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comparison lib/libpng/pngwrite.c @ 2296:6e178010fc29

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libpng
author Ritor1
date Mon, 17 Mar 2014 01:21:55 +0600
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2295:6fd03869f65c 2296:6e178010fc29
1
2 /* pngwrite.c - general routines to write a PNG file
3 *
4 * Last changed in libpng 1.6.10 [March 6, 2014]
5 * Copyright (c) 1998-2014 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 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 #if defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
16 # include <errno.h>
17 #endif
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 */
23 static void
24 write_unknown_chunks(png_structrp png_ptr, png_const_inforp info_ptr,
25 unsigned int where)
26 {
27 if (info_ptr->unknown_chunks_num)
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)
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 /* PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED */
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_ flag, and check info_ptr->valid before writing
79 * the chunk, as that will keep the code from breaking if you want to just
80 * write a plain PNG file. If you have long comments, I suggest writing
81 * them in png_write_end(), and compressing them.
82 */
83 void PNGAPI
84 png_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))
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) && \
98 (png_ptr->mng_features_permitted))
99 {
100 png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
101 png_ptr->mng_features_permitted = 0;
102 }
103 #endif
104
105 /* Write IHDR information. */
106 png_write_IHDR(png_ptr, info_ptr->width, info_ptr->height,
107 info_ptr->bit_depth, info_ptr->color_type, info_ptr->compression_type,
108 info_ptr->filter_type,
109 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
110 info_ptr->interlace_type
111 #else
112 0
113 #endif
114 );
115
116 /* The rest of these check to see if the valid field has the appropriate
117 * flag set, and if it does, writes the chunk.
118 *
119 * 1.6.0: COLORSPACE support controls the writing of these chunks too, and
120 * the chunks will be written if the WRITE routine is there and information
121 * is available in the COLORSPACE. (See png_colorspace_sync_info in png.c
122 * for where the valid flags get set.)
123 *
124 * Under certain circumstances the colorspace can be invalidated without
125 * syncing the info_struct 'valid' flags; this happens if libpng detects and
126 * error and calls png_error while the color space is being set, yet the
127 * application continues writing the PNG. So check the 'invalid' flag here
128 * too.
129 */
130 #ifdef PNG_GAMMA_SUPPORTED
131 # ifdef PNG_WRITE_gAMA_SUPPORTED
132 if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
133 (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_gAMA) &&
134 (info_ptr->valid & PNG_INFO_gAMA))
135 png_write_gAMA_fixed(png_ptr, info_ptr->colorspace.gamma);
136 # endif
137 #endif
138
139 #ifdef PNG_COLORSPACE_SUPPORTED
140 /* Write only one of sRGB or an ICC profile. If a profile was supplied
141 * and it matches one of the known sRGB ones issue a warning.
142 */
143 # ifdef PNG_WRITE_iCCP_SUPPORTED
144 if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
145 (info_ptr->valid & PNG_INFO_iCCP))
146 {
147 # ifdef PNG_WRITE_sRGB_SUPPORTED
148 if (info_ptr->valid & PNG_INFO_sRGB)
149 png_app_warning(png_ptr,
150 "profile matches sRGB but writing iCCP instead");
151 # endif
152
153 png_write_iCCP(png_ptr, info_ptr->iccp_name,
154 info_ptr->iccp_profile);
155 }
156 # ifdef PNG_WRITE_sRGB_SUPPORTED
157 else
158 # endif
159 # endif
160
161 # ifdef PNG_WRITE_sRGB_SUPPORTED
162 if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
163 (info_ptr->valid & PNG_INFO_sRGB))
164 png_write_sRGB(png_ptr, info_ptr->colorspace.rendering_intent);
165 # endif /* WRITE_sRGB */
166 #endif /* COLORSPACE */
167
168 #ifdef PNG_WRITE_sBIT_SUPPORTED
169 if (info_ptr->valid & PNG_INFO_sBIT)
170 png_write_sBIT(png_ptr, &(info_ptr->sig_bit), info_ptr->color_type);
171 #endif
172
173 #ifdef PNG_COLORSPACE_SUPPORTED
174 # ifdef PNG_WRITE_cHRM_SUPPORTED
175 if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
176 (info_ptr->colorspace.flags & PNG_COLORSPACE_FROM_cHRM) &&
177 (info_ptr->valid & PNG_INFO_cHRM))
178 png_write_cHRM_fixed(png_ptr, &info_ptr->colorspace.end_points_xy);
179 # endif
180 #endif
181
182 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
183 write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_IHDR);
184 #endif
185
186 png_ptr->mode |= PNG_WROTE_INFO_BEFORE_PLTE;
187 }
188 }
189
190 void PNGAPI
191 png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
192 {
193 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
194 int i;
195 #endif
196
197 png_debug(1, "in png_write_info");
198
199 if (png_ptr == NULL || info_ptr == NULL)
200 return;
201
202 png_write_info_before_PLTE(png_ptr, info_ptr);
203
204 if (info_ptr->valid & PNG_INFO_PLTE)
205 png_write_PLTE(png_ptr, info_ptr->palette,
206 (png_uint_32)info_ptr->num_palette);
207
208 else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
209 png_error(png_ptr, "Valid palette required for paletted images");
210
211 #ifdef PNG_WRITE_tRNS_SUPPORTED
212 if (info_ptr->valid & PNG_INFO_tRNS)
213 {
214 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
215 /* Invert the alpha channel (in tRNS) */
216 if ((png_ptr->transformations & PNG_INVERT_ALPHA) &&
217 info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
218 {
219 int j;
220 for (j = 0; j<(int)info_ptr->num_trans; j++)
221 info_ptr->trans_alpha[j] =
222 (png_byte)(255 - info_ptr->trans_alpha[j]);
223 }
224 #endif
225 png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color),
226 info_ptr->num_trans, info_ptr->color_type);
227 }
228 #endif
229 #ifdef PNG_WRITE_bKGD_SUPPORTED
230 if (info_ptr->valid & PNG_INFO_bKGD)
231 png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
232 #endif
233
234 #ifdef PNG_WRITE_hIST_SUPPORTED
235 if (info_ptr->valid & PNG_INFO_hIST)
236 png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
237 #endif
238
239 #ifdef PNG_WRITE_oFFs_SUPPORTED
240 if (info_ptr->valid & PNG_INFO_oFFs)
241 png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
242 info_ptr->offset_unit_type);
243 #endif
244
245 #ifdef PNG_WRITE_pCAL_SUPPORTED
246 if (info_ptr->valid & PNG_INFO_pCAL)
247 png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0,
248 info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams,
249 info_ptr->pcal_units, info_ptr->pcal_params);
250 #endif
251
252 #ifdef PNG_WRITE_sCAL_SUPPORTED
253 if (info_ptr->valid & PNG_INFO_sCAL)
254 png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit,
255 info_ptr->scal_s_width, info_ptr->scal_s_height);
256 #endif /* sCAL */
257
258 #ifdef PNG_WRITE_pHYs_SUPPORTED
259 if (info_ptr->valid & PNG_INFO_pHYs)
260 png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
261 info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
262 #endif /* pHYs */
263
264 #ifdef PNG_WRITE_tIME_SUPPORTED
265 if (info_ptr->valid & PNG_INFO_tIME)
266 {
267 png_write_tIME(png_ptr, &(info_ptr->mod_time));
268 png_ptr->mode |= PNG_WROTE_tIME;
269 }
270 #endif /* tIME */
271
272 #ifdef PNG_WRITE_sPLT_SUPPORTED
273 if (info_ptr->valid & PNG_INFO_sPLT)
274 for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
275 png_write_sPLT(png_ptr, info_ptr->splt_palettes + i);
276 #endif /* sPLT */
277
278 #ifdef PNG_WRITE_TEXT_SUPPORTED
279 /* Check to see if we need to write text chunks */
280 for (i = 0; i < info_ptr->num_text; i++)
281 {
282 png_debug2(2, "Writing header text chunk %d, type %d", i,
283 info_ptr->text[i].compression);
284 /* An internationalized chunk? */
285 if (info_ptr->text[i].compression > 0)
286 {
287 #ifdef PNG_WRITE_iTXt_SUPPORTED
288 /* Write international chunk */
289 png_write_iTXt(png_ptr,
290 info_ptr->text[i].compression,
291 info_ptr->text[i].key,
292 info_ptr->text[i].lang,
293 info_ptr->text[i].lang_key,
294 info_ptr->text[i].text);
295 #else
296 png_warning(png_ptr, "Unable to write international text");
297 #endif
298 /* Mark this chunk as written */
299 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
300 }
301
302 /* If we want a compressed text chunk */
303 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_zTXt)
304 {
305 #ifdef PNG_WRITE_zTXt_SUPPORTED
306 /* Write compressed chunk */
307 png_write_zTXt(png_ptr, info_ptr->text[i].key,
308 info_ptr->text[i].text, 0,
309 info_ptr->text[i].compression);
310 #else
311 png_warning(png_ptr, "Unable to write compressed text");
312 #endif
313 /* Mark this chunk as written */
314 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
315 }
316
317 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
318 {
319 #ifdef PNG_WRITE_tEXt_SUPPORTED
320 /* Write uncompressed chunk */
321 png_write_tEXt(png_ptr, info_ptr->text[i].key,
322 info_ptr->text[i].text,
323 0);
324 /* Mark this chunk as written */
325 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
326 #else
327 /* Can't get here */
328 png_warning(png_ptr, "Unable to write uncompressed text");
329 #endif
330 }
331 }
332 #endif /* tEXt */
333
334 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
335 write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_PLTE);
336 #endif
337 }
338
339 /* Writes the end of the PNG file. If you don't want to write comments or
340 * time information, you can pass NULL for info. If you already wrote these
341 * in png_write_info(), do not write them again here. If you have long
342 * comments, I suggest writing them here, and compressing them.
