2 /* pngwrite.c - general routines to write a PNG file
4 * Last changed in libpng 1.7.0 [(PENDING RELEASE)]
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)
221 jend = info_ptr->num_trans;
222 if (jend > PNG_MAX_PALETTE_LENGTH)
223 jend = PNG_MAX_PALETTE_LENGTH;
225 for (j = 0; j<jend; ++j)
226 info_ptr->trans_alpha[j] =
227 (png_byte)(255 - info_ptr->trans_alpha[j]);
230 png_write_tRNS(png_ptr, info_ptr->trans_alpha, &(info_ptr->trans_color),
231 info_ptr->num_trans, info_ptr->color_type);
234 #ifdef PNG_WRITE_bKGD_SUPPORTED
235 if (info_ptr->valid & PNG_INFO_bKGD)
236 png_write_bKGD(png_ptr, &(info_ptr->background), info_ptr->color_type);
239 #ifdef PNG_WRITE_hIST_SUPPORTED
240 if (info_ptr->valid & PNG_INFO_hIST)
241 png_write_hIST(png_ptr, info_ptr->hist, info_ptr->num_palette);
244 #ifdef PNG_WRITE_oFFs_SUPPORTED
245 if (info_ptr->valid & PNG_INFO_oFFs)
246 png_write_oFFs(png_ptr, info_ptr->x_offset, info_ptr->y_offset,
247 info_ptr->offset_unit_type);
250 #ifdef PNG_WRITE_pCAL_SUPPORTED
251 if (info_ptr->valid & PNG_INFO_pCAL)
252 png_write_pCAL(png_ptr, info_ptr->pcal_purpose, info_ptr->pcal_X0,
253 info_ptr->pcal_X1, info_ptr->pcal_type, info_ptr->pcal_nparams,
254 info_ptr->pcal_units, info_ptr->pcal_params);
257 #ifdef PNG_WRITE_sCAL_SUPPORTED
258 if (info_ptr->valid & PNG_INFO_sCAL)
259 png_write_sCAL_s(png_ptr, (int)info_ptr->scal_unit,
260 info_ptr->scal_s_width, info_ptr->scal_s_height);
263 #ifdef PNG_WRITE_pHYs_SUPPORTED
264 if (info_ptr->valid & PNG_INFO_pHYs)
265 png_write_pHYs(png_ptr, info_ptr->x_pixels_per_unit,
266 info_ptr->y_pixels_per_unit, info_ptr->phys_unit_type);
269 #ifdef PNG_WRITE_tIME_SUPPORTED
270 if (info_ptr->valid & PNG_INFO_tIME)
272 png_write_tIME(png_ptr, &(info_ptr->mod_time));
273 png_ptr->mode |= PNG_WROTE_tIME;
277 #ifdef PNG_WRITE_sPLT_SUPPORTED
278 if (info_ptr->valid & PNG_INFO_sPLT)
279 for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
280 png_write_sPLT(png_ptr, info_ptr->splt_palettes + i);
283 #ifdef PNG_WRITE_TEXT_SUPPORTED
284 /* Check to see if we need to write text chunks */
285 for (i = 0; i < info_ptr->num_text; i++)
287 png_debug2(2, "Writing header text chunk %d, type %d", i,
288 info_ptr->text[i].compression);
289 /* An internationalized chunk? */
290 if (info_ptr->text[i].compression > 0)
292 #ifdef PNG_WRITE_iTXt_SUPPORTED
293 /* Write international chunk */
294 png_write_iTXt(png_ptr,
295 info_ptr->text[i].compression,
296 info_ptr->text[i].key,
297 info_ptr->text[i].lang,
298 info_ptr->text[i].lang_key,
299 info_ptr->text[i].text);
301 png_warning(png_ptr, "Unable to write international text");
303 /* Mark this chunk as written */
304 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
307 /* If we want a compressed text chunk */
308 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_zTXt)
310 #ifdef PNG_WRITE_zTXt_SUPPORTED
311 /* Write compressed chunk */
312 png_write_zTXt(png_ptr, info_ptr->text[i].key,
313 info_ptr->text[i].text, 0,
314 info_ptr->text[i].compression);
316 png_warning(png_ptr, "Unable to write compressed text");
318 /* Mark this chunk as written */
319 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
322 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
324 #ifdef PNG_WRITE_tEXt_SUPPORTED
325 /* Write uncompressed chunk */
326 png_write_tEXt(png_ptr, info_ptr->text[i].key,
327 info_ptr->text[i].text,
329 /* Mark this chunk as written */
330 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
333 png_warning(png_ptr, "Unable to write uncompressed text");
339 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
340 write_unknown_chunks(png_ptr, info_ptr, PNG_HAVE_PLTE);
344 /* Writes the end of the PNG file. If you don't want to write comments or
345 * time information, you can pass NULL for info. If you already wrote these
346 * in png_write_info(), do not write them again here. If you have long
347 * comments, I suggest writing them here, and compressing them.
350 png_write_end(png_structrp png_ptr, png_inforp info_ptr)
352 png_debug(1, "in png_write_end");
357 if (!(png_ptr->mode & PNG_HAVE_IDAT))
358 png_error(png_ptr, "No IDATs written into file");
360 #ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
361 if (png_ptr->num_palette_max > png_ptr->num_palette)
362 png_benign_error(png_ptr, "Wrote palette index exceeding num_palette");
365 /* See if user wants us to write information chunks */
366 if (info_ptr != NULL)
368 #ifdef PNG_WRITE_TEXT_SUPPORTED
369 int i; /* local index variable */
371 #ifdef PNG_WRITE_tIME_SUPPORTED
372 /* Check to see if user has supplied a time chunk */
373 if ((info_ptr->valid & PNG_INFO_tIME) &&
374 !(png_ptr->mode & PNG_WROTE_tIME))
375 png_write_tIME(png_ptr, &(info_ptr->mod_time));
378 #ifdef PNG_WRITE_TEXT_SUPPORTED
379 /* Loop through comment chunks */
380 for (i = 0; i < info_ptr->num_text; i++)
382 png_debug2(2, "Writing trailer text chunk %d, type %d", i,
383 info_ptr->text[i].compression);
384 /* An internationalized chunk? */
385 if (info_ptr->text[i].compression > 0)
387 #ifdef PNG_WRITE_iTXt_SUPPORTED
388 /* Write international chunk */
389 png_write_iTXt(png_ptr,
390 info_ptr->text[i].compression,
391 info_ptr->text[i].key,
392 info_ptr->text[i].lang,
393 info_ptr->text[i].lang_key,
394 info_ptr->text[i].text);
396 png_warning(png_ptr, "Unable to write international text");
398 /* Mark this chunk as written */
399 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
402 else if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
404 #ifdef PNG_WRITE_zTXt_SUPPORTED
405 /* Write compressed chunk */
406 png_write_zTXt(png_ptr, info_ptr->text[i].key,
407 info_ptr->text[i].text, 0,
408 info_ptr->text[i].compression);
410 png_warning(png_ptr, "Unable to write compressed text");
412 /* Mark this chunk as written */
413 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
416 else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
418 #ifdef PNG_WRITE_tEXt_SUPPORTED
419 /* Write uncompressed chunk */
420 png_write_tEXt(png_ptr, info_ptr->text[i].key,
421 info_ptr->text[i].text, 0);
423 png_warning(png_ptr, "Unable to write uncompressed text");
426 /* Mark this chunk as written */
427 info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
431 #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
432 write_unknown_chunks(png_ptr, info_ptr, PNG_AFTER_IDAT);
436 png_ptr->mode |= PNG_AFTER_IDAT;
438 /* Write end of PNG file */
439 png_write_IEND(png_ptr);
440 /* This flush, added in libpng-1.0.8, removed from libpng-1.0.9beta03,
441 * and restored again in libpng-1.2.30, may cause some applications that
442 * do not set png_ptr->output_flush_fn to crash. If your application
443 * experiences a problem, please try building libpng with
444 * PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED defined, and report the event to
445 * png-mng-implement at lists.sf.net .
