2 /* pngread.c - read a PNG file
4 * Copyright (c) 2018-2019 Cosmin Truta
5 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
6 * Copyright (c) 1996-1997 Andreas Dilger
7 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
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
13 * This file contains routines that an application calls directly to
14 * read a PNG file or stream.
18 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
22 #ifdef PNG_READ_SUPPORTED
24 /* Create a PNG structure for reading, and allocate any memory needed. */
25 PNG_FUNCTION(png_structp,PNGAPI
26 png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
27 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
29 #ifndef PNG_USER_MEM_SUPPORTED
30 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
31 error_fn, warn_fn, NULL, NULL, NULL);
33 return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
34 warn_fn, NULL, NULL, NULL);
37 /* Alternate create PNG structure for reading, and allocate any memory
40 PNG_FUNCTION(png_structp,PNGAPI
41 png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
42 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
43 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
45 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
46 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
51 png_ptr->mode = PNG_IS_READ_STRUCT;
53 /* Added in libpng-1.6.0; this can be used to detect a read structure if
54 * required (it will be zero in a write structure.)
56 # ifdef PNG_SEQUENTIAL_READ_SUPPORTED
57 png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
60 # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
61 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
63 /* In stable builds only warn if an application error can be completely
66 # if PNG_RELEASE_BUILD
67 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
71 /* TODO: delay this, it can be done in png_init_io (if the app doesn't
72 * do it itself) avoiding setting the default function if it is not
75 png_set_read_fn(png_ptr, NULL, NULL);
82 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
83 /* Read the information before the actual image data. This has been
84 * changed in v0.90 to allow reading a file that already has the magic
85 * bytes read from the stream. You can tell libpng how many bytes have
86 * been read from the beginning of the stream (up to the maximum of 8)
87 * via png_set_sig_bytes(), and we will only check the remaining bytes
88 * here. The application can then have access to the signature bytes we
89 * read if it is determined that this isn't a valid PNG file.
92 png_read_info(png_structrp png_ptr, png_inforp info_ptr)
94 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
98 png_debug(1, "in png_read_info");
100 if (png_ptr == NULL || info_ptr == NULL)
103 /* Read and check the PNG file signature. */
104 png_read_sig(png_ptr, info_ptr);
108 png_uint_32 length = png_read_chunk_header(png_ptr);
109 png_uint_32 chunk_name = png_ptr->chunk_name;
111 /* IDAT logic needs to happen here to simplify getting the two flags
114 if (chunk_name == png_IDAT)
116 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
117 png_chunk_error(png_ptr, "Missing IHDR before IDAT");
119 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
120 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
121 png_chunk_error(png_ptr, "Missing PLTE before IDAT");
123 else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
124 png_chunk_benign_error(png_ptr, "Too many IDATs found");
126 png_ptr->mode |= PNG_HAVE_IDAT;
129 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
131 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
132 png_ptr->mode |= PNG_AFTER_IDAT;
135 /* This should be a binary subdivision search or a hash for
136 * matching the chunk name rather than a linear search.
138 if (chunk_name == png_IHDR)
139 png_handle_IHDR(png_ptr, info_ptr, length);
141 else if (chunk_name == png_IEND)
142 png_handle_IEND(png_ptr, info_ptr, length);
144 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
145 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
147 png_handle_unknown(png_ptr, info_ptr, length, keep);
149 if (chunk_name == png_PLTE)
150 png_ptr->mode |= PNG_HAVE_PLTE;
152 else if (chunk_name == png_IDAT)
154 png_ptr->idat_size = 0; /* It has been consumed */
159 else if (chunk_name == png_PLTE)
160 png_handle_PLTE(png_ptr, info_ptr, length);
162 else if (chunk_name == png_IDAT)
164 #ifdef PNG_READ_APNG_SUPPORTED
165 png_have_info(png_ptr, info_ptr);
167 png_ptr->idat_size = length;
171 #ifdef PNG_READ_bKGD_SUPPORTED
172 else if (chunk_name == png_bKGD)
173 png_handle_bKGD(png_ptr, info_ptr, length);
176 #ifdef PNG_READ_cHRM_SUPPORTED
177 else if (chunk_name == png_cHRM)
178 png_handle_cHRM(png_ptr, info_ptr, length);
181 #ifdef PNG_READ_eXIf_SUPPORTED
182 else if (chunk_name == png_eXIf)
183 png_handle_eXIf(png_ptr, info_ptr, length);
186 #ifdef PNG_READ_gAMA_SUPPORTED
187 else if (chunk_name == png_gAMA)
188 png_handle_gAMA(png_ptr, info_ptr, length);
191 #ifdef PNG_READ_hIST_SUPPORTED
192 else if (chunk_name == png_hIST)
193 png_handle_hIST(png_ptr, info_ptr, length);
196 #ifdef PNG_READ_oFFs_SUPPORTED
197 else if (chunk_name == png_oFFs)
198 png_handle_oFFs(png_ptr, info_ptr, length);
201 #ifdef PNG_READ_pCAL_SUPPORTED
202 else if (chunk_name == png_pCAL)
203 png_handle_pCAL(png_ptr, info_ptr, length);
206 #ifdef PNG_READ_sCAL_SUPPORTED
207 else if (chunk_name == png_sCAL)
208 png_handle_sCAL(png_ptr, info_ptr, length);
211 #ifdef PNG_READ_pHYs_SUPPORTED
212 else if (chunk_name == png_pHYs)
213 png_handle_pHYs(png_ptr, info_ptr, length);
216 #ifdef PNG_READ_sBIT_SUPPORTED
217 else if (chunk_name == png_sBIT)
218 png_handle_sBIT(png_ptr, info_ptr, length);
221 #ifdef PNG_READ_sRGB_SUPPORTED
222 else if (chunk_name == png_sRGB)
223 png_handle_sRGB(png_ptr, info_ptr, length);
226 #ifdef PNG_READ_iCCP_SUPPORTED
227 else if (chunk_name == png_iCCP)
228 png_handle_iCCP(png_ptr, info_ptr, length);
231 #ifdef PNG_READ_sPLT_SUPPORTED
232 else if (chunk_name == png_sPLT)
233 png_handle_sPLT(png_ptr, info_ptr, length);
236 #ifdef PNG_READ_tEXt_SUPPORTED
237 else if (chunk_name == png_tEXt)
238 png_handle_tEXt(png_ptr, info_ptr, length);
241 #ifdef PNG_READ_tIME_SUPPORTED
242 else if (chunk_name == png_tIME)
243 png_handle_tIME(png_ptr, info_ptr, length);
246 #ifdef PNG_READ_tRNS_SUPPORTED
247 else if (chunk_name == png_tRNS)
248 png_handle_tRNS(png_ptr, info_ptr, length);
251 #ifdef PNG_READ_zTXt_SUPPORTED
252 else if (chunk_name == png_zTXt)
253 png_handle_zTXt(png_ptr, info_ptr, length);
256 #ifdef PNG_READ_iTXt_SUPPORTED
257 else if (chunk_name == png_iTXt)
258 png_handle_iTXt(png_ptr, info_ptr, length);
261 #ifdef PNG_READ_APNG_SUPPORTED
262 else if (chunk_name == png_acTL)
263 png_handle_acTL(png_ptr, info_ptr, length);
265 else if (chunk_name == png_fcTL)
266 png_handle_fcTL(png_ptr, info_ptr, length);
268 else if (chunk_name == png_fdAT)
269 png_handle_fdAT(png_ptr, info_ptr, length);
273 png_handle_unknown(png_ptr, info_ptr, length,
274 PNG_HANDLE_CHUNK_AS_DEFAULT);
277 #endif /* SEQUENTIAL_READ */
279 #ifdef PNG_READ_APNG_SUPPORTED
281 png_read_frame_head(png_structp png_ptr, png_infop info_ptr)
283 png_byte have_chunk_after_DAT; /* after IDAT or after fdAT */
285 png_debug(0, "Reading frame head");
287 if (!(png_ptr->mode & PNG_HAVE_acTL))
288 png_error(png_ptr, "attempt to png_read_frame_head() but "
291 /* do nothing for the main IDAT */
292 if (png_ptr->num_frames_read == 0)
295 png_read_reset(png_ptr);
296 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
297 png_ptr->mode &= ~PNG_HAVE_fcTL;
299 have_chunk_after_DAT = 0;
302 png_uint_32 length = png_read_chunk_header(png_ptr);
304 if (png_ptr->chunk_name == png_IDAT)
306 /* discard trailing IDATs for the first frame */
307 if (have_chunk_after_DAT || png_ptr->num_frames_read > 1)
308 png_error(png_ptr, "png_read_frame_head(): out of place IDAT");
309 png_crc_finish(png_ptr, length);
312 else if (png_ptr->chunk_name == png_fcTL)
314 png_handle_fcTL(png_ptr, info_ptr, length);
315 have_chunk_after_DAT = 1;
318 else if (png_ptr->chunk_name == png_fdAT)
320 png_ensure_sequence_number(png_ptr, length);
322 /* discard trailing fdATs for frames other than the first */
323 if (!have_chunk_after_DAT && png_ptr->num_frames_read > 1)
324 png_crc_finish(png_ptr, length - 4);
325 else if(png_ptr->mode & PNG_HAVE_fcTL)
327 png_ptr->idat_size = length - 4;
328 png_ptr->mode |= PNG_HAVE_IDAT;
333 png_error(png_ptr, "png_read_frame_head(): out of place fdAT");
337 png_warning(png_ptr, "Skipped (ignored) a chunk "
338 "between APNG chunks");
339 png_crc_finish(png_ptr, length);
343 #endif /* PNG_READ_APNG_SUPPORTED */
345 /* Optional call to update the users info_ptr structure */
347 png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
349 png_debug(1, "in png_read_update_info");
353 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
355 png_read_start_row(png_ptr);
357 # ifdef PNG_READ_TRANSFORMS_SUPPORTED
358 png_read_transform_info(png_ptr, info_ptr);
364 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
366 png_app_error(png_ptr,
367 "png_read_update_info/png_start_read_image: duplicate call");
371 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
372 /* Initialize palette, background, etc, after transformations
373 * are set, but before any reading takes place. This allows
374 * the user to obtain a gamma-corrected palette, for example.
375 * If the user doesn't call this, we will do it ourselves.
378 png_start_read_image(png_structrp png_ptr)
380 png_debug(1, "in png_start_read_image");
384 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
385 png_read_start_row(png_ptr);
387 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
389 png_app_error(png_ptr,
390 "png_start_read_image/png_read_update_info: duplicate call");
393 #endif /* SEQUENTIAL_READ */
395 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
396 #ifdef PNG_MNG_FEATURES_SUPPORTED
397 /* Undoes intrapixel differencing,
398 * NOTE: this is apparently only supported in the 'sequential' reader.