343 */
344 void PNGAPI
345 png_write_end(png_structrp png_ptr, png_inforp info_ptr)
346 {
347 png_debug(1, "in png_write_end");
348
349 if (png_ptr == NULL)
350 return;
351
352 if (!(png_ptr->mode & PNG_HAVE_IDAT))
353 png_error(png_ptr, "No IDATs written into file");
354
355 #ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
356 if (png_ptr->num_palette_max > png_ptr->num_palette)
357 png_benign_error(png_ptr, "Wrote palette index exceeding num_palette");
358 #endif
359
360 /* See if user wants us to write information chunks */
361 if (info_ptr != NULL)
362 {
363 #ifdef PNG_WRITE_TEXT_SUPPORTED
364 int i; /* local index variable */
365 #endif
366 #ifdef PNG_WRITE_tIME_SUPPORTED
367 /* Check to see if user has supplied a time chunk */
368 if ((info_ptr->valid & PNG_INFO_tIME) &&
369 !(png_ptr->mode & PNG_WROTE_tIME))
370 png_write_tIME(png_ptr, &(info_ptr->mod_time));
371
372 #endif
373 #ifdef PNG_WRITE_TEXT_SUPPORTED
374 /* Loop through comment chunks */
375 for (i = 0; i < info_ptr->num_text; i++)
376 {
377 png_debug2(2, "Writing trailer text chunk %d, type %d", i,
378 info_ptr->text[i].compression);
379 /* An internationalized chunk? */
380 if (info_ptr->text[i].compression > 0)
381 {
382 #ifdef PNG_WRITE_iTXt_SUPPORTED
383 /* Write international chunk */
384 png_write_iTXt(png_ptr,
385 info_ptr->text[i].compression,
386 info_ptr->text[i].key,
387 info_ptr->text[i].lang,
388 info_ptr->text[i].lang_key,
389 info_ptr->text[i].text);
390 #else
391 png_warning(png_ptr, "Unable to write international text");
392 #endif
393 /* Mark this chunk as written */
394 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
395 }
396
397 else if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
398 {
399 #ifdef PNG_WRITE_zTXt_SUPPORTED
400 /* Write compressed chunk */
401 png_write_zTXt(png_ptr, info_ptr->text[i].key,
402 info_ptr->text[i].text, 0,
403 info_ptr->text[i].compression);
404 #else
405 png_warning(png_ptr, "Unable to write compressed text");
406 #endif
407 /* Mark this chunk as written */
408 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
409 }
410
411 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
412 {
413 #ifdef PNG_WRITE_tEXt_SUPPORTED
414 /* Write uncompressed chunk */
415 png_write_tEXt(png_ptr, info_ptr->text[i].key,
416 info_ptr->text[i].text, 0);
417 #else
418 png_warning(png_ptr, "Unable to write uncompressed text");
419 #endif
420
421 /* Mark this chunk as written */
422 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
423 }
424 }
425 #endif
426 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
427 write_unknown_chunks(png_ptr, info_ptr, PNG_AFTER_IDAT);
428 #endif
429 }
430
431 png_ptr->mode |= PNG_AFTER_IDAT;
432
433 /* Write end of PNG file */
434 png_write_IEND(png_ptr);
435 /* This flush, added in libpng-1.0.8, removed from libpng-1.0.9beta03,
436 * and restored again in libpng-1.2.30, may cause some applications that
437 * do not set png_ptr->output_flush_fn to crash. If your application
438 * experiences a problem, please try building libpng with
439 * PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED defined, and report the event to
440 * png-mng-implement at lists.sf.net .
441 */
442 #ifdef PNG_WRITE_FLUSH_SUPPORTED
443 # ifdef PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED
444 png_flush(png_ptr);
445 # endif
446 #endif
447 }
448
449 #ifdef PNG_CONVERT_tIME_SUPPORTED
450 void PNGAPI
451 png_convert_from_struct_tm(png_timep ptime, PNG_CONST struct tm * ttime)
452 {
453 png_debug(1, "in png_convert_from_struct_tm");
454
455 ptime->year = (png_uint_16)(1900 + ttime->tm_year);
456 ptime->month = (png_byte)(ttime->tm_mon + 1);
457 ptime->day = (png_byte)ttime->tm_mday;
458 ptime->hour = (png_byte)ttime->tm_hour;
459 ptime->minute = (png_byte)ttime->tm_min;
460 ptime->second = (png_byte)ttime->tm_sec;
461 }
462
463 void PNGAPI
464 png_convert_from_time_t(png_timep ptime, time_t ttime)
465 {
466 struct tm *tbuf;
467
468 png_debug(1, "in png_convert_from_time_t");
469
470 tbuf = gmtime(&ttime);
471 png_convert_from_struct_tm(ptime, tbuf);
472 }
473 #endif
474
475 /* Initialize png_ptr structure, and allocate any memory needed */
476 PNG_FUNCTION(png_structp,PNGAPI
477 png_create_write_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
478 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
479 {
480 #ifndef PNG_USER_MEM_SUPPORTED
481 png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
482 error_fn, warn_fn, NULL, NULL, NULL);
483 #else
484 return png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
485 warn_fn, NULL, NULL, NULL);
486 }
487
488 /* Alternate initialize png_ptr structure, and allocate any memory needed */
489 PNG_FUNCTION(png_structp,PNGAPI
490 png_create_write_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
491 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
492 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
493 {
494 png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
495 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
496 #endif /* PNG_USER_MEM_SUPPORTED */
497 if (png_ptr != NULL)
498 {
499 /* Set the zlib control values to defaults; they can be overridden by the
500 * application after the struct has been created.
501 */
502 png_ptr->zbuffer_size = PNG_ZBUF_SIZE;
503
504 /* The 'zlib_strategy' setting is irrelevant because png_default_claim in
505 * pngwutil.c defaults it according to whether or not filters will be
506 * used, and ignores this setting.
507 */
508 png_ptr->zlib_strategy = PNG_Z_DEFAULT_STRATEGY;
509 png_ptr->zlib_level = PNG_Z_DEFAULT_COMPRESSION;
510 png_ptr->zlib_mem_level = 8;
511 png_ptr->zlib_window_bits = 15;
512 png_ptr->zlib_method = 8;
513
514 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
515 png_ptr->zlib_text_strategy = PNG_TEXT_Z_DEFAULT_STRATEGY;
516 png_ptr->zlib_text_level = PNG_TEXT_Z_DEFAULT_COMPRESSION;
517 png_ptr->zlib_text_mem_level = 8;
518 png_ptr->zlib_text_window_bits = 15;
519 png_ptr->zlib_text_method = 8;
520 #endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
521
522 /* This is a highly dubious configuration option; by default it is off,
523 * but it may be appropriate for private builds that are testing
524 * extensions not conformant to the current specification, or of
525 * applications that must not fail to write at all costs!
526 */
527 #ifdef PNG_BENIGN_WRITE_ERRORS_SUPPORTED
528 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
529 /* In stable builds only warn if an application error can be completely
530 * handled.
531 */
532 #endif
533
534 /* App warnings are warnings in release (or release candidate) builds but
535 * are errors during development.
536 */
537 #if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
538 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
539 #endif
540
541 /* TODO: delay this, it can be done in png_init_io() (if the app doesn't
542 * do it itself) avoiding setting the default function if it is not
543 * required.
544 */
545 png_set_write_fn(png_ptr, NULL, NULL, NULL);
546 }
547
548 return png_ptr;
549 }
550
551
552 /* Write a few rows of image data. If the image is interlaced,
553 * either you will have to write the 7 sub images, or, if you
554 * have called png_set_interlace_handling(), you will have to
555 * "write" the image seven times.
556 */
557 void PNGAPI
558 png_write_rows(png_structrp png_ptr, png_bytepp row,
559 png_uint_32 num_rows)
560 {
561 png_uint_32 i; /* row counter */
562 png_bytepp rp; /* row pointer */
563
564 png_debug(1, "in png_write_rows");
565
566 if (png_ptr == NULL)
567 return;
568
569 /* Loop through the rows */
570 for (i = 0, rp = row; i < num_rows; i++, rp++)
571 {
572 png_write_row(png_ptr, *rp);
573 }
574 }
575
576 /* Write the image. You only need to call this function once, even
577 * if you are writing an interlaced image.
