2 /* pngwrite.c - general routines to write a PNG file
4 * Last changed in libpng 1.6.11 [June 5, 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.)
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
15 #if defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
19 #ifdef PNG_WRITE_SUPPORTED
21 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
22 /* Write out all the unknown chunks for the current given location */
24 write_unknown_chunks(png_structrp png_ptr, png_const_inforp info_ptr,
27 if (info_ptr->unknown_chunks_num)
29 png_const_unknown_chunkp up;
31 png_debug(5, "writing extra chunks");
33 for (up = info_ptr->unknown_chunks;
34 up < info_ptr->unknown_chunks + info_ptr->unknown_chunks_num;
36 if (up->location & where)
38 /* If per-chunk unknown chunk handling is enabled use it, otherwise
39 * just write the chunks the application has set.
41 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
42 int keep = png_handle_as_unknown(png_ptr, up->name);
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
51 * The default handling is also slightly weird - it is not possible to
52 * stop the writing of all unsafe-to-copy chunks!
54 * TODO: REVIEW: this would seem to be a bug.
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)))
63 /* TODO: review, what is wrong with a zero length unknown chunk? */
65 png_warning(png_ptr, "Writing zero-length unknown chunk");
67 png_write_chunk(png_ptr, up->name, up->data, up->size);
72 #endif /* PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED */
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.
84 png_write_info_before_PLTE(png_structrp png_ptr, png_const_inforp info_ptr)
86 png_debug(1, "in png_write_info_before_PLTE");
88 if (png_ptr == NULL || info_ptr == NULL)
91 if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
93 /* Write PNG signature */
94 png_write_sig(png_ptr);
96 #ifdef PNG_MNG_FEATURES_SUPPORTED
97 if ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) && \
98 (png_ptr->mng_features_permitted))
100 png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
101 png_ptr->mng_features_permitted = 0;
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
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.
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.)
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
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);
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.
143 # ifdef PNG_WRITE_iCCP_SUPPORTED
144 if (!(info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) &&
145 (info_ptr->valid & PNG_INFO_iCCP))
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");
153 png_write_iCCP(png_ptr, info_ptr->iccp_name,
154 info_ptr->iccp_profile);
156 # ifdef PNG_WRITE_sRGB_SUPPORTED
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 */
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);
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);
182 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
183 write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_IHDR);
186 png_ptr->mode |= PNG_WROTE_INFO_BEFORE_PLTE;
191 png_write_info(png_structrp png_ptr, png_const_inforp info_ptr)
193 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
197 png_debug(1, "in png_write_info");
199 if (png_ptr == NULL || info_ptr == NULL)
202 png_write_info_before_PLTE(png_ptr, info_ptr);
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);
208 else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
209 png_error(png_ptr, "Valid palette required for paletted images");
211 #ifdef PNG_WRITE_tRNS_SUPPORTED
212 if (info_ptr->valid & PNG_INFO_tRNS)
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)
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]);
225 png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color),
226 info_ptr->num_trans, info_ptr->color_type);
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);
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);
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);
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);
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);
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);
264 #ifdef PNG_WRITE_tIME_SUPPORTED
265 if (info_ptr->valid & PNG_INFO_tIME)
267 png_write_tIME(png_ptr, &(info_ptr->mod_time));
268 png_ptr->mode |= PNG_WROTE_tIME;
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);
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++)
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)
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);
296 png_warning(png_ptr, "Unable to write international text");
298 /* Mark this chunk as written */
299 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
302 /* If we want a compressed text chunk */
303 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_zTXt)
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);
311 png_warning(png_ptr, "Unable to write compressed text");
313 /* Mark this chunk as written */
314 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
317 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
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,
324 /* Mark this chunk as written */
325 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
328 png_warning(png_ptr, "Unable to write uncompressed text");
334 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
335 write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_PLTE);
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.
345 png_write_end(png_structrp png_ptr, png_inforp info_ptr)
347 png_debug(1, "in png_write_end");
352 if (!(png_ptr->mode & PNG_HAVE_IDAT))
353 png_error(png_ptr, "No IDATs written into file");
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");
360 /* See if user wants us to write information chunks */
361 if (info_ptr != NULL)
363 #ifdef PNG_WRITE_TEXT_SUPPORTED
364 int i; /* local index variable */
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));
373 #ifdef PNG_WRITE_TEXT_SUPPORTED
374 /* Loop through comment chunks */
375 for (i = 0; i < info_ptr->num_text; i++)
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)
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);
391 png_warning(png_ptr, "Unable to write international text");
393 /* Mark this chunk as written */
394 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
397 else if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
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);
405 png_warning(png_ptr, "Unable to write compressed text");
407 /* Mark this chunk as written */
408 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
411 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
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);
418 png_warning(png_ptr, "Unable to write uncompressed text");
421 /* Mark this chunk as written */
422 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
426 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
427 write_unknown_chunks(png_ptr, info_ptr, PNG_AFTER_IDAT);
431 png_ptr->mode |= PNG_AFTER_IDAT;
433 /* Write end of PNG file */
434 png_write_IEND(png_ptr);
436 /* This flush, added in libpng-1.0.8, removed from libpng-1.0.9beta03,
437 * and restored again in libpng-1.2.30, may cause some applications that
438 * do not set png_ptr->output_flush_fn to crash. If your application
439 * experiences a problem, please try building libpng with
440 * PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED defined, and report the event to
441 * png-mng-implement at lists.sf.net .
443 #ifdef PNG_WRITE_FLUSH_SUPPORTED
444 # ifdef PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED
450 #ifdef PNG_CONVERT_tIME_SUPPORTED
452 png_convert_from_struct_tm(png_timep ptime, PNG_CONST struct tm * ttime)
454 png_debug(1, "in png_convert_from_struct_tm");
456 ptime->year = (png_uint_16)(1900 + ttime->tm_year);
457 ptime->month = (png_byte)(ttime->tm_mon + 1);
458 ptime->day = (png_byte)ttime->tm_mday;
459 ptime->hour = (png_byte)ttime->tm_hour;
460 ptime->minute = (png_byte)ttime->tm_min;
461 ptime->second = (png_byte)ttime->tm_sec;
465 png_convert_from_time_t(png_timep ptime, time_t ttime)
469 png_debug(1, "in png_convert_from_time_t");
471 tbuf = gmtime(&ttime);
472 png_convert_from_struct_tm(ptime, tbuf);
476 /* Initialize png_ptr structure, and allocate any memory needed */
477 PNG_FUNCTION(png_structp,PNGAPI
478 png_create_write_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
479 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
481 #ifndef PNG_USER_MEM_SUPPORTED
482 png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
483 error_fn, warn_fn, NULL, NULL, NULL);
485 return png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
486 warn_fn, NULL, NULL, NULL);
489 /* Alternate initialize png_ptr structure, and allocate any memory needed */
490 PNG_FUNCTION(png_structp,PNGAPI
491 png_create_write_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
492 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
493 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
495 png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
496 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
497 #endif /* PNG_USER_MEM_SUPPORTED */
500 /* Set the zlib control values to defaults; they can be overridden by the
501 * application after the struct has been created.
503 png_ptr->zbuffer_size = PNG_ZBUF_SIZE;
505 /* The 'zlib_strategy' setting is irrelevant because png_default_claim in
506 * pngwutil.c defaults it according to whether or not filters will be
507 * used, and ignores this setting.