401 png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
403 png_debug(1, "in png_do_read_intrapixel");
406 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
409 png_uint_32 row_width = row_info->width;
411 if (row_info->bit_depth == 8)
416 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
419 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
425 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
427 *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
428 *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
431 else if (row_info->bit_depth == 16)
436 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
439 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
445 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
447 png_uint_32 s0 = (png_uint_32)(*(rp ) << 8) | *(rp + 1);
448 png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
449 png_uint_32 s2 = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
450 png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
451 png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
452 *(rp ) = (png_byte)((red >> 8) & 0xff);
453 *(rp + 1) = (png_byte)(red & 0xff);
454 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
455 *(rp + 5) = (png_byte)(blue & 0xff);
460 #endif /* MNG_FEATURES */
463 png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
465 png_row_info row_info;
470 png_debug2(1, "in png_read_row (row %lu, pass %d)",
471 (unsigned long)png_ptr->row_number, png_ptr->pass);
473 /* png_read_start_row sets the information (in particular iwidth) for this
476 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
477 png_read_start_row(png_ptr);
479 /* 1.5.6: row_info moved out of png_struct to a local here. */
480 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
481 row_info.color_type = png_ptr->color_type;
482 row_info.bit_depth = png_ptr->bit_depth;
483 row_info.channels = png_ptr->channels;
484 row_info.pixel_depth = png_ptr->pixel_depth;
485 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
487 #ifdef PNG_WARNINGS_SUPPORTED
488 if (png_ptr->row_number == 0 && png_ptr->pass == 0)
490 /* Check for transforms that have been set but were defined out */
491 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
492 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
493 png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
496 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
497 if ((png_ptr->transformations & PNG_FILLER) != 0)
498 png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
501 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
502 !defined(PNG_READ_PACKSWAP_SUPPORTED)
503 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
504 png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
507 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
508 if ((png_ptr->transformations & PNG_PACK) != 0)
509 png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
512 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
513 if ((png_ptr->transformations & PNG_SHIFT) != 0)
514 png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
517 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
518 if ((png_ptr->transformations & PNG_BGR) != 0)
519 png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
522 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
523 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
524 png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
527 #endif /* WARNINGS */
529 #ifdef PNG_READ_INTERLACING_SUPPORTED
530 /* If interlaced and we do not need a new row, combine row and return.
531 * Notice that the pixels we have from previous rows have been transformed
532 * already; we can only combine like with like (transformed or
533 * untransformed) and, because of the libpng API for interlaced images, this
534 * means we must transform before de-interlacing.
536 if (png_ptr->interlaced != 0 &&
537 (png_ptr->transformations & PNG_INTERLACE) != 0)
539 switch (png_ptr->pass)
542 if (png_ptr->row_number & 0x07)
545 png_combine_row(png_ptr, dsp_row, 1/*display*/);
546 png_read_finish_row(png_ptr);
552 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
555 png_combine_row(png_ptr, dsp_row, 1/*display*/);
557 png_read_finish_row(png_ptr);
563 if ((png_ptr->row_number & 0x07) != 4)
565 if (dsp_row != NULL && (png_ptr->row_number & 4))
566 png_combine_row(png_ptr, dsp_row, 1/*display*/);
568 png_read_finish_row(png_ptr);
574 if ((png_ptr->row_number & 3) || png_ptr->width < 3)
577 png_combine_row(png_ptr, dsp_row, 1/*display*/);
579 png_read_finish_row(png_ptr);
585 if ((png_ptr->row_number & 3) != 2)
587 if (dsp_row != NULL && (png_ptr->row_number & 2))
588 png_combine_row(png_ptr, dsp_row, 1/*display*/);
590 png_read_finish_row(png_ptr);
596 if ((png_ptr->row_number & 1) || png_ptr->width < 2)
599 png_combine_row(png_ptr, dsp_row, 1/*display*/);
601 png_read_finish_row(png_ptr);
608 if ((png_ptr->row_number & 1) == 0)
610 png_read_finish_row(png_ptr);
618 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
619 png_error(png_ptr, "Invalid attempt to read row data");
621 /* Fill the row with IDAT data: */
622 png_ptr->row_buf[0]=255; /* to force error if no data was found */
623 png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
625 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
627 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
628 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
629 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
631 png_error(png_ptr, "bad adaptive filter value");
634 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
635 * 1.5.6, while the buffer really is this big in current versions of libpng
636 * it may not be in the future, so this was changed just to copy the
639 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
641 #ifdef PNG_MNG_FEATURES_SUPPORTED
642 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
643 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
645 /* Intrapixel differencing */
646 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
650 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
651 if (png_ptr->transformations)
652 png_do_read_transformations(png_ptr, &row_info);
655 /* The transformed pixel depth should match the depth now in row_info. */
656 if (png_ptr->transformed_pixel_depth == 0)
658 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
659 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
660 png_error(png_ptr, "sequential row overflow");
663 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
664 png_error(png_ptr, "internal sequential row size calculation error");
666 #ifdef PNG_READ_INTERLACING_SUPPORTED
667 /* Expand interlaced rows to full size */
668 if (png_ptr->interlaced != 0 &&
669 (png_ptr->transformations & PNG_INTERLACE) != 0)
671 if (png_ptr->pass < 6)
672 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
673 png_ptr->transformations);
676 png_combine_row(png_ptr, dsp_row, 1/*display*/);
679 png_combine_row(png_ptr, row, 0/*row*/);
686 png_combine_row(png_ptr, row, -1/*ignored*/);
689 png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
691 png_read_finish_row(png_ptr);
693 if (png_ptr->read_row_fn != NULL)
694 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
697 #endif /* SEQUENTIAL_READ */
699 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
700 /* Read one or more rows of image data. If the image is interlaced,
701 * and png_set_interlace_handling() has been called, the rows need to
702 * contain the contents of the rows from the previous pass. If the
703 * image has alpha or transparency, and png_handle_alpha()[*] has been
704 * called, the rows contents must be initialized to the contents of the
707 * "row" holds the actual image, and pixels are placed in it
708 * as they arrive. If the image is displayed after each pass, it will
709 * appear to "sparkle" in. "display_row" can be used to display a
710 * "chunky" progressive image, with finer detail added as it becomes
711 * available. If you do not want this "chunky" display, you may pass
712 * NULL for display_row. If you do not want the sparkle display, and
713 * you have not called png_handle_alpha(), you may pass NULL for rows.
714 * If you have called png_handle_alpha(), and the image has either an
715 * alpha channel or a transparency chunk, you must provide a buffer for
716 * rows. In this case, you do not have to provide a display_row buffer
717 * also, but you may. If the image is not interlaced, or if you have
718 * not called png_set_interlace_handling(), the display_row buffer will
719 * be ignored, so pass NULL to it.
721 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
725 png_read_rows(png_structrp png_ptr, png_bytepp row,
726 png_bytepp display_row, png_uint_32 num_rows)
732 png_debug(1, "in png_read_rows");
739 if (rp != NULL && dp != NULL)
740 for (i = 0; i < num_rows; i++)
742 png_bytep rptr = *rp++;
743 png_bytep dptr = *dp++;
745 png_read_row(png_ptr, rptr, dptr);
749 for (i = 0; i < num_rows; i++)
751 png_bytep rptr = *rp;
752 png_read_row(png_ptr, rptr, NULL);
757 for (i = 0; i < num_rows; i++)
759 png_bytep dptr = *dp;
760 png_read_row(png_ptr, NULL, dptr);
764 #endif /* SEQUENTIAL_READ */
766 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
767 /* Read the entire image. If the image has an alpha channel or a tRNS
768 * chunk, and you have called png_handle_alpha()[*], you will need to
769 * initialize the image to the current image that PNG will be overlaying.
770 * We set the num_rows again here, in case it was incorrectly set in
771 * png_read_start_row() by a call to png_read_update_info() or
772 * png_start_read_image() if png_set_interlace_handling() wasn't called
773 * prior to either of these functions like it should have been. You can
774 * only call this function once. If you desire to have an image for
775 * each pass of a interlaced image, use png_read_rows() instead.
777 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
780 png_read_image(png_structrp png_ptr, png_bytepp image)
782 png_uint_32 i, image_height;
786 png_debug(1, "in png_read_image");
791 #ifdef PNG_READ_INTERLACING_SUPPORTED
792 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
794 pass = png_set_interlace_handling(png_ptr);
795 /* And make sure transforms are initialized. */
796 png_start_read_image(png_ptr);
800 if (png_ptr->interlaced != 0 &&
801 (png_ptr->transformations & PNG_INTERLACE) == 0)
803 /* Caller called png_start_read_image or png_read_update_info without
804 * first turning on the PNG_INTERLACE transform. We can fix this here,
805 * but the caller should do it!
807 png_warning(png_ptr, "Interlace handling should be turned on when "
808 "using png_read_image");
809 /* Make sure this is set correctly */
810 png_ptr->num_rows = png_ptr->height;
813 /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
814 * the above error case.
816 pass = png_set_interlace_handling(png_ptr);
819 if (png_ptr->interlaced)
821 "Cannot read interlaced image -- interlace handler disabled");
826 image_height=png_ptr->height;
828 for (j = 0; j < pass; j++)
831 for (i = 0; i < image_height; i++)
833 png_read_row(png_ptr, *rp, NULL);
841 png_read_image_with_pick_color(png_structp png_ptr, png_bytepp image, PngPickColor *pickcolor)
843 png_uint_32 i, image_height;
845 png_uint_32 /*k = 0,*/ image_bpp = 0, image_width;
848 unsigned int npixels;
849 int perc_enable_y1, perc_enable_y2;
850 png_debug(1, "in png_read_image");
852 if (png_ptr == NULL || pickcolor == NULL)
855 #ifdef PNG_READ_INTERLACING_SUPPORTED
856 if (!(png_ptr->flags & PNG_FLAG_ROW_INIT))
858 pass = png_set_interlace_handling(png_ptr);
859 /* And make sure transforms are initialized. */
860 png_start_read_image(png_ptr);
864 if (png_ptr->interlaced && !(png_ptr->transformations & PNG_INTERLACE))
866 /* Caller called png_start_read_image or png_read_update_info without
867 * first turning on the PNG_INTERLACE transform. We can fix this here,
868 * but the caller should do it!
870 png_warning(png_ptr, "Interlace handling should be turned on when "
871 "using png_read_image");
872 /* Make sure this is set correctly */
873 png_ptr->num_rows = png_ptr->height;
876 /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
877 * the above error case.
879 pass = png_set_interlace_handling(png_ptr);
882 if (png_ptr->interlaced)
884 "Cannot read interlaced image -- interlace handler disabled");
889 image_height=png_ptr->height;
890 image_bpp=png_ptr->rowbytes;
891 image_width=png_ptr->width;
892 png_ptr->user_chunk_ptr = pickcolor;
894 if(pickcolor->perc < 0)
896 png_error(png_ptr, "ColorPick percentage is negative");
899 if( (pickcolor->region < PNG_COLORPICK_TOP) || (pickcolor->region > PNG_COLORPICK_BOTTOM))
901 png_error(png_ptr, "ColorPick Region is out of bound");
904 if(pickcolor->region == PNG_COLORPICK_TOP)
907 perc_enable_y2 = (pickcolor->perc*image_height/100) - 1;
909 else if(pickcolor->region == PNG_COLORPICK_MIDDLE)
911 perc_enable_y1 = (image_height/2) - (((pickcolor->perc/2)*image_height)/100);
912 perc_enable_y2 = perc_enable_y1 + ((pickcolor->perc*image_height)/100) - 1;
916 perc_enable_y1 = (image_height) - ( pickcolor->perc * image_height / 100 );
917 perc_enable_y2 = image_height - 1;
920 for (j = 0; j < pass; j++)
923 for (i = 0; i < image_height; i++)
925 pickcolor->enable = 0;
926 if( pickcolor->perc > 0 )
928 if( (int)i >= perc_enable_y1 && (int)i <= perc_enable_y2)
930 pickcolor->enable = 1;
935 if( ((int)i >= pickcolor->y1) && ((int)i <= pickcolor->y2) )
937 pickcolor->enable = 1;
940 png_read_row(png_ptr, *rp, NULL);
946 if(pickcolor->perc > 0)
948 npixels = (pickcolor->perc*image_height*image_width)/100;
952 npixels = (pickcolor->x2-pickcolor->x1+1)*(pickcolor->y2-pickcolor->y1+1);
956 pickcolor->sumR = pickcolor->sumR/npixels;
957 pickcolor->sumG = pickcolor->sumG/npixels;
958 pickcolor->sumB = pickcolor->sumB/npixels;
961 #endif /* __TIZEN__ */
962 #endif /* SEQUENTIAL_READ */
964 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
965 /* Read the end of the PNG file. Will not read past the end of the
966 * file, will verify the end is accurate, and will read any comments
967 * or time information at the end of the file, if info is not NULL.