447 #ifdef PNG_WRITE_FLUSH_SUPPORTED
448 # ifdef PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED
454 #ifdef PNG_CONVERT_tIME_SUPPORTED
456 png_convert_from_struct_tm(png_timep ptime, PNG_CONST struct tm * ttime)
458 png_debug(1, "in png_convert_from_struct_tm");
460 ptime->year = (png_uint_16)(1900 + ttime->tm_year);
461 ptime->month = (png_byte)(ttime->tm_mon + 1);
462 ptime->day = (png_byte)ttime->tm_mday;
463 ptime->hour = (png_byte)ttime->tm_hour;
464 ptime->minute = (png_byte)ttime->tm_min;
465 ptime->second = (png_byte)ttime->tm_sec;
469 png_convert_from_time_t(png_timep ptime, time_t ttime)
473 png_debug(1, "in png_convert_from_time_t");
475 tbuf = gmtime(&ttime);
476 png_convert_from_struct_tm(ptime, tbuf);
480 /* Initialize png_ptr structure, and allocate any memory needed */
481 PNG_FUNCTION(png_structp,PNGAPI
482 png_create_write_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
483 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
485 #ifndef PNG_USER_MEM_SUPPORTED
486 png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
487 error_fn, warn_fn, NULL, NULL, NULL);
489 return png_create_write_struct_2(user_png_ver, error_ptr, error_fn,
490 warn_fn, NULL, NULL, NULL);
493 /* Alternate initialize png_ptr structure, and allocate any memory needed */
494 PNG_FUNCTION(png_structp,PNGAPI
495 png_create_write_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
496 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
497 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
499 png_structrp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
500 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
501 #endif /* PNG_USER_MEM_SUPPORTED */
505 /* Set the zlib control values to defaults; they can be overridden by the
506 * application after the struct has been created.
508 png_ptr->zbuffer_size = PNG_ZBUF_SIZE;
510 /* The 'zlib_strategy' setting is irrelevant because png_default_claim in
511 * pngwutil.c defaults it according to whether or not filters will be
512 * used, and ignores this setting.
514 png_ptr->zlib_strategy = PNG_Z_DEFAULT_STRATEGY;
515 png_ptr->zlib_level = PNG_Z_DEFAULT_COMPRESSION;
516 png_ptr->zlib_mem_level = 8;
517 png_ptr->zlib_window_bits = 15;
518 png_ptr->zlib_method = 8;
520 #ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
521 png_ptr->zlib_text_strategy = PNG_TEXT_Z_DEFAULT_STRATEGY;
522 png_ptr->zlib_text_level = PNG_TEXT_Z_DEFAULT_COMPRESSION;
523 png_ptr->zlib_text_mem_level = 8;
524 png_ptr->zlib_text_window_bits = 15;
525 png_ptr->zlib_text_method = 8;
526 #endif /* PNG_WRITE_COMPRESSED_TEXT_SUPPORTED */
528 /* This is a highly dubious configuration option; by default it is off,
529 * but it may be appropriate for private builds that are testing
530 * extensions not conformant to the current specification, or of
531 * applications that must not fail to write at all costs!
533 #ifdef PNG_BENIGN_WRITE_ERRORS_SUPPORTED
534 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
535 /* In stable builds only warn if an application error can be completely
540 /* App warnings are warnings in release (or release candidate) builds but
541 * are errors during development.
543 #if PNG_LIBPNG_BUILD_BASE_TYPE >= PNG_LIBPNG_BUILD_RC
544 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
547 /* TODO: delay this, it can be done in png_init_io() (if the app doesn't
548 * do it itself) avoiding setting the default function if it is not
551 png_set_write_fn(png_ptr, NULL, NULL, NULL);
558 /* Write a few rows of image data. If the image is interlaced,
559 * either you will have to write the 7 sub images, or, if you
560 * have called png_set_interlace_handling(), you will have to
561 * "write" the image seven times.
564 png_write_rows(png_structrp png_ptr, png_bytepp row,
565 png_uint_32 num_rows)
567 png_uint_32 i; /* row counter */
568 png_bytepp rp; /* row pointer */
570 png_debug(1, "in png_write_rows");
575 /* Loop through the rows */
576 for (i = 0, rp = row; i < num_rows; i++, rp++)
578 png_write_row(png_ptr, *rp);
582 /* Write the image. You only need to call this function once, even
583 * if you are writing an interlaced image.
586 png_write_image(png_structrp png_ptr, png_bytepp image)
588 png_uint_32 i; /* row index */
589 int pass, num_pass; /* pass variables */
590 png_bytepp rp; /* points to current row */
595 png_debug(1, "in png_write_image");
597 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
598 /* Initialize interlace handling. If image is not interlaced,
599 * this will set pass to 1
601 num_pass = png_set_interlace_handling(png_ptr);
605 /* Loop through passes */
606 for (pass = 0; pass < num_pass; pass++)
608 /* Loop through image */
609 for (i = 0, rp = image; i < png_ptr->height; i++, rp++)
611 png_write_row(png_ptr, *rp);
616 #ifdef PNG_MNG_FEATURES_SUPPORTED
617 /* Performs intrapixel differencing */
619 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
621 png_debug(1, "in png_do_write_intrapixel");
623 if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
626 png_uint_32 row_width = row_info->width;
627 if (row_info->bit_depth == 8)
632 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
635 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
641 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
643 *(rp) = (png_byte)((*rp - *(rp + 1)) & 0xff);
644 *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
648 #ifdef PNG_WRITE_16BIT_SUPPORTED
649 else if (row_info->bit_depth == 16)
654 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
657 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
663 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
665 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
666 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
667 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
668 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
669 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
670 *(rp ) = (png_byte)((red >> 8) & 0xff);
671 *(rp + 1) = (png_byte)(red & 0xff);
672 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
673 *(rp + 5) = (png_byte)(blue & 0xff);
676 #endif /* PNG_WRITE_16BIT_SUPPORTED */
679 #endif /* PNG_MNG_FEATURES_SUPPORTED */
681 /* Called by user to write a row of image data */
683 png_write_row(png_structrp png_ptr, png_const_bytep row)
685 /* 1.5.6: moved from png_struct to be a local structure: */
686 png_row_info row_info;
691 png_debug2(1, "in png_write_row (row %u, pass %d)",
692 png_ptr->row_number, png_ptr->pass);
694 /* Initialize transformations and other stuff if first time */
695 if (png_ptr->row_number == 0 && png_ptr->pass == 0)
697 /* Make sure we wrote the header info */
698 if (!(png_ptr->mode & PNG_WROTE_INFO_BEFORE_PLTE))
700 "png_write_info was never called before png_write_row");
702 /* Check for transforms that have been set but were defined out */
703 #if !defined(PNG_WRITE_INVERT_SUPPORTED) && defined(PNG_READ_INVERT_SUPPORTED)
704 if (png_ptr->transformations & PNG_INVERT_MONO)
705 png_warning(png_ptr, "PNG_WRITE_INVERT_SUPPORTED is not defined");
708 #if !defined(PNG_WRITE_FILLER_SUPPORTED) && defined(PNG_READ_FILLER_SUPPORTED)
709 if (png_ptr->transformations & PNG_FILLER)
710 png_warning(png_ptr, "PNG_WRITE_FILLER_SUPPORTED is not defined");
712 #if !defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
713 defined(PNG_READ_PACKSWAP_SUPPORTED)
714 if (png_ptr->transformations & PNG_PACKSWAP)
716 "PNG_WRITE_PACKSWAP_SUPPORTED is not defined");
719 #if !defined(PNG_WRITE_PACK_SUPPORTED) && defined(PNG_READ_PACK_SUPPORTED)
720 if (png_ptr->transformations & PNG_PACK)
721 png_warning(png_ptr, "PNG_WRITE_PACK_SUPPORTED is not defined");
724 #if !defined(PNG_WRITE_SHIFT_SUPPORTED) && defined(PNG_READ_SHIFT_SUPPORTED)
