */
1653# define UNP_RECIPROCAL(alpha) ((((0xffff*0xff)<<7)+((alpha)>>1))/(alpha))
1654
1655static png_byte
1656png_unpremultiply(png_uint_32 component, png_uint_32 alpha,
1657 png_uint_32 reciprocal/*from the above macro*/)
1658{
1659 /* The following gives 1.0 for an alpha of 0, which is fine, otherwise if 0/0
1660 * is represented as some other value there is more likely to be a
1661 * discontinuity which will probably damage compression when moving from a
1662 * fully transparent area to a nearly transparent one. (The assumption here
1663 * is that opaque areas tend not to be 0 intensity.)
1664 *
1665 * There is a rounding problem here; if alpha is less than 128 it will end up
1666 * as 0 when scaled to 8 bits. To avoid introducing spurious colors into the
1667 * output change for this too.
1668 */
1669 if (component >= alpha || alpha < 128)
1670 return 255;
1671
1672 /* component<alpha, so component/alpha is less than one and
1673 * component*reciprocal is less than 2^31.
1674 */
1675 else if (component > 0)
1676 {
1677 /* The test is that alpha/257 (rounded) is less than 255, the first value
1678 * that becomes 255 is 65407.
1679 * NOTE: this must agree with the PNG_DIV257 macro (which must, therefore,
1680 * be exact!) [Could also test reciprocal != 0]
1681 */
1682 if (alpha < 65407)
1683 {
1684 component *= reciprocal;
1685 component += 64; /* round to nearest */
1686 component >>= 7;
1687 }
1688
1689 else
1690 component *= 255;
1691
1692 /* Convert the component to sRGB. */
1693 return (png_byte)PNG_sRGB_FROM_LINEAR(component);
1694 }
1695
1696 else
1697 return 0;
1698}
1699
1700static int
1701png_write_image_8bit(png_voidp argument)
1702{
1703 png_image_write_control *display = png_voidcast(png_image_write_control*,
1704 argument);
1705 png_imagep image = display->image;
1706 png_structrp png_ptr = image->opaque->png_ptr;
1707
1708 png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
1709 display->first_row);
1710 png_bytep output_row = png_voidcast(png_bytep, display->local_row);
1711 png_uint_32 y = image->height;
1712 unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
1713 3 : 1;
1714
1715 if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
1716 {
1717 png_bytep row_end;
1718 int aindex;
1719
1720# ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
1721 if ((image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
1722 {
1723 aindex = -1;
1724 ++input_row; /* To point to the first component */
1725 ++output_row;
1726 }
1727
1728 else
1729# endif
1730 aindex = (int)channels;
1731
1732 /* Use row_end in place of a loop counter: */
1733 row_end = output_row + image->width * (channels+1);
1734
1735 for (; y > 0; --y)
1736 {
1737 png_const_uint_16p in_ptr = input_row;
1738 png_bytep out_ptr = output_row;
1739
1740 while (out_ptr < row_end)
1741 {
1742 png_uint_16 alpha = in_ptr[aindex];
1743 png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
1744 png_uint_32 reciprocal = 0;
1745 int c;
1746
1747 /* Scale and write the alpha channel. */
1748 out_ptr[aindex] = alphabyte;
1749
1750 if (alphabyte > 0 && alphabyte < 255)
1751 reciprocal = UNP_RECIPROCAL(alpha);
1752
1753 c = (int)channels;
1754 do /* always at least one channel */
1755 *out_ptr++ = png_unpremultiply(*in_ptr++, alpha, reciprocal);
1756 while (--c > 0);
1757
1758 /* Skip to next component (skip the intervening alpha channel) */
1759 ++in_ptr;
1760 ++out_ptr;
1761 } /* while out_ptr < row_end */
1762
1763 png_write_row(png_ptr, png_voidcast(png_const_bytep,
1764 display->local_row));
1765 input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
1766 } /* while y */
1767 }
1768
1769 else
1770 {
1771 /* No alpha channel, so the row_end really is the end of the row and it
1772 * is sufficient to loop over the components one by one.