578 */
579 void PNGAPI
580 png_write_image(png_structrp png_ptr, png_bytepp image)
581 {
582 png_uint_32 i; /* row index */
583 int pass, num_pass; /* pass variables */
584 png_bytepp rp; /* points to current row */
585
586 if (png_ptr == NULL)
587 return;
588
589 png_debug(1, "in png_write_image");
590
591 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
592 /* Initialize interlace handling. If image is not interlaced,
593 * this will set pass to 1
594 */
595 num_pass = png_set_interlace_handling(png_ptr);
596 #else
597 num_pass = 1;
598 #endif
599 /* Loop through passes */
600 for (pass = 0; pass < num_pass; pass++)
601 {
602 /* Loop through image */
603 for (i = 0, rp = image; i < png_ptr->height; i++, rp++)
604 {
605 png_write_row(png_ptr, *rp);
606 }
607 }
608 }
609
610 #ifdef PNG_MNG_FEATURES_SUPPORTED
611 /* Performs intrapixel differencing */
612 static void
613 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
614 {
615 png_debug(1, "in png_do_write_intrapixel");
616
617 if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
618 {
619 int bytes_per_pixel;
620 png_uint_32 row_width = row_info->width;
621 if (row_info->bit_depth == 8)
622 {
623 png_bytep rp;
624 png_uint_32 i;
625
626 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
627 bytes_per_pixel = 3;
628
629 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
630 bytes_per_pixel = 4;
631
632 else
633 return;
634
635 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
636 {
637 *(rp) = (png_byte)((*rp - *(rp + 1)) & 0xff);
638 *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
639 }
640 }
641
642 #ifdef PNG_WRITE_16BIT_SUPPORTED
643 else if (row_info->bit_depth == 16)
644 {
645 png_bytep rp;
646 png_uint_32 i;
647
648 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
649 bytes_per_pixel = 6;
650
651 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
652 bytes_per_pixel = 8;
653
654 else
655 return;
656
657 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
658 {
659 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
660 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
661 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
662 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
663 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
664 *(rp ) = (png_byte)((red >> 8) & 0xff);
665 *(rp + 1) = (png_byte)(red & 0xff);
666 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
667 *(rp + 5) = (png_byte)(blue & 0xff);
668 }
669 }
670 #endif /* PNG_WRITE_16BIT_SUPPORTED */
671 }
672 }
673 #endif /* PNG_MNG_FEATURES_SUPPORTED */
674
675 /* Called by user to write a row of image data */
676 void PNGAPI
677 png_write_row(png_structrp png_ptr, png_const_bytep row)
678 {
679 /* 1.5.6: moved from png_struct to be a local structure: */
680 png_row_info row_info;
681
682 if (png_ptr == NULL)
683 return;
684
685 png_debug2(1, "in png_write_row (row %u, pass %d)",
686 png_ptr->row_number, png_ptr->pass);
687
688 /* Initialize transformations and other stuff if first time */
689 if (png_ptr->row_number == 0 && png_ptr->pass == 0)
690 {
691 /* Make sure we wrote the header info */
692 if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
693 png_error(png_ptr,
694 "png_write_info was never called before png_write_row");
695
696 /* Check for transforms that have been set but were defined out */
697 #if !defined(PNG_WRITE_INVERT_SUPPORTED) && defined(PNG_READ_INVERT_SUPPORTED)
698 if (png_ptr->transformations & PNG_INVERT_MONO)
699 png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined");
700 #endif
701
702 #if !defined(PNG_WRITE_FILLER_SUPPORTED) && defined(PNG_READ_FILLER_SUPPORTED)
703 if (png_ptr->transformations & PNG_FILLER)
704 png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined");
705 #endif
706 #if !defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
707 defined(PNG_READ_PACKSWAP_SUPPORTED)
708 if (png_ptr->transformations & PNG_PACKSWAP)
709 png_warning(png_ptr,
710 "PNG_WRITE_PACKSWAP_SUPPORTED is not defined");
711 #endif
712
713 #if !defined(PNG_WRITE_PACK_SUPPORTED) && defined(PNG_READ_PACK_SUPPORTED)
714 if (png_ptr->transformations & PNG_PACK)
715 png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined");
716 #endif
717
718 #if !defined(PNG_WRITE_SHIFT_SUPPORTED) && defined(PNG_READ_SHIFT_SUPPORTED)
719 if (png_ptr->transformations & PNG_SHIFT)
720 png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined");
721 #endif
722
723 #if !defined(PNG_WRITE_BGR_SUPPORTED) && defined(PNG_READ_BGR_SUPPORTED)
724 if (png_ptr->transformations & PNG_BGR)
725 png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined");
726 #endif
727
728 #if !defined(PNG_WRITE_SWAP_SUPPORTED) && defined(PNG_READ_SWAP_SUPPORTED)
729 if (png_ptr->transformations & PNG_SWAP_BYTES)
730 png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined");
731 #endif
732
733 png_write_start_row(png_ptr);
734 }
735
736 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
737 /* If interlaced and not interested in row, return */
738 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
739 {
740 switch (png_ptr->pass)
741 {
742 case 0:
743 if (png_ptr->row_number & 0x07)
744 {
745 png_write_finish_row(png_ptr);
746 return;
747 }
748 break;
749
750 case 1:
751 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
752 {
753 png_write_finish_row(png_ptr);
754 return;
755 }
756 break;
757
758 case 2:
759 if ((png_ptr->row_number & 0x07) != 4)
760 {
761 png_write_finish_row(png_ptr);
762 return;
763 }
764 break;
765
766 case 3:
767 if ((png_ptr->row_number & 0x03) || png_ptr->width < 3)
768 {
769 png_write_finish_row(png_ptr);
770 return;
771 }
772 break;
773
774 case 4:
775 if ((png_ptr->row_number & 0x03) != 2)
776 {
777 png_write_finish_row(png_ptr);
778 return;
779 }
780 break;
781
782 case 5:
783 if ((png_ptr->row_number & 0x01) || png_ptr->width < 2)
784 {
785 png_write_finish_row(png_ptr);
786 return;
787 }
788 break;
789
790 case 6:
791 if (!(png_ptr->row_number & 0x01))
792 {
793 png_write_finish_row(png_ptr);
794 return;
795 }
796 break;
797
798 default: /* error: ignore it */
799 break;
800 }
801 }
802 #endif
803
804 /* Set up row info for transformations */
805 row_info.color_type = png_ptr->color_type;
806 row_info.width = png_ptr->usr_width;
807 row_info.channels = png_ptr->usr_channels;
808 row_info.bit_depth = png_ptr->usr_bit_depth;
809 row_info.pixel_depth = (png_byte)(row_info.bit_depth * row_info.channels);
810 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
811
812 png_debug1(3, "row_info->color_type = %d", row_info.color_type);
813 png_debug1(3, "row_info->width = %u", row_info.width);
814 png_debug1(3, "row_info->channels = %d", row_info.channels);
815 png_debug1(3, "row_info->bit_depth = %d", row_info.bit_depth);
816 png_debug1(3, "row_info->pixel_depth = %d", row_info.pixel_depth);
817 png_debug1(3, "row_info->rowbytes = %lu", (unsigned long)row_info.rowbytes);
818
819 /* Copy user's row into buffer, leaving room for filter byte. */
820 memcpy(png_ptr->row_buf + 1, row, row_info.rowbytes);
821
822 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
823 /* Handle interlacing */
824 if (png_ptr->interlaced && png_ptr->pass < 6 &&
825 (png_ptr->transformations & PNG_INTERLACE))
826 {
827 png_do_write_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass);
828 /* This should always get caught above, but still ... */
829 if (!(row_info.width))
830 {
831 png_write_finish_row(png_ptr);
832 return;
833 }
834 }
835 #endif
836
837 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
838 /* Handle other transformations */
839 if (png_ptr->transformations)
840 png_do_write_transformations(png_ptr, &row_info);
841 #endif
842
843 /* At this point the row_info pixel depth must match the 'transformed' depth,
844 * which is also the output depth.
845 */
846 if (row_info.pixel_depth != png_ptr->pixel_depth ||
847 row_info.pixel_depth != png_ptr->transformed_pixel_depth)
848 png_error(png_ptr, "internal write transform logic error");
849
850 #ifdef PNG_MNG_FEATURES_SUPPORTED
851 /* Write filter_method 64 (intrapixel differencing) only if
852 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
853 * 2. Libpng did not write a PNG signature (this filter_method is only
854 * used in PNG datastreams that are embedded in MNG datastreams) and
855 * 3. The application called png_permit_mng_features with a mask that
856 * included PNG_FLAG_MNG_FILTER_64 and
857 * 4. The filter_method is 64 and
858 * 5. The color_type is RGB or RGBA
859 */
860 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
861 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
862 {
863 /* Intrapixel differencing */
864 png_do_write_intrapixel(&row_info, png_ptr->row_buf + 1);
865 }
866 #endif
867
868 /* Added at libpng-1.5.10 */
869 #ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
870 /* Check for out-of-range palette index */
871 if (row_info.color_type == PNG_COLOR_TYPE_PALETTE &&
872 png_ptr->num_palette_max >= 0)
873 png_do_check_palette_indexes(png_ptr, &row_info);
874 #endif
875
876 /* Find a filter if necessary, filter the row and write it out. */
877 png_write_find_filter(png_ptr, &row_info);
878
879 if (png_ptr->write_row_fn != NULL)
880 (*(png_ptr->write_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
881 }
882
883 #ifdef PNG_WRITE_FLUSH_SUPPORTED
884 /* Set the automatic flush interval or 0 to turn flushing off */
885 void PNGAPI
886 png_set_flush(png_structrp png_ptr, int nrows)
887 {
888 png_debug(1, "in png_set_flush");
889
890 if (png_ptr == NULL)
891 return;
892
893 png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
894 }
895
896 /* Flush the current output buffers now */
897 void PNGAPI
898 png_write_flush(png_structrp png_ptr)
899 {
900 png_debug(1, "in png_write_flush");
901
902 if (png_ptr == NULL)
903 return;
904
905 /* We have already written out all of the data */
906 if (png_ptr->row_number >= png_ptr->num_rows)
907 return;
908
909 png_compress_IDAT(png_ptr, NULL, 0, Z_SYNC_FLUSH);
910 png_ptr->flush_rows = 0;
911 png_flush(png_ptr);
912 }
913 #endif /* PNG_WRITE_FLUSH_SUPPORTED */
914
915 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
916 static void png_reset_filter_heuristics(png_structrp png_ptr);/* forward decl */
917 #endif
918
919 /* Free any memory used in png_ptr struct without freeing the struct itself. */
920 static void
921 png_write_destroy(png_structrp png_ptr)
922 {
923 png_debug(1, "in png_write_destroy");
924
925 /* Free any memory zlib uses */
926 if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
927 deflateEnd(&png_ptr->zstream);
928
929 /* Free our memory. png_free checks NULL for us. */
930 png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
931 png_free(png_ptr, png_ptr->row_buf);
932 #ifdef PNG_WRITE_FILTER_SUPPORTED
933 png_free(png_ptr, png_ptr->prev_row);
934 png_free(png_ptr, png_ptr->sub_row);
935 png_free(png_ptr, png_ptr->up_row);
936 png_free(png_ptr, png_ptr->avg_row);
937 png_free(png_ptr, png_ptr->paeth_row);
938 #endif
939
940 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
941 /* Use this to save a little code space, it doesn't free the filter_costs */
942 png_reset_filter_heuristics(png_ptr);
943 png_free(png_ptr, png_ptr->filter_costs);
944 png_free(png_ptr, png_ptr->inv_filter_costs);
945 #endif
946
947 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
948 png_free(png_ptr, png_ptr->chunk_list);
949 #endif
950
951 /* The error handling and memory handling information is left intact at this
952 * point: the jmp_buf may still have to be freed. See png_destroy_png_struct
953 * for how this happens.
954 */
955 }
956
957 /* Free all memory used by the write.