509 png_ptr->zlib_strategy = PNG_Z_DEFAULT_STRATEGY;
510 png_ptr->zlib_level = PNG_Z_DEFAULT_COMPRESSION;
511 png_ptr->zlib_mem_level = 8;
512 png_ptr->zlib_window_bits = 15;
513 png_ptr->zlib_method = 8;
515 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
516 png_ptr->zlib_text_strategy = PNG_TEXT_Z_DEFAULT_STRATEGY;
517 png_ptr->zlib_text_level = PNG_TEXT_Z_DEFAULT_COMPRESSION;
518 png_ptr->zlib_text_mem_level = 8;
519 png_ptr->zlib_text_window_bits = 15;
520 png_ptr->zlib_text_method = 8;
521 #endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
523 /* This is a highly dubious configuration option; by default it is off,
524 * but it may be appropriate for private builds that are testing
525 * extensions not conformant to the current specification, or of
526 * applications that must not fail to write at all costs!
528 #ifdef PNG_BENIGN_WRITE_ERRORS_SUPPORTED
529 /* In stable builds only warn if an application error can be completely
532 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
535 /* App warnings are warnings in release (or release candidate) builds but
536 * are errors during development.
538 #if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
539 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
542 /* TODO: delay this, it can be done in png_init_io() (if the app doesn't
543 * do it itself) avoiding setting the default function if it is not
546 png_set_write_fn(png_ptr, NULL, NULL, NULL);
553 /* Write a few rows of image data. If the image is interlaced,
554 * either you will have to write the 7 sub images, or, if you
555 * have called png_set_interlace_handling(), you will have to
556 * "write" the image seven times.
559 png_write_rows(png_structrp png_ptr, png_bytepp row,
560 png_uint_32 num_rows)
562 png_uint_32 i; /* row counter */
563 png_bytepp rp; /* row pointer */
565 png_debug(1, "in png_write_rows");
570 /* Loop through the rows */
571 for (i = 0, rp = row; i < num_rows; i++, rp++)
573 png_write_row(png_ptr, *rp);
577 /* Write the image. You only need to call this function once, even
578 * if you are writing an interlaced image.
581 png_write_image(png_structrp png_ptr, png_bytepp image)
583 png_uint_32 i; /* row index */
584 int pass, num_pass; /* pass variables */
585 png_bytepp rp; /* points to current row */
590 png_debug(1, "in png_write_image");
592 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
593 /* Initialize interlace handling. If image is not interlaced,
594 * this will set pass to 1
596 num_pass = png_set_interlace_handling(png_ptr);
600 /* Loop through passes */
601 for (pass = 0; pass < num_pass; pass++)
603 /* Loop through image */
604 for (i = 0, rp = image; i < png_ptr->height; i++, rp++)
606 png_write_row(png_ptr, *rp);
611 #ifdef PNG_MNG_FEATURES_SUPPORTED
612 /* Performs intrapixel differencing */
614 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
616 png_debug(1, "in png_do_write_intrapixel");
618 if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
621 png_uint_32 row_width = row_info->width;
622 if (row_info->bit_depth == 8)
627 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
630 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
636 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
638 *(rp) = (png_byte)((*rp - *(rp + 1)) & 0xff);
639 *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
643 #ifdef PNG_WRITE_16BIT_SUPPORTED
644 else if (row_info->bit_depth == 16)
649 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
652 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
658 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
660 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
661 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
662 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
663 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
664 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
665 *(rp ) = (png_byte)((red >> 8) & 0xff);
666 *(rp + 1) = (png_byte)(red & 0xff);
667 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
668 *(rp + 5) = (png_byte)(blue & 0xff);
671 #endif /* PNG_WRITE_16BIT_SUPPORTED */
674 #endif /* PNG_MNG_FEATURES_SUPPORTED */
676 /* Called by user to write a row of image data */
678 png_write_row(png_structrp png_ptr, png_const_bytep row)
680 /* 1.5.6: moved from png_struct to be a local structure: */
681 png_row_info row_info;
686 png_debug2(1, "in png_write_row (row %u, pass %d)",
687 png_ptr->row_number, png_ptr->pass);
689 /* Initialize transformations and other stuff if first time */
690 if (png_ptr->row_number == 0 && png_ptr->pass == 0)
692 /* Make sure we wrote the header info */
693 if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
695 "png_write_info was never called before png_write_row");
697 /* Check for transforms that have been set but were defined out */
698 #if !defined(PNG_WRITE_INVERT_SUPPORTED) && defined(PNG_READ_INVERT_SUPPORTED)
699 if (png_ptr->transformations & PNG_INVERT_MONO)
700 png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined");
703 #if !defined(PNG_WRITE_FILLER_SUPPORTED) && defined(PNG_READ_FILLER_SUPPORTED)
704 if (png_ptr->transformations & PNG_FILLER)
705 png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined");
707 #if !defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
708 defined(PNG_READ_PACKSWAP_SUPPORTED)
709 if (png_ptr->transformations & PNG_PACKSWAP)
711 "PNG_WRITE_PACKSWAP_SUPPORTED is not defined");
714 #if !defined(PNG_WRITE_PACK_SUPPORTED) && defined(PNG_READ_PACK_SUPPORTED)
715 if (png_ptr->transformations & PNG_PACK)
716 png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined");
719 #if !defined(PNG_WRITE_SHIFT_SUPPORTED) && defined(PNG_READ_SHIFT_SUPPORTED)
720 if (png_ptr->transformations & PNG_SHIFT)
721 png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined");
724 #if !defined(PNG_WRITE_BGR_SUPPORTED) && defined(PNG_READ_BGR_SUPPORTED)
725 if (png_ptr->transformations & PNG_BGR)
726 png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined");
729 #if !defined(PNG_WRITE_SWAP_SUPPORTED) && defined(PNG_READ_SWAP_SUPPORTED)
730 if (png_ptr->transformations & PNG_SWAP_BYTES)
731 png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined");
734 png_write_start_row(png_ptr);
737 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
738 /* If interlaced and not interested in row, return */
739 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
741 switch (png_ptr->pass)
744 if (png_ptr->row_number & 0x07)
746 png_write_finish_row(png_ptr);
752 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
754 png_write_finish_row(png_ptr);
760 if ((png_ptr->row_number & 0x07) != 4)
762 png_write_finish_row(png_ptr);
768 if ((png_ptr->row_number & 0x03) || png_ptr->width < 3)
770 png_write_finish_row(png_ptr);
776 if ((png_ptr->row_number & 0x03) != 2)
778 png_write_finish_row(png_ptr);
784 if ((png_ptr->row_number & 0x01) || png_ptr->width < 2)
786 png_write_finish_row(png_ptr);
792 if (!(png_ptr->row_number & 0x01))
794 png_write_finish_row(png_ptr);
799 default: /* error: ignore it */
805 /* Set up row info for transformations */
806 row_info.color_type = png_ptr->color_type;
807 row_info.width = png_ptr->usr_width;
808 row_info.channels = png_ptr->usr_channels;
809 row_info.bit_depth = png_ptr->usr_bit_depth;
810 row_info.pixel_depth = (png_byte)(row_info.bit_depth * row_info.channels);
811 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
813 png_debug1(3, "row_info->color_type = %d", row_info.color_type);
814 png_debug1(3, "row_info->width = %u", row_info.width);
815 png_debug1(3, "row_info->channels = %d", row_info.channels);
816 png_debug1(3, "row_info->bit_depth = %d", row_info.bit_depth);
817 png_debug1(3, "row_info->pixel_depth = %d", row_info.pixel_depth);
818 png_debug1(3, "row_info->rowbytes = %lu", (unsigned long)row_info.rowbytes);
820 /* Copy user's row into buffer, leaving room for filter byte. */
821 memcpy(png_ptr->row_buf + 1, row, row_info.rowbytes);
823 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
824 /* Handle interlacing */
825 if (png_ptr->interlaced && png_ptr->pass < 6 &&
826 (png_ptr->transformations & PNG_INTERLACE))
828 png_do_write_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass);
829 /* This should always get caught above, but still ... */
830 if (row_info.width == 0)
832 png_write_finish_row(png_ptr);
838 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
839 /* Handle other transformations */
840 if (png_ptr->transformations)
841 png_do_write_transformations(png_ptr, &row_info);
844 /* At this point the row_info pixel depth must match the 'transformed' depth,
845 * which is also the output depth.