1773 */
1774 png_bytep row_end = output_row + image->width * channels;
1775
1776 for (; y > 0; --y)
1777 {
1778 png_const_uint_16p in_ptr = input_row;
1779 png_bytep out_ptr = output_row;
1780
1781 while (out_ptr < row_end)
1782 {
1783 png_uint_32 component = *in_ptr++;
1784
1785 component *= 255;
1786 *out_ptr++ = (png_byte)PNG_sRGB_FROM_LINEAR(component);
1787 }
1788
1789 png_write_row(png_ptr, output_row);
1790 input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
1791 }
1792 }
1793
1794 return 1;
1795}
1796
1797static void
1798png_image_set_PLTE(png_image_write_control *display)
1799{
1800 png_imagep image = display->image;
1801 const void *cmap = display->colormap;
1802 int entries = image->colormap_entries > 256 ? 256 :
1803 (int)image->colormap_entries;
1804
1805 /* NOTE: the caller must check for cmap != NULL and entries != 0 */
1806 png_uint_32 format = image->format;
1807 unsigned int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
1808
1809# if defined(PNG_FORMAT_BGR_SUPPORTED) &&\
1810 defined(PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED)
1811 int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1812 (format & PNG_FORMAT_FLAG_ALPHA) != 0;
1813# else
1814# define afirst 0
1815# endif
1816
1817# ifdef PNG_FORMAT_BGR_SUPPORTED
1818 int bgr = (format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
1819# else
1820# define bgr 0
1821# endif
1822
1823 int i, num_trans;
1824 png_color palette[256];
1825 png_byte tRNS[256];
1826
1827 memset(tRNS, 255, (sizeof tRNS));
1828 memset(palette, 0, (sizeof palette));
1829
1830 for (i=num_trans=0; i<entries; ++i)
1831 {
1832 /* This gets automatically converted to sRGB with reversal of the
1833 * pre-multiplication if the color-map has an alpha channel.
1834 */
1835 if ((format & PNG_FORMAT_FLAG_LINEAR) != 0)
1836 {
1837 png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);
1838
1839 entry += (unsigned int)i * channels;
1840
1841 if ((channels & 1) != 0) /* no alpha */
1842 {
1843 if (channels >= 3) /* RGB */
1844 {
1845 palette[i].blue = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
1846 entry[(2 ^ bgr)]);
1847 palette[i].green = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
1848 entry[1]);
1849 palette[i].red = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
1850 entry[bgr]);
1851 }
1852
1853 else /* Gray */
1854 palette[i].blue = palette[i].red = palette[i].green =
1855 (png_byte)PNG_sRGB_FROM_LINEAR(255 * *entry);
1856 }
1857
1858 else /* alpha */
1859 {
1860 png_uint_16 alpha = entry[afirst ? 0 : channels-1];
1861 png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
1862 png_uint_32 reciprocal = 0;
1863
1864 /* Calculate a reciprocal, as in the png_write_image_8bit code above
1865 * this is designed to produce a value scaled to 255*65535 when
1866 * divided by 128 (i.e. asr 7).
1867 */
1868 if (alphabyte > 0 && alphabyte < 255)
1869 reciprocal = (((0xffff*0xff)<<7)+(alpha>>1))/alpha;
1870
1871 tRNS[i] = alphabyte;
1872 if (alphabyte < 255)
1873 num_trans = i+1;
1874
1875 if (channels >= 3) /* RGB */
1876 {
1877 palette[i].blue = png_unpremultiply(entry[afirst + (2 ^ bgr)],
1878 alpha, reciprocal);
1879 palette[i].green = png_unpremultiply(entry[afirst + 1], alpha,
1880 reciprocal);
1881 palette[i].red = png_unpremultiply(entry[afirst + bgr], alpha,
1882 reciprocal);
1883 }
1884
1885 else /* gray */
1886 palette[i].blue = palette[i].red = palette[i].green =
1887 png_unpremultiply(entry[afirst], alpha, reciprocal);
1888 }
1889 }
1890
1891 else /* Color-map has sRGB values */
1892 {
1893 png_const_bytep entry = png_voidcast(png_const_bytep, cmap);
1894
1895 entry += (unsigned int)i * channels;
1896
1897 switch (channels)
1898 {
1899 case 4:
1900 tRNS[i] = entry[afirst ? 0 : 3];
1901 if (tRNS[i] < 255)
1902 num_trans = i+1;
1903 /* FALLTHROUGH */
1904 case 3:
1905 palette[i].blue = entry[afirst + (2 ^ bgr)];
1906 palette[i].green = entry[afirst + 1];
1907 palette[i].red = entry[afirst + bgr];
1908 break;
1909