958 * In libpng 1.6.0 this API changed quietly to no longer accept a NULL value for
959 * *png_ptr_ptr. Prior to 1.6.0 it would accept such a value and it would free
960 * the passed in info_structs but it would quietly fail to free any of the data
961 * inside them. In 1.6.0 it quietly does nothing (it has to be quiet because it
962 * has no png_ptr.)
963 */
964 void PNGAPI
965 png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
966 {
967 png_debug(1, "in png_destroy_write_struct");
968
969 if (png_ptr_ptr != NULL)
970 {
971 png_structrp png_ptr = *png_ptr_ptr;
972
973 if (png_ptr != NULL) /* added in libpng 1.6.0 */
974 {
975 png_destroy_info_struct(png_ptr, info_ptr_ptr);
976
977 *png_ptr_ptr = NULL;
978 png_write_destroy(png_ptr);
979 png_destroy_png_struct(png_ptr);
980 }
981 }
982 }
983
984 /* Allow the application to select one or more row filters to use. */
985 void PNGAPI
986 png_set_filter(png_structrp png_ptr, int method, int filters)
987 {
988 png_debug(1, "in png_set_filter");
989
990 if (png_ptr == NULL)
991 return;
992
993 #ifdef PNG_MNG_FEATURES_SUPPORTED
994 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
995 (method == PNG_INTRAPIXEL_DIFFERENCING))
996 method = PNG_FILTER_TYPE_BASE;
997
998 #endif
999 if (method == PNG_FILTER_TYPE_BASE)
1000 {
1001 switch (filters & (PNG_ALL_FILTERS | 0x07))
1002 {
1003 #ifdef PNG_WRITE_FILTER_SUPPORTED
1004 case 5:
1005 case 6:
1006 case 7: png_app_error(png_ptr, "Unknown row filter for method 0");
1007 /* FALL THROUGH */
1008 #endif /* PNG_WRITE_FILTER_SUPPORTED */
1009 case PNG_FILTER_VALUE_NONE:
1010 png_ptr->do_filter = PNG_FILTER_NONE; break;
1011
1012 #ifdef PNG_WRITE_FILTER_SUPPORTED
1013 case PNG_FILTER_VALUE_SUB:
1014 png_ptr->do_filter = PNG_FILTER_SUB; break;
1015
1016 case PNG_FILTER_VALUE_UP:
1017 png_ptr->do_filter = PNG_FILTER_UP; break;
1018
1019 case PNG_FILTER_VALUE_AVG:
1020 png_ptr->do_filter = PNG_FILTER_AVG; break;
1021
1022 case PNG_FILTER_VALUE_PAETH:
1023 png_ptr->do_filter = PNG_FILTER_PAETH; break;
1024
1025 default:
1026 png_ptr->do_filter = (png_byte)filters; break;
1027 #else
1028 default:
1029 png_app_error(png_ptr, "Unknown row filter for method 0");
1030 #endif /* PNG_WRITE_FILTER_SUPPORTED */
1031 }
1032
1033 /* If we have allocated the row_buf, this means we have already started
1034 * with the image and we should have allocated all of the filter buffers
1035 * that have been selected. If prev_row isn't already allocated, then
1036 * it is too late to start using the filters that need it, since we
1037 * will be missing the data in the previous row. If an application
1038 * wants to start and stop using particular filters during compression,
1039 * it should start out with all of the filters, and then add and
1040 * remove them after the start of compression.
1041 */
1042 if (png_ptr->row_buf != NULL)
1043 {
1044 #ifdef PNG_WRITE_FILTER_SUPPORTED
1045 if ((png_ptr->do_filter & PNG_FILTER_SUB) && png_ptr->sub_row == NULL)
1046 {
1047 png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
1048 (png_ptr->rowbytes + 1));
1049 png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
1050 }
1051
1052 if ((png_ptr->do_filter & PNG_FILTER_UP) && png_ptr->up_row == NULL)
1053 {
1054 if (png_ptr->prev_row == NULL)
1055 {
1056 png_warning(png_ptr, "Can't add Up filter after starting");
1057 png_ptr->do_filter = (png_byte)(png_ptr->do_filter &
1058 ~PNG_FILTER_UP);
1059 }
1060
1061 else
1062 {
1063 png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
1064 (png_ptr->rowbytes + 1));
1065 png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
1066 }
1067 }
1068
1069 if ((png_ptr->do_filter & PNG_FILTER_AVG) && png_ptr->avg_row == NULL)
1070 {
1071 if (png_ptr->prev_row == NULL)
1072 {
1073 png_warning(png_ptr, "Can't add Average filter after starting");
1074 png_ptr->do_filter = (png_byte)(png_ptr->do_filter &
1075 ~PNG_FILTER_AVG);
1076 }
1077
1078 else
1079 {
1080 png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
1081 (png_ptr->rowbytes + 1));
1082 png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
1083 }
1084 }
1085
1086 if ((png_ptr->do_filter & PNG_FILTER_PAETH) &&
1087 png_ptr->paeth_row == NULL)
1088 {
1089 if (png_ptr->prev_row == NULL)
1090 {
1091 png_warning(png_ptr, "Can't add Paeth filter after starting");
1092 png_ptr->do_filter &= (png_byte)(~PNG_FILTER_PAETH);
1093 }
1094
1095 else
1096 {
1097 png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
1098 (png_ptr->rowbytes + 1));
1099 png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
1100 }
1101 }
1102
1103 if (png_ptr->do_filter == PNG_NO_FILTERS)
1104 #endif /* PNG_WRITE_FILTER_SUPPORTED */
1105 png_ptr->do_filter = PNG_FILTER_NONE;
1106 }
1107 }
1108 else
1109 png_error(png_ptr, "Unknown custom filter method");
1110 }
1111
1112 /* This allows us to influence the way in which libpng chooses the "best"
1113 * filter for the current scanline. While the "minimum-sum-of-absolute-
1114 * differences metric is relatively fast and effective, there is some
1115 * question as to whether it can be improved upon by trying to keep the
1116 * filtered data going to zlib more consistent, hopefully resulting in
1117 * better compression.
1118 */
1119 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* GRR 970116 */
1120 /* Convenience reset API. */
1121 static void
1122 png_reset_filter_heuristics(png_structrp png_ptr)
1123 {
1124 /* Clear out any old values in the 'weights' - this must be done because if
1125 * the app calls set_filter_heuristics multiple times with different
1126 * 'num_weights' values we would otherwise potentially have wrong sized
1127 * arrays.
1128 */
1129 png_ptr->num_prev_filters = 0;
1130 png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
1131 if (png_ptr->prev_filters != NULL)
1132 {
1133 png_bytep old = png_ptr->prev_filters;
1134 png_ptr->prev_filters = NULL;
1135 png_free(png_ptr, old);
1136 }
1137 if (png_ptr->filter_weights != NULL)
1138 {
1139 png_uint_16p old = png_ptr->filter_weights;
1140 png_ptr->filter_weights = NULL;
1141 png_free(png_ptr, old);
1142 }
1143
1144 if (png_ptr->inv_filter_weights != NULL)
1145 {
1146 png_uint_16p old = png_ptr->inv_filter_weights;
1147 png_ptr->inv_filter_weights = NULL;
1148 png_free(png_ptr, old);
1149 }
1150
1151 /* Leave the filter_costs - this array is fixed size. */
1152 }
1153
1154 static int
1155 png_init_filter_heuristics(png_structrp png_ptr, int heuristic_method,
1156 int num_weights)
1157 {
1158 if (png_ptr == NULL)
1159 return 0;
1160
1161 /* Clear out the arrays */
1162 png_reset_filter_heuristics(png_ptr);
1163
1164 /* Check arguments; the 'reset' function makes the correct settings for the
1165 * unweighted case, but we must handle the weight case by initializing the
1166 * arrays for the caller.
1167 */
1168 if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1169 {
1170 int i;
1171
1172 if (num_weights > 0)
1173 {
1174 png_ptr->prev_filters = (png_bytep)png_malloc(png_ptr,
1175 (png_uint_32)((sizeof (png_byte)) * num_weights));
1176
1177 /* To make sure that the weighting starts out fairly */
1178 for (i = 0; i < num_weights; i++)
1179 {
1180 png_ptr->prev_filters[i] = 255;
1181 }
1182
1183 png_ptr->filter_weights = (png_uint_16p)png_malloc(png_ptr,
1184 (png_uint_32)((sizeof (png_uint_16)) * num_weights));
1185
1186 png_ptr->inv_filter_weights = (png_uint_16p)png_malloc(png_ptr,
1187 (png_uint_32)((sizeof (png_uint_16)) * num_weights));
1188
1189 for (i = 0; i < num_weights; i++)
1190 {
1191 png_ptr->inv_filter_weights[i] =
1192 png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
1193 }
1194
1195 /* Safe to set this now */
1196 png_ptr->num_prev_filters = (png_byte)num_weights;
1197 }
1198
1199 /* If, in the future, there are other filter methods, this would
1200 * need to be based on png_ptr->filter.
1201 */
1202 if (png_ptr->filter_costs == NULL)
1203 {
1204 png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
1205 (png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
1206
1207 png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
1208 (png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
1209 }
1210
1211 for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
1212 {
1213 png_ptr->inv_filter_costs[i] =
1214 png_ptr->filter_costs[i] = PNG_COST_FACTOR;
1215 }
1216
1217 /* All the arrays are inited, safe to set this: */
1218 png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_WEIGHTED;
1219
1220 /* Return the 'ok' code. */
1221 return 1;
1222 }
1223 else if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT ||
1224 heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
1225 {
1226 return 1;
1227 }
1228 else
1229 {
1230 png_warning(png_ptr, "Unknown filter heuristic method");
1231 return 0;
1232 }
1233 }
1234
1235 /* Provide floating and fixed point APIs */
1236 #ifdef PNG_FLOATING_POINT_SUPPORTED
1237 void PNGAPI
1238 png_set_filter_heuristics(png_structrp png_ptr, int heuristic_method,
1239 int num_weights, png_const_doublep filter_weights,
1240 png_const_doublep filter_costs)
1241 {
1242 png_debug(1, "in png_set_filter_heuristics");
1243
1244 /* The internal API allocates all the arrays and ensures that the elements of
1245 * those arrays are set to the default value.