847 if (row_info.pixel_depth != png_ptr->pixel_depth ||
848 row_info.pixel_depth != png_ptr->transformed_pixel_depth)
849 png_error(png_ptr, "internal write transform logic error");
851 #ifdef PNG_MNG_FEATURES_SUPPORTED
852 /* Write filter_method 64 (intrapixel differencing) only if
853 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
854 * 2. Libpng did not write a PNG signature (this filter_method is only
855 * used in PNG datastreams that are embedded in MNG datastreams) and
856 * 3. The application called png_permit_mng_features with a mask that
857 * included PNG_FLAG_MNG_FILTER_64 and
858 * 4. The filter_method is 64 and
859 * 5. The color_type is RGB or RGBA
861 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
862 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
864 /* Intrapixel differencing */
865 png_do_write_intrapixel(&row_info, png_ptr->row_buf + 1);
869 /* Added at libpng-1.5.10 */
870 #ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
871 /* Check for out-of-range palette index */
872 if (row_info.color_type == PNG_COLOR_TYPE_PALETTE &&
873 png_ptr->num_palette_max >= 0)
874 png_do_check_palette_indexes(png_ptr, &row_info);
877 /* Find a filter if necessary, filter the row and write it out. */
878 png_write_find_filter(png_ptr, &row_info);
880 if (png_ptr->write_row_fn != NULL)
881 (*(png_ptr->write_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
884 #ifdef PNG_WRITE_FLUSH_SUPPORTED
885 /* Set the automatic flush interval or 0 to turn flushing off */
887 png_set_flush(png_structrp png_ptr, int nrows)
889 png_debug(1, "in png_set_flush");
894 png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
897 /* Flush the current output buffers now */
899 png_write_flush(png_structrp png_ptr)
901 png_debug(1, "in png_write_flush");
906 /* We have already written out all of the data */
907 if (png_ptr->row_number >= png_ptr->num_rows)
910 png_compress_IDAT(png_ptr, NULL, 0, Z_SYNC_FLUSH);
911 png_ptr->flush_rows = 0;
914 #endif /* PNG_WRITE_FLUSH_SUPPORTED */
916 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
917 static void png_reset_filter_heuristics(png_structrp png_ptr);/* forward decl */
920 /* Free any memory used in png_ptr struct without freeing the struct itself. */
922 png_write_destroy(png_structrp png_ptr)
924 png_debug(1, "in png_write_destroy");
926 /* Free any memory zlib uses */
927 if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
928 deflateEnd(&png_ptr->zstream);
930 /* Free our memory. png_free checks NULL for us. */
931 png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
932 png_free(png_ptr, png_ptr->row_buf);
933 #ifdef PNG_WRITE_FILTER_SUPPORTED
934 png_free(png_ptr, png_ptr->prev_row);
935 png_free(png_ptr, png_ptr->sub_row);
936 png_free(png_ptr, png_ptr->up_row);
937 png_free(png_ptr, png_ptr->avg_row);
938 png_free(png_ptr, png_ptr->paeth_row);
941 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
942 /* Use this to save a little code space, it doesn't free the filter_costs */
943 png_reset_filter_heuristics(png_ptr);
944 png_free(png_ptr, png_ptr->filter_costs);
945 png_free(png_ptr, png_ptr->inv_filter_costs);
948 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
949 png_free(png_ptr, png_ptr->chunk_list);
952 /* The error handling and memory handling information is left intact at this
953 * point: the jmp_buf may still have to be freed. See png_destroy_png_struct
954 * for how this happens.
958 /* Free all memory used by the write.
959 * In libpng 1.6.0 this API changed quietly to no longer accept a NULL value for
960 * *png_ptr_ptr. Prior to 1.6.0 it would accept such a value and it would free
961 * the passed in info_structs but it would quietly fail to free any of the data
962 * inside them. In 1.6.0 it quietly does nothing (it has to be quiet because it
966 png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
968 png_debug(1, "in png_destroy_write_struct");
970 if (png_ptr_ptr != NULL)
972 png_structrp png_ptr = *png_ptr_ptr;
974 if (png_ptr != NULL) /* added in libpng 1.6.0 */
976 png_destroy_info_struct(png_ptr, info_ptr_ptr);
979 png_write_destroy(png_ptr);
980 png_destroy_png_struct(png_ptr);
985 /* Allow the application to select one or more row filters to use. */
987 png_set_filter(png_structrp png_ptr, int method, int filters)
989 png_debug(1, "in png_set_filter");
994 #ifdef PNG_MNG_FEATURES_SUPPORTED
995 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
996 (method == PNG_INTRAPIXEL_DIFFERENCING))
997 method = PNG_FILTER_TYPE_BASE;
1000 if (method == PNG_FILTER_TYPE_BASE)
1002 switch (filters & (PNG_ALL_FILTERS | 0x07))
1004 #ifdef PNG_WRITE_FILTER_SUPPORTED
1007 case 7: png_app_error(png_ptr, "Unknown row filter for method 0");
1009 #endif /* PNG_WRITE_FILTER_SUPPORTED */
1010 case PNG_FILTER_VALUE_NONE:
1011 png_ptr->do_filter = PNG_FILTER_NONE; break;
1013 #ifdef PNG_WRITE_FILTER_SUPPORTED
1014 case PNG_FILTER_VALUE_SUB:
1015 png_ptr->do_filter = PNG_FILTER_SUB; break;
1017 case PNG_FILTER_VALUE_UP:
1018 png_ptr->do_filter = PNG_FILTER_UP; break;
1020 case PNG_FILTER_VALUE_AVG:
1021 png_ptr->do_filter = PNG_FILTER_AVG; break;
1023 case PNG_FILTER_VALUE_PAETH:
1024 png_ptr->do_filter = PNG_FILTER_PAETH; break;
1027 png_ptr->do_filter = (png_byte)filters; break;
1030 png_app_error(png_ptr, "Unknown row filter for method 0");
1031 #endif /* PNG_WRITE_FILTER_SUPPORTED */
1034 /* If we have allocated the row_buf, this means we have already started
1035 * with the image and we should have allocated all of the filter buffers
1036 * that have been selected. If prev_row isn't already allocated, then
1037 * it is too late to start using the filters that need it, since we
1038 * will be missing the data in the previous row. If an application
1039 * wants to start and stop using particular filters during compression,
1040 * it should start out with all of the filters, and then add and
1041 * remove them after the start of compression.