725 if (png_ptr->transformations & PNG_SHIFT)
726 png_warning(png_ptr, "PNG_WRITE_SHIFT_SUPPORTED is not defined");
729 #if !defined(PNG_WRITE_BGR_SUPPORTED) && defined(PNG_READ_BGR_SUPPORTED)
730 if (png_ptr->transformations & PNG_BGR)
731 png_warning(png_ptr, "PNG_WRITE_BGR_SUPPORTED is not defined");
734 #if !defined(PNG_WRITE_SWAP_SUPPORTED) && defined(PNG_READ_SWAP_SUPPORTED)
735 if (png_ptr->transformations & PNG_SWAP_BYTES)
736 png_warning(png_ptr, "PNG_WRITE_SWAP_SUPPORTED is not defined");
739 png_write_start_row(png_ptr);
742 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
743 /* If interlaced and not interested in row, return */
744 if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
746 switch (png_ptr->pass)
749 if (png_ptr->row_number & 0x07)
751 png_write_finish_row(png_ptr);
757 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
759 png_write_finish_row(png_ptr);
765 if ((png_ptr->row_number & 0x07) != 4)
767 png_write_finish_row(png_ptr);
773 if ((png_ptr->row_number & 0x03) || png_ptr->width < 3)
775 png_write_finish_row(png_ptr);
781 if ((png_ptr->row_number & 0x03) != 2)
783 png_write_finish_row(png_ptr);
789 if ((png_ptr->row_number & 0x01) || png_ptr->width < 2)
791 png_write_finish_row(png_ptr);
797 if (!(png_ptr->row_number & 0x01))
799 png_write_finish_row(png_ptr);
804 default: /* error: ignore it */
810 /* Set up row info for transformations */
811 row_info.color_type = png_ptr->color_type;
812 row_info.width = png_ptr->usr_width;
813 row_info.channels = png_ptr->usr_channels;
814 row_info.bit_depth = png_ptr->usr_bit_depth;
815 row_info.pixel_depth = (png_byte)(row_info.bit_depth * row_info.channels);
816 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
818 png_debug1(3, "row_info->color_type = %d", row_info.color_type);
819 png_debug1(3, "row_info->width = %u", row_info.width);
820 png_debug1(3, "row_info->channels = %d", row_info.channels);
821 png_debug1(3, "row_info->bit_depth = %d", row_info.bit_depth);
822 png_debug1(3, "row_info->pixel_depth = %d", row_info.pixel_depth);
823 png_debug1(3, "row_info->rowbytes = %lu", (unsigned long)row_info.rowbytes);
825 /* Copy user's row into buffer, leaving room for filter byte. */
826 memcpy(png_ptr->row_buf + 1, row, row_info.rowbytes);
828 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
829 /* Handle interlacing */
830 if (png_ptr->interlaced && png_ptr->pass < 6 &&
831 (png_ptr->transformations & PNG_INTERLACE))
833 png_do_write_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass);
834 /* This should always get caught above, but still ... */
835 if (!(row_info.width))
837 png_write_finish_row(png_ptr);
843 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
844 /* Handle other transformations */
845 if (png_ptr->transformations)
846 png_do_write_transformations(png_ptr, &row_info);
849 /* At this point the row_info pixel depth must match the 'transformed' depth,
850 * which is also the output depth.
852 if (row_info.pixel_depth != png_ptr->pixel_depth ||
853 row_info.pixel_depth != png_ptr->transformed_pixel_depth)
854 png_error(png_ptr, "internal write transform logic error");
856 #ifdef PNG_MNG_FEATURES_SUPPORTED
857 /* Write filter_method 64 (intrapixel differencing) only if
858 * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
859 * 2. Libpng did not write a PNG signature (this filter_method is only
860 * used in PNG datastreams that are embedded in MNG datastreams) and
861 * 3. The application called png_permit_mng_features with a mask that
862 * included PNG_FLAG_MNG_FILTER_64 and
863 * 4. The filter_method is 64 and
864 * 5. The color_type is RGB or RGBA
866 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
867 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
869 /* Intrapixel differencing */
870 png_do_write_intrapixel(&row_info, png_ptr->row_buf + 1);
874 /* Added at libpng-1.5.10 */
875 #ifdef PNG_WRITE_CHECK_FOR_INVALID_INDEX_SUPPORTED
876 /* Check for out-of-range palette index */
877 if (row_info.color_type == PNG_COLOR_TYPE_PALETTE &&
878 png_ptr->num_palette_max >= 0)
879 png_do_check_palette_indexes(png_ptr, &row_info);
882 /* Find a filter if necessary, filter the row and write it out. */
883 png_write_find_filter(png_ptr, &row_info);
885 if (png_ptr->write_row_fn != NULL)
886 (*(png_ptr->write_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
889 #ifdef PNG_WRITE_FLUSH_SUPPORTED
890 /* Set the automatic flush interval or 0 to turn flushing off */
892 png_set_flush(png_structrp png_ptr, int nrows)
894 png_debug(1, "in png_set_flush");
899 png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
902 /* Flush the current output buffers now */
904 png_write_flush(png_structrp png_ptr)
906 png_debug(1, "in png_write_flush");
911 /* We have already written out all of the data */
912 if (png_ptr->row_number >= png_ptr->num_rows)
915 png_compress_IDAT(png_ptr, NULL, 0, Z_SYNC_FLUSH);
916 png_ptr->flush_rows = 0;
919 #endif /* PNG_WRITE_FLUSH_SUPPORTED */
921 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
922 static void png_reset_filter_heuristics(png_structrp png_ptr);/* forward decl */
925 /* Free any memory used in png_ptr struct without freeing the struct itself. */
927 png_write_destroy(png_structrp png_ptr)
929 png_debug(1, "in png_write_destroy");
931 /* Free any memory zlib uses */
932 if (png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED)
933 deflateEnd(&png_ptr->zstream);
935 /* Free our memory. png_free checks NULL for us. */
936 png_free_buffer_list(png_ptr, &png_ptr->zbuffer_list);
937 png_free(png_ptr, png_ptr->row_buf);
938 #ifdef PNG_WRITE_FILTER_SUPPORTED
939 png_free(png_ptr, png_ptr->prev_row);
940 png_free(png_ptr, png_ptr->sub_row);
941 png_free(png_ptr, png_ptr->up_row);
942 png_free(png_ptr, png_ptr->avg_row);
943 png_free(png_ptr, png_ptr->paeth_row);
946 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
947 /* Use this to save a little code space, it doesn't free the filter_costs */
948 png_reset_filter_heuristics(png_ptr);
949 png_free(png_ptr, png_ptr->filter_costs);
950 png_free(png_ptr, png_ptr->inv_filter_costs);
953 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
954 png_free(png_ptr, png_ptr->chunk_list);
957 /* The error handling and memory handling information is left intact at this
958 * point: the jmp_buf may still have to be freed. See png_destroy_png_struct
959 * for how this happens.
963 /* Free all memory used by the write.
964 * In libpng 1.6.0 this API changed quietly to no longer accept a NULL value for
965 * *png_ptr_ptr. Prior to 1.6.0 it would accept such a value and it would free
966 * the passed in info_structs but it would quietly fail to free any of the data
967 * inside them. In 1.6.0 it quietly does nothing (it has to be quiet because it
971 png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
973 png_debug(1, "in png_destroy_write_struct");
975 if (png_ptr_ptr != NULL)
977 png_structrp png_ptr = *png_ptr_ptr;
979 if (png_ptr != NULL) /* added in libpng 1.6.0 */
981 png_destroy_info_struct(png_ptr, info_ptr_ptr);
984 png_write_destroy(png_ptr);
985 png_destroy_png_struct(png_ptr);
990 /* Allow the application to select one or more row filters to use. */
992 png_set_filter(png_structrp png_ptr, int method, int filters)
994 png_debug(1, "in png_set_filter");
999 #ifdef PNG_MNG_FEATURES_SUPPORTED
1000 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
1001 (method == PNG_INTRAPIXEL_DIFFERENCING))
1002 method = PNG_FILTER_TYPE_BASE;
1005 /* The only supported method, except for the check above, is
1006 * PNG_FILTER_TYPE_BASE. The code below does not use 'method' other than
1007 * for the check, so just keep going if png_app_error returns.