970 png_read_end(png_structrp png_ptr, png_inforp info_ptr)
972 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
976 png_debug(1, "in png_read_end");
981 /* If png_read_end is called in the middle of reading the rows there may
982 * still be pending IDAT data and an owned zstream. Deal with this here.
984 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
985 if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
987 png_read_finish_IDAT(png_ptr);
989 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
990 /* Report invalid palette index; added at libng-1.5.10 */
991 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
992 png_ptr->num_palette_max > png_ptr->num_palette)
993 png_benign_error(png_ptr, "Read palette index exceeding num_palette");
998 png_uint_32 length = png_read_chunk_header(png_ptr);
999 png_uint_32 chunk_name = png_ptr->chunk_name;
1001 if (chunk_name != png_IDAT)
1002 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
1004 if (chunk_name == png_IEND)
1005 png_handle_IEND(png_ptr, info_ptr, length);
1007 else if (chunk_name == png_IHDR)
1008 png_handle_IHDR(png_ptr, info_ptr, length);
1010 else if (info_ptr == NULL)
1011 png_crc_finish(png_ptr, length);
1013 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1014 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
1016 if (chunk_name == png_IDAT)
1018 if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
1019 || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
1020 png_benign_error(png_ptr, ".Too many IDATs found");
1022 png_handle_unknown(png_ptr, info_ptr, length, keep);
1023 if (chunk_name == png_PLTE)
1024 png_ptr->mode |= PNG_HAVE_PLTE;
1028 else if (chunk_name == png_IDAT)
1030 /* Zero length IDATs are legal after the last IDAT has been
1031 * read, but not after other chunks have been read. 1.6 does not
1032 * always read all the deflate data; specifically it cannot be relied
1033 * upon to read the Adler32 at the end. If it doesn't ignore IDAT
1034 * chunks which are longer than zero as well:
1036 if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
1037 || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
1038 png_benign_error(png_ptr, "..Too many IDATs found");
1040 png_crc_finish(png_ptr, length);
1042 else if (chunk_name == png_PLTE)
1043 png_handle_PLTE(png_ptr, info_ptr, length);
1045 #ifdef PNG_READ_bKGD_SUPPORTED
1046 else if (chunk_name == png_bKGD)
1047 png_handle_bKGD(png_ptr, info_ptr, length);
1050 #ifdef PNG_READ_cHRM_SUPPORTED
1051 else if (chunk_name == png_cHRM)
1052 png_handle_cHRM(png_ptr, info_ptr, length);
1055 #ifdef PNG_READ_eXIf_SUPPORTED
1056 else if (chunk_name == png_eXIf)
1057 png_handle_eXIf(png_ptr, info_ptr, length);
1060 #ifdef PNG_READ_gAMA_SUPPORTED
1061 else if (chunk_name == png_gAMA)
1062 png_handle_gAMA(png_ptr, info_ptr, length);
1065 #ifdef PNG_READ_hIST_SUPPORTED
1066 else if (chunk_name == png_hIST)
1067 png_handle_hIST(png_ptr, info_ptr, length);
1070 #ifdef PNG_READ_oFFs_SUPPORTED
1071 else if (chunk_name == png_oFFs)
1072 png_handle_oFFs(png_ptr, info_ptr, length);
1075 #ifdef PNG_READ_pCAL_SUPPORTED
1076 else if (chunk_name == png_pCAL)
1077 png_handle_pCAL(png_ptr, info_ptr, length);
1080 #ifdef PNG_READ_sCAL_SUPPORTED
1081 else if (chunk_name == png_sCAL)
1082 png_handle_sCAL(png_ptr, info_ptr, length);
1085 #ifdef PNG_READ_pHYs_SUPPORTED
1086 else if (chunk_name == png_pHYs)
1087 png_handle_pHYs(png_ptr, info_ptr, length);
1090 #ifdef PNG_READ_sBIT_SUPPORTED
1091 else if (chunk_name == png_sBIT)
1092 png_handle_sBIT(png_ptr, info_ptr, length);
1095 #ifdef PNG_READ_sRGB_SUPPORTED
1096 else if (chunk_name == png_sRGB)
1097 png_handle_sRGB(png_ptr, info_ptr, length);
1100 #ifdef PNG_READ_iCCP_SUPPORTED
1101 else if (chunk_name == png_iCCP)
1102 png_handle_iCCP(png_ptr, info_ptr, length);
1105 #ifdef PNG_READ_sPLT_SUPPORTED
1106 else if (chunk_name == png_sPLT)
1107 png_handle_sPLT(png_ptr, info_ptr, length);
1110 #ifdef PNG_READ_tEXt_SUPPORTED
1111 else if (chunk_name == png_tEXt)
1112 png_handle_tEXt(png_ptr, info_ptr, length);
1115 #ifdef PNG_READ_tIME_SUPPORTED
1116 else if (chunk_name == png_tIME)
1117 png_handle_tIME(png_ptr, info_ptr, length);
1120 #ifdef PNG_READ_tRNS_SUPPORTED
1121 else if (chunk_name == png_tRNS)
1122 png_handle_tRNS(png_ptr, info_ptr, length);
1125 #ifdef PNG_READ_zTXt_SUPPORTED
1126 else if (chunk_name == png_zTXt)
1127 png_handle_zTXt(png_ptr, info_ptr, length);
1130 #ifdef PNG_READ_iTXt_SUPPORTED
1131 else if (chunk_name == png_iTXt)
1132 png_handle_iTXt(png_ptr, info_ptr, length);
1136 png_handle_unknown(png_ptr, info_ptr, length,
1137 PNG_HANDLE_CHUNK_AS_DEFAULT);
1138 } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
1140 #endif /* SEQUENTIAL_READ */
1142 /* Free all memory used in the read struct */
1144 png_read_destroy(png_structrp png_ptr)
1146 png_debug(1, "in png_read_destroy");
1148 #ifdef PNG_READ_GAMMA_SUPPORTED
1149 png_destroy_gamma_table(png_ptr);
1152 png_free(png_ptr, png_ptr->big_row_buf);
1153 png_ptr->big_row_buf = NULL;
1154 png_free(png_ptr, png_ptr->big_prev_row);
1155 png_ptr->big_prev_row = NULL;
1156 png_free(png_ptr, png_ptr->read_buffer);
1157 png_ptr->read_buffer = NULL;
1159 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1160 png_free(png_ptr, png_ptr->palette_lookup);
1161 png_ptr->palette_lookup = NULL;
1162 png_free(png_ptr, png_ptr->quantize_index);
1163 png_ptr->quantize_index = NULL;
1166 if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
1168 png_zfree(png_ptr, png_ptr->palette);
1169 png_ptr->palette = NULL;
1171 png_ptr->free_me &= ~PNG_FREE_PLTE;
1173 #if defined(PNG_tRNS_SUPPORTED) || \
1174 defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
1175 if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
1177 png_free(png_ptr, png_ptr->trans_alpha);
1178 png_ptr->trans_alpha = NULL;
1180 png_ptr->free_me &= ~PNG_FREE_TRNS;
1183 inflateEnd(&png_ptr->zstream);
1185 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1186 png_free(png_ptr, png_ptr->save_buffer);
1187 png_ptr->save_buffer = NULL;
1190 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
1191 defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
1192 png_free(png_ptr, png_ptr->unknown_chunk.data);
1193 png_ptr->unknown_chunk.data = NULL;
1196 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
1197 png_free(png_ptr, png_ptr->chunk_list);
1198 png_ptr->chunk_list = NULL;
1201 #if defined(PNG_READ_EXPAND_SUPPORTED) && \
1202 defined(PNG_ARM_NEON_IMPLEMENTATION)
1203 png_free(png_ptr, png_ptr->riffled_palette);
1204 png_ptr->riffled_palette = NULL;
1207 /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
1208 * callbacks are still set at this point. They are required to complete the
1209 * destruction of the png_struct itself.
1213 /* Free all memory used by the read */
1215 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
1216 png_infopp end_info_ptr_ptr)
1218 png_structrp png_ptr = NULL;
1220 png_debug(1, "in png_destroy_read_struct");
1222 if (png_ptr_ptr != NULL)
1223 png_ptr = *png_ptr_ptr;
1225 if (png_ptr == NULL)
1228 /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
1229 * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API.
1230 * The extra was, apparently, unnecessary yet this hides memory leak bugs.
1232 png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
1233 png_destroy_info_struct(png_ptr, info_ptr_ptr);
1235 *png_ptr_ptr = NULL;
1236 png_read_destroy(png_ptr);
1237 png_destroy_png_struct(png_ptr);
1241 png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
1243 if (png_ptr == NULL)
1246 png_ptr->read_row_fn = read_row_fn;
1250 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1251 #ifdef PNG_INFO_IMAGE_SUPPORTED
1253 png_read_png(png_structrp png_ptr, png_inforp info_ptr,
1254 int transforms, voidp params)
1256 if (png_ptr == NULL || info_ptr == NULL)
1259 /* png_read_info() gives us all of the information from the
1260 * PNG file before the first IDAT (image data chunk).
1262 png_read_info(png_ptr, info_ptr);
1263 if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
1264 png_error(png_ptr, "Image is too high to process with png_read_png()");
1266 /* -------------- image transformations start here ------------------- */
1267 /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
1268 * is not implemented. This will only happen in de-configured (non-default)
1269 * libpng builds. The results can be unexpected - png_read_png may return
1270 * short or mal-formed rows because the transform is skipped.
1273 /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
1275 if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
1276 /* Added at libpng-1.5.4. "strip_16" produces the same result that it
1277 * did in earlier versions, while "scale_16" is now more accurate.
1279 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1280 png_set_scale_16(png_ptr);
1282 png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
1285 /* If both SCALE and STRIP are required pngrtran will effectively cancel the
1286 * latter by doing SCALE first. This is ok and allows apps not to check for
1287 * which is supported to get the right answer.
1289 if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
1290 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1291 png_set_strip_16(png_ptr);
1293 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
1296 /* Strip alpha bytes from the input data without combining with
1297 * the background (not recommended).
1299 if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
1300 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1301 png_set_strip_alpha(png_ptr);
1303 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
1306 /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
1307 * byte into separate bytes (useful for paletted and grayscale images).
1309 if ((transforms & PNG_TRANSFORM_PACKING) != 0)
1310 #ifdef PNG_READ_PACK_SUPPORTED
1311 png_set_packing(png_ptr);
1313 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1316 /* Change the order of packed pixels to least significant bit first
1317 * (not useful if you are using png_set_packing).
1319 if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
1320 #ifdef PNG_READ_PACKSWAP_SUPPORTED
1321 png_set_packswap(png_ptr);
1323 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1326 /* Expand paletted colors into true RGB triplets
1327 * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
1328 * Expand paletted or RGB images with transparency to full alpha
1329 * channels so the data will be available as RGBA quartets.
1331 if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
1332 #ifdef PNG_READ_EXPAND_SUPPORTED
1333 png_set_expand(png_ptr);
1335 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
1338 /* We don't handle background color or gamma transformation or quantizing.