1246 */
1247 if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
1248 return;
1249
1250 /* If using the weighted method copy in the weights. */
1251 if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1252 {
1253 int i;
1254 for (i = 0; i < num_weights; i++)
1255 {
1256 if (filter_weights[i] <= 0.0)
1257 {
1258 png_ptr->inv_filter_weights[i] =
1259 png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
1260 }
1261
1262 else
1263 {
1264 png_ptr->inv_filter_weights[i] =
1265 (png_uint_16)(PNG_WEIGHT_FACTOR*filter_weights[i]+.5);
1266
1267 png_ptr->filter_weights[i] =
1268 (png_uint_16)(PNG_WEIGHT_FACTOR/filter_weights[i]+.5);
1269 }
1270 }
1271
1272 /* Here is where we set the relative costs of the different filters. We
1273 * should take the desired compression level into account when setting
1274 * the costs, so that Paeth, for instance, has a high relative cost at low
1275 * compression levels, while it has a lower relative cost at higher
1276 * compression settings. The filter types are in order of increasing
1277 * relative cost, so it would be possible to do this with an algorithm.
1278 */
1279 for (i = 0; i < PNG_FILTER_VALUE_LAST; i++) if (filter_costs[i] >= 1.0)
1280 {
1281 png_ptr->inv_filter_costs[i] =
1282 (png_uint_16)(PNG_COST_FACTOR / filter_costs[i] + .5);
1283
1284 png_ptr->filter_costs[i] =
1285 (png_uint_16)(PNG_COST_FACTOR * filter_costs[i] + .5);
1286 }
1287 }
1288 }
1289 #endif /* FLOATING_POINT */
1290
1291 #ifdef PNG_FIXED_POINT_SUPPORTED
1292 void PNGAPI
1293 png_set_filter_heuristics_fixed(png_structrp png_ptr, int heuristic_method,
1294 int num_weights, png_const_fixed_point_p filter_weights,
1295 png_const_fixed_point_p filter_costs)
1296 {
1297 png_debug(1, "in png_set_filter_heuristics_fixed");
1298
1299 /* The internal API allocates all the arrays and ensures that the elements of
1300 * those arrays are set to the default value.
1301 */
1302 if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
1303 return;
1304
1305 /* If using the weighted method copy in the weights. */
1306 if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1307 {
1308 int i;
1309 for (i = 0; i < num_weights; i++)
1310 {
1311 if (filter_weights[i] <= 0)
1312 {
1313 png_ptr->inv_filter_weights[i] =
1314 png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
1315 }
1316
1317 else
1318 {
1319 png_ptr->inv_filter_weights[i] = (png_uint_16)
1320 ((PNG_WEIGHT_FACTOR*filter_weights[i]+PNG_FP_HALF)/PNG_FP_1);
1321
1322 png_ptr->filter_weights[i] = (png_uint_16)((PNG_WEIGHT_FACTOR*
1323 PNG_FP_1+(filter_weights[i]/2))/filter_weights[i]);
1324 }
1325 }
1326
1327 /* Here is where we set the relative costs of the different filters. We
1328 * should take the desired compression level into account when setting
1329 * the costs, so that Paeth, for instance, has a high relative cost at low
1330 * compression levels, while it has a lower relative cost at higher
1331 * compression settings. The filter types are in order of increasing
1332 * relative cost, so it would be possible to do this with an algorithm.
1333 */
1334 for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
1335 if (filter_costs[i] >= PNG_FP_1)
1336 {
1337 png_uint_32 tmp;
1338
1339 /* Use a 32 bit unsigned temporary here because otherwise the
1340 * intermediate value will be a 32 bit *signed* integer (ANSI rules)
1341 * and this will get the wrong answer on division.
1342 */
1343 tmp = PNG_COST_FACTOR*PNG_FP_1 + (filter_costs[i]/2);
1344 tmp /= filter_costs[i];
1345
1346 png_ptr->inv_filter_costs[i] = (png_uint_16)tmp;
1347
1348 tmp = PNG_COST_FACTOR * filter_costs[i] + PNG_FP_HALF;
1349 tmp /= PNG_FP_1;
1350
1351 png_ptr->filter_costs[i] = (png_uint_16)tmp;
1352 }
1353 }
1354 }
1355 #endif /* FIXED_POINT */
1356 #endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
1357
1358 void PNGAPI
1359 png_set_compression_level(png_structrp png_ptr, int level)
1360 {
1361 png_debug(1, "in png_set_compression_level");
1362
1363 if (png_ptr == NULL)
1364 return;
1365
1366 png_ptr->zlib_level = level;
1367 }
1368
1369 void PNGAPI
1370 png_set_compression_mem_level(png_structrp png_ptr, int mem_level)
1371 {
1372 png_debug(1, "in png_set_compression_mem_level");
1373
1374 if (png_ptr == NULL)
1375 return;
1376
1377 png_ptr->zlib_mem_level = mem_level;
1378 }
1379
1380 void PNGAPI
1381 png_set_compression_strategy(png_structrp png_ptr, int strategy)
1382 {
1383 png_debug(1, "in png_set_compression_strategy");
1384
1385 if (png_ptr == NULL)
1386 return;
1387
1388 /* The flag setting here prevents the libpng dynamic selection of strategy.
1389 */
1390 png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
1391 png_ptr->zlib_strategy = strategy;
1392 }
1393
1394 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1395 * smaller value of window_bits if it can do so safely.
1396 */
1397 void PNGAPI
1398 png_set_compression_window_bits(png_structrp png_ptr, int window_bits)
1399 {
1400 if (png_ptr == NULL)
1401 return;
1402
1403 /* Prior to 1.6.0 this would warn but then set the window_bits value, this
1404 * meant that negative window bits values could be selected which would cause
1405 * libpng to write a non-standard PNG file with raw deflate or gzip
1406 * compressed IDAT or ancillary chunks. Such files can be read and there is
1407 * no warning on read, so this seems like a very bad idea.
1408 */
1409 if (window_bits > 15)
1410 {
1411 png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
1412 window_bits = 15;
1413 }
1414
1415 else if (window_bits < 8)
1416 {
1417 png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
1418 window_bits = 8;
1419 }
1420
1421 png_ptr->zlib_window_bits = window_bits;
1422 }
1423
1424 void PNGAPI
1425 png_set_compression_method(png_structrp png_ptr, int method)
1426 {
1427 png_debug(1, "in png_set_compression_method");
1428
1429 if (png_ptr == NULL)
1430 return;
1431
1432 /* This would produce an invalid PNG file if it worked, but it doesn't and
1433 * deflate will fault it, so it is harmless to just warn here.
1434 */
1435 if (method != 8)
1436 png_warning(png_ptr, "Only compression method 8 is supported by PNG");
1437
1438 png_ptr->zlib_method = method;
1439 }
1440
1441 /* The following were added to libpng-1.5.4 */
1442 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
1443 void PNGAPI
1444 png_set_text_compression_level(png_structrp png_ptr, int level)
1445 {
1446 png_debug(1, "in png_set_text_compression_level");
1447
1448 if (png_ptr == NULL)
1449 return;
1450
1451 png_ptr->zlib_text_level = level;
1452 }
1453
1454 void PNGAPI
1455 png_set_text_compression_mem_level(png_structrp png_ptr, int mem_level)
1456 {
1457 png_debug(1, "in png_set_text_compression_mem_level");
1458
1459 if (png_ptr == NULL)
1460 return;
1461
1462 png_ptr->zlib_text_mem_level = mem_level;
1463 }
1464
1465 void PNGAPI
1466 png_set_text_compression_strategy(png_structrp png_ptr, int strategy)
1467 {
1468 png_debug(1, "in png_set_text_compression_strategy");
1469
1470 if (png_ptr == NULL)
1471 return;
1472
1473 png_ptr->zlib_text_strategy = strategy;
1474 }
1475
1476 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1477 * smaller value of window_bits if it can do so safely.
1478 */
1479 void PNGAPI
1480 png_set_text_compression_window_bits(png_structrp png_ptr, int window_bits)
1481 {
1482 if (png_ptr == NULL)
1483 return;
1484
1485 if (window_bits > 15)
1486 {
1487 png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
1488 window_bits = 15;
1489 }
1490
1491 else if (window_bits < 8)
1492 {
1493 png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
1494 window_bits = 8;
1495 }
1496
1497 png_ptr->zlib_text_window_bits = window_bits;
1498 }
1499
1500 void PNGAPI
1501 png_set_text_compression_method(png_structrp png_ptr, int method)
1502 {
1503 png_debug(1, "in png_set_text_compression_method");
1504
1505 if (png_ptr == NULL)
1506 return;
1507
1508 if (method != 8)
1509 png_warning(png_ptr, "Only compression method 8 is supported by PNG");
1510
1511 png_ptr->zlib_text_method = method;
1512 }
1513 #endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
1514 /* end of API added to libpng-1.5.4 */
1515
1516 void PNGAPI
1517 png_set_write_status_fn(png_structrp png_ptr, png_write_status_ptr write_row_fn)
1518 {
1519 if (png_ptr == NULL)
1520 return;
1521
1522 png_ptr->write_row_fn = write_row_fn;
1523 }
1524
1525 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
1526 void PNGAPI
1527 png_set_write_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1528 write_user_transform_fn)
1529 {
1530 png_debug(1, "in png_set_write_user_transform_fn");
1531
1532 if (png_ptr == NULL)
1533 return;
1534
1535 png_ptr->transformations |= PNG_USER_TRANSFORM;
1536 png_ptr->write_user_transform_fn = write_user_transform_fn;
1537 }
1538 #endif
1539
1540
1541 #ifdef PNG_INFO_IMAGE_SUPPORTED
1542 void PNGAPI
1543 png_write_png(png_structrp png_ptr, png_inforp info_ptr,
1544 int transforms, voidp params)
1545 {
1546 if (png_ptr == NULL || info_ptr == NULL)
1547 return;
1548
1549 if ((info_ptr->valid & PNG_INFO_IDAT) == 0)
1550 {
1551 png_app_error(png_ptr, "no rows for png_write_image to write");
1552 return;
1553 }
1554
1555 /* Write the file header information. */
1556 png_write_info(png_ptr, info_ptr);
1557
1558 /* ------ these transformations don't touch the info structure ------- */
1559
1560 /* Invert monochrome pixels */
1561 if (transforms & PNG_TRANSFORM_INVERT_MONO)
1562 #ifdef PNG_WRITE_INVERT_SUPPORTED
1563 png_set_invert_mono(png_ptr);
1564 #else
1565 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1566 #endif
1567
1568 /* Shift the pixels up to a legal bit depth and fill in
1569 * as appropriate to correctly scale the image.