1910 case 2:
1911 tRNS[i] = entry[1 ^ afirst];
1912 if (tRNS[i] < 255)
1913 num_trans = i+1;
1914 /* FALLTHROUGH */
1915 case 1:
1916 palette[i].blue = palette[i].red = palette[i].green =
1917 entry[afirst];
1918 break;
1919
1920 default:
1921 break;
1922 }
1923 }
1924 }
1925
1926# ifdef afirst
1927# undef afirst
1928# endif
1929# ifdef bgr
1930# undef bgr
1931# endif
1932
1933 png_set_PLTE(image->opaque->png_ptr, image->opaque->info_ptr, palette,
1934 entries);
1935
1936 if (num_trans > 0)
1937 png_set_tRNS(image->opaque->png_ptr, image->opaque->info_ptr, tRNS,
1938 num_trans, NULL);
1939
1940 image->colormap_entries = (png_uint_32)entries;
1941}
1942
1943static int
1944png_image_write_main(png_voidp argument)
1945{
1946 png_image_write_control *display = png_voidcast(png_image_write_control*,
1947 argument);
1948 png_imagep image = display->image;
1949 png_structrp png_ptr = image->opaque->png_ptr;
1950 png_inforp info_ptr = image->opaque->info_ptr;
1951 png_uint_32 format = image->format;
1952
1953 /* The following four ints are actually booleans */
1954 int colormap = (format & PNG_FORMAT_FLAG_COLORMAP);
1955 int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR); /* input */
1956 int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA);
1957 int write_16bit = linear && (display->convert_to_8bit == 0);
1958
1959# ifdef PNG_BENIGN_ERRORS_SUPPORTED
1960 /* Make sure we error out on any bad situation */
1961 png_set_benign_errors(png_ptr, 0/*error*/);
1962# endif
1963
1964 /* Default the 'row_stride' parameter if required, also check the row stride
1965 * and total image size to ensure that they are within the system limits.
1966 */
1967 {
1968 unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
1969
1970 if (image->width <= 0x7fffffffU/channels) /* no overflow */
1971 {
1972 png_uint_32 check;
1973 png_uint_32 png_row_stride = image->width * channels;
1974
1975 if (display->row_stride == 0)
1976 display->row_stride = (png_int_32)/*SAFE*/png_row_stride;
1977
1978 if (display->row_stride < 0)
1979 check = (png_uint_32)(-display->row_stride);
1980
1981 else
1982 check = (png_uint_32)display->row_stride;
1983
1984 if (check >= png_row_stride)
1985 {
1986 /* Now check for overflow of the image buffer calculation; this
1987 * limits the whole image size to 32 bits for API compatibility with
1988 * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
1989 */
1990 if (image->height > 0xffffffffU/png_row_stride)
1991 png_error(image->opaque->png_ptr, "memory image too large");
1992 }
1993
1994 else
1995 png_error(image->opaque->png_ptr, "supplied row stride too small");
1996 }
1997
1998 else
1999 png_error(image->opaque->png_ptr, "image row stride too large");
2000 }
2001
2002 /* Set the required transforms then write the rows in the correct order. */
2003 if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0)
2004 {
2005 if (display->colormap != NULL && image->colormap_entries > 0)
2006 {
2007 png_uint_32 entries = image->colormap_entries;
2008
2009 png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
2010 entries > 16 ? 8 : (entries > 4 ? 4 : (entries > 2 ? 2 : 1)),
2011 PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
2012 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
2013
2014 png_image_set_PLTE(display);
2015 }
2016
2017 else
2018 png_error(image->opaque->png_ptr,
2019 "no color-map for color-mapped image");
2020 }
2021
2022 else
2023 png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
2024 write_16bit ? 16 : 8,
2025 ((format & PNG_FORMAT_FLAG_COLOR) ? PNG_COLOR_MASK_COLOR : 0) +
2026 ((format & PNG_FORMAT_FLAG_ALPHA) ? PNG_COLOR_MASK_ALPHA : 0),
2027 PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
2028
2029 /* Counter-intuitively the data transformations must be called *after*
2030 * png_write_info, not before as in the read code, but the 'set' functions
2031 * must still be called before. Just set the color space information, never
2032 * write an interlaced image.