1341 /* Invert monochrome files to have 0 as white and 1 as black
1343 if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
1344 #ifdef PNG_READ_INVERT_SUPPORTED
1345 png_set_invert_mono(png_ptr);
1347 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1350 /* If you want to shift the pixel values from the range [0,255] or
1351 * [0,65535] to the original [0,7] or [0,31], or whatever range the
1352 * colors were originally in:
1354 if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
1355 #ifdef PNG_READ_SHIFT_SUPPORTED
1356 if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
1357 png_set_shift(png_ptr, &info_ptr->sig_bit);
1359 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1362 /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
1363 if ((transforms & PNG_TRANSFORM_BGR) != 0)
1364 #ifdef PNG_READ_BGR_SUPPORTED
1365 png_set_bgr(png_ptr);
1367 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1370 /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
1371 if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
1372 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
1373 png_set_swap_alpha(png_ptr);
1375 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1378 /* Swap bytes of 16-bit files to least significant byte first */
1379 if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
1380 #ifdef PNG_READ_SWAP_SUPPORTED
1381 png_set_swap(png_ptr);
1383 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1386 /* Added at libpng-1.2.41 */
1387 /* Invert the alpha channel from opacity to transparency */
1388 if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
1389 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1390 png_set_invert_alpha(png_ptr);
1392 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1395 /* Added at libpng-1.2.41 */
1396 /* Expand grayscale image to RGB */
1397 if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
1398 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1399 png_set_gray_to_rgb(png_ptr);
1401 png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
1404 /* Added at libpng-1.5.4 */
1405 if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
1406 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1407 png_set_expand_16(png_ptr);
1409 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
1412 /* We don't handle adding filler bytes */
1414 /* We use png_read_image and rely on that for interlace handling, but we also
1415 * call png_read_update_info therefore must turn on interlace handling now:
1417 (void)png_set_interlace_handling(png_ptr);
1419 /* Optional call to gamma correct and add the background to the palette
1420 * and update info structure. REQUIRED if you are expecting libpng to
1421 * update the palette for you (i.e., you selected such a transform above).
1423 png_read_update_info(png_ptr, info_ptr);
1425 /* -------------- image transformations end here ------------------- */
1427 png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
1428 if (info_ptr->row_pointers == NULL)
1432 info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
1433 info_ptr->height * (sizeof (png_bytep))));
1435 for (iptr=0; iptr<info_ptr->height; iptr++)
1436 info_ptr->row_pointers[iptr] = NULL;
1438 info_ptr->free_me |= PNG_FREE_ROWS;
1440 for (iptr = 0; iptr < info_ptr->height; iptr++)
1441 info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
1442 png_malloc(png_ptr, info_ptr->rowbytes));
1445 png_read_image(png_ptr, info_ptr->row_pointers);
1446 info_ptr->valid |= PNG_INFO_IDAT;
1448 /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
1449 png_read_end(png_ptr, info_ptr);
1453 #endif /* INFO_IMAGE */
1454 #endif /* SEQUENTIAL_READ */
1456 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
1459 * This code currently relies on the sequential reader, though it could easily
1460 * be made to work with the progressive one.
1462 /* Arguments to png_image_finish_read: */
1464 /* Encoding of PNG data (used by the color-map code) */
1465 # define P_NOTSET 0 /* File encoding not yet known */
1466 # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
1467 # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
1468 # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
1469 # define P_LINEAR8 4 /* 8-bit linear: only from a file value */
1471 /* Color-map processing: after libpng has run on the PNG image further
1472 * processing may be needed to convert the data to color-map indices.
1474 #define PNG_CMAP_NONE 0
1475 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
1476 #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
1477 #define PNG_CMAP_RGB 3 /* Process RGB data */
1478 #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
1480 /* The following document where the background is for each processing case. */
1481 #define PNG_CMAP_NONE_BACKGROUND 256
1482 #define PNG_CMAP_GA_BACKGROUND 231
1483 #define PNG_CMAP_TRANS_BACKGROUND 254
1484 #define PNG_CMAP_RGB_BACKGROUND 256
1485 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
1492 png_int_32 row_stride;
1494 png_const_colorp background;
1495 /* Local variables: */
1496 png_voidp local_row;
1497 png_voidp first_row;
1498 ptrdiff_t row_bytes; /* step between rows */
1499 int file_encoding; /* E_ values above */
1500 png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
1501 int colormap_processing; /* PNG_CMAP_ values above */
1502 } png_image_read_control;
1504 /* Do all the *safe* initialization - 'safe' means that png_error won't be
1505 * called, so setting up the jmp_buf is not required. This means that anything
1506 * called from here must *not* call png_malloc - it has to call png_malloc_warn
1507 * instead so that control is returned safely back to this routine.
1510 png_image_read_init(png_imagep image)
1512 if (image->opaque == NULL)
1514 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
1515 png_safe_error, png_safe_warning);
1517 /* And set the rest of the structure to NULL to ensure that the various
1518 * fields are consistent.
1520 memset(image, 0, (sizeof *image));
1521 image->version = PNG_IMAGE_VERSION;
1523 if (png_ptr != NULL)
1525 png_infop info_ptr = png_create_info_struct(png_ptr);
1527 if (info_ptr != NULL)
1529 png_controlp control = png_voidcast(png_controlp,
1530 png_malloc_warn(png_ptr, (sizeof *control)));
1532 if (control != NULL)
1534 memset(control, 0, (sizeof *control));
1536 control->png_ptr = png_ptr;
1537 control->info_ptr = info_ptr;
1538 control->for_write = 0;
1540 image->opaque = control;
1544 /* Error clean up */
1545 png_destroy_info_struct(png_ptr, &info_ptr);
1548 png_destroy_read_struct(&png_ptr, NULL, NULL);
1551 return png_image_error(image, "png_image_read: out of memory");
1554 return png_image_error(image, "png_image_read: opaque pointer not NULL");
1557 /* Utility to find the base format of a PNG file from a png_struct. */
1559 png_image_format(png_structrp png_ptr)
1561 png_uint_32 format = 0;
1563 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1564 format |= PNG_FORMAT_FLAG_COLOR;
1566 if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
1567 format |= PNG_FORMAT_FLAG_ALPHA;
1569 /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
1570 * sets the png_struct fields; that's all we are interested in here. The
1571 * precise interaction with an app call to png_set_tRNS and PNG file reading
1574 else if (png_ptr->num_trans > 0)
1575 format |= PNG_FORMAT_FLAG_ALPHA;
1577 if (png_ptr->bit_depth == 16)
1578 format |= PNG_FORMAT_FLAG_LINEAR;
1580 if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
1581 format |= PNG_FORMAT_FLAG_COLORMAP;
1586 /* Is the given gamma significantly different from sRGB? The test is the same
1587 * one used in pngrtran.c when deciding whether to do gamma correction. The
1588 * arithmetic optimizes the division by using the fact that the inverse of the
1589 * file sRGB gamma is 2.2
1592 png_gamma_not_sRGB(png_fixed_point g)
1596 /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
1600 return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
1606 /* Do the main body of a 'png_image_begin_read' function; read the PNG file
1607 * header and fill in all the information. This is executed in a safe context,
1608 * unlike the init routine above.
1611 png_image_read_header(png_voidp argument)
1613 png_imagep image = png_voidcast(png_imagep, argument);
1614 png_structrp png_ptr = image->opaque->png_ptr;
1615 png_inforp info_ptr = image->opaque->info_ptr;
1617 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
1618 png_set_benign_errors(png_ptr, 1/*warn*/);
1620 png_read_info(png_ptr, info_ptr);
1622 /* Do this the fast way; just read directly out of png_struct. */
1623 image->width = png_ptr->width;
1624 image->height = png_ptr->height;
1627 png_uint_32 format = png_image_format(png_ptr);
1629 image->format = format;
1631 #ifdef PNG_COLORSPACE_SUPPORTED
1632 /* Does the colorspace match sRGB? If there is no color endpoint
1633 * (colorant) information assume yes, otherwise require the
1634 * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
1635 * colorspace has been determined to be invalid ignore it.
1637 if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
1638 & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
1639 PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
1640 image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
1644 /* We need the maximum number of entries regardless of the format the
1645 * application sets here.
1648 png_uint_32 cmap_entries;
1650 switch (png_ptr->color_type)
1652 case PNG_COLOR_TYPE_GRAY:
1653 cmap_entries = 1U << png_ptr->bit_depth;
1656 case PNG_COLOR_TYPE_PALETTE:
1657 cmap_entries = (png_uint_32)png_ptr->num_palette;
1665 if (cmap_entries > 256)
1668 image->colormap_entries = cmap_entries;
1674 #ifdef PNG_STDIO_SUPPORTED
1676 png_image_begin_read_from_stdio(png_imagep image, FILE* file)
1678 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1682 if (png_image_read_init(image) != 0)
1684 /* This is slightly evil, but png_init_io doesn't do anything other
1685 * than this and we haven't changed the standard IO functions so
1686 * this saves a 'safe' function.
1688 image->opaque->png_ptr->io_ptr = file;
1689 return png_safe_execute(image, png_image_read_header, image);
1694 return png_image_error(image,
1695 "png_image_begin_read_from_stdio: invalid argument");
1698 else if (image != NULL)
1699 return png_image_error(image,
1700 "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
1706 png_image_begin_read_from_file(png_imagep image, const char *file_name)
1708 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1710 if (file_name != NULL)
1712 FILE *fp = fopen(file_name, "rb");
1716 if (png_image_read_init(image) != 0)
1718 image->opaque->png_ptr->io_ptr = fp;
1719 image->opaque->owned_file = 1;
1720 return png_safe_execute(image, png_image_read_header, image);
1723 /* Clean up: just the opened file. */
1728 return png_image_error(image, strerror(errno));
1732 return png_image_error(image,
1733 "png_image_begin_read_from_file: invalid argument");
1736 else if (image != NULL)
1737 return png_image_error(image,
1738 "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
1744 static void PNGCBAPI
1745 png_image_memory_read(png_structp png_ptr, png_bytep out, size_t need)
1747 if (png_ptr != NULL)
1749 png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
1752 png_controlp cp = image->opaque;
1755 png_const_bytep memory = cp->memory;
1756 size_t size = cp->size;
1758 if (memory != NULL && size >= need)
1760 memcpy(out, memory, need);
1761 cp->memory = memory + need;
1762 cp->size = size - need;
1766 png_error(png_ptr, "read beyond end of data");
1770 png_error(png_ptr, "invalid memory read");
1774 int PNGAPI png_image_begin_read_from_memory(png_imagep image,
1775 png_const_voidp memory, size_t size)
1777 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1779 if (memory != NULL && size > 0)
1781 if (png_image_read_init(image) != 0)
1783 /* Now set the IO functions to read from the memory buffer and
1784 * store it into io_ptr. Again do this in-place to avoid calling a
1785 * libpng function that requires error handling.
1787 image->opaque->memory = png_voidcast(png_const_bytep, memory);
1788 image->opaque->size = size;
1789 image->opaque->png_ptr->io_ptr = image;
1790 image->opaque->png_ptr->read_data_fn = png_image_memory_read;
1792 return png_safe_execute(image, png_image_read_header, image);
1797 return png_image_error(image,
1798 "png_image_begin_read_from_memory: invalid argument");
1801 else if (image != NULL)
1802 return png_image_error(image,
1803 "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
1808 /* Utility function to skip chunks that are not used by the simplified image
1809 * read functions and an appropriate macro to call it.
1811 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1813 png_image_skip_unused_chunks(png_structrp png_ptr)
1815 /* Prepare the reader to ignore all recognized chunks whose data will not
1816 * be used, i.e., all chunks recognized by libpng except for those
1817 * involved in basic image reading:
1819 * IHDR, PLTE, IDAT, IEND
1821 * Or image data handling:
1823 * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
1825 * This provides a small performance improvement and eliminates any
1826 * potential vulnerability to security problems in the unused chunks.
1828 * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
1829 * too. This allows the simplified API to be compiled without iCCP support,
1830 * however if the support is there the chunk is still checked to detect
1831 * errors (which are unfortunately quite common.)