1009 if (method != PNG_FILTER_TYPE_BASE)
1010 png_app_error(png_ptr, "Unknown custom filter method");
1012 /* If filter writing is not supported the 'filters' value must be zero,
1013 * otherwise the value must be a single, valid, filter value or a set of the
1014 * mask values. The defines in png.h are such that the filter masks used in
1015 * this API and internally are 1<<(3+value), value is in the range 0..4, so
1016 * this fits in a byte.
1018 # ifdef PNG_WRITE_FILTER_SUPPORTED
1019 /* Notice that PNG_NO_FILTERS is 0 and passes this test; this is OK
1020 * because filters then gets set to PNG_FILTER_NONE, as is required.
1022 if (filters < PNG_FILTER_VALUE_LAST)
1023 filters = 0x08 << filters;
1025 else if ((filters & ~PNG_ALL_FILTERS) != 0)
1027 png_app_error(png_ptr, "png_set_filter: invalid filters mask/value");
1029 /* For compatibility with the previous behavior assume a mask value was
1030 * passed and ignore the non-mask bits.
1032 filters &= PNG_ALL_FILTERS;
1034 /* For a possibly foolish consistency (it shouldn't matter) set
1035 * PNG_FILTER_NONE rather than 0.
1038 filters = PNG_FILTER_NONE;
1041 /* PNG_FILTER_VALUE_NONE and PNG_NO_FILTERS are both 0. */
1042 if (filters != 0 && filters != PNG_FILTER_NONE)
1043 png_app_error(png_ptr, "png_set_filter: no filters supported");
1045 filters = PNG_FILTER_NONE;
1048 # ifdef PNG_WRITE_FILTER_SUPPORTED
1049 /* If we have allocated the row_buf, this means we have already started
1050 * with the image and we should have allocated all of the filter buffers
1051 * that have been selected. If prev_row isn't already allocated, then
1052 * it is too late to start using the filters that need it, since we
1053 * will be missing the data in the previous row. If an application
1054 * wants to start and stop using particular filters during compression,
1055 * it should start out with all of the filters, and then add and
1056 * remove them after the start of compression.
1058 * NOTE: this is a nasty constraint on the code, because it means that the
1059 * prev_row buffer must be maintained even if there are currently no
1060 * 'prev_row' requiring filters active.
1062 if (png_ptr->row_buf != NULL)
1064 /* Repeat the checks in png_write_start_row; 1 pixel high or wide
1065 * images cannot benefit from certain filters. If this isn't done here
1066 * the check below will fire on 1 pixel high images.
1068 if (png_ptr->height == 1)
1069 filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1071 if (png_ptr->width == 1)
1072 filters &= ~(PNG_FILTER_SUB|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1074 if ((filters & (PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH)) != 0
1075 && png_ptr->prev_row == NULL)
1077 /* This is the error case, however it is benign - the previous row
1078 * is not available so the filter can't be used. Just warn here.
1080 png_app_warning(png_ptr,
1081 "png_set_filter: UP/AVG/PAETH cannot be added after start");
1082 filters &= ~(PNG_FILTER_UP|PNG_FILTER_AVG|PNG_FILTER_PAETH);
1085 /* Allocate any required buffers that have not already been allocated.
1087 png_write_alloc_filter_row_buffers(png_ptr, filters);
1089 # endif /* PNG_WRITE_FILTER_SUPPORTED */
1091 /* Finally store the value.
1092 * TODO: this field could probably be removed if neither READ nor
1093 * WRITE_FILTER are supported.
1095 png_ptr->do_filter = (png_byte)filters; /* SAFE: checked above */
1098 /* This allows us to influence the way in which libpng chooses the "best"
1099 * filter for the current scanline. While the "minimum-sum-of-absolute-
1100 * differences metric is relatively fast and effective, there is some
1101 * question as to whether it can be improved upon by trying to keep the
1102 * filtered data going to zlib more consistent, hopefully resulting in
1103 * better compression.
1105 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* GRR 970116 */
1106 /* Convenience reset API. */
1108 png_reset_filter_heuristics(png_structrp png_ptr)
1110 /* Clear out any old values in the 'weights' - this must be done because if
1111 * the app calls set_filter_heuristics multiple times with different
1112 * 'num_weights' values we would otherwise potentially have wrong sized
1115 png_ptr->num_prev_filters = 0;
1116 png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
1117 if (png_ptr->prev_filters != NULL)
1119 png_bytep old = png_ptr->prev_filters;
1120 png_ptr->prev_filters = NULL;
1121 png_free(png_ptr, old);
1123 if (png_ptr->filter_weights != NULL)
1125 png_uint_16p old = png_ptr->filter_weights;
1126 png_ptr->filter_weights = NULL;
1127 png_free(png_ptr, old);
1130 if (png_ptr->inv_filter_weights != NULL)
1132 png_uint_16p old = png_ptr->inv_filter_weights;
1133 png_ptr->inv_filter_weights = NULL;
1134 png_free(png_ptr, old);
1137 /* Leave the filter_costs - this array is fixed size. */
1141 png_init_filter_heuristics(png_structrp png_ptr, int heuristic_method,
1144 if (png_ptr == NULL)
1147 /* Clear out the arrays */
1148 png_reset_filter_heuristics(png_ptr);
1150 /* Check arguments; the 'reset' function makes the correct settings for the
1151 * unweighted case, but we must handle the weight case by initializing the
1152 * arrays for the caller.
1154 if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1158 if (num_weights > 0)
1160 png_ptr->prev_filters = (png_bytep)png_malloc(png_ptr,
1161 (png_uint_32)((sizeof (png_byte)) * num_weights));
1163 /* To make sure that the weighting starts out fairly */
1164 for (i = 0; i < num_weights; i++)
1166 png_ptr->prev_filters[i] = 255;
1169 png_ptr->filter_weights = (png_uint_16p)png_malloc(png_ptr,
1170 (png_uint_32)((sizeof (png_uint_16)) * num_weights));
1172 png_ptr->inv_filter_weights = (png_uint_16p)png_malloc(png_ptr,
1173 (png_uint_32)((sizeof (png_uint_16)) * num_weights));
1175 for (i = 0; i < num_weights; i++)
1177 png_ptr->inv_filter_weights[i] =
1178 png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
1181 /* Safe to set this now */
1182 png_ptr->num_prev_filters = (png_byte)num_weights;
1185 /* If, in the future, there are other filter methods, this would
1186 * need to be based on png_ptr->filter.
1188 if (png_ptr->filter_costs == NULL)
1190 png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
1191 (png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
1193 png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
1194 (png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
1197 for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
1199 png_ptr->inv_filter_costs[i] =
1200 png_ptr->filter_costs[i] = PNG_COST_FACTOR;
1203 /* All the arrays are inited, safe to set this: */
1204 png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_WEIGHTED;
1206 /* Return the 'ok' code. */
1209 else if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT ||
1210 heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
1216 png_warning(png_ptr, "Unknown filter heuristic method");
1221 /* Provide floating and fixed point APIs */
1222 #ifdef PNG_FLOATING_POINT_SUPPORTED
1224 png_set_filter_heuristics(png_structrp png_ptr, int heuristic_method,
1225 int num_weights, png_const_doublep filter_weights,
1226 png_const_doublep filter_costs)
1228 png_debug(1, "in png_set_filter_heuristics");
1230 /* The internal API allocates all the arrays and ensures that the elements of
1231 * those arrays are set to the default value.
1233 if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
1236 /* If using the weighted method copy in the weights. */
1237 if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1240 for (i = 0; i < num_weights; i++)
1242 if (filter_weights[i] <= 0.0)
1244 png_ptr->inv_filter_weights[i] =
1245 png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
1250 png_ptr->inv_filter_weights[i] =
1251 (png_uint_16)(PNG_WEIGHT_FACTOR*filter_weights[i]+.5);
1253 png_ptr->filter_weights[i] =
1254 (png_uint_16)(PNG_WEIGHT_FACTOR/filter_weights[i]+.5);
1258 /* Here is where we set the relative costs of the different filters. We
1259 * should take the desired compression level into account when setting
1260 * the costs, so that Paeth, for instance, has a high relative cost at low
1261 * compression levels, while it has a lower relative cost at higher
1262 * compression settings. The filter types are in order of increasing
1263 * relative cost, so it would be possible to do this with an algorithm.