1570 */
1571 if (transforms & PNG_TRANSFORM_SHIFT)
1572 #ifdef PNG_WRITE_SHIFT_SUPPORTED
1573 if (info_ptr->valid & PNG_INFO_sBIT)
1574 png_set_shift(png_ptr, &info_ptr->sig_bit);
1575 #else
1576 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1577 #endif
1578
1579 /* Pack pixels into bytes */
1580 if (transforms & PNG_TRANSFORM_PACKING)
1581 #ifdef PNG_WRITE_PACK_SUPPORTED
1582 png_set_packing(png_ptr);
1583 #else
1584 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1585 #endif
1586
1587 /* Swap location of alpha bytes from ARGB to RGBA */
1588 if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
1589 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
1590 png_set_swap_alpha(png_ptr);
1591 #else
1592 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1593 #endif
1594
1595 /* Remove a filler (X) from XRGB/RGBX/AG/GA into to convert it into
1596 * RGB, note that the code expects the input color type to be G or RGB; no
1597 * alpha channel.
1598 */
1599 if (transforms &
1600 (PNG_TRANSFORM_STRIP_FILLER_AFTER|PNG_TRANSFORM_STRIP_FILLER_BEFORE))
1601 {
1602 #ifdef PNG_WRITE_FILLER_SUPPORTED
1603 if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
1604 {
1605 if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
1606 png_app_error(png_ptr,
1607 "PNG_TRANSFORM_STRIP_FILLER: BEFORE+AFTER not supported");
1608
1609 /* Continue if ignored - this is the pre-1.6.10 behavior */
1610 png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
1611 }
1612
1613 else if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
1614 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
1615 #else
1616 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_FILLER not supported");
1617 #endif
1618 }
1619
1620 /* Flip BGR pixels to RGB */
1621 if (transforms & PNG_TRANSFORM_BGR)
1622 #ifdef PNG_WRITE_BGR_SUPPORTED
1623 png_set_bgr(png_ptr);
1624 #else
1625 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1626 #endif
1627
1628 /* Swap bytes of 16-bit files to most significant byte first */
1629 if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
1630 #ifdef PNG_WRITE_SWAP_SUPPORTED
1631 png_set_swap(png_ptr);
1632 #else
1633 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1634 #endif
1635
1636 /* Swap bits of 1, 2, 4 bit packed pixel formats */
1637 if (transforms & PNG_TRANSFORM_PACKSWAP)
1638 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
1639 png_set_packswap(png_ptr);
1640 #else
1641 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1642 #endif
1643
1644 /* Invert the alpha channel from opacity to transparency */
1645 if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
1646 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
1647 png_set_invert_alpha(png_ptr);
1648 #else
1649 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1650 #endif
1651
1652 /* ----------------------- end of transformations ------------------- */
1653
1654 /* Write the bits */
1655 png_write_image(png_ptr, info_ptr->row_pointers);
1656
1657 /* It is REQUIRED to call this to finish writing the rest of the file */
1658 png_write_end(png_ptr, info_ptr);
1659
1660 PNG_UNUSED(params)
1661 }
1662 #endif
1663
1664
1665 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
1666 #ifdef PNG_STDIO_SUPPORTED /* currently required for png_image_write_* */
1667 /* Initialize the write structure - general purpose utility. */
1668 static int
1669 png_image_write_init(png_imagep image)
1670 {
1671 png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, image,
1672 png_safe_error, png_safe_warning);
1673
1674 if (png_ptr != NULL)
1675 {
1676 png_infop info_ptr = png_create_info_struct(png_ptr);
1677
1678 if (info_ptr != NULL)
1679 {
1680 png_controlp control = png_voidcast(png_controlp,
1681 png_malloc_warn(png_ptr, (sizeof *control)));
1682
1683 if (control != NULL)
1684 {
1685 memset(control, 0, (sizeof *control));
1686
1687 control->png_ptr = png_ptr;
1688 control->info_ptr = info_ptr;
1689 control->for_write = 1;
1690
1691 image->opaque = control;
1692 return 1;
1693 }
1694
1695 /* Error clean up */
1696 png_destroy_info_struct(png_ptr, &info_ptr);
1697 }
1698
1699 png_destroy_write_struct(&png_ptr, NULL);
1700 }
1701
1702 return png_image_error(image, "png_image_write_: out of memory");
1703 }
1704
1705 /* Arguments to png_image_write_main: */
1706 typedef struct
1707 {
1708 /* Arguments: */
1709 png_imagep image;
1710 png_const_voidp buffer;
1711 png_int_32 row_stride;
1712 png_const_voidp colormap;
1713 int convert_to_8bit;
1714 /* Local variables: */
1715 png_const_voidp first_row;
1716 ptrdiff_t row_bytes;
1717 png_voidp local_row;
1718 } png_image_write_control;
1719
1720 /* Write png_uint_16 input to a 16-bit PNG; the png_ptr has already been set to
1721 * do any necessary byte swapping. The component order is defined by the
1722 * png_image format value.
1723 */
1724 static int
1725 png_write_image_16bit(png_voidp argument)
1726 {
1727 png_image_write_control *display = png_voidcast(png_image_write_control*,
1728 argument);
1729 png_imagep image = display->image;
1730 png_structrp png_ptr = image->opaque->png_ptr;
1731
1732 png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
1733 display->first_row);
1734 png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
1735 png_uint_16p row_end;
1736 const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
1737 int aindex = 0;
1738 png_uint_32 y = image->height;
1739
1740 if (image->format & PNG_FORMAT_FLAG_ALPHA)
1741 {
1742 # ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
1743 if (image->format & PNG_FORMAT_FLAG_AFIRST)
1744 {
1745 aindex = -1;
1746 ++input_row; /* To point to the first component */
1747 ++output_row;
1748 }
1749
1750 else
1751 # endif
1752 aindex = channels;
1753 }
1754
1755 else
1756 png_error(png_ptr, "png_write_image: internal call error");
1757
1758 /* Work out the output row end and count over this, note that the increment
1759 * above to 'row' means that row_end can actually be beyond the end of the
1760 * row; this is correct.
1761 */
1762 row_end = output_row + image->width * (channels+1);
1763
1764 while (y-- > 0)
1765 {
1766 png_const_uint_16p in_ptr = input_row;
1767 png_uint_16p out_ptr = output_row;
1768
1769 while (out_ptr < row_end)
1770 {
1771 const png_uint_16 alpha = in_ptr[aindex];
1772 png_uint_32 reciprocal = 0;
1773 int c;
1774
1775 out_ptr[aindex] = alpha;
1776
1777 /* Calculate a reciprocal. The correct calculation is simply
1778 * component/alpha*65535 << 15. (I.e. 15 bits of precision); this
1779 * allows correct rounding by adding .5 before the shift. 'reciprocal'
1780 * is only initialized when required.
1781 */
1782 if (alpha > 0 && alpha < 65535)
1783 reciprocal = ((0xffff<<15)+(alpha>>1))/alpha;
1784
1785 c = channels;
1786 do /* always at least one channel */
1787 {
1788 png_uint_16 component = *in_ptr++;
1789
1790 /* The following gives 65535 for an alpha of 0, which is fine,
1791 * otherwise if 0/0 is represented as some other value there is more
1792 * likely to be a discontinuity which will probably damage
1793 * compression when moving from a fully transparent area to a
1794 * nearly transparent one. (The assumption here is that opaque
1795 * areas tend not to be 0 intensity.)
1796 */
1797 if (component >= alpha)
1798 component = 65535;
1799
1800 /* component<alpha, so component/alpha is less than one and
1801 * component*reciprocal is less than 2^31.
1802 */
1803 else if (component > 0 && alpha < 65535)
1804 {
1805 png_uint_32 calc = component * reciprocal;
1806 calc += 16384; /* round to nearest */
1807 component = (png_uint_16)(calc >> 15);
1808 }
1809
1810 *out_ptr++ = component;
1811 }
1812 while (--c > 0);
1813
1814 /* Skip to next component (skip the intervening alpha channel) */
1815 ++in_ptr;
1816 ++out_ptr;
1817 }
1818
1819 png_write_row(png_ptr, png_voidcast(png_const_bytep, display->local_row));
1820 input_row += display->row_bytes/(sizeof (png_uint_16));
1821 }
1822
1823 return 1;
1824 }
1825
1826 /* Given 16-bit input (1 to 4 channels) write 8-bit output. If an alpha channel
1827 * is present it must be removed from the components, the components are then
1828 * written in sRGB encoding. No components are added or removed.
1829 *
1830 * Calculate an alpha reciprocal to reverse pre-multiplication. As above the
1831 * calculation can be done to 15 bits of accuracy; however, the output needs to
1832 * be scaled in the range 0..255*65535, so include that scaling here.
1833 */
1834 #define UNP_RECIPROCAL(alpha) ((((0xffff*0xff)<<7)+(alpha>>1))/alpha)
1835
1836 static png_byte
1837 png_unpremultiply(png_uint_32 component, png_uint_32 alpha,
1838 png_uint_32 reciprocal/*from the above macro*/)
1839 {
1840 /* The following gives 1.0 for an alpha of 0, which is fine, otherwise if 0/0
1841 * is represented as some other value there is more likely to be a
1842 * discontinuity which will probably damage compression when moving from a
1843 * fully transparent area to a nearly transparent one. (The assumption here
1844 * is that opaque areas tend not to be 0 intensity.)