1834 static const png_byte chunks_to_process[] = {
1835 98, 75, 71, 68, '\0', /* bKGD */
1836 99, 72, 82, 77, '\0', /* cHRM */
1837 103, 65, 77, 65, '\0', /* gAMA */
1838 # ifdef PNG_READ_iCCP_SUPPORTED
1839 105, 67, 67, 80, '\0', /* iCCP */
1841 115, 66, 73, 84, '\0', /* sBIT */
1842 115, 82, 71, 66, '\0', /* sRGB */
1845 /* Ignore unknown chunks and all other chunks except for the
1846 * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
1848 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
1851 /* But do not ignore image data handling chunks */
1852 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
1853 chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
1857 # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
1859 # define PNG_SKIP_CHUNKS(p) ((void)0)
1860 #endif /* HANDLE_AS_UNKNOWN */
1862 /* The following macro gives the exact rounded answer for all values in the
1863 * range 0..255 (it actually divides by 51.2, but the rounding still generates
1864 * the correct numbers 0..5
1866 #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
1868 /* Utility functions to make particular color-maps */
1870 set_file_encoding(png_image_read_control *display)
1872 png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
1873 if (png_gamma_significant(g) != 0)
1875 if (png_gamma_not_sRGB(g) != 0)
1877 display->file_encoding = P_FILE;
1878 display->gamma_to_linear = png_reciprocal(g);
1882 display->file_encoding = P_sRGB;
1886 display->file_encoding = P_LINEAR8;
1890 decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
1892 if (encoding == P_FILE) /* double check */
1893 encoding = display->file_encoding;
1895 if (encoding == P_NOTSET) /* must be the file encoding */
1897 set_file_encoding(display);
1898 encoding = display->file_encoding;
1904 value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
1908 value = png_sRGB_table[value];
1920 png_error(display->image->opaque->png_ptr,
1921 "unexpected encoding (internal error)");
1929 png_colormap_compose(png_image_read_control *display,
1930 png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
1931 png_uint_32 background, int encoding)
1933 /* The file value is composed on the background, the background has the given
1934 * encoding and so does the result, the file is encoded with P_FILE and the
1935 * file and alpha are 8-bit values. The (output) encoding will always be
1936 * P_LINEAR or P_sRGB.
1938 png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
1939 png_uint_32 b = decode_gamma(display, background, encoding);
1941 /* The alpha is always an 8-bit value (it comes from the palette), the value
1942 * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
1944 f = f * alpha + b * (255-alpha);
1946 if (encoding == P_LINEAR)
1948 /* Scale to 65535; divide by 255, approximately (in fact this is extremely
1949 * accurate, it divides by 255.00000005937181414556, with no overflow.)
1951 f *= 257; /* Now scaled by 65535 */
1953 f = (f+32768) >> 16;
1957 f = PNG_sRGB_FROM_LINEAR(f);
1962 /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
1966 png_create_colormap_entry(png_image_read_control *display,
1967 png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
1968 png_uint_32 alpha, int encoding)
1970 png_imagep image = display->image;
1971 int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
1973 int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
1974 (red != green || green != blue);
1977 png_error(image->opaque->png_ptr, "color-map index out of range");
1979 /* Update the cache with whether the file gamma is significantly different
1982 if (encoding == P_FILE)
1984 if (display->file_encoding == P_NOTSET)
1985 set_file_encoding(display);
1987 /* Note that the cached value may be P_FILE too, but if it is then the
1988 * gamma_to_linear member has been set.
1990 encoding = display->file_encoding;
1993 if (encoding == P_FILE)
1995 png_fixed_point g = display->gamma_to_linear;
1997 red = png_gamma_16bit_correct(red*257, g);
1998 green = png_gamma_16bit_correct(green*257, g);
1999 blue = png_gamma_16bit_correct(blue*257, g);
2001 if (convert_to_Y != 0 || output_encoding == P_LINEAR)
2004 encoding = P_LINEAR;
2009 red = PNG_sRGB_FROM_LINEAR(red * 255);
2010 green = PNG_sRGB_FROM_LINEAR(green * 255);
2011 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
2016 else if (encoding == P_LINEAR8)
2018 /* This encoding occurs quite frequently in test cases because PngSuite
2019 * includes a gAMA 1.0 chunk with most images.
2025 encoding = P_LINEAR;
2028 else if (encoding == P_sRGB &&
2029 (convert_to_Y != 0 || output_encoding == P_LINEAR))
2031 /* The values are 8-bit sRGB values, but must be converted to 16-bit
2034 red = png_sRGB_table[red];
2035 green = png_sRGB_table[green];
2036 blue = png_sRGB_table[blue];
2038 encoding = P_LINEAR;
2041 /* This is set if the color isn't gray but the output is. */
2042 if (encoding == P_LINEAR)
2044 if (convert_to_Y != 0)
2046 /* NOTE: these values are copied from png_do_rgb_to_gray */
2047 png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green +
2048 (png_uint_32)2366 * blue;
2050 if (output_encoding == P_LINEAR)
2051 y = (y + 16384) >> 15;
2055 /* y is scaled by 32768, we need it scaled by 255: */
2058 y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
2059 alpha = PNG_DIV257(alpha);
2063 blue = red = green = y;
2066 else if (output_encoding == P_sRGB)
2068 red = PNG_sRGB_FROM_LINEAR(red * 255);
2069 green = PNG_sRGB_FROM_LINEAR(green * 255);
2070 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
2071 alpha = PNG_DIV257(alpha);
2076 if (encoding != output_encoding)
2077 png_error(image->opaque->png_ptr, "bad encoding (internal error)");
2079 /* Store the value. */
2081 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
2082 int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
2083 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
2087 # ifdef PNG_FORMAT_BGR_SUPPORTED
2088 int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
2093 if (output_encoding == P_LINEAR)
2095 png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
2097 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
2099 /* The linear 16-bit values must be pre-multiplied by the alpha channel
2100 * value, if less than 65535 (this is, effectively, composite on black
2101 * if the alpha channel is removed.)
2103 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
2106 entry[afirst ? 0 : 3] = (png_uint_16)alpha;
2114 blue = (blue * alpha + 32767U)/65535U;
2115 green = (green * alpha + 32767U)/65535U;
2116 red = (red * alpha + 32767U)/65535U;
2120 red = green = blue = 0;
2122 entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
2123 entry[afirst + 1] = (png_uint_16)green;
2124 entry[afirst + bgr] = (png_uint_16)red;
2128 entry[1 ^ afirst] = (png_uint_16)alpha;
2135 green = (green * alpha + 32767U)/65535U;
2140 entry[afirst] = (png_uint_16)green;
2148 else /* output encoding is P_sRGB */
2150 png_bytep entry = png_voidcast(png_bytep, display->colormap);
2152 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
2154 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
2157 entry[afirst ? 0 : 3] = (png_byte)alpha;
2160 entry[afirst + (2 ^ bgr)] = (png_byte)blue;
2161 entry[afirst + 1] = (png_byte)green;
2162 entry[afirst + bgr] = (png_byte)red;
2166 entry[1 ^ afirst] = (png_byte)alpha;
2169 entry[afirst] = (png_byte)green;
2187 make_gray_file_colormap(png_image_read_control *display)
2191 for (i=0; i<256; ++i)
2192 png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
2198 make_gray_colormap(png_image_read_control *display)
2202 for (i=0; i<256; ++i)
2203 png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
2207 #define PNG_GRAY_COLORMAP_ENTRIES 256
2210 make_ga_colormap(png_image_read_control *display)
2214 /* Alpha is retained, the output will be a color-map with entries
2215 * selected by six levels of alpha. One transparent entry, 6 gray
2216 * levels for all the intermediate alpha values, leaving 230 entries
2217 * for the opaque grays. The color-map entries are the six values
2218 * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
2221 * if (alpha > 229) // opaque
2223 * // The 231 entries are selected to make the math below work:
2225 * entry = (231 * gray + 128) >> 8;
2227 * else if (alpha < 26) // transparent
2232 * else // partially opaque
2234 * base = 226 + 6 * PNG_DIV51(alpha);
2235 * entry = PNG_DIV51(gray);
2241 unsigned int gray = (i * 256 + 115) / 231;
2242 png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
2245 /* 255 is used here for the component values for consistency with the code
2246 * that undoes premultiplication in pngwrite.c.
2248 png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
2255 png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
2262 #define PNG_GA_COLORMAP_ENTRIES 256
2265 make_rgb_colormap(png_image_read_control *display)
2269 /* Build a 6x6x6 opaque RGB cube */
2270 for (i=r=0; r<6; ++r)
2279 png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
2287 #define PNG_RGB_COLORMAP_ENTRIES 216
2289 /* Return a palette index to the above palette given three 8-bit sRGB values. */
2290 #define PNG_RGB_INDEX(r,g,b) \
2291 ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
2294 png_image_read_colormap(png_voidp argument)
2296 png_image_read_control *display =
2297 png_voidcast(png_image_read_control*, argument);
2298 png_imagep image = display->image;
2300 png_structrp png_ptr = image->opaque->png_ptr;
2301 png_uint_32 output_format = image->format;
2302 int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
2305 unsigned int cmap_entries;
2306 unsigned int output_processing; /* Output processing option */
2307 unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
2309 /* Background information; the background color and the index of this color
2310 * in the color-map if it exists (else 256).
2312 unsigned int background_index = 256;
2313 png_uint_32 back_r, back_g, back_b;
2315 /* Flags to accumulate things that need to be done to the input. */
2316 int expand_tRNS = 0;
2318 /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
2319 * very difficult to do, the results look awful, and it is difficult to see
2320 * what possible use it is because the application can't control the
2323 if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
2324 png_ptr->num_trans > 0) /* alpha in input */ &&
2325 ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
2327 if (output_encoding == P_LINEAR) /* compose on black */
2328 back_b = back_g = back_r = 0;
2330 else if (display->background == NULL /* no way to remove it */)
2332 "background color must be supplied to remove alpha/transparency");
2334 /* Get a copy of the background color (this avoids repeating the checks
2335 * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
2340 back_g = display->background->green;
2341 if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
2343 back_r = display->background->red;
2344 back_b = display->background->blue;
2347 back_b = back_r = back_g;
2351 else if (output_encoding == P_LINEAR)
2352 back_b = back_r = back_g = 65535;
2355 back_b = back_r = back_g = 255;
2357 /* Default the input file gamma if required - this is necessary because
2358 * libpng assumes that if no gamma information is present the data is in the
2359 * output format, but the simplified API deduces the gamma from the input
2362 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
2364 /* Do this directly, not using the png_colorspace functions, to ensure
2365 * that it happens even if the colorspace is invalid (though probably if
2366 * it is the setting will be ignored) Note that the same thing can be
2367 * achieved at the application interface with png_set_gAMA.
2369 if (png_ptr->bit_depth == 16 &&
2370 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
2371 png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
2374 png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
2376 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
2379 /* Decide what to do based on the PNG color type of the input data. The
2380 * utility function png_create_colormap_entry deals with most aspects of the
2381 * output transformations; this code works out how to produce bytes of
2382 * color-map entries from the original format.
2384 switch (png_ptr->color_type)
2386 case PNG_COLOR_TYPE_GRAY:
2387 if (png_ptr->bit_depth <= 8)
2389 /* There at most 256 colors in the output, regardless of
2392 unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
2394 cmap_entries = 1U << png_ptr->bit_depth;
2395 if (cmap_entries > image->colormap_entries)
2396 png_error(png_ptr, "gray[8] color-map: too few entries");
2398 step = 255 / (cmap_entries - 1);
2399 output_processing = PNG_CMAP_NONE;
2401 /* If there is a tRNS chunk then this either selects a transparent
2402 * value or, if the output has no alpha, the background color.
2404 if (png_ptr->num_trans > 0)
2406 trans = png_ptr->trans_color.gray;
2408 if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
2409 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2412 /* png_create_colormap_entry just takes an RGBA and writes the
2413 * corresponding color-map entry using the format from 'image',
2414 * including the required conversion to sRGB or linear as
2415 * appropriate. The input values are always either sRGB (if the
2416 * gamma correction flag is 0) or 0..255 scaled file encoded values
2417 * (if the function must gamma correct them).