1043 if (png_ptr->row_buf != NULL)
1045 #ifdef PNG_WRITE_FILTER_SUPPORTED
1046 if ((png_ptr->do_filter & PNG_FILTER_SUB) && png_ptr->sub_row == NULL)
1048 png_ptr->sub_row = (png_bytep)png_malloc(png_ptr,
1049 (png_ptr->rowbytes + 1));
1050 png_ptr->sub_row[0] = PNG_FILTER_VALUE_SUB;
1053 if ((png_ptr->do_filter & PNG_FILTER_UP) && png_ptr->up_row == NULL)
1055 if (png_ptr->prev_row == NULL)
1057 png_warning(png_ptr, "Can't add Up filter after starting");
1058 png_ptr->do_filter = (png_byte)(png_ptr->do_filter &
1064 png_ptr->up_row = (png_bytep)png_malloc(png_ptr,
1065 (png_ptr->rowbytes + 1));
1066 png_ptr->up_row[0] = PNG_FILTER_VALUE_UP;
1070 if ((png_ptr->do_filter & PNG_FILTER_AVG) && png_ptr->avg_row == NULL)
1072 if (png_ptr->prev_row == NULL)
1074 png_warning(png_ptr, "Can't add Average filter after starting");
1075 png_ptr->do_filter = (png_byte)(png_ptr->do_filter &
1081 png_ptr->avg_row = (png_bytep)png_malloc(png_ptr,
1082 (png_ptr->rowbytes + 1));
1083 png_ptr->avg_row[0] = PNG_FILTER_VALUE_AVG;
1087 if ((png_ptr->do_filter & PNG_FILTER_PAETH) &&
1088 png_ptr->paeth_row == NULL)
1090 if (png_ptr->prev_row == NULL)
1092 png_warning(png_ptr, "Can't add Paeth filter after starting");
1093 png_ptr->do_filter &= (png_byte)(~PNG_FILTER_PAETH);
1098 png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
1099 (png_ptr->rowbytes + 1));
1100 png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
1104 if (png_ptr->do_filter == PNG_NO_FILTERS)
1105 #endif /* PNG_WRITE_FILTER_SUPPORTED */
1106 png_ptr->do_filter = PNG_FILTER_NONE;
1110 png_error(png_ptr, "Unknown custom filter method");
1113 /* This allows us to influence the way in which libpng chooses the "best"
1114 * filter for the current scanline. While the "minimum-sum-of-absolute-
1115 * differences metric is relatively fast and effective, there is some
1116 * question as to whether it can be improved upon by trying to keep the
1117 * filtered data going to zlib more consistent, hopefully resulting in
1118 * better compression.
1120 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* GRR 970116 */
1121 /* Convenience reset API. */
1123 png_reset_filter_heuristics(png_structrp png_ptr)
1125 /* Clear out any old values in the 'weights' - this must be done because if
1126 * the app calls set_filter_heuristics multiple times with different
1127 * 'num_weights' values we would otherwise potentially have wrong sized
1130 png_ptr->num_prev_filters = 0;
1131 png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
1132 if (png_ptr->prev_filters != NULL)
1134 png_bytep old = png_ptr->prev_filters;
1135 png_ptr->prev_filters = NULL;
1136 png_free(png_ptr, old);
1138 if (png_ptr->filter_weights != NULL)
1140 png_uint_16p old = png_ptr->filter_weights;
1141 png_ptr->filter_weights = NULL;
1142 png_free(png_ptr, old);
1145 if (png_ptr->inv_filter_weights != NULL)
1147 png_uint_16p old = png_ptr->inv_filter_weights;
1148 png_ptr->inv_filter_weights = NULL;
1149 png_free(png_ptr, old);
1152 /* Leave the filter_costs - this array is fixed size. */
1156 png_init_filter_heuristics(png_structrp png_ptr, int heuristic_method,
1159 if (png_ptr == NULL)
1162 /* Clear out the arrays */
1163 png_reset_filter_heuristics(png_ptr);
1165 /* Check arguments; the 'reset' function makes the correct settings for the
1166 * unweighted case, but we must handle the weight case by initializing the
1167 * arrays for the caller.
1169 if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1173 if (num_weights > 0)
1175 png_ptr->prev_filters = (png_bytep)png_malloc(png_ptr,
1176 (png_uint_32)((sizeof (png_byte)) * num_weights));
1178 /* To make sure that the weighting starts out fairly */
1179 for (i = 0; i < num_weights; i++)
1181 png_ptr->prev_filters[i] = 255;
1184 png_ptr->filter_weights = (png_uint_16p)png_malloc(png_ptr,
1185 (png_uint_32)((sizeof (png_uint_16)) * num_weights));
1187 png_ptr->inv_filter_weights = (png_uint_16p)png_malloc(png_ptr,
1188 (png_uint_32)((sizeof (png_uint_16)) * num_weights));
1190 for (i = 0; i < num_weights; i++)
1192 png_ptr->inv_filter_weights[i] =
1193 png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
1196 /* Safe to set this now */
1197 png_ptr->num_prev_filters = (png_byte)num_weights;
1200 /* If, in the future, there are other filter methods, this would
1201 * need to be based on png_ptr->filter.
1203 if (png_ptr->filter_costs == NULL)
1205 png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
1206 (png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
1208 png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
1209 (png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
1212 for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
1214 png_ptr->inv_filter_costs[i] =
1215 png_ptr->filter_costs[i] = PNG_COST_FACTOR;
1218 /* All the arrays are inited, safe to set this: */
1219 png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_WEIGHTED;
1221 /* Return the 'ok' code. */
1224 else if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT ||
1225 heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
1231 png_warning(png_ptr, "Unknown filter heuristic method");
1236 /* Provide floating and fixed point APIs */
1237 #ifdef PNG_FLOATING_POINT_SUPPORTED
1239 png_set_filter_heuristics(png_structrp png_ptr, int heuristic_method,
1240 int num_weights, png_const_doublep filter_weights,
1241 png_const_doublep filter_costs)
1243 png_debug(1, "in png_set_filter_heuristics");
1245 /* The internal API allocates all the arrays and ensures that the elements of
1246 * those arrays are set to the default value.
1248 if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
1251 /* If using the weighted method copy in the weights. */
1252 if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1255 for (i = 0; i < num_weights; i++)
1257 if (filter_weights[i] <= 0.0)
1259 png_ptr->inv_filter_weights[i] =
1260 png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
1265 png_ptr->inv_filter_weights[i] =
1266 (png_uint_16)(PNG_WEIGHT_FACTOR*filter_weights[i]+.5);
1268 png_ptr->filter_weights[i] =
1269 (png_uint_16)(PNG_WEIGHT_FACTOR/filter_weights[i]+.5);
1273 /* Here is where we set the relative costs of the different filters. We
1274 * should take the desired compression level into account when setting
1275 * the costs, so that Paeth, for instance, has a high relative cost at low
1276 * compression levels, while it has a lower relative cost at higher
1277 * compression settings. The filter types are in order of increasing
1278 * relative cost, so it would be possible to do this with an algorithm.
1280 for (i = 0; i < PNG_FILTER_VALUE_LAST; i++) if (filter_costs[i] >= 1.0)
1282 png_ptr->inv_filter_costs[i] =
1283 (png_uint_16)(PNG_COST_FACTOR / filter_costs[i] + .5);
1285 png_ptr->filter_costs[i] =
1286 (png_uint_16)(PNG_COST_FACTOR * filter_costs[i] + .5);
1290 #endif /* FLOATING_POINT */
1292 #ifdef PNG_FIXED_POINT_SUPPORTED
1294 png_set_filter_heuristics_fixed(png_structrp png_ptr, int heuristic_method,
1295 int num_weights, png_const_fixed_point_p filter_weights,
1296 png_const_fixed_point_p filter_costs)
1298 png_debug(1, "in png_set_filter_heuristics_fixed");
1300 /* The internal API allocates all the arrays and ensures that the elements of
1301 * those arrays are set to the default value.