1845 *
1846 * There is a rounding problem here; if alpha is less than 128 it will end up
1847 * as 0 when scaled to 8 bits. To avoid introducing spurious colors into the
1848 * output change for this too.
1849 */
1850 if (component >= alpha || alpha < 128)
1851 return 255;
1852
1853 /* component<alpha, so component/alpha is less than one and
1854 * component*reciprocal is less than 2^31.
1855 */
1856 else if (component > 0)
1857 {
1858 /* The test is that alpha/257 (rounded) is less than 255, the first value
1859 * that becomes 255 is 65407.
1860 * NOTE: this must agree with the PNG_DIV257 macro (which must, therefore,
1861 * be exact!) [Could also test reciprocal != 0]
1862 */
1863 if (alpha < 65407)
1864 {
1865 component *= reciprocal;
1866 component += 64; /* round to nearest */
1867 component >>= 7;
1868 }
1869
1870 else
1871 component *= 255;
1872
1873 /* Convert the component to sRGB. */
1874 return (png_byte)PNG_sRGB_FROM_LINEAR(component);
1875 }
1876
1877 else
1878 return 0;
1879 }
1880
1881 static int
1882 png_write_image_8bit(png_voidp argument)
1883 {
1884 png_image_write_control *display = png_voidcast(png_image_write_control*,
1885 argument);
1886 png_imagep image = display->image;
1887 png_structrp png_ptr = image->opaque->png_ptr;
1888
1889 png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
1890 display->first_row);
1891 png_bytep output_row = png_voidcast(png_bytep, display->local_row);
1892 png_uint_32 y = image->height;
1893 const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
1894
1895 if (image->format & PNG_FORMAT_FLAG_ALPHA)
1896 {
1897 png_bytep row_end;
1898 int aindex;
1899
1900 # ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
1901 if (image->format & PNG_FORMAT_FLAG_AFIRST)
1902 {
1903 aindex = -1;
1904 ++input_row; /* To point to the first component */
1905 ++output_row;
1906 }
1907
1908 else
1909 # endif
1910 aindex = channels;
1911
1912 /* Use row_end in place of a loop counter: */
1913 row_end = output_row + image->width * (channels+1);
1914
1915 while (y-- > 0)
1916 {
1917 png_const_uint_16p in_ptr = input_row;
1918 png_bytep out_ptr = output_row;
1919
1920 while (out_ptr < row_end)
1921 {
1922 png_uint_16 alpha = in_ptr[aindex];
1923 png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
1924 png_uint_32 reciprocal = 0;
1925 int c;
1926
1927 /* Scale and write the alpha channel. */
1928 out_ptr[aindex] = alphabyte;
1929
1930 if (alphabyte > 0 && alphabyte < 255)
1931 reciprocal = UNP_RECIPROCAL(alpha);
1932
1933 c = channels;
1934 do /* always at least one channel */
1935 *out_ptr++ = png_unpremultiply(*in_ptr++, alpha, reciprocal);
1936 while (--c > 0);
1937
1938 /* Skip to next component (skip the intervening alpha channel) */
1939 ++in_ptr;
1940 ++out_ptr;
1941 } /* while out_ptr < row_end */
1942
1943 png_write_row(png_ptr, png_voidcast(png_const_bytep,
1944 display->local_row));
1945 input_row += display->row_bytes/(sizeof (png_uint_16));
1946 } /* while y */
1947 }
1948
1949 else
1950 {
1951 /* No alpha channel, so the row_end really is the end of the row and it
1952 * is sufficient to loop over the components one by one.
1953 */
1954 png_bytep row_end = output_row + image->width * channels;
1955
1956 while (y-- > 0)
1957 {
1958 png_const_uint_16p in_ptr = input_row;
1959 png_bytep out_ptr = output_row;
1960
1961 while (out_ptr < row_end)
1962 {
1963 png_uint_32 component = *in_ptr++;
1964
1965 component *= 255;
1966 *out_ptr++ = (png_byte)PNG_sRGB_FROM_LINEAR(component);
1967 }
1968
1969 png_write_row(png_ptr, output_row);
1970 input_row += display->row_bytes/(sizeof (png_uint_16));
1971 }
1972 }
1973
1974 return 1;
1975 }
1976
1977 static void
1978 png_image_set_PLTE(png_image_write_control *display)
1979 {
1980 const png_imagep image = display->image;
1981 const void *cmap = display->colormap;
1982 const int entries = image->colormap_entries > 256 ? 256 :
1983 (int)image->colormap_entries;
1984
1985 /* NOTE: the caller must check for cmap != NULL and entries != 0 */
1986 const png_uint_32 format = image->format;
1987 const int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
1988
1989 # if defined(PNG_FORMAT_BGR_SUPPORTED) &&\
1990 defined(PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED)
1991 const int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1992 (format & PNG_FORMAT_FLAG_ALPHA) != 0;
1993 # else
1994 # define afirst 0
1995 # endif
1996
1997 # ifdef PNG_FORMAT_BGR_SUPPORTED
1998 const int bgr = (format & PNG_FORMAT_FLAG_BGR) ? 2 : 0;
1999 # else
2000 # define bgr 0
2001 # endif
2002
2003 int i, num_trans;
2004 png_color palette[256];
2005 png_byte tRNS[256];
2006
2007 memset(tRNS, 255, (sizeof tRNS));
2008 memset(palette, 0, (sizeof palette));
2009
2010 for (i=num_trans=0; i<entries; ++i)
2011 {
2012 /* This gets automatically converted to sRGB with reversal of the
2013 * pre-multiplication if the color-map has an alpha channel.
2014 */
2015 if (format & PNG_FORMAT_FLAG_LINEAR)
2016 {
2017 png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);
2018
2019 entry += i * channels;
2020
2021 if (channels & 1) /* no alpha */
2022 {
2023 if (channels >= 3) /* RGB */
2024 {
2025 palette[i].blue = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
2026 entry[(2 ^ bgr)]);
2027 palette[i].green = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
2028 entry[1]);
2029 palette[i].red = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
2030 entry[bgr]);
2031 }
2032
2033 else /* Gray */
2034 palette[i].blue = palette[i].red = palette[i].green =
2035 (png_byte)PNG_sRGB_FROM_LINEAR(255 * *entry);
2036 }
2037
2038 else /* alpha */
2039 {
2040 png_uint_16 alpha = entry[afirst ? 0 : channels-1];
2041 png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
2042 png_uint_32 reciprocal = 0;
2043
2044 /* Calculate a reciprocal, as in the png_write_image_8bit code above
2045 * this is designed to produce a value scaled to 255*65535 when
2046 * divided by 128 (i.e. asr 7).
2047 */
2048 if (alphabyte > 0 && alphabyte < 255)
2049 reciprocal = (((0xffff*0xff)<<7)+(alpha>>1))/alpha;
2050
2051 tRNS[i] = alphabyte;
2052 if (alphabyte < 255)
2053 num_trans = i+1;
2054
2055 if (channels >= 3) /* RGB */
2056 {
2057 palette[i].blue = png_unpremultiply(entry[afirst + (2 ^ bgr)],
2058 alpha, reciprocal);
2059 palette[i].green = png_unpremultiply(entry[afirst + 1], alpha,
2060 reciprocal);
2061 palette[i].red = png_unpremultiply(entry[afirst + bgr], alpha,
2062 reciprocal);
2063 }
2064
2065 else /* gray */
2066 palette[i].blue = palette[i].red = palette[i].green =
2067 png_unpremultiply(entry[afirst], alpha, reciprocal);
2068 }
2069 }
2070
2071 else /* Color-map has sRGB values */
2072 {
2073 png_const_bytep entry = png_voidcast(png_const_bytep, cmap);
2074
2075 entry += i * channels;
2076
2077 switch (channels)
2078 {
2079 case 4:
2080 tRNS[i] = entry[afirst ? 0 : 3];
2081 if (tRNS[i] < 255)
2082 num_trans = i+1;
2083 /* FALL THROUGH */
2084 case 3:
2085 palette[i].blue = entry[afirst + (2 ^ bgr)];
2086 palette[i].green = entry[afirst + 1];
2087 palette[i].red = entry[afirst + bgr];
2088 break;
2089
2090 case 2:
2091 tRNS[i] = entry[1 ^ afirst];
2092 if (tRNS[i] < 255)
2093 num_trans = i+1;
2094 /* FALL THROUGH */
2095 case 1:
2096 palette[i].blue = palette[i].red = palette[i].green =
2097 entry[afirst];
2098 break;
2099
2100 default:
2101 break;
2102 }
2103 }
2104 }
2105
2106 # ifdef afirst
2107 # undef afirst
2108 # endif
2109 # ifdef bgr
2110 # undef bgr
2111 # endif
2112
2113 png_set_PLTE(image->opaque->png_ptr, image->opaque->info_ptr, palette,
2114 entries);
2115
2116 if (num_trans > 0)
2117 png_set_tRNS(image->opaque->png_ptr, image->opaque->info_ptr, tRNS,
2118 num_trans, NULL);
2119
2120 image->colormap_entries = entries;
2121 }
2122
2123 static int
2124 png_image_write_main(png_voidp argument)
2125 {
2126 png_image_write_control *display = png_voidcast(png_image_write_control*,
2127 argument);
2128 png_imagep image = display->image;
2129 png_structrp png_ptr = image->opaque->png_ptr;
2130 png_inforp info_ptr = image->opaque->info_ptr;
2131 png_uint_32 format = image->format;
2132
2133 int colormap = (format & PNG_FORMAT_FLAG_COLORMAP) != 0;
2134 int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR) != 0; /* input */
2135 int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA) != 0;
2136 int write_16bit = linear && !colormap && !display->convert_to_8bit;
2137
2138 # ifdef PNG_BENIGN_ERRORS_SUPPORTED
2139 /* Make sure we error out on any bad situation */
2140 png_set_benign_errors(png_ptr, 0/*error*/);
2141 # endif
2142
2143 /* Default the 'row_stride' parameter if required. */
2144 if (display->row_stride == 0)
2145 display->row_stride = PNG_IMAGE_ROW_STRIDE(*image);
2146
2147 /* Set the required transforms then write the rows in the correct order. */
2148 if (format & PNG_FORMAT_FLAG_COLORMAP)
2149 {
2150 if (display->colormap != NULL && image->colormap_entries > 0)
2151 {
2152 png_uint_32 entries = image->colormap_entries;
2153
2154 png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
2155 entries > 16 ? 8 : (entries > 4 ? 4 : (entries > 2 ? 2 : 1)),
2156 PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
2157 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
2158
2159 png_image_set_PLTE(display);
2160 }
2161
2162 else
2163 png_error(image->opaque->png_ptr,
2164 "no color-map for color-mapped image");
2165 }
2166
2167 else
2168 png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
2169 write_16bit ? 16 : 8,
2170 ((format & PNG_FORMAT_FLAG_COLOR) ? PNG_COLOR_MASK_COLOR : 0) +
2171 ((format & PNG_FORMAT_FLAG_ALPHA) ? PNG_COLOR_MASK_ALPHA : 0),
2172 PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
2173
2174 /* Counter-intuitively the data transformations must be called *after*
2175 * png_write_info, not before as in the read code, but the 'set' functions
2176 * must still be called before. Just set the color space information, never
2177 * write an interlaced image.