2419 for (i=val=0; i<cmap_entries; ++i, val += step)
2421 /* 'i' is a file value. While this will result in duplicated
2422 * entries for 8-bit non-sRGB encoded files it is necessary to
2423 * have non-gamma corrected values to do tRNS handling.
2426 png_create_colormap_entry(display, i, val, val, val, 255,
2427 P_FILE/*8-bit with file gamma*/);
2429 /* Else this entry is transparent. The colors don't matter if
2430 * there is an alpha channel (back_alpha == 0), but it does no
2431 * harm to pass them in; the values are not set above so this
2434 * NOTE: this preserves the full precision of the application
2435 * supplied background color when it is used.
2438 png_create_colormap_entry(display, i, back_r, back_g, back_b,
2439 back_alpha, output_encoding);
2442 /* We need libpng to preserve the original encoding. */
2443 data_encoding = P_FILE;
2445 /* The rows from libpng, while technically gray values, are now also
2446 * color-map indices; however, they may need to be expanded to 1
2447 * byte per pixel. This is what png_set_packing does (i.e., it
2448 * unpacks the bit values into bytes.)
2450 if (png_ptr->bit_depth < 8)
2451 png_set_packing(png_ptr);
2454 else /* bit depth is 16 */
2456 /* The 16-bit input values can be converted directly to 8-bit gamma
2457 * encoded values; however, if a tRNS chunk is present 257 color-map
2458 * entries are required. This means that the extra entry requires
2459 * special processing; add an alpha channel, sacrifice gray level
2460 * 254 and convert transparent (alpha==0) entries to that.
2462 * Use libpng to chop the data to 8 bits. Convert it to sRGB at the
2463 * same time to minimize quality loss. If a tRNS chunk is present
2464 * this means libpng must handle it too; otherwise it is impossible
2465 * to do the exact match on the 16-bit value.
2467 * If the output has no alpha channel *and* the background color is
2468 * gray then it is possible to let libpng handle the substitution by
2469 * ensuring that the corresponding gray level matches the background
2472 data_encoding = P_sRGB;
2474 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2475 png_error(png_ptr, "gray[16] color-map: too few entries");
2477 cmap_entries = (unsigned int)make_gray_colormap(display);
2479 if (png_ptr->num_trans > 0)
2481 unsigned int back_alpha;
2483 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2488 if (back_r == back_g && back_g == back_b)
2490 /* Background is gray; no special processing will be
2494 png_uint_32 gray = back_g;
2496 if (output_encoding == P_LINEAR)
2498 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2500 /* And make sure the corresponding palette entry
2503 png_create_colormap_entry(display, gray, back_g, back_g,
2504 back_g, 65535, P_LINEAR);
2507 /* The background passed to libpng, however, must be the
2510 c.index = 0; /*unused*/
2511 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2513 /* NOTE: does this work without expanding tRNS to alpha?
2514 * It should be the color->gray case below apparently
2517 png_set_background_fixed(png_ptr, &c,
2518 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2519 0/*gamma: not used*/);
2521 output_processing = PNG_CMAP_NONE;
2525 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
2530 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2534 /* output_processing means that the libpng-processed row will be
2535 * 8-bit GA and it has to be processing to single byte color-map
2536 * values. Entry 254 is replaced by either a completely
2537 * transparent entry or by the background color at full
2538 * precision (and the background color is not a simple gray
2539 * level in this case.)
2542 output_processing = PNG_CMAP_TRANS;
2543 background_index = 254;
2545 /* And set (overwrite) color-map entry 254 to the actual
2546 * background color at full precision.
2548 png_create_colormap_entry(display, 254, back_r, back_g, back_b,
2549 back_alpha, output_encoding);
2553 output_processing = PNG_CMAP_NONE;
2557 case PNG_COLOR_TYPE_GRAY_ALPHA:
2558 /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
2559 * of 65536 combinations. If, however, the alpha channel is to be
2560 * removed there are only 256 possibilities if the background is gray.
2561 * (Otherwise there is a subset of the 65536 possibilities defined by
2562 * the triangle between black, white and the background color.)
2564 * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
2565 * worry about tRNS matching - tRNS is ignored if there is an alpha
2568 data_encoding = P_sRGB;
2570 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2572 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2573 png_error(png_ptr, "gray+alpha color-map: too few entries");
2575 cmap_entries = (unsigned int)make_ga_colormap(display);
2577 background_index = PNG_CMAP_GA_BACKGROUND;
2578 output_processing = PNG_CMAP_GA;
2581 else /* alpha is removed */
2583 /* Alpha must be removed as the PNG data is processed when the
2584 * background is a color because the G and A channels are
2585 * independent and the vector addition (non-parallel vectors) is a
2588 * This can be reduced to the same algorithm as above by making a
2589 * colormap containing gray levels (for the opaque grays), a
2590 * background entry (for a transparent pixel) and a set of four six
2591 * level color values, one set for each intermediate alpha value.
2592 * See the comments in make_ga_colormap for how this works in the
2593 * per-pixel processing.
2595 * If the background is gray, however, we only need a 256 entry gray
2596 * level color map. It is sufficient to make the entry generated
2597 * for the background color be exactly the color specified.
2599 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
2600 (back_r == back_g && back_g == back_b))
2602 /* Background is gray; no special processing will be required. */
2604 png_uint_32 gray = back_g;
2606 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2607 png_error(png_ptr, "gray-alpha color-map: too few entries");
2609 cmap_entries = (unsigned int)make_gray_colormap(display);
2611 if (output_encoding == P_LINEAR)
2613 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2615 /* And make sure the corresponding palette entry matches. */
2616 png_create_colormap_entry(display, gray, back_g, back_g,
2617 back_g, 65535, P_LINEAR);
2620 /* The background passed to libpng, however, must be the sRGB
2623 c.index = 0; /*unused*/
2624 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2626 png_set_background_fixed(png_ptr, &c,
2627 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2628 0/*gamma: not used*/);
2630 output_processing = PNG_CMAP_NONE;
2637 /* This is the same as png_make_ga_colormap, above, except that
2638 * the entries are all opaque.
2640 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2641 png_error(png_ptr, "ga-alpha color-map: too few entries");
2646 png_uint_32 gray = (i * 256 + 115) / 231;
2647 png_create_colormap_entry(display, i++, gray, gray, gray,
2651 /* NOTE: this preserves the full precision of the application
2654 background_index = i;
2655 png_create_colormap_entry(display, i++, back_r, back_g, back_b,
2657 /* Coverity claims that output_encoding
2658 * cannot be 2 (P_LINEAR) here.
2661 output_encoding == P_LINEAR ? 65535U : 255U,
2665 /* For non-opaque input composite on the sRGB background - this
2666 * requires inverting the encoding for each component. The input
2667 * is still converted to the sRGB encoding because this is a
2668 * reasonable approximate to the logarithmic curve of human
2669 * visual sensitivity, at least over the narrow range which PNG
2670 * represents. Consequently 'G' is always sRGB encoded, while
2671 * 'A' is linear. We need the linear background colors.
2673 if (output_encoding == P_sRGB) /* else already linear */
2675 /* This may produce a value not exactly matching the
2676 * background, but that's ok because these numbers are only
2677 * used when alpha != 0
2679 back_r = png_sRGB_table[back_r];
2680 back_g = png_sRGB_table[back_g];
2681 back_b = png_sRGB_table[back_b];
2688 /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
2689 * by an 8-bit alpha value (0..255).
2691 png_uint_32 alpha = 51 * a;
2692 png_uint_32 back_rx = (255-alpha) * back_r;
2693 png_uint_32 back_gx = (255-alpha) * back_g;
2694 png_uint_32 back_bx = (255-alpha) * back_b;
2698 png_uint_32 gray = png_sRGB_table[g*51] * alpha;
2700 png_create_colormap_entry(display, i++,
2701 PNG_sRGB_FROM_LINEAR(gray + back_rx),
2702 PNG_sRGB_FROM_LINEAR(gray + back_gx),
2703 PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
2708 output_processing = PNG_CMAP_GA;
2713 case PNG_COLOR_TYPE_RGB:
2714 case PNG_COLOR_TYPE_RGB_ALPHA:
2715 /* Exclude the case where the output is gray; we can always handle this
2716 * with the cases above.
2718 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
2720 /* The color-map will be grayscale, so we may as well convert the
2721 * input RGB values to a simple grayscale and use the grayscale
2724 * NOTE: calling this apparently damages the recognition of the
2725 * transparent color in background color handling; call
2726 * png_set_tRNS_to_alpha before png_set_background_fixed.
2728 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
2730 data_encoding = P_sRGB;
2732 /* The output will now be one or two 8-bit gray or gray+alpha
2733 * channels. The more complex case arises when the input has alpha.
2735 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2736 png_ptr->num_trans > 0) &&
2737 (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2739 /* Both input and output have an alpha channel, so no background
2740 * processing is required; just map the GA bytes to the right
2745 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2746 png_error(png_ptr, "rgb[ga] color-map: too few entries");
2748 cmap_entries = (unsigned int)make_ga_colormap(display);
2749 background_index = PNG_CMAP_GA_BACKGROUND;
2750 output_processing = PNG_CMAP_GA;
2755 /* Either the input or the output has no alpha channel, so there
2756 * will be no non-opaque pixels in the color-map; it will just be
2759 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2760 png_error(png_ptr, "rgb[gray] color-map: too few entries");
2762 /* Ideally this code would use libpng to do the gamma correction,
2763 * but if an input alpha channel is to be removed we will hit the
2764 * libpng bug in gamma+compose+rgb-to-gray (the double gamma
2765 * correction bug). Fix this by dropping the gamma correction in
2766 * this case and doing it in the palette; this will result in
2767 * duplicate palette entries, but that's better than the
2768 * alternative of double gamma correction.
2770 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2771 png_ptr->num_trans > 0) &&
2772 png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
2774 cmap_entries = (unsigned int)make_gray_file_colormap(display);
2775 data_encoding = P_FILE;
2779 cmap_entries = (unsigned int)make_gray_colormap(display);
2781 /* But if the input has alpha or transparency it must be removed
2783 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2784 png_ptr->num_trans > 0)
2787 png_uint_32 gray = back_g;
2789 /* We need to ensure that the application background exists in
2790 * the colormap and that completely transparent pixels map to
2791 * it. Achieve this simply by ensuring that the entry
2792 * selected for the background really is the background color.
2794 if (data_encoding == P_FILE) /* from the fixup above */
2796 /* The app supplied a gray which is in output_encoding, we
2797 * need to convert it to a value of the input (P_FILE)
2798 * encoding then set this palette entry to the required
2801 if (output_encoding == P_sRGB)
2802 gray = png_sRGB_table[gray]; /* now P_LINEAR */
2804 gray = PNG_DIV257(png_gamma_16bit_correct(gray,
2805 png_ptr->colorspace.gamma)); /* now P_FILE */
2807 /* And make sure the corresponding palette entry contains
2808 * exactly the required sRGB value.
2810 png_create_colormap_entry(display, gray, back_g, back_g,
2811 back_g, 0/*unused*/, output_encoding);
2814 else if (output_encoding == P_LINEAR)
2816 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2818 /* And make sure the corresponding palette entry matches.
2820 png_create_colormap_entry(display, gray, back_g, back_g,
2821 back_g, 0/*unused*/, P_LINEAR);
2824 /* The background passed to libpng, however, must be the
2825 * output (normally sRGB) value.
2827 c.index = 0; /*unused*/
2828 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2830 /* NOTE: the following is apparently a bug in libpng. Without
2831 * it the transparent color recognition in
2832 * png_set_background_fixed seems to go wrong.