1265 for (i = 0; i < PNG_FILTER_VALUE_LAST; i++) if (filter_costs[i] >= 1.0)
1267 png_ptr->inv_filter_costs[i] =
1268 (png_uint_16)(PNG_COST_FACTOR / filter_costs[i] + .5);
1270 png_ptr->filter_costs[i] =
1271 (png_uint_16)(PNG_COST_FACTOR * filter_costs[i] + .5);
1275 #endif /* FLOATING_POINT */
1277 #ifdef PNG_FIXED_POINT_SUPPORTED
1279 png_set_filter_heuristics_fixed(png_structrp png_ptr, int heuristic_method,
1280 int num_weights, png_const_fixed_point_p filter_weights,
1281 png_const_fixed_point_p filter_costs)
1283 png_debug(1, "in png_set_filter_heuristics_fixed");
1285 /* The internal API allocates all the arrays and ensures that the elements of
1286 * those arrays are set to the default value.
1288 if (!png_init_filter_heuristics(png_ptr, heuristic_method, num_weights))
1291 /* If using the weighted method copy in the weights. */
1292 if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
1295 for (i = 0; i < num_weights; i++)
1297 if (filter_weights[i] <= 0)
1299 png_ptr->inv_filter_weights[i] =
1300 png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
1305 png_ptr->inv_filter_weights[i] = (png_uint_16)
1306 ((PNG_WEIGHT_FACTOR*filter_weights[i]+PNG_FP_HALF)/PNG_FP_1);
1308 png_ptr->filter_weights[i] = (png_uint_16)((PNG_WEIGHT_FACTOR*
1309 PNG_FP_1+(filter_weights[i]/2))/filter_weights[i]);
1313 /* Here is where we set the relative costs of the different filters. We
1314 * should take the desired compression level into account when setting
1315 * the costs, so that Paeth, for instance, has a high relative cost at low
1316 * compression levels, while it has a lower relative cost at higher
1317 * compression settings. The filter types are in order of increasing
1318 * relative cost, so it would be possible to do this with an algorithm.
1320 for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
1321 if (filter_costs[i] >= PNG_FP_1)
1325 /* Use a 32 bit unsigned temporary here because otherwise the
1326 * intermediate value will be a 32 bit *signed* integer (ANSI rules)
1327 * and this will get the wrong answer on division.
1329 tmp = PNG_COST_FACTOR*PNG_FP_1 + (filter_costs[i]/2);
1330 tmp /= filter_costs[i];
1332 png_ptr->inv_filter_costs[i] = (png_uint_16)tmp;
1334 tmp = PNG_COST_FACTOR * filter_costs[i] + PNG_FP_HALF;
1337 png_ptr->filter_costs[i] = (png_uint_16)tmp;
1341 #endif /* FIXED_POINT */
1342 #endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
1345 png_set_compression_level(png_structrp png_ptr, int level)
1347 png_debug(1, "in png_set_compression_level");
1349 if (png_ptr == NULL)
1352 png_ptr->zlib_level = level;
1356 png_set_compression_mem_level(png_structrp png_ptr, int mem_level)
1358 png_debug(1, "in png_set_compression_mem_level");
1360 if (png_ptr == NULL)
1363 png_ptr->zlib_mem_level = mem_level;
1367 png_set_compression_strategy(png_structrp png_ptr, int strategy)
1369 png_debug(1, "in png_set_compression_strategy");
1371 if (png_ptr == NULL)
1374 /* The flag setting here prevents the libpng dynamic selection of strategy.
1376 png_ptr->flags |= PNG_FLAG_ZLIB_CUSTOM_STRATEGY;
1377 png_ptr->zlib_strategy = strategy;
1380 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1381 * smaller value of window_bits if it can do so safely.
1384 png_set_compression_window_bits(png_structrp png_ptr, int window_bits)
1386 if (png_ptr == NULL)
1389 /* Prior to 1.6.0 this would warn but then set the window_bits value, this
1390 * meant that negative window bits values could be selected which would cause
1391 * libpng to write a non-standard PNG file with raw deflate or gzip
1392 * compressed IDAT or ancillary chunks. Such files can be read and there is
1393 * no warning on read, so this seems like a very bad idea.
1395 if (window_bits > 15)
1397 png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
1401 else if (window_bits < 8)
1403 png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
1407 png_ptr->zlib_window_bits = window_bits;
1411 png_set_compression_method(png_structrp png_ptr, int method)
1413 png_debug(1, "in png_set_compression_method");
1415 if (png_ptr == NULL)
1418 /* This would produce an invalid PNG file if it worked, but it doesn't and
1419 * deflate will fault it, so it is harmless to just warn here.
1422 png_warning(png_ptr, "Only compression method 8 is supported by PNG");
1424 png_ptr->zlib_method = method;
1427 /* The following were added to libpng-1.5.4 */
1428 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
1430 png_set_text_compression_level(png_structrp png_ptr, int level)
1432 png_debug(1, "in png_set_text_compression_level");
1434 if (png_ptr == NULL)
1437 png_ptr->zlib_text_level = level;
1441 png_set_text_compression_mem_level(png_structrp png_ptr, int mem_level)
1443 png_debug(1, "in png_set_text_compression_mem_level");
1445 if (png_ptr == NULL)
1448 png_ptr->zlib_text_mem_level = mem_level;
1452 png_set_text_compression_strategy(png_structrp png_ptr, int strategy)
1454 png_debug(1, "in png_set_text_compression_strategy");
1456 if (png_ptr == NULL)
1459 png_ptr->zlib_text_strategy = strategy;
1462 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1463 * smaller value of window_bits if it can do so safely.
1466 png_set_text_compression_window_bits(png_structrp png_ptr, int window_bits)
1468 if (png_ptr == NULL)
1471 if (window_bits > 15)
1473 png_warning(png_ptr, "Only compression windows <= 32k supported by PNG");
1477 else if (window_bits < 8)
1479 png_warning(png_ptr, "Only compression windows >= 256 supported by PNG");
1483 png_ptr->zlib_text_window_bits = window_bits;
1487 png_set_text_compression_method(png_structrp png_ptr, int method)
1489 png_debug(1, "in png_set_text_compression_method");
1491 if (png_ptr == NULL)
1495 png_warning(png_ptr, "Only compression method 8 is supported by PNG");
1497 png_ptr->zlib_text_method = method;
1499 #endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
1500 /* end of API added to libpng-1.5.4 */
1503 png_set_write_status_fn(png_structrp png_ptr, png_write_status_ptr write_row_fn)
1505 if (png_ptr == NULL)
1508 png_ptr->write_row_fn = write_row_fn;
1511 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
1513 png_set_write_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr
1514 write_user_transform_fn)
1516 png_debug(1, "in png_set_write_user_transform_fn");
1518 if (png_ptr == NULL)
1521 png_ptr->transformations |= PNG_USER_TRANSFORM;
1522 png_ptr->write_user_transform_fn = write_user_transform_fn;
1527 #ifdef PNG_INFO_IMAGE_SUPPORTED
1529 png_write_png(png_structrp png_ptr, png_inforp info_ptr,
1530 int transforms, voidp params)
1532 if (png_ptr == NULL || info_ptr == NULL)
1535 if ((info_ptr->valid & PNG_INFO_IDAT) == 0)
1537 png_app_error(png_ptr, "no rows for png_write_image to write");
1541 /* Write the file header information. */
1542 png_write_info(png_ptr, info_ptr);
1544 /* ------ these transformations don't touch the info structure ------- */
1546 /* Invert monochrome pixels */
1547 if (transforms & PNG_TRANSFORM_INVERT_MONO)
1548 #ifdef PNG_WRITE_INVERT_SUPPORTED
1549 png_set_invert_mono(png_ptr);
1551 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1554 /* Shift the pixels up to a legal bit depth and fill in
1555 * as appropriate to correctly scale the image.