2033 */
2034
2035 if (write_16bit != 0)
2036 {
2037 /* The gamma here is 1.0 (linear) and the cHRM chunk matches sRGB. */
2038 png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_LINEAR);
2039
2040 if ((image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB) == 0)
2041 png_set_cHRM_fixed(png_ptr, info_ptr,
2042 /* color x y */
2043 /* white */ 31270, 32900,
2044 /* red */ 64000, 33000,
2045 /* green */ 30000, 60000,
2046 /* blue */ 15000, 6000
2047 );
2048 }
2049
2050 else if ((image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB) == 0)
2051 png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_PERCEPTUAL);
2052
2053 /* Else writing an 8-bit file and the *colors* aren't sRGB, but the 8-bit
2054 * space must still be gamma encoded.
2055 */
2056 else
2057 png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_sRGB_INVERSE);
2058
2059 /* Write the file header. */
2060 png_write_info(png_ptr, info_ptr);
2061
2062 /* Now set up the data transformations (*after* the header is written),
2063 * remove the handled transformations from the 'format' flags for checking.
2064 *
2065 * First check for a little endian system if writing 16-bit files.
2066 */
2067 if (write_16bit != 0)
2068 {
2069 png_uint_16 le = 0x0001;
2070
2071 if ((*(png_const_bytep) & le) != 0)
2072 png_set_swap(png_ptr);
2073 }
2074
2075# ifdef PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
2076 if ((format & PNG_FORMAT_FLAG_BGR) != 0)
2077 {
2078 if (colormap == 0 && (format & PNG_FORMAT_FLAG_COLOR) != 0)
2079 png_set_bgr(png_ptr);
2080 format &= ~PNG_FORMAT_FLAG_BGR;
2081 }
2082# endif
2083
2084# ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
2085 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
2086 {
2087 if (colormap == 0 && (format & PNG_FORMAT_FLAG_ALPHA) != 0)
2088 png_set_swap_alpha(png_ptr);
2089 format &= ~PNG_FORMAT_FLAG_AFIRST;
2090 }
2091# endif
2092
2093 /* If there are 16 or fewer color-map entries we wrote a lower bit depth
2094 * above, but the application data is still byte packed.
2095 */
2096 if (colormap != 0 && image->colormap_entries <= 16)
2097 png_set_packing(png_ptr);
2098
2099 /* That should have handled all (both) the transforms. */
2100 if ((format & ~(png_uint_32)(PNG_FORMAT_FLAG_COLOR | PNG_FORMAT_FLAG_LINEAR |
2101 PNG_FORMAT_FLAG_ALPHA | PNG_FORMAT_FLAG_COLORMAP)) != 0)
2102 png_error(png_ptr, "png_write_image: unsupported transformation");
2103
2104 {
2105 png_const_bytep row = png_voidcast(png_const_bytep, display->buffer);
2106 ptrdiff_t row_bytes = display->row_stride;
2107
2108 if (linear != 0)
2109 row_bytes *= (sizeof (png_uint_16));
2110
2111 if (row_bytes < 0)
2112 row += (image->height-1) * (-row_bytes);
2113
2114 display->first_row = row;
2115 display->row_bytes = row_bytes;
2116 }
2117
2118 /* Apply 'fast' options if the flag is set. */
2119 if ((image->flags & PNG_IMAGE_FLAG_FAST) != 0)
2120 {
2121 png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_NO_FILTERS);
2122 /* NOTE: determined by experiment using pngstest, this reflects some
2123 * balance between the time to write the image once and the time to read
2124 * it about 50 times. The speed-up in pngstest was about 10-20% of the
2125 * total (user) time on a heavily loaded system.
2126 */
2127# ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
2128 png_set_compression_level(png_ptr, 3);
2129# endif
2130 }
2131
2132 /* Check for the cases that currently require a pre-transform on the row
2133 * before it is written. This only applies when the input is 16-bit and
2134 * either there is an alpha channel or it is converted to 8-bit.