2835 png_set_background_fixed(png_ptr, &c,
2836 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2837 0/*gamma: not used*/);
2840 output_processing = PNG_CMAP_NONE;
2844 else /* output is color */
2846 /* We could use png_quantize here so long as there is no transparent
2847 * color or alpha; png_quantize ignores alpha. Easier overall just
2848 * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
2849 * Consequently we always want libpng to produce sRGB data.
2851 data_encoding = P_sRGB;
2853 /* Is there any transparency or alpha? */
2854 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2855 png_ptr->num_trans > 0)
2857 /* Is there alpha in the output too? If so all four channels are
2858 * processed into a special RGB cube with alpha support.
2860 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2864 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2865 png_error(png_ptr, "rgb+alpha color-map: too few entries");
2867 cmap_entries = (unsigned int)make_rgb_colormap(display);
2869 /* Add a transparent entry. */
2870 png_create_colormap_entry(display, cmap_entries, 255, 255,
2873 /* This is stored as the background index for the processing
2876 background_index = cmap_entries++;
2878 /* Add 27 r,g,b entries each with alpha 0.5. */
2879 for (r=0; r<256; r = (r << 1) | 0x7f)
2883 for (g=0; g<256; g = (g << 1) | 0x7f)
2887 /* This generates components with the values 0, 127 and
2890 for (b=0; b<256; b = (b << 1) | 0x7f)
2891 png_create_colormap_entry(display, cmap_entries++,
2892 r, g, b, 128, P_sRGB);
2897 output_processing = PNG_CMAP_RGB_ALPHA;
2902 /* Alpha/transparency must be removed. The background must
2903 * exist in the color map (achieved by setting adding it after
2904 * the 666 color-map). If the standard processing code will
2905 * pick up this entry automatically that's all that is
2906 * required; libpng can be called to do the background
2909 unsigned int sample_size =
2910 PNG_IMAGE_SAMPLE_SIZE(output_format);
2911 png_uint_32 r, g, b; /* sRGB background */
2913 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2914 png_error(png_ptr, "rgb-alpha color-map: too few entries");
2916 cmap_entries = (unsigned int)make_rgb_colormap(display);
2918 png_create_colormap_entry(display, cmap_entries, back_r,
2919 back_g, back_b, 0/*unused*/, output_encoding);
2921 if (output_encoding == P_LINEAR)
2923 r = PNG_sRGB_FROM_LINEAR(back_r * 255);
2924 g = PNG_sRGB_FROM_LINEAR(back_g * 255);
2925 b = PNG_sRGB_FROM_LINEAR(back_b * 255);
2935 /* Compare the newly-created color-map entry with the one the
2936 * PNG_CMAP_RGB algorithm will use. If the two entries don't
2937 * match, add the new one and set this as the background
2940 if (memcmp((png_const_bytep)display->colormap +
2941 sample_size * cmap_entries,
2942 (png_const_bytep)display->colormap +
2943 sample_size * PNG_RGB_INDEX(r,g,b),
2946 /* The background color must be added. */
2947 background_index = cmap_entries++;
2949 /* Add 27 r,g,b entries each with created by composing with
2950 * the background at alpha 0.5.
2952 for (r=0; r<256; r = (r << 1) | 0x7f)
2954 for (g=0; g<256; g = (g << 1) | 0x7f)
2956 /* This generates components with the values 0, 127
2959 for (b=0; b<256; b = (b << 1) | 0x7f)
2960 png_create_colormap_entry(display, cmap_entries++,
2961 png_colormap_compose(display, r, P_sRGB, 128,
2962 back_r, output_encoding),
2963 png_colormap_compose(display, g, P_sRGB, 128,
2964 back_g, output_encoding),
2965 png_colormap_compose(display, b, P_sRGB, 128,
2966 back_b, output_encoding),
2967 0/*unused*/, output_encoding);
2972 output_processing = PNG_CMAP_RGB_ALPHA;
2975 else /* background color is in the standard color-map */
2979 c.index = 0; /*unused*/
2980 c.red = (png_uint_16)back_r;
2981 c.gray = c.green = (png_uint_16)back_g;
2982 c.blue = (png_uint_16)back_b;
2984 png_set_background_fixed(png_ptr, &c,
2985 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2986 0/*gamma: not used*/);
2988 output_processing = PNG_CMAP_RGB;
2993 else /* no alpha or transparency in the input */
2995 /* Alpha in the output is irrelevant, simply map the opaque input
2996 * pixels to the 6x6x6 color-map.
2998 if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
2999 png_error(png_ptr, "rgb color-map: too few entries");
3001 cmap_entries = (unsigned int)make_rgb_colormap(display);
3002 output_processing = PNG_CMAP_RGB;
3007 case PNG_COLOR_TYPE_PALETTE:
3008 /* It's already got a color-map. It may be necessary to eliminate the
3009 * tRNS entries though.
3012 unsigned int num_trans = png_ptr->num_trans;
3013 png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
3014 png_const_colorp colormap = png_ptr->palette;
3015 int do_background = trans != NULL &&
3016 (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
3023 output_processing = PNG_CMAP_NONE;
3024 data_encoding = P_FILE; /* Don't change from color-map indices */
3025 cmap_entries = (unsigned int)png_ptr->num_palette;
3026 if (cmap_entries > 256)
3029 if (cmap_entries > (unsigned int)image->colormap_entries)
3030 png_error(png_ptr, "palette color-map: too few entries");
3032 for (i=0; i < cmap_entries; ++i)
3034 if (do_background != 0 && i < num_trans && trans[i] < 255)
3037 png_create_colormap_entry(display, i, back_r, back_g,
3038 back_b, 0, output_encoding);
3042 /* Must compose the PNG file color in the color-map entry
3043 * on the sRGB color in 'back'.
3045 png_create_colormap_entry(display, i,
3046 png_colormap_compose(display, colormap[i].red,
3047 P_FILE, trans[i], back_r, output_encoding),
3048 png_colormap_compose(display, colormap[i].green,
3049 P_FILE, trans[i], back_g, output_encoding),
3050 png_colormap_compose(display, colormap[i].blue,
3051 P_FILE, trans[i], back_b, output_encoding),
3052 output_encoding == P_LINEAR ? trans[i] * 257U :
3059 png_create_colormap_entry(display, i, colormap[i].red,
3060 colormap[i].green, colormap[i].blue,
3061 i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
3064 /* The PNG data may have indices packed in fewer than 8 bits, it
3065 * must be expanded if so.
3067 if (png_ptr->bit_depth < 8)
3068 png_set_packing(png_ptr);
3073 png_error(png_ptr, "invalid PNG color type");
3077 /* Now deal with the output processing */
3078 if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
3079 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
3080 png_set_tRNS_to_alpha(png_ptr);
3082 switch (data_encoding)
3085 /* Change to 8-bit sRGB */
3086 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
3090 if (png_ptr->bit_depth > 8)
3091 png_set_scale_16(png_ptr);
3096 png_error(png_ptr, "bad data option (internal error)");
3100 if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
3101 png_error(png_ptr, "color map overflow (BAD internal error)");
3103 image->colormap_entries = cmap_entries;
3105 /* Double check using the recorded background index */
3106 switch (output_processing)
3109 if (background_index != PNG_CMAP_NONE_BACKGROUND)
3110 goto bad_background;
3114 if (background_index != PNG_CMAP_GA_BACKGROUND)
3115 goto bad_background;
3118 case PNG_CMAP_TRANS:
3119 if (background_index >= cmap_entries ||
3120 background_index != PNG_CMAP_TRANS_BACKGROUND)
3121 goto bad_background;
3125 if (background_index != PNG_CMAP_RGB_BACKGROUND)
3126 goto bad_background;
3129 case PNG_CMAP_RGB_ALPHA:
3130 if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
3131 goto bad_background;
3135 png_error(png_ptr, "bad processing option (internal error)");
3138 png_error(png_ptr, "bad background index (internal error)");
3141 display->colormap_processing = (int)output_processing;
3146 /* The final part of the color-map read called from png_image_finish_read. */
3148 png_image_read_and_map(png_voidp argument)
3150 png_image_read_control *display = png_voidcast(png_image_read_control*,
3152 png_imagep image = display->image;
3153 png_structrp png_ptr = image->opaque->png_ptr;
3156 /* Called when the libpng data must be transformed into the color-mapped
3157 * form. There is a local row buffer in display->local and this routine must
3158 * do the interlace handling.
3160 switch (png_ptr->interlaced)
3162 case PNG_INTERLACE_NONE:
3166 case PNG_INTERLACE_ADAM7:
3167 passes = PNG_INTERLACE_ADAM7_PASSES;
3171 png_error(png_ptr, "unknown interlace type");
3175 png_uint_32 height = image->height;
3176 png_uint_32 width = image->width;
3177 int proc = display->colormap_processing;
3178 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3179 ptrdiff_t step_row = display->row_bytes;
3182 for (pass = 0; pass < passes; ++pass)
3184 unsigned int startx, stepx, stepy;
3187 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3189 /* The row may be empty for a short image: */
3190 if (PNG_PASS_COLS(width, pass) == 0)
3193 startx = PNG_PASS_START_COL(pass);
3194 stepx = PNG_PASS_COL_OFFSET(pass);
3195 y = PNG_PASS_START_ROW(pass);
3196 stepy = PNG_PASS_ROW_OFFSET(pass);
3206 for (; y<height; y += stepy)
3208 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3209 png_bytep outrow = first_row + y * step_row;
3210 png_const_bytep end_row = outrow + width;
3212 /* Read read the libpng data into the temporary buffer. */
3213 png_read_row(png_ptr, inrow, NULL);
3215 /* Now process the row according to the processing option, note
3216 * that the caller verifies that the format of the libpng output
3217 * data is as required.
3223 for (; outrow < end_row; outrow += stepx)
3225 /* The data is always in the PNG order */
3226 unsigned int gray = *inrow++;
3227 unsigned int alpha = *inrow++;
3230 /* NOTE: this code is copied as a comment in
3231 * make_ga_colormap above. Please update the
3232 * comment if you change this code!
3234 if (alpha > 229) /* opaque */
3236 entry = (231 * gray + 128) >> 8;
3238 else if (alpha < 26) /* transparent */
3242 else /* partially opaque */
3244 entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
3247 *outrow = (png_byte)entry;
3251 case PNG_CMAP_TRANS:
3252 for (; outrow < end_row; outrow += stepx)
3254 png_byte gray = *inrow++;
3255 png_byte alpha = *inrow++;
3258 *outrow = PNG_CMAP_TRANS_BACKGROUND;
3260 else if (gray != PNG_CMAP_TRANS_BACKGROUND)
3264 *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
3269 for (; outrow < end_row; outrow += stepx)
3271 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
3276 case PNG_CMAP_RGB_ALPHA:
3277 for (; outrow < end_row; outrow += stepx)
3279 unsigned int alpha = inrow[3];
3281 /* Because the alpha entries only hold alpha==0.5 values
3282 * split the processing at alpha==0.25 (64) and 0.75
3287 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
3290 else if (alpha < 64)
3291 *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
3295 /* Likewise there are three entries for each of r, g
3296 * and b. We could select the entry by popcount on
3297 * the top two bits on those architectures that
3298 * support it, this is what the code below does,
3301 unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
3303 /* Here are how the values map:
3309 * So, as above with the explicit alpha checks, the
3310 * breakpoints are at 64 and 196.