1303 if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
1306 /* If using the weighted method copy in the weights. */
1307 if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1310 for (i = 0; i < num_weights; i++)
1312 if (filter_weights[i] <= 0)
1314 png_ptr->inv_filter_weights[i] =
1315 png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
1320 png_ptr->inv_filter_weights[i] = (png_uint_16)
1321 ((PNG_WEIGHT_FACTOR*filter_weights[i]+PNG_FP_HALF)/PNG_FP_1);
1323 png_ptr->filter_weights[i] = (png_uint_16)((PNG_WEIGHT_FACTOR*
1324 PNG_FP_1+(filter_weights[i]/2))/filter_weights[i]);
1328 /* Here is where we set the relative costs of the different filters. We
1329 * should take the desired compression level into account when setting
1330 * the costs, so that Paeth, for instance, has a high relative cost at low
1331 * compression levels, while it has a lower relative cost at higher
1332 * compression settings. The filter types are in order of increasing
1333 * relative cost, so it would be possible to do this with an algorithm.
1335 for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
1336 if (filter_costs[i] >= PNG_FP_1)
1340 /* Use a 32 bit unsigned temporary here because otherwise the
1341 * intermediate value will be a 32 bit *signed* integer (ANSI rules)
1342 * and this will get the wrong answer on division.
1344 tmp = PNG_COST_FACTOR*PNG_FP_1 + (filter_costs[i]/2);
1345 tmp /= filter_costs[i];
1347 png_ptr->inv_filter_costs[i] = (png_uint_16)tmp;
1349 tmp = PNG_COST_FACTOR * filter_costs[i] + PNG_FP_HALF;
1352 png_ptr->filter_costs[i] = (png_uint_16)tmp;
1356 #endif /* FIXED_POINT */
1357 #endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
1360 png_set_compression_level(png_structrp png_ptr, int level)
1362 png_debug(1, "in png_set_compression_level");
1364 if (png_ptr == NULL)
1367 png_ptr->zlib_level = level;
1371 png_set_compression_mem_level(png_structrp png_ptr, int mem_level)
1373 png_debug(1, "in png_set_compression_mem_level");
1375 if (png_ptr == NULL)
1378 png_ptr->zlib_mem_level = mem_level;
1382 png_set_compression_strategy(png_structrp png_ptr, int strategy)
1384 png_debug(1, "in png_set_compression_strategy");
1386 if (png_ptr == NULL)
1389 /* The flag setting here prevents the libpng dynamic selection of strategy.
1391 png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
1392 png_ptr->zlib_strategy = strategy;
1395 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1396 * smaller value of window_bits if it can do so safely.
1399 png_set_compression_window_bits(png_structrp png_ptr, int window_bits)
1401 if (png_ptr == NULL)
1404 /* Prior to 1.6.0 this would warn but then set the window_bits value, this
1405 * meant that negative window bits values could be selected which would cause
1406 * libpng to write a non-standard PNG file with raw deflate or gzip
1407 * compressed IDAT or ancillary chunks. Such files can be read and there is
1408 * no warning on read, so this seems like a very bad idea.
1410 if (window_bits > 15)
1412 png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
1416 else if (window_bits < 8)
1418 png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
1422 png_ptr->zlib_window_bits = window_bits;
1426 png_set_compression_method(png_structrp png_ptr, int method)
1428 png_debug(1, "in png_set_compression_method");
1430 if (png_ptr == NULL)
1433 /* This would produce an invalid PNG file if it worked, but it doesn't and
1434 * deflate will fault it, so it is harmless to just warn here.
1437 png_warning(png_ptr, "Only compression method 8 is supported by PNG");
1439 png_ptr->zlib_method = method;
1442 /* The following were added to libpng-1.5.4 */
1443 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
1445 png_set_text_compression_level(png_structrp png_ptr, int level)
1447 png_debug(1, "in png_set_text_compression_level");
1449 if (png_ptr == NULL)
1452 png_ptr->zlib_text_level = level;
1456 png_set_text_compression_mem_level(png_structrp png_ptr, int mem_level)
1458 png_debug(1, "in png_set_text_compression_mem_level");
1460 if (png_ptr == NULL)
1463 png_ptr->zlib_text_mem_level = mem_level;
1467 png_set_text_compression_strategy(png_structrp png_ptr, int strategy)
1469 png_debug(1, "in png_set_text_compression_strategy");
1471 if (png_ptr == NULL)
1474 png_ptr->zlib_text_strategy = strategy;
1477 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1478 * smaller value of window_bits if it can do so safely.
1481 png_set_text_compression_window_bits(png_structrp png_ptr, int window_bits)
1483 if (png_ptr == NULL)
1486 if (window_bits > 15)
1488 png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
1492 else if (window_bits < 8)
1494 png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
1498 png_ptr->zlib_text_window_bits = window_bits;
1502 png_set_text_compression_method(png_structrp png_ptr, int method)
1504 png_debug(1, "in png_set_text_compression_method");
1506 if (png_ptr == NULL)
1510 png_warning(png_ptr, "Only compression method 8 is supported by PNG");
1512 png_ptr->zlib_text_method = method;
1514 #endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
1515 /* end of API added to libpng-1.5.4 */
1518 png_set_write_status_fn(png_structrp png_ptr, png_write_status_ptr write_row_fn)
1520 if (png_ptr == NULL)
1523 png_ptr->write_row_fn = write_row_fn;
1526 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
1528 png_set_write_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1529 write_user_transform_fn)
1531 png_debug(1, "in png_set_write_user_transform_fn");
1533 if (png_ptr == NULL)
1536 png_ptr->transformations |= PNG_USER_TRANSFORM;
1537 png_ptr->write_user_transform_fn = write_user_transform_fn;
1542 #ifdef PNG_INFO_IMAGE_SUPPORTED
1544 png_write_png(png_structrp png_ptr, png_inforp info_ptr,
1545 int transforms, voidp params)
1547 if (png_ptr == NULL || info_ptr == NULL)
1550 if ((info_ptr->valid & PNG_INFO_IDAT) == 0)
1552 png_app_error(png_ptr, "no rows for png_write_image to write");
1556 /* Write the file header information. */
1557 png_write_info(png_ptr, info_ptr);
1559 /* ------ these transformations don't touch the info structure ------- */
1561 /* Invert monochrome pixels */
1562 if (transforms & PNG_TRANSFORM_INVERT_MONO)
1563 #ifdef PNG_WRITE_INVERT_SUPPORTED
1564 png_set_invert_mono(png_ptr);
1566 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1569 /* Shift the pixels up to a legal bit depth and fill in
1570 * as appropriate to correctly scale the image.