2135 */
2136 if ((linear != 0 && alpha != 0 ) ||
2137 (colormap == 0 && display->convert_to_8bit != 0))
2138 {
2139 png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr,
2140 png_get_rowbytes(png_ptr, info_ptr)));
2141 int result;
2142
2143 display->local_row = row;
2144 if (write_16bit != 0)
2145 result = png_safe_execute(image, png_write_image_16bit, display);
2146 else
2147 result = png_safe_execute(image, png_write_image_8bit, display);
2148 display->local_row = NULL;
2149
2150 png_free(png_ptr, row);
2151
2152 /* Skip the 'write_end' on error: */
2153 if (result == 0)
2154 return 0;
2155 }
2156
2157 /* Otherwise this is the case where the input is in a format currently
2158 * supported by the rest of the libpng write code; call it directly.
2159 */
2160 else
2161 {
2162 png_const_bytep row = png_voidcast(png_const_bytep, display->first_row);
2163 ptrdiff_t row_bytes = display->row_bytes;
2164 png_uint_32 y = image->height;
2165
2166 for (; y > 0; --y)
2167 {
2168 png_write_row(png_ptr, row);
2169 row += row_bytes;
2170 }
2171 }
2172
2173 png_write_end(png_ptr, info_ptr);
2174 return 1;
2175}
2176
2177
2178static void (PNGCBAPI
2179image_memory_write)(png_structp png_ptr, png_bytep/*const*/ data, size_t size)
2180{
2181 png_image_write_control *display = png_voidcast(png_image_write_control*,
2182 png_ptr->io_ptr/*backdoor: png_get_io_ptr(png_ptr)*/);
2183 png_alloc_size_t ob = display->output_bytes;
2184
2185 /* Check for overflow; this should never happen: */
2186 if (size <= ((png_alloc_size_t)-1) - ob)
2187 {
2188 /* I don't think libpng ever does this, but just in case: */
2189 if (size > 0)
2190 {
2191 if (display->memory_bytes >= ob+size) /* writing */
2192 memcpy(display->memory+ob, data, size);
2193
2194 /* Always update the size: */
2195 display->output_bytes = ob+size;
2196 }
2197 }
2198
2199 else
2200 png_error(png_ptr, "png_image_write_to_memory: PNG too big");
2201}
2202
2203static void (PNGCBAPI
2204image_memory_flush)(png_structp png_ptr)
2205{
2206 PNG_UNUSED(png_ptr)
2207}
2208
2209static int
2210png_image_write_memory(png_voidp argument)
2211{
2212 png_image_write_control *display = png_voidcast(png_image_write_control*,
2213 argument);
2214
2215 /* The rest of the memory-specific init and write_main in an error protected
2216 * environment. This case needs to use callbacks for the write operations
2217 * since libpng has no built in support for writing to memory.
2218 */
2219 png_set_write_fn(display->image->opaque->png_ptr, display/*io_ptr*/,
2220 image_memory_write, image_memory_flush);
2221
2222 return png_image_write_main(display);
2223}
2224
2225int PNGAPI
2226png_image_write_to_memory(png_imagep image, void *memory,
2227 png_alloc_size_t * PNG_RESTRICT memory_bytes, int convert_to_8bit,
2228 const void *buffer, png_int_32 row_stride, const void *colormap)
2229{
2230 /* Write the image to the given buffer, or count the bytes if it is NULL */
2231 if (image != NULL && image->version == PNG_IMAGE_VERSION)
2232 {
2233 if (memory_bytes != NULL && buffer != NULL)
2234 {
2235 /* This is to give the caller an easier error detection in the NULL
2236 * case and guard against uninitialized variable problems:
2237 */
2238 if (memory == NULL)
2239 *memory_bytes = 0;
2240
2241 if (png_image_write_init(image) != 0)
2242 {
2243 png_image_write_control display;
2244 int result;
2245
2246 memset(&display, 0, (sizeof display));
2247 display.image = image;
2248 display.buffer = buffer;
2249 display.row_stride = row_stride;
2250 display.colormap = colormap;
2251 display.convert_to_8bit = convert_to_8bit;
2252 display.memory = png_voidcast(png_bytep, memory);
2253 display.memory_bytes = *memory_bytes;
2254 display.output_bytes = 0;
2255
2256 result = png_safe_execute(image, png_image_write_memory, &display);