2178 */
2179
2180 if (write_16bit)
2181 {
2182 /* The gamma here is 1.0 (linear) and the cHRM chunk matches sRGB. */
2183 png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_LINEAR);
2184
2185 if (!(image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB))
2186 png_set_cHRM_fixed(png_ptr, info_ptr,
2187 /* color x y */
2188 /* white */ 31270, 32900,
2189 /* red */ 64000, 33000,
2190 /* green */ 30000, 60000,
2191 /* blue */ 15000, 6000
2192 );
2193 }
2194
2195 else if (!(image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB))
2196 png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_PERCEPTUAL);
2197
2198 /* Else writing an 8-bit file and the *colors* aren't sRGB, but the 8-bit
2199 * space must still be gamma encoded.
2200 */
2201 else
2202 png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_sRGB_INVERSE);
2203
2204 /* Write the file header. */
2205 png_write_info(png_ptr, info_ptr);
2206
2207 /* Now set up the data transformations (*after* the header is written),
2208 * remove the handled transformations from the 'format' flags for checking.
2209 *
2210 * First check for a little endian system if writing 16 bit files.
2211 */
2212 if (write_16bit)
2213 {
2214 PNG_CONST png_uint_16 le = 0x0001;
2215
2216 if (*(png_const_bytep)&le)
2217 png_set_swap(png_ptr);
2218 }
2219
2220 # ifdef PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
2221 if (format & PNG_FORMAT_FLAG_BGR)
2222 {
2223 if (!colormap && (format & PNG_FORMAT_FLAG_COLOR) != 0)
2224 png_set_bgr(png_ptr);
2225 format &= ~PNG_FORMAT_FLAG_BGR;
2226 }
2227 # endif
2228
2229 # ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
2230 if (format & PNG_FORMAT_FLAG_AFIRST)
2231 {
2232 if (!colormap && (format & PNG_FORMAT_FLAG_ALPHA) != 0)
2233 png_set_swap_alpha(png_ptr);
2234 format &= ~PNG_FORMAT_FLAG_AFIRST;
2235 }
2236 # endif
2237
2238 /* If there are 16 or fewer color-map entries we wrote a lower bit depth
2239 * above, but the application data is still byte packed.
2240 */
2241 if (colormap && image->colormap_entries <= 16)
2242 png_set_packing(png_ptr);
2243
2244 /* That should have handled all (both) the transforms. */
2245 if ((format & ~(png_uint_32)(PNG_FORMAT_FLAG_COLOR | PNG_FORMAT_FLAG_LINEAR |
2246 PNG_FORMAT_FLAG_ALPHA | PNG_FORMAT_FLAG_COLORMAP)) != 0)
2247 png_error(png_ptr, "png_write_image: unsupported transformation");
2248
2249 {
2250 png_const_bytep row = png_voidcast(png_const_bytep, display->buffer);
2251 ptrdiff_t row_bytes = display->row_stride;
2252
2253 if (linear)
2254 row_bytes *= (sizeof (png_uint_16));
2255
2256 if (row_bytes < 0)
2257 row += (image->height-1) * (-row_bytes);
2258
2259 display->first_row = row;
2260 display->row_bytes = row_bytes;
2261 }
2262
2263 /* Apply 'fast' options if the flag is set. */
2264 if ((image->flags & PNG_IMAGE_FLAG_FAST) != 0)
2265 {
2266 png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_NO_FILTERS);
2267 /* NOTE: determined by experiment using pngstest, this reflects some
2268 * balance between the time to write the image once and the time to read
2269 * it about 50 times. The speed-up in pngstest was about 10-20% of the
2270 * total (user) time on a heavily loaded system.
2271 */
2272 png_set_compression_level(png_ptr, 3);
2273 }
2274
2275 /* Check for the cases that currently require a pre-transform on the row
2276 * before it is written. This only applies when the input is 16-bit and
2277 * either there is an alpha channel or it is converted to 8-bit.
2278 */
2279 if ((linear && alpha) || (!colormap && display->convert_to_8bit))
2280 {
2281 png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr,
2282 png_get_rowbytes(png_ptr, info_ptr)));
2283 int result;
2284
2285 display->local_row = row;
2286 if (write_16bit)
2287 result = png_safe_execute(image, png_write_image_16bit, display);
2288 else
2289 result = png_safe_execute(image, png_write_image_8bit, display);
2290 display->local_row = NULL;
2291
2292 png_free(png_ptr, row);
2293
2294 /* Skip the 'write_end' on error: */
2295 if (!result)
2296 return 0;
2297 }
2298
2299 /* Otherwise this is the case where the input is in a format currently
2300 * supported by the rest of the libpng write code; call it directly.
2301 */
2302 else
2303 {
2304 png_const_bytep row = png_voidcast(png_const_bytep, display->first_row);
2305 ptrdiff_t row_bytes = display->row_bytes;
2306 png_uint_32 y = image->height;
2307
2308 while (y-- > 0)
2309 {
2310 png_write_row(png_ptr, row);
2311 row += row_bytes;
2312 }
2313 }
2314
2315 png_write_end(png_ptr, info_ptr);
2316 return 1;
2317 }
2318
2319 int PNGAPI
2320 png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
2321 const void *buffer, png_int_32 row_stride, const void *colormap)
2322 {
2323 /* Write the image to the given (FILE*). */
2324 if (image != NULL && image->version == PNG_IMAGE_VERSION)
2325 {
2326 if (file != NULL)
2327 {
2328 if (png_image_write_init(image))
2329 {
2330 png_image_write_control display;
2331 int result;
2332
2333 /* This is slightly evil, but png_init_io doesn't do anything other
2334 * than this and we haven't changed the standard IO functions so
2335 * this saves a 'safe' function.
2336 */
2337 image->opaque->png_ptr->io_ptr = file;
2338
2339 memset(&display, 0, (sizeof display));
2340 display.image = image;
2341 display.buffer = buffer;
2342 display.row_stride = row_stride;
2343 display.colormap = colormap;
2344 display.convert_to_8bit = convert_to_8bit;
2345
2346 result = png_safe_execute(image, png_image_write_main, &display);
2347 png_image_free(image);
2348 return result;
2349 }
2350
2351 else
2352 return 0;
2353 }
2354
2355 else
2356 return png_image_error(image,
2357 "png_image_write_to_stdio: invalid argument");
2358 }
2359
2360 else if (image != NULL)
2361 return png_image_error(image,
2362 "png_image_write_to_stdio: incorrect PNG_IMAGE_VERSION");
2363
2364 else
2365 return 0;
2366 }
2367
2368 int PNGAPI
2369 png_image_write_to_file(png_imagep image, const char *file_name,
2370 int convert_to_8bit, const void *buffer, png_int_32 row_stride,
2371 const void *colormap)
2372 {
2373 /* Write the image to the named file. */
2374 if (image != NULL && image->version == PNG_IMAGE_VERSION)
2375 {
2376 if (file_name != NULL)
2377 {
2378 FILE *fp = fopen(file_name, "wb");
2379
2380 if (fp != NULL)
2381 {
2382 if (png_image_write_to_stdio(image, fp, convert_to_8bit, buffer,
2383 row_stride, colormap))
2384 {
2385 int error; /* from fflush/fclose */
2386
2387 /* Make sure the file is flushed correctly. */
2388 if (fflush(fp) == 0 && ferror(fp) == 0)
2389 {
2390 if (fclose(fp) == 0)
2391 return 1;
2392
2393 error = errno; /* from fclose */
2394 }
2395
2396 else
2397 {
2398 error = errno; /* from fflush or ferror */
2399 (void)fclose(fp);
2400 }
2401
2402 (void)remove(file_name);
2403 /* The image has already been cleaned up; this is just used to
2404 * set the error (because the original write succeeded).
2405 */
2406 return png_image_error(image, strerror(error));
2407 }
2408
2409 else
2410 {
2411 /* Clean up: just the opened file. */
2412 (void)fclose(fp);
2413 (void)remove(file_name);
2414 return 0;
2415 }
2416 }
2417
2418 else
2419 return png_image_error(image, strerror(errno));
2420 }
2421
2422 else
2423 return png_image_error(image,
2424 "png_image_write_to_file: invalid argument");
2425 }
2426
2427 else if (image != NULL)
2428 return png_image_error(image,
2429 "png_image_write_to_file: incorrect PNG_IMAGE_VERSION");
2430
2431 else
2432 return 0;
2433 }
2434 #endif /* PNG_STDIO_SUPPORTED */
2435 #endif /* SIMPLIFIED_WRITE */
2436 #endif /* PNG_WRITE_SUPPORTED */