1572 if (transforms & PNG_TRANSFORM_SHIFT)
1573 #ifdef PNG_WRITE_SHIFT_SUPPORTED
1574 if (info_ptr->valid & PNG_INFO_sBIT)
1575 png_set_shift(png_ptr, &info_ptr->sig_bit);
1577 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1580 /* Pack pixels into bytes */
1581 if (transforms & PNG_TRANSFORM_PACKING)
1582 #ifdef PNG_WRITE_PACK_SUPPORTED
1583 png_set_packing(png_ptr);
1585 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1588 /* Swap location of alpha bytes from ARGB to RGBA */
1589 if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
1590 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
1591 png_set_swap_alpha(png_ptr);
1593 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1596 /* Remove a filler (X) from XRGB/RGBX/AG/GA into to convert it into
1597 * RGB, note that the code expects the input color type to be G or RGB; no
1601 (PNG_TRANSFORM_STRIP_FILLER_AFTER|PNG_TRANSFORM_STRIP_FILLER_BEFORE))
1603 #ifdef PNG_WRITE_FILLER_SUPPORTED
1604 if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
1606 if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
1607 png_app_error(png_ptr,
1608 "PNG_TRANSFORM_STRIP_FILLER: BEFORE+AFTER not supported");
1610 /* Continue if ignored - this is the pre-1.6.10 behavior */
1611 png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
1614 else if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
1615 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
1617 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_FILLER not supported");
1621 /* Flip BGR pixels to RGB */
1622 if (transforms & PNG_TRANSFORM_BGR)
1623 #ifdef PNG_WRITE_BGR_SUPPORTED
1624 png_set_bgr(png_ptr);
1626 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1629 /* Swap bytes of 16-bit files to most significant byte first */
1630 if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
1631 #ifdef PNG_WRITE_SWAP_SUPPORTED
1632 png_set_swap(png_ptr);
1634 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1637 /* Swap bits of 1, 2, 4 bit packed pixel formats */
1638 if (transforms & PNG_TRANSFORM_PACKSWAP)
1639 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
1640 png_set_packswap(png_ptr);
1642 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1645 /* Invert the alpha channel from opacity to transparency */
1646 if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
1647 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
1648 png_set_invert_alpha(png_ptr);
1650 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1653 /* ----------------------- end of transformations ------------------- */
1655 /* Write the bits */
1656 png_write_image(png_ptr, info_ptr->row_pointers);
1658 /* It is REQUIRED to call this to finish writing the rest of the file */
1659 png_write_end(png_ptr, info_ptr);
1666 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
1667 #ifdef PNG_STDIO_SUPPORTED /* currently required for png_image_write_* */
1668 /* Initialize the write structure - general purpose utility. */
1670 png_image_write_init(png_imagep image)
1672 png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, image,
1673 png_safe_error, png_safe_warning);
1675 if (png_ptr != NULL)
1677 png_infop info_ptr = png_create_info_struct(png_ptr);
1679 if (info_ptr != NULL)
1681 png_controlp control = png_voidcast(png_controlp,
1682 png_malloc_warn(png_ptr, (sizeof *control)));
1684 if (control != NULL)
1686 memset(control, 0, (sizeof *control));
1688 control->png_ptr = png_ptr;
1689 control->info_ptr = info_ptr;
1690 control->for_write = 1;
1692 image->opaque = control;
1696 /* Error clean up */
1697 png_destroy_info_struct(png_ptr, &info_ptr);
1700 png_destroy_write_struct(&png_ptr, NULL);
1703 return png_image_error(image, "png_image_write_: out of memory");
1706 /* Arguments to png_image_write_main: */
1711 png_const_voidp buffer;
1712 png_int_32 row_stride;
1713 png_const_voidp colormap;
1714 int convert_to_8bit;
1715 /* Local variables: */
1716 png_const_voidp first_row;
1717 ptrdiff_t row_bytes;
1718 png_voidp local_row;
1719 } png_image_write_control;
1721 /* Write png_uint_16 input to a 16-bit PNG; the png_ptr has already been set to
1722 * do any necessary byte swapping. The component order is defined by the
1723 * png_image format value.
1726 png_write_image_16bit(png_voidp argument)
1728 png_image_write_control *display = png_voidcast(png_image_write_control*,
1730 png_imagep image = display->image;
1731 png_structrp png_ptr = image->opaque->png_ptr;
1733 png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
1734 display->first_row);
1735 png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
1736 png_uint_16p row_end;
1737 const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
1739 png_uint_32 y = image->height;
1741 if (image->format & PNG_FORMAT_FLAG_ALPHA)
1743 # ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
1744 if (image->format & PNG_FORMAT_FLAG_AFIRST)
1747 ++input_row; /* To point to the first component */
1757 png_error(png_ptr, "png_write_image: internal call error");
1759 /* Work out the output row end and count over this, note that the increment
1760 * above to 'row' means that row_end can actually be beyond the end of the
1761 * row; this is correct.
1763 row_end = output_row + image->width * (channels+1);
1767 png_const_uint_16p in_ptr = input_row;
1768 png_uint_16p out_ptr = output_row;
1770 while (out_ptr < row_end)
1772 const png_uint_16 alpha = in_ptr[aindex];
1773 png_uint_32 reciprocal = 0;
1776 out_ptr[aindex] = alpha;
1778 /* Calculate a reciprocal. The correct calculation is simply
1779 * component/alpha*65535 << 15. (I.e. 15 bits of precision); this
1780 * allows correct rounding by adding .5 before the shift. 'reciprocal'
1781 * is only initialized when required.
1783 if (alpha > 0 && alpha < 65535)
1784 reciprocal = ((0xffff<<15)+(alpha>>1))/alpha;
1787 do /* always at least one channel */
1789 png_uint_16 component = *in_ptr++;
1791 /* The following gives 65535 for an alpha of 0, which is fine,
1792 * otherwise if 0/0 is represented as some other value there is more
1793 * likely to be a discontinuity which will probably damage
1794 * compression when moving from a fully transparent area to a
1795 * nearly transparent one. (The assumption here is that opaque
1796 * areas tend not to be 0 intensity.)
1798 if (component >= alpha)
1801 /* component<alpha, so component/alpha is less than one and
1802 * component*reciprocal is less than 2^31.
1804 else if (component > 0 && alpha < 65535)
1806 png_uint_32 calc = component * reciprocal;
1807 calc += 16384; /* round to nearest */
1808 component = (png_uint_16)(calc >> 15);
1811 *out_ptr++ = component;
1815 /* Skip to next component (skip the intervening alpha channel) */
1820 png_write_row(png_ptr, png_voidcast(png_const_bytep, display->local_row));
1821 input_row += display->row_bytes/(sizeof (png_uint_16));
1827 /* Given 16-bit input (1 to 4 channels) write 8-bit output. If an alpha channel
1828 * is present it must be removed from the components, the components are then
1829 * written in sRGB encoding. No components are added or removed.
1831 * Calculate an alpha reciprocal to reverse pre-multiplication. As above the
1832 * calculation can be done to 15 bits of accuracy; however, the output needs to
1833 * be scaled in the range 0..255*65535, so include that scaling here.
1835 #define UNP_RECIPROCAL(alpha) ((((0xffff*0xff)<<7)+(alpha>>1))/alpha)
1838 png_unpremultiply(png_uint_32 component, png_uint_32 alpha,
1839 png_uint_32 reciprocal/*from the above macro*/)
1841 /* The following gives 1.0 for an alpha of 0, which is fine, otherwise if 0/0
1842 * is represented as some other value there is more likely to be a
1843 * discontinuity which will probably damage compression when moving from a
1844 * fully transparent area to a nearly transparent one. (The assumption here
1845 * is that opaque areas tend not to be 0 intensity.)
1847 * There is a rounding problem here; if alpha is less than 128 it will end up
1848 * as 0 when scaled to 8 bits. To avoid introducing spurious colors into the
1849 * output change for this too.
1851 if (component >= alpha || alpha < 128)
1854 /* component<alpha, so component/alpha is less than one and
1855 * component*reciprocal is less than 2^31.
1857 else if (component > 0)
1859 /* The test is that alpha/257 (rounded) is less than 255, the first value
1860 * that becomes 255 is 65407.