2257 png_image_free(image);
2258
2259 /* write_memory returns true even if we ran out of buffer. */
2260 if (result)
2261 {
2262 /* On out-of-buffer this function returns '0' but still updates
2263 * memory_bytes:
2264 */
2265 if (memory != NULL && display.output_bytes > *memory_bytes)
2266 result = 0;
2267
2268 *memory_bytes = display.output_bytes;
2269 }
2270
2271 return result;
2272 }
2273
2274 else
2275 return 0;
2276 }
2277
2278 else
2279 return png_image_error(image,
2280 "png_image_write_to_memory: invalid argument");
2281 }
2282
2283 else if (image != NULL)
2284 return png_image_error(image,
2285 "png_image_write_to_memory: incorrect PNG_IMAGE_VERSION");
2286
2287 else
2288 return 0;
2289}
2290
2291#ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED
2292int PNGAPI
2293png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
2294 const void *buffer, png_int_32 row_stride, const void *colormap)
2295{
2296 /* Write the image to the given (FILE*). */
2297 if (image != NULL && image->version == PNG_IMAGE_VERSION)
2298 {
2299 if (file != NULL && buffer != NULL)
2300 {
2301 if (png_image_write_init(image) != 0)
2302 {
2303 png_image_write_control display;
2304 int result;
2305
2306 /* This is slightly evil, but png_init_io doesn't do anything other
2307 * than this and we haven't changed the standard IO functions so
2308 * this saves a 'safe' function.
2309 */
2310 image->opaque->png_ptr->io_ptr = file;
2311
2312 memset(&display, 0, (sizeof display));
2313 display.image = image;
2314 display.buffer = buffer;
2315 display.row_stride = row_stride;
2316 display.colormap = colormap;
2317 display.convert_to_8bit = convert_to_8bit;
2318
2319 result = png_safe_execute(image, png_image_write_main, &display);
2320 png_image_free(image);
2321 return result;
2322 }
2323
2324 else
2325 return 0;
2326 }
2327
2328 else
2329 return png_image_error(image,
2330 "png_image_write_to_stdio: invalid argument");
2331 }
2332
2333 else if (image != NULL)
2334 return png_image_error(image,
2335 "png_image_write_to_stdio: incorrect PNG_IMAGE_VERSION");
2336
2337 else
2338 return 0;
2339}
2340
2341int PNGAPI
2342png_image_write_to_file(png_imagep image, const char *file_name,
2343 int convert_to_8bit, const void *buffer, png_int_32 row_stride,
2344 const void *colormap)
2345{
2346 /* Write the image to the named file. */
2347 if (image != NULL && image->version == PNG_IMAGE_VERSION)
2348 {
2349 if (file_name != NULL && buffer != NULL)
2350 {
2351 FILE *fp = fopen(file_name, "wb");
2352
2353 if (fp != NULL)
2354 {
2355 if (png_image_write_to_stdio(image, fp, convert_to_8bit, buffer,
2356 row_stride, colormap) != 0)
2357 {
2358 int error; /* from fflush/fclose */
2359
2360 /* Make sure the file is flushed correctly. */
2361 if (fflush(fp) == 0 && ferror(fp) == 0)
2362 {
2363 if (fclose(fp) == 0)
2364 return 1;
2365
2366 error = errno; /* from fclose */
2367 }
2368
2369 else
2370 {
2371 error = errno; /* from fflush or ferror */
2372 (void)fclose(fp);
2373 }
2374
2375 (void)remove(file_name);
2376 /* The image has already been cleaned up; this is just used to
2377 * set the error (because the original write succeeded).
2378 */
2379 return png_image_error(image, strerror(error));
2380 }
2381
2382 else
2383 {
2384 /* Clean up: just the opened file. */
2385 (void)fclose(fp);
2386 (void)remove(file_name);
2387 return 0;
2388 }
2389 }
2390
2391 else
2392 return png_image_error(image, strerror(errno));
2393 }
2394
2395 else
2396 return png_image_error(image,
2397 "png_image_write_to_file: invalid argument");
2398 }
2399
2400 else if (image != NULL)
2401 return png_image_error(image,
2402 "png_image_write_to_file: incorrect PNG_IMAGE_VERSION");
2403
2404 else
2405 return 0;
2406}
2407#endif /* SIMPLIFIED_WRITE_STDIO */
2408#endif /* SIMPLIFIED_WRITE */
2409#endif /* WRITE */
2410