1557 if (transforms & PNG_TRANSFORM_SHIFT)
1558 #ifdef PNG_WRITE_SHIFT_SUPPORTED
1559 if (info_ptr->valid & PNG_INFO_sBIT)
1560 png_set_shift(png_ptr, &info_ptr->sig_bit);
1562 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1565 /* Pack pixels into bytes */
1566 if (transforms & PNG_TRANSFORM_PACKING)
1567 #ifdef PNG_WRITE_PACK_SUPPORTED
1568 png_set_packing(png_ptr);
1570 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1573 /* Swap location of alpha bytes from ARGB to RGBA */
1574 if (transforms & PNG_TRANSFORM_SWAP_ALPHA)
1575 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
1576 png_set_swap_alpha(png_ptr);
1578 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1581 /* Remove a filler (X) from XRGB/RGBX/AG/GA into to convert it into
1582 * RGB, note that the code expects the input color type to be G or RGB; no
1586 (PNG_TRANSFORM_STRIP_FILLER_AFTER|PNG_TRANSFORM_STRIP_FILLER_BEFORE))
1588 #ifdef PNG_WRITE_FILLER_SUPPORTED
1589 if (transforms & PNG_TRANSFORM_STRIP_FILLER_AFTER)
1591 if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
1592 png_app_error(png_ptr,
1593 "PNG_TRANSFORM_STRIP_FILLER: BEFORE+AFTER not supported");
1595 /* Continue if ignored - this is the pre-1.6.10 behavior */
1596 png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
1599 else if (transforms & PNG_TRANSFORM_STRIP_FILLER_BEFORE)
1600 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
1602 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_FILLER not supported");
1606 /* Flip BGR pixels to RGB */
1607 if (transforms & PNG_TRANSFORM_BGR)
1608 #ifdef PNG_WRITE_BGR_SUPPORTED
1609 png_set_bgr(png_ptr);
1611 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1614 /* Swap bytes of 16-bit files to most significant byte first */
1615 if (transforms & PNG_TRANSFORM_SWAP_ENDIAN)
1616 #ifdef PNG_WRITE_SWAP_SUPPORTED
1617 png_set_swap(png_ptr);
1619 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1622 /* Swap bits of 1, 2, 4 bit packed pixel formats */
1623 if (transforms & PNG_TRANSFORM_PACKSWAP)
1624 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
1625 png_set_packswap(png_ptr);
1627 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1630 /* Invert the alpha channel from opacity to transparency */
1631 if (transforms & PNG_TRANSFORM_INVERT_ALPHA)
1632 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
1633 png_set_invert_alpha(png_ptr);
1635 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1638 /* ----------------------- end of transformations ------------------- */
1640 /* Write the bits */
1641 png_write_image(png_ptr, info_ptr->row_pointers);
1643 /* It is REQUIRED to call this to finish writing the rest of the file */
1644 png_write_end(png_ptr, info_ptr);
1651 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
1652 #ifdef PNG_STDIO_SUPPORTED /* currently required for png_image_write_* */
1653 /* Initialize the write structure - general purpose utility. */
1655 png_image_write_init(png_imagep image)
1657 png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, image,
1658 png_safe_error, png_safe_warning);
1660 if (png_ptr != NULL)
1662 png_infop info_ptr = png_create_info_struct(png_ptr);
1664 if (info_ptr != NULL)
1666 png_controlp control = png_voidcast(png_controlp,
1667 png_malloc_warn(png_ptr, (sizeof *control)));
1669 if (control != NULL)
1671 memset(control, 0, (sizeof *control));
1673 control->png_ptr = png_ptr;
1674 control->info_ptr = info_ptr;
1675 control->for_write = 1;
1677 image->opaque = control;
1681 /* Error clean up */
1682 png_destroy_info_struct(png_ptr, &info_ptr);
1685 png_destroy_write_struct(&png_ptr, NULL);
1688 return png_image_error(image, "png_image_write_: out of memory");
1691 /* Arguments to png_image_write_main: */
1696 png_const_voidp buffer;
1697 png_int_32 row_stride;
1698 png_const_voidp colormap;
1699 int convert_to_8bit;
1700 /* Local variables: */
1701 png_const_voidp first_row;
1702 ptrdiff_t row_bytes;
1703 png_voidp local_row;
1704 } png_image_write_control;
1706 /* Write png_uint_16 input to a 16-bit PNG; the png_ptr has already been set to
1707 * do any necessary byte swapping. The component order is defined by the
1708 * png_image format value.
1711 png_write_image_16bit(png_voidp argument)
1713 png_image_write_control *display = png_voidcast(png_image_write_control*,
1715 png_imagep image = display->image;
1716 png_structrp png_ptr = image->opaque->png_ptr;
1718 png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
1719 display->first_row);
1720 png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
1721 png_uint_16p row_end;
1722 const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
1724 png_uint_32 y = image->height;
1726 if (image->format & PNG_FORMAT_FLAG_ALPHA)
1728 # ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
1729 if (image->format & PNG_FORMAT_FLAG_AFIRST)
1732 ++input_row; /* To point to the first component */
1742 png_error(png_ptr, "png_write_image: internal call error");
1744 /* Work out the output row end and count over this, note that the increment
1745 * above to 'row' means that row_end can actually be beyond the end of the
1746 * row; this is correct.
1748 row_end = output_row + image->width * (channels+1);
1752 png_const_uint_16p in_ptr = input_row;
1753 png_uint_16p out_ptr = output_row;
1755 while (out_ptr < row_end)
1757 const png_uint_16 alpha = in_ptr[aindex];
1758 png_uint_32 reciprocal = 0;
1761 out_ptr[aindex] = alpha;
1763 /* Calculate a reciprocal. The correct calculation is simply
1764 * component/alpha*65535 << 15. (I.e. 15 bits of precision); this
1765 * allows correct rounding by adding .5 before the shift. 'reciprocal'
1766 * is only initialized when required.
1768 if (alpha > 0 && alpha < 65535)
1769 reciprocal = ((0xffff<<15)+(alpha>>1))/alpha;
1772 do /* always at least one channel */
1774 png_uint_16 component = *in_ptr++;
1776 /* The following gives 65535 for an alpha of 0, which is fine,
1777 * otherwise if 0/0 is represented as some other value there is more
1778 * likely to be a discontinuity which will probably damage
1779 * compression when moving from a fully transparent area to a
1780 * nearly transparent one. (The assumption here is that opaque
1781 * areas tend not to be 0 intensity.)
1783 if (component >= alpha)
1786 /* component<alpha, so component/alpha is less than one and
1787 * component*reciprocal is less than 2^31.
1789 else if (component > 0 && alpha < 65535)
1791 png_uint_32 calc = component * reciprocal;
1792 calc += 16384; /* round to nearest */
1793 component = (png_uint_16)(calc >> 15);
1796 *out_ptr++ = component;
1800 /* Skip to next component (skip the intervening alpha channel) */
1805 png_write_row(png_ptr, png_voidcast(png_const_bytep, display->local_row));
1806 input_row += display->row_bytes/(sizeof (png_uint_16));
1812 /* Given 16-bit input (1 to 4 channels) write 8-bit output. If an alpha channel
1813 * is present it must be removed from the components, the components are then
1814 * written in sRGB encoding. No components are added or removed.
1816 * Calculate an alpha reciprocal to reverse pre-multiplication. As above the
1817 * calculation can be done to 15 bits of accuracy; however, the output needs to
1818 * be scaled in the range 0..255*65535, so include that scaling here.
1820 #define UNP_RECIPROCAL(alpha) ((((0xffff*0xff)<<7)+(alpha>>1))/alpha)
1823 png_unpremultiply(png_uint_32 component, png_uint_32 alpha,
1824 png_uint_32 reciprocal/*from the above macro*/)
1826 /* The following gives 1.0 for an alpha of 0, which is fine, otherwise if 0/0
1827 * is represented as some other value there is more likely to be a
1828 * discontinuity which will probably damage compression when moving from a
1829 * fully transparent area to a nearly transparent one. (The assumption here
1830 * is that opaque areas tend not to be 0 intensity.)