1861 * NOTE: this must agree with the PNG_DIV257 macro (which must, therefore,
1862 * be exact!) [Could also test reciprocal != 0]
1866 component *= reciprocal;
1867 component += 64; /* round to nearest */
1874 /* Convert the component to sRGB. */
1875 return (png_byte)PNG_sRGB_FROM_LINEAR(component);
1883 png_write_image_8bit(png_voidp argument)
1885 png_image_write_control *display = png_voidcast(png_image_write_control*,
1887 png_imagep image = display->image;
1888 png_structrp png_ptr = image->opaque->png_ptr;
1890 png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
1891 display->first_row);
1892 png_bytep output_row = png_voidcast(png_bytep, display->local_row);
1893 png_uint_32 y = image->height;
1894 const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
1896 if (image->format & PNG_FORMAT_FLAG_ALPHA)
1901 # ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
1902 if (image->format & PNG_FORMAT_FLAG_AFIRST)
1905 ++input_row; /* To point to the first component */
1913 /* Use row_end in place of a loop counter: */
1914 row_end = output_row + image->width * (channels+1);
1918 png_const_uint_16p in_ptr = input_row;
1919 png_bytep out_ptr = output_row;
1921 while (out_ptr < row_end)
1923 png_uint_16 alpha = in_ptr[aindex];
1924 png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
1925 png_uint_32 reciprocal = 0;
1928 /* Scale and write the alpha channel. */
1929 out_ptr[aindex] = alphabyte;
1931 if (alphabyte > 0 && alphabyte < 255)
1932 reciprocal = UNP_RECIPROCAL(alpha);
1935 do /* always at least one channel */
1936 *out_ptr++ = png_unpremultiply(*in_ptr++, alpha, reciprocal);
1939 /* Skip to next component (skip the intervening alpha channel) */
1942 } /* while out_ptr < row_end */
1944 png_write_row(png_ptr, png_voidcast(png_const_bytep,
1945 display->local_row));
1946 input_row += display->row_bytes/(sizeof (png_uint_16));
1952 /* No alpha channel, so the row_end really is the end of the row and it
1953 * is sufficient to loop over the components one by one.
1955 png_bytep row_end = output_row + image->width * channels;
1959 png_const_uint_16p in_ptr = input_row;
1960 png_bytep out_ptr = output_row;
1962 while (out_ptr < row_end)
1964 png_uint_32 component = *in_ptr++;
1967 *out_ptr++ = (png_byte)PNG_sRGB_FROM_LINEAR(component);
1970 png_write_row(png_ptr, output_row);
1971 input_row += display->row_bytes/(sizeof (png_uint_16));
1979 png_image_set_PLTE(png_image_write_control *display)
1981 const png_imagep image = display->image;
1982 const void *cmap = display->colormap;
1983 const int entries = image->colormap_entries > 256 ? 256 :
1984 (int)image->colormap_entries;
1986 /* NOTE: the caller must check for cmap != NULL and entries != 0 */
1987 const png_uint_32 format = image->format;
1988 const int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
1990 # if defined(PNG_FORMAT_BGR_SUPPORTED) &&\
1991 defined(PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED)
1992 const int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1993 (format & PNG_FORMAT_FLAG_ALPHA) != 0;
1998 # ifdef PNG_FORMAT_BGR_SUPPORTED
1999 const int bgr = (format & PNG_FORMAT_FLAG_BGR) ? 2 : 0;
2005 png_color palette[256];
2008 memset(tRNS, 255, (sizeof tRNS));
2009 memset(palette, 0, (sizeof palette));
2011 for (i=num_trans=0; i<entries; ++i)
2013 /* This gets automatically converted to sRGB with reversal of the
2014 * pre-multiplication if the color-map has an alpha channel.
2016 if (format & PNG_FORMAT_FLAG_LINEAR)
2018 png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);
2020 entry += i * channels;
2022 if (channels & 1) /* no alpha */
2024 if (channels >= 3) /* RGB */
2026 palette[i].blue = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
2028 palette[i].green = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
2030 palette[i].red = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
2035 palette[i].blue = palette[i].red = palette[i].green =
2036 (png_byte)PNG_sRGB_FROM_LINEAR(255 * *entry);
2041 png_uint_16 alpha = entry[afirst ? 0 : channels-1];
2042 png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
2043 png_uint_32 reciprocal = 0;
2045 /* Calculate a reciprocal, as in the png_write_image_8bit code above
2046 * this is designed to produce a value scaled to 255*65535 when
2047 * divided by 128 (i.e. asr 7).
2049 if (alphabyte > 0 && alphabyte < 255)
2050 reciprocal = (((0xffff*0xff)<<7)+(alpha>>1))/alpha;
2052 tRNS[i] = alphabyte;
2053 if (alphabyte < 255)
2056 if (channels >= 3) /* RGB */
2058 palette[i].blue = png_unpremultiply(entry[afirst + (2 ^ bgr)],
2060 palette[i].green = png_unpremultiply(entry[afirst + 1], alpha,
2062 palette[i].red = png_unpremultiply(entry[afirst + bgr], alpha,
2067 palette[i].blue = palette[i].red = palette[i].green =
2068 png_unpremultiply(entry[afirst], alpha, reciprocal);
2072 else /* Color-map has sRGB values */
2074 png_const_bytep entry = png_voidcast(png_const_bytep, cmap);
2076 entry += i * channels;
2081 tRNS[i] = entry[afirst ? 0 : 3];
2086 palette[i].blue = entry[afirst + (2 ^ bgr)];
2087 palette[i].green = entry[afirst + 1];
2088 palette[i].red = entry[afirst + bgr];
2092 tRNS[i] = entry[1 ^ afirst];
2097 palette[i].blue = palette[i].red = palette[i].green =
2114 png_set_PLTE(image->opaque->png_ptr, image->opaque->info_ptr, palette,
2118 png_set_tRNS(image->opaque->png_ptr, image->opaque->info_ptr, tRNS,
2121 image->colormap_entries = entries;
2125 png_image_write_main(png_voidp argument)
2127 png_image_write_control *display = png_voidcast(png_image_write_control*,
2129 png_imagep image = display->image;
2130 png_structrp png_ptr = image->opaque->png_ptr;
2131 png_inforp info_ptr = image->opaque->info_ptr;
2132 png_uint_32 format = image->format;
2134 int colormap = (format & PNG_FORMAT_FLAG_COLORMAP) != 0;
2135 int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR) != 0; /* input */
2136 int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA) != 0;
2137 int write_16bit = linear && !colormap && !display->convert_to_8bit;
2139 # ifdef PNG_BENIGN_ERRORS_SUPPORTED
2140 /* Make sure we error out on any bad situation */
2141 png_set_benign_errors(png_ptr, 0/*error*/);
2144 /* Default the 'row_stride' parameter if required. */
2145 if (display->row_stride == 0)
2146 display->row_stride = PNG_IMAGE_ROW_STRIDE(*image);
2148 /* Set the required transforms then write the rows in the correct order. */
2149 if (format & PNG_FORMAT_FLAG_COLORMAP)
2151 if (display->colormap != NULL && image->colormap_entries > 0)
2153 png_uint_32 entries = image->colormap_entries;
2155 png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
2156 entries > 16 ? 8 : (entries > 4 ? 4 : (entries > 2 ? 2 : 1)),
2157 PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
2158 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
2160 png_image_set_PLTE(display);
2164 png_error(image->opaque->png_ptr,
2165 "no color-map for color-mapped image");
2169 png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
2170 write_16bit ? 16 : 8,
2171 ((format & PNG_FORMAT_FLAG_COLOR) ? PNG_COLOR_MASK_COLOR : 0) +
2172 ((format & PNG_FORMAT_FLAG_ALPHA) ? PNG_COLOR_MASK_ALPHA : 0),
2173 PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
2175 /* Counter-intuitively the data transformations must be called *after*
2176 * png_write_info, not before as in the read code, but the 'set' functions
2177 * must still be called before. Just set the color space information, never
2178 * write an interlaced image.
2181 if (write_16bit != 0)
2183 /* The gamma here is 1.0 (linear) and the cHRM chunk matches sRGB. */
2184 png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_LINEAR);
2186 if (!(image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB))
2187 png_set_cHRM_fixed(png_ptr, info_ptr,
2189 /* white */ 31270, 32900,
2190 /* red */ 64000, 33000,
2191 /* green */ 30000, 60000,
2192 /* blue */ 15000, 6000
2196 else if (!(image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB))
2197 png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_PERCEPTUAL);
2199 /* Else writing an 8-bit file and the *colors* aren't sRGB, but the 8-bit
2200 * space must still be gamma encoded.
2203 png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_sRGB_INVERSE);
2205 /* Write the file header. */
2206 png_write_info(png_ptr, info_ptr);
2208 /* Now set up the data transformations (*after* the header is written),
2209 * remove the handled transformations from the 'format' flags for checking.
2211 * First check for a little endian system if writing 16 bit files.
2213 if (write_16bit != 0)
2215 PNG_CONST png_uint_16 le = 0x0001;
2217 if (*(png_const_bytep)&le)
2218 png_set_swap(png_ptr);
2221 # ifdef PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
2222 if (format & PNG_FORMAT_FLAG_BGR)
2224 if (!colormap && (format & PNG_FORMAT_FLAG_COLOR) != 0)
2225 png_set_bgr(png_ptr);
2226 format &= ~PNG_FORMAT_FLAG_BGR;
2230 # ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
2231 if (format & PNG_FORMAT_FLAG_AFIRST)
2233 if (!colormap && (format & PNG_FORMAT_FLAG_ALPHA) != 0)
2234 png_set_swap_alpha(png_ptr);
2235 format &= ~PNG_FORMAT_FLAG_AFIRST;
2239 /* If there are 16 or fewer color-map entries we wrote a lower bit depth
2240 * above, but the application data is still byte packed.
2242 if (colormap && image->colormap_entries <= 16)
2243 png_set_packing(png_ptr);
2245 /* That should have handled all (both) the transforms. */
2246 if ((format & ~(png_uint_32)(PNG_FORMAT_FLAG_COLOR | PNG_FORMAT_FLAG_LINEAR |
2247 PNG_FORMAT_FLAG_ALPHA | PNG_FORMAT_FLAG_COLORMAP)) != 0)
2248 png_error(png_ptr, "png_write_image: unsupported transformation");
2251 png_const_bytep row = png_voidcast(png_const_bytep, display->buffer);
2252 ptrdiff_t row_bytes = display->row_stride;
2255 row_bytes *= (sizeof (png_uint_16));
2258 row += (image->height-1) * (-row_bytes);
2260 display->first_row = row;
2261 display->row_bytes = row_bytes;
2264 /* Apply 'fast' options if the flag is set. */
2265 if ((image->flags & PNG_IMAGE_FLAG_FAST) != 0)
2267 png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_NO_FILTERS);
2268 /* NOTE: determined by experiment using pngstest, this reflects some
2269 * balance between the time to write the image once and the time to read
2270 * it about 50 times. The speed-up in pngstest was about 10-20% of the
2271 * total (user) time on a heavily loaded system.
2273 png_set_compression_level(png_ptr, 3);
2276 /* Check for the cases that currently require a pre-transform on the row
2277 * before it is written. This only applies when the input is 16-bit and
2278 * either there is an alpha channel or it is converted to 8-bit.
2280 if ((linear && alpha) || (!colormap && display->convert_to_8bit))
2282 png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr,
2283 png_get_rowbytes(png_ptr, info_ptr)));
2286 display->local_row = row;
2287 if (write_16bit != 0)
2288 result = png_safe_execute(image, png_write_image_16bit, display);
2290 result = png_safe_execute(image, png_write_image_8bit, display);
2291 display->local_row = NULL;
2293 png_free(png_ptr, row);
2295 /* Skip the 'write_end' on error: */
2300 /* Otherwise this is the case where the input is in a format currently
2301 * supported by the rest of the libpng write code; call it directly.
2305 png_const_bytep row = png_voidcast(png_const_bytep, display->first_row);
2306 ptrdiff_t row_bytes = display->row_bytes;
2307 png_uint_32 y = image->height;
2311 png_write_row(png_ptr, row);
2316 png_write_end(png_ptr, info_ptr);
2321 png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
2322 const void *buffer, png_int_32 row_stride, const void *colormap)
2324 /* Write the image to the given (FILE*). */
2325 if (image != NULL && image->version == PNG_IMAGE_VERSION)
2329 if (png_image_write_init(image))
2331 png_image_write_control display;
2334 /* This is slightly evil, but png_init_io doesn't do anything other
2335 * than this and we haven't changed the standard IO functions so
2336 * this saves a 'safe' function.
2338 image->opaque->png_ptr->io_ptr = file;
2340 memset(&display, 0, (sizeof display));
2341 display.image = image;
2342 display.buffer = buffer;
2343 display.row_stride = row_stride;
2344 display.colormap = colormap;
2345 display.convert_to_8bit = convert_to_8bit;
2347 result = png_safe_execute(image, png_image_write_main, &display);
2348 png_image_free(image);
2357 return png_image_error(image,
2358 "png_image_write_to_stdio: invalid argument");
2361 else if (image != NULL)
2362 return png_image_error(image,
2363 "png_image_write_to_stdio: incorrect PNG_IMAGE_VERSION");
2370 png_image_write_to_file(png_imagep image, const char *file_name,
2371 int convert_to_8bit, const void *buffer, png_int_32 row_stride,
2372 const void *colormap)
2374 /* Write the image to the named file. */
2375 if (image != NULL && image->version == PNG_IMAGE_VERSION)
2377 if (file_name != NULL)
2379 FILE *fp = fopen(file_name, "wb");
2383 if (png_image_write_to_stdio(image, fp, convert_to_8bit, buffer,
2384 row_stride, colormap))
2386 int error; /* from fflush/fclose */
2388 /* Make sure the file is flushed correctly. */
2389 if (fflush(fp) == 0 && ferror(fp) == 0)
2391 if (fclose(fp) == 0)
2394 error = errno; /* from fclose */
2399 error = errno; /* from fflush or ferror */
2403 (void)remove(file_name);
2404 /* The image has already been cleaned up; this is just used to
2405 * set the error (because the original write succeeded).
2407 return png_image_error(image, strerror(error));
2412 /* Clean up: just the opened file. */
2414 (void)remove(file_name);
2420 return png_image_error(image, strerror(errno));
2424 return png_image_error(image,
2425 "png_image_write_to_file: invalid argument");
2428 else if (image != NULL)
2429 return png_image_error(image,
2430 "png_image_write_to_file: incorrect PNG_IMAGE_VERSION");
2435 #endif /* PNG_STDIO_SUPPORTED */
2436 #endif /* SIMPLIFIED_WRITE */
2437 #endif /* PNG_WRITE_SUPPORTED */