1832 * There is a rounding problem here; if alpha is less than 128 it will end up
1833 * as 0 when scaled to 8 bits. To avoid introducing spurious colors into the
1834 * output change for this too.
1836 if (component >= alpha || alpha < 128)
1839 /* component<alpha, so component/alpha is less than one and
1840 * component*reciprocal is less than 2^31.
1842 else if (component > 0)
1844 /* The test is that alpha/257 (rounded) is less than 255, the first value
1845 * that becomes 255 is 65407.
1846 * NOTE: this must agree with the PNG_DIV257 macro (which must, therefore,
1847 * be exact!) [Could also test reciprocal != 0]
1851 component *= reciprocal;
1852 component += 64; /* round to nearest */
1859 /* Convert the component to sRGB. */
1860 return (png_byte)PNG_sRGB_FROM_LINEAR(component);
1868 png_write_image_8bit(png_voidp argument)
1870 png_image_write_control *display = png_voidcast(png_image_write_control*,
1872 png_imagep image = display->image;
1873 png_structrp png_ptr = image->opaque->png_ptr;
1875 png_const_uint_16p input_row = png_voidcast(png_const_uint_16p,
1876 display->first_row);
1877 png_bytep output_row = png_voidcast(png_bytep, display->local_row);
1878 png_uint_32 y = image->height;
1879 const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) ? 3 : 1;
1881 if (image->format & PNG_FORMAT_FLAG_ALPHA)
1886 # ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
1887 if (image->format & PNG_FORMAT_FLAG_AFIRST)
1890 ++input_row; /* To point to the first component */
1898 /* Use row_end in place of a loop counter: */
1899 row_end = output_row + image->width * (channels+1);
1903 png_const_uint_16p in_ptr = input_row;
1904 png_bytep out_ptr = output_row;
1906 while (out_ptr < row_end)
1908 png_uint_16 alpha = in_ptr[aindex];
1909 png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
1910 png_uint_32 reciprocal = 0;
1913 /* Scale and write the alpha channel. */
1914 out_ptr[aindex] = alphabyte;
1916 if (alphabyte > 0 && alphabyte < 255)
1917 reciprocal = UNP_RECIPROCAL(alpha);
1920 do /* always at least one channel */
1921 *out_ptr++ = png_unpremultiply(*in_ptr++, alpha, reciprocal);
1924 /* Skip to next component (skip the intervening alpha channel) */
1927 } /* while out_ptr < row_end */
1929 png_write_row(png_ptr, png_voidcast(png_const_bytep,
1930 display->local_row));
1931 input_row += display->row_bytes/(sizeof (png_uint_16));
1937 /* No alpha channel, so the row_end really is the end of the row and it
1938 * is sufficient to loop over the components one by one.
1940 png_bytep row_end = output_row + image->width * channels;
1944 png_const_uint_16p in_ptr = input_row;
1945 png_bytep out_ptr = output_row;
1947 while (out_ptr < row_end)
1949 png_uint_32 component = *in_ptr++;
1952 *out_ptr++ = (png_byte)PNG_sRGB_FROM_LINEAR(component);
1955 png_write_row(png_ptr, output_row);
1956 input_row += display->row_bytes/(sizeof (png_uint_16));
1964 png_image_set_PLTE(png_image_write_control *display)
1966 const png_imagep image = display->image;
1967 const void *cmap = display->colormap;
1968 const int entries = image->colormap_entries > 256 ? 256 :
1969 (int)image->colormap_entries;
1971 /* NOTE: the caller must check for cmap != NULL and entries != 0 */
1972 const png_uint_32 format = image->format;
1973 const int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
1975 # if defined(PNG_FORMAT_BGR_SUPPORTED) &&\
1976 defined(PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED)
1977 const int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1978 (format & PNG_FORMAT_FLAG_ALPHA) != 0;
1983 # ifdef PNG_FORMAT_BGR_SUPPORTED
1984 const int bgr = (format & PNG_FORMAT_FLAG_BGR) ? 2 : 0;
1990 png_color palette[256];
1993 memset(tRNS, 255, (sizeof tRNS));
1994 memset(palette, 0, (sizeof palette));
1996 for (i=num_trans=0; i<entries; ++i)
1998 /* This gets automatically converted to sRGB with reversal of the
1999 * pre-multiplication if the color-map has an alpha channel.
2001 if (format & PNG_FORMAT_FLAG_LINEAR)
2003 png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);
2005 entry += i * channels;
2007 if (channels & 1) /* no alpha */
2009 if (channels >= 3) /* RGB */
2011 palette[i].blue = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
2013 palette[i].green = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
2015 palette[i].red = (png_byte)PNG_sRGB_FROM_LINEAR(255 *
2020 palette[i].blue = palette[i].red = palette[i].green =
2021 (png_byte)PNG_sRGB_FROM_LINEAR(255 * *entry);
2026 png_uint_16 alpha = entry[afirst ? 0 : channels-1];
2027 png_byte alphabyte = (png_byte)PNG_DIV257(alpha);
2028 png_uint_32 reciprocal = 0;
2030 /* Calculate a reciprocal, as in the png_write_image_8bit code above
2031 * this is designed to produce a value scaled to 255*65535 when
2032 * divided by 128 (i.e. asr 7).
2034 if (alphabyte > 0 && alphabyte < 255)
2035 reciprocal = (((0xffff*0xff)<<7)+(alpha>>1))/alpha;
2037 tRNS[i] = alphabyte;
2038 if (alphabyte < 255)
2041 if (channels >= 3) /* RGB */
2043 palette[i].blue = png_unpremultiply(entry[afirst + (2 ^ bgr)],
2045 palette[i].green = png_unpremultiply(entry[afirst + 1], alpha,
2047 palette[i].red = png_unpremultiply(entry[afirst + bgr], alpha,
2052 palette[i].blue = palette[i].red = palette[i].green =
2053 png_unpremultiply(entry[afirst], alpha, reciprocal);
2057 else /* Color-map has sRGB values */
2059 png_const_bytep entry = png_voidcast(png_const_bytep, cmap);
2061 entry += i * channels;
2066 tRNS[i] = entry[afirst ? 0 : 3];
2071 palette[i].blue = entry[afirst + (2 ^ bgr)];
2072 palette[i].green = entry[afirst + 1];
2073 palette[i].red = entry[afirst + bgr];
2077 tRNS[i] = entry[1 ^ afirst];
2082 palette[i].blue = palette[i].red = palette[i].green =
2099 png_set_PLTE(image->opaque->png_ptr, image->opaque->info_ptr, palette,
2103 png_set_tRNS(image->opaque->png_ptr, image->opaque->info_ptr, tRNS,
2106 image->colormap_entries = entries;
2110 png_image_write_main(png_voidp argument)
2112 png_image_write_control *display = png_voidcast(png_image_write_control*,
2114 png_imagep image = display->image;
2115 png_structrp png_ptr = image->opaque->png_ptr;
2116 png_inforp info_ptr = image->opaque->info_ptr;
2117 png_uint_32 format = image->format;
2119 int colormap = (format & PNG_FORMAT_FLAG_COLORMAP) != 0;
2120 int linear = !colormap && (format & PNG_FORMAT_FLAG_LINEAR) != 0; /* input */
2121 int alpha = !colormap && (format & PNG_FORMAT_FLAG_ALPHA) != 0;
2122 int write_16bit = linear && !colormap && !display->convert_to_8bit;
2124 # ifdef PNG_BENIGN_ERRORS_SUPPORTED
2125 /* Make sure we error out on any bad situation */
2126 png_set_benign_errors(png_ptr, 0/*error*/);
2129 /* Default the 'row_stride' parameter if required. */
2130 if (display->row_stride == 0)
2131 display->row_stride = PNG_IMAGE_ROW_STRIDE(*image);
2133 /* Set the required transforms then write the rows in the correct order. */
2134 if (format & PNG_FORMAT_FLAG_COLORMAP)
2136 if (display->colormap != NULL && image->colormap_entries > 0)
2138 png_uint_32 entries = image->colormap_entries;
2140 png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
2141 entries > 16 ? 8 : (entries > 4 ? 4 : (entries > 2 ? 2 : 1)),
2142 PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
2143 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
2145 png_image_set_PLTE(display);
2149 png_error(image->opaque->png_ptr,
2150 "no color-map for color-mapped image");
2154 png_set_IHDR(png_ptr, info_ptr, image->width, image->height,
2155 write_16bit ? 16 : 8,
2156 ((format & PNG_FORMAT_FLAG_COLOR) ? PNG_COLOR_MASK_COLOR : 0) +
2157 ((format & PNG_FORMAT_FLAG_ALPHA) ? PNG_COLOR_MASK_ALPHA : 0),
2158 PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
2160 /* Counter-intuitively the data transformations must be called *after*
2161 * png_write_info, not before as in the read code, but the 'set' functions
2162 * must still be called before. Just set the color space information, never
2163 * write an interlaced image.
2168 /* The gamma here is 1.0 (linear) and the cHRM chunk matches sRGB. */
2169 png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_LINEAR);
2171 if (!(image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB))
2172 png_set_cHRM_fixed(png_ptr, info_ptr,
2174 /* white */ 31270, 32900,
2175 /* red */ 64000, 33000,
2176 /* green */ 30000, 60000,
2177 /* blue */ 15000, 6000
2181 else if (!(image->flags & PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB))
2182 png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_PERCEPTUAL);
2184 /* Else writing an 8-bit file and the *colors* aren't sRGB, but the 8-bit
2185 * space must still be gamma encoded.
2188 png_set_gAMA_fixed(png_ptr, info_ptr, PNG_GAMMA_sRGB_INVERSE);
2190 /* Write the file header. */
2191 png_write_info(png_ptr, info_ptr);
2193 /* Now set up the data transformations (*after* the header is written),
2194 * remove the handled transformations from the 'format' flags for checking.
2196 * First check for a little endian system if writing 16 bit files.
2200 PNG_CONST png_uint_16 le = 0x0001;
2202 if (*(png_const_bytep)&le)
2203 png_set_swap(png_ptr);
2206 # ifdef PNG_SIMPLIFIED_WRITE_BGR_SUPPORTED
2207 if (format & PNG_FORMAT_FLAG_BGR)
2209 if (!colormap && (format & PNG_FORMAT_FLAG_COLOR) != 0)
2210 png_set_bgr(png_ptr);
2211 format &= ~PNG_FORMAT_FLAG_BGR;
2215 # ifdef PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED
2216 if (format & PNG_FORMAT_FLAG_AFIRST)
2218 if (!colormap && (format & PNG_FORMAT_FLAG_ALPHA) != 0)
2219 png_set_swap_alpha(png_ptr);
2220 format &= ~PNG_FORMAT_FLAG_AFIRST;
2224 /* If there are 16 or fewer color-map entries we wrote a lower bit depth
2225 * above, but the application data is still byte packed.
2227 if (colormap && image->colormap_entries <= 16)
2228 png_set_packing(png_ptr);
2230 /* That should have handled all (both) the transforms. */
2231 if ((format & ~(png_uint_32)(PNG_FORMAT_FLAG_COLOR | PNG_FORMAT_FLAG_LINEAR |
2232 PNG_FORMAT_FLAG_ALPHA | PNG_FORMAT_FLAG_COLORMAP)) != 0)
2233 png_error(png_ptr, "png_write_image: unsupported transformation");
2236 png_const_bytep row = png_voidcast(png_const_bytep, display->buffer);
2237 ptrdiff_t row_bytes = display->row_stride;
2240 row_bytes *= (sizeof (png_uint_16));
2243 row += (image->height-1) * (-row_bytes);
2245 display->first_row = row;
2246 display->row_bytes = row_bytes;
2249 /* Apply 'fast' options if the flag is set. */
2250 if ((image->flags & PNG_IMAGE_FLAG_FAST) != 0)
2252 png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, PNG_NO_FILTERS);
2253 /* NOTE: determined by experiment using pngstest, this reflects some
2254 * balance between the time to write the image once and the time to read
2255 * it about 50 times. The speed-up in pngstest was about 10-20% of the
2256 * total (user) time on a heavily loaded system.
2258 png_set_compression_level(png_ptr, 3);
2261 /* Check for the cases that currently require a pre-transform on the row
2262 * before it is written. This only applies when the input is 16-bit and
2263 * either there is an alpha channel or it is converted to 8-bit.
2265 if ((linear && alpha) || (!colormap && display->convert_to_8bit))
2267 png_bytep row = png_voidcast(png_bytep, png_malloc(png_ptr,
2268 png_get_rowbytes(png_ptr, info_ptr)));
2271 display->local_row = row;
2273 result = png_safe_execute(image, png_write_image_16bit, display);
2275 result = png_safe_execute(image, png_write_image_8bit, display);
2276 display->local_row = NULL;
2278 png_free(png_ptr, row);
2280 /* Skip the 'write_end' on error: */
2285 /* Otherwise this is the case where the input is in a format currently
2286 * supported by the rest of the libpng write code; call it directly.
2290 png_const_bytep row = png_voidcast(png_const_bytep, display->first_row);
2291 ptrdiff_t row_bytes = display->row_bytes;
2292 png_uint_32 y = image->height;
2296 png_write_row(png_ptr, row);
2301 png_write_end(png_ptr, info_ptr);
2306 png_image_write_to_stdio(png_imagep image, FILE *file, int convert_to_8bit,
2307 const void *buffer, png_int_32 row_stride, const void *colormap)
2309 /* Write the image to the given (FILE*). */
2310 if (image != NULL && image->version == PNG_IMAGE_VERSION)
2314 if (png_image_write_init(image))
2316 png_image_write_control display;
2319 /* This is slightly evil, but png_init_io doesn't do anything other
2320 * than this and we haven't changed the standard IO functions so
2321 * this saves a 'safe' function.
2323 image->opaque->png_ptr->io_ptr = file;
2325 memset(&display, 0, (sizeof display));
2326 display.image = image;
2327 display.buffer = buffer;
2328 display.row_stride = row_stride;
2329 display.colormap = colormap;
2330 display.convert_to_8bit = convert_to_8bit;
2332 result = png_safe_execute(image, png_image_write_main, &display);
2333 png_image_free(image);
2342 return png_image_error(image,
2343 "png_image_write_to_stdio: invalid argument");
2346 else if (image != NULL)
2347 return png_image_error(image,
2348 "png_image_write_to_stdio: incorrect PNG_IMAGE_VERSION");
2355 png_image_write_to_file(png_imagep image, const char *file_name,
2356 int convert_to_8bit, const void *buffer, png_int_32 row_stride,
2357 const void *colormap)
2359 /* Write the image to the named file. */
2360 if (image != NULL && image->version == PNG_IMAGE_VERSION)
2362 if (file_name != NULL)
2364 FILE *fp = fopen(file_name, "wb");
2368 if (png_image_write_to_stdio(image, fp, convert_to_8bit, buffer,
2369 row_stride, colormap))
2371 int error; /* from fflush/fclose */
2373 /* Make sure the file is flushed correctly. */
2374 if (fflush(fp) == 0 && ferror(fp) == 0)
2376 if (fclose(fp) == 0)
2379 error = errno; /* from fclose */
2384 error = errno; /* from fflush or ferror */
2388 (void)remove(file_name);
2389 /* The image has already been cleaned up; this is just used to
2390 * set the error (because the original write succeeded).
2392 return png_image_error(image, strerror(error));
2397 /* Clean up: just the opened file. */
2399 (void)remove(file_name);
2405 return png_image_error(image, strerror(errno));
2409 return png_image_error(image,
2410 "png_image_write_to_file: invalid argument");
2413 else if (image != NULL)
2414 return png_image_error(image,
2415 "png_image_write_to_file: incorrect PNG_IMAGE_VERSION");
2420 #endif /* PNG_STDIO_SUPPORTED */
2421 #endif /* SIMPLIFIED_WRITE */
2422 #endif /* PNG_WRITE_SUPPORTED */