3312 if (inrow[0] & 0x80) back_i += 9; /* red */
3313 if (inrow[0] & 0x40) back_i += 9;
3314 if (inrow[0] & 0x80) back_i += 3; /* green */
3315 if (inrow[0] & 0x40) back_i += 3;
3316 if (inrow[0] & 0x80) back_i += 1; /* blue */
3317 if (inrow[0] & 0x40) back_i += 1;
3319 *outrow = (png_byte)back_i;
3337 png_image_read_colormapped(png_voidp argument)
3339 png_image_read_control *display = png_voidcast(png_image_read_control*,
3341 png_imagep image = display->image;
3342 png_controlp control = image->opaque;
3343 png_structrp png_ptr = control->png_ptr;
3344 png_inforp info_ptr = control->info_ptr;
3346 int passes = 0; /* As a flag */
3348 PNG_SKIP_CHUNKS(png_ptr);
3350 /* Update the 'info' structure and make sure the result is as required; first
3351 * make sure to turn on the interlace handling if it will be required
3352 * (because it can't be turned on *after* the call to png_read_update_info!)
3354 if (display->colormap_processing == PNG_CMAP_NONE)
3355 passes = png_set_interlace_handling(png_ptr);
3357 png_read_update_info(png_ptr, info_ptr);
3359 /* The expected output can be deduced from the colormap_processing option. */
3360 switch (display->colormap_processing)
3363 /* Output must be one channel and one byte per pixel, the output
3364 * encoding can be anything.
3366 if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
3367 info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
3368 info_ptr->bit_depth == 8)
3373 case PNG_CMAP_TRANS:
3375 /* Output must be two channels and the 'G' one must be sRGB, the latter
3376 * can be checked with an exact number because it should have been set
3377 * to this number above!
3379 if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
3380 info_ptr->bit_depth == 8 &&
3381 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3382 image->colormap_entries == 256)
3388 /* Output must be 8-bit sRGB encoded RGB */
3389 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
3390 info_ptr->bit_depth == 8 &&
3391 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3392 image->colormap_entries == 216)
3397 case PNG_CMAP_RGB_ALPHA:
3398 /* Output must be 8-bit sRGB encoded RGBA */
3399 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
3400 info_ptr->bit_depth == 8 &&
3401 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3402 image->colormap_entries == 244 /* 216 + 1 + 27 */)
3409 png_error(png_ptr, "bad color-map processing (internal error)");
3412 /* Now read the rows. Do this here if it is possible to read directly into
3413 * the output buffer, otherwise allocate a local row buffer of the maximum
3414 * size libpng requires and call the relevant processing routine safely.
3417 png_voidp first_row = display->buffer;
3418 ptrdiff_t row_bytes = display->row_stride;
3420 /* The following expression is designed to work correctly whether it gives
3421 * a signed or an unsigned result.
3425 char *ptr = png_voidcast(char*, first_row);
3426 ptr += (image->height-1) * (-row_bytes);
3427 first_row = png_voidcast(png_voidp, ptr);
3430 display->first_row = first_row;
3431 display->row_bytes = row_bytes;
3437 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
3439 display->local_row = row;
3440 result = png_safe_execute(image, png_image_read_and_map, display);
3441 display->local_row = NULL;
3442 png_free(png_ptr, row);
3449 png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
3451 while (--passes >= 0)
3453 png_uint_32 y = image->height;
3454 png_bytep row = png_voidcast(png_bytep, display->first_row);
3458 png_read_row(png_ptr, row, NULL);
3467 /* Just the row reading part of png_image_read. */
3469 png_image_read_composite(png_voidp argument)
3471 png_image_read_control *display = png_voidcast(png_image_read_control*,
3473 png_imagep image = display->image;
3474 png_structrp png_ptr = image->opaque->png_ptr;
3477 switch (png_ptr->interlaced)
3479 case PNG_INTERLACE_NONE:
3483 case PNG_INTERLACE_ADAM7:
3484 passes = PNG_INTERLACE_ADAM7_PASSES;
3488 png_error(png_ptr, "unknown interlace type");
3492 png_uint_32 height = image->height;
3493 png_uint_32 width = image->width;
3494 ptrdiff_t step_row = display->row_bytes;
3495 unsigned int channels =
3496 (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
3499 for (pass = 0; pass < passes; ++pass)
3501 unsigned int startx, stepx, stepy;
3504 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3506 /* The row may be empty for a short image: */
3507 if (PNG_PASS_COLS(width, pass) == 0)
3510 startx = PNG_PASS_START_COL(pass) * channels;
3511 stepx = PNG_PASS_COL_OFFSET(pass) * channels;
3512 y = PNG_PASS_START_ROW(pass);
3513 stepy = PNG_PASS_ROW_OFFSET(pass);
3524 for (; y<height; y += stepy)
3526 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3528 png_const_bytep end_row;
3530 /* Read the row, which is packed: */
3531 png_read_row(png_ptr, inrow, NULL);
3533 outrow = png_voidcast(png_bytep, display->first_row);
3534 outrow += y * step_row;
3535 end_row = outrow + width * channels;
3537 /* Now do the composition on each pixel in this row. */
3539 for (; outrow < end_row; outrow += stepx)
3541 png_byte alpha = inrow[channels];
3543 if (alpha > 0) /* else no change to the output */
3547 for (c=0; c<channels; ++c)
3549 png_uint_32 component = inrow[c];
3551 if (alpha < 255) /* else just use component */
3553 /* This is PNG_OPTIMIZED_ALPHA, the component value
3554 * is a linear 8-bit value. Combine this with the
3555 * current outrow[c] value which is sRGB encoded.
3556 * Arithmetic here is 16-bits to preserve the output
3559 component *= 257*255; /* =65535 */
3560 component += (255-alpha)*png_sRGB_table[outrow[c]];
3562 /* So 'component' is scaled by 255*65535 and is
3563 * therefore appropriate for the sRGB to linear
3566 component = PNG_sRGB_FROM_LINEAR(component);
3569 outrow[c] = (png_byte)component;
3573 inrow += channels+1; /* components and alpha channel */
3582 /* The do_local_background case; called when all the following transforms are to
3589 * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
3590 * PNG_COMPOSITE code performs gamma correction, so we get double gamma
3591 * correction. The fix-up is to prevent the PNG_COMPOSITE operation from
3592 * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
3593 * row and handles the removal or pre-multiplication of the alpha channel.
3596 png_image_read_background(png_voidp argument)
3598 png_image_read_control *display = png_voidcast(png_image_read_control*,
3600 png_imagep image = display->image;
3601 png_structrp png_ptr = image->opaque->png_ptr;
3602 png_inforp info_ptr = image->opaque->info_ptr;
3603 png_uint_32 height = image->height;
3604 png_uint_32 width = image->width;
3607 /* Double check the convoluted logic below. We expect to get here with
3608 * libpng doing rgb to gray and gamma correction but background processing
3609 * left to the png_image_read_background function. The rows libpng produce
3610 * might be 8 or 16-bit but should always have two channels; gray plus alpha.
3612 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
3613 png_error(png_ptr, "lost rgb to gray");
3615 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
3616 png_error(png_ptr, "unexpected compose");
3618 if (png_get_channels(png_ptr, info_ptr) != 2)
3619 png_error(png_ptr, "lost/gained channels");
3621 /* Expect the 8-bit case to always remove the alpha channel */
3622 if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
3623 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
3624 png_error(png_ptr, "unexpected 8-bit transformation");
3626 switch (png_ptr->interlaced)
3628 case PNG_INTERLACE_NONE:
3632 case PNG_INTERLACE_ADAM7:
3633 passes = PNG_INTERLACE_ADAM7_PASSES;
3637 png_error(png_ptr, "unknown interlace type");
3640 /* Use direct access to info_ptr here because otherwise the simplified API
3641 * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
3642 * checking the value after libpng expansions, not the original value in the
3645 switch (info_ptr->bit_depth)
3648 /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
3649 * to be removed by composing on a background: either the row if
3650 * display->background is NULL or display->background->green if not.
3651 * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
3654 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3655 ptrdiff_t step_row = display->row_bytes;
3657 for (pass = 0; pass < passes; ++pass)
3659 png_bytep row = png_voidcast(png_bytep, display->first_row);
3660 unsigned int startx, stepx, stepy;
3663 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3665 /* The row may be empty for a short image: */
3666 if (PNG_PASS_COLS(width, pass) == 0)
3669 startx = PNG_PASS_START_COL(pass);
3670 stepx = PNG_PASS_COL_OFFSET(pass);
3671 y = PNG_PASS_START_ROW(pass);
3672 stepy = PNG_PASS_ROW_OFFSET(pass);
3682 if (display->background == NULL)
3684 for (; y<height; y += stepy)
3686 png_bytep inrow = png_voidcast(png_bytep,
3687 display->local_row);
3688 png_bytep outrow = first_row + y * step_row;
3689 png_const_bytep end_row = outrow + width;
3691 /* Read the row, which is packed: */
3692 png_read_row(png_ptr, inrow, NULL);
3694 /* Now do the composition on each pixel in this row. */
3696 for (; outrow < end_row; outrow += stepx)
3698 png_byte alpha = inrow[1];
3700 if (alpha > 0) /* else no change to the output */
3702 png_uint_32 component = inrow[0];
3704 if (alpha < 255) /* else just use component */
3706 /* Since PNG_OPTIMIZED_ALPHA was not set it is
3707 * necessary to invert the sRGB transfer
3708 * function and multiply the alpha out.
3710 component = png_sRGB_table[component] * alpha;
3711 component += png_sRGB_table[outrow[0]] *
3713 component = PNG_sRGB_FROM_LINEAR(component);
3716 outrow[0] = (png_byte)component;
3719 inrow += 2; /* gray and alpha channel */
3724 else /* constant background value */
3726 png_byte background8 = display->background->green;
3727 png_uint_16 background = png_sRGB_table[background8];
3729 for (; y<height; y += stepy)
3731 png_bytep inrow = png_voidcast(png_bytep,
3732 display->local_row);
3733 png_bytep outrow = first_row + y * step_row;
3734 png_const_bytep end_row = outrow + width;
3736 /* Read the row, which is packed: */
3737 png_read_row(png_ptr, inrow, NULL);
3739 /* Now do the composition on each pixel in this row. */
3741 for (; outrow < end_row; outrow += stepx)
3743 png_byte alpha = inrow[1];
3745 if (alpha > 0) /* else use background */
3747 png_uint_32 component = inrow[0];
3749 if (alpha < 255) /* else just use component */
3751 component = png_sRGB_table[component] * alpha;
3752 component += background * (255-alpha);
3753 component = PNG_sRGB_FROM_LINEAR(component);
3756 outrow[0] = (png_byte)component;
3760 outrow[0] = background8;
3762 inrow += 2; /* gray and alpha channel */
3765 row += display->row_bytes;
3773 /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
3774 * still be done and, maybe, the alpha channel removed. This code also
3775 * handles the alpha-first option.
3778 png_uint_16p first_row = png_voidcast(png_uint_16p,
3779 display->first_row);
3780 /* The division by two is safe because the caller passed in a
3781 * stride which was multiplied by 2 (below) to get row_bytes.
3783 ptrdiff_t step_row = display->row_bytes / 2;
3784 unsigned int preserve_alpha = (image->format &
3785 PNG_FORMAT_FLAG_ALPHA) != 0;
3786 unsigned int outchannels = 1U+preserve_alpha;
3789 # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
3790 if (preserve_alpha != 0 &&
3791 (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
3795 for (pass = 0; pass < passes; ++pass)
3797 unsigned int startx, stepx, stepy;
3800 /* The 'x' start and step are adjusted to output components here.
3802 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3804 /* The row may be empty for a short image: */
3805 if (PNG_PASS_COLS(width, pass) == 0)
3808 startx = PNG_PASS_START_COL(pass) * outchannels;
3809 stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
3810 y = PNG_PASS_START_ROW(pass);
3811 stepy = PNG_PASS_ROW_OFFSET(pass);
3818 stepx = outchannels;
3822 for (; y<height; y += stepy)
3824 png_const_uint_16p inrow;
3825 png_uint_16p outrow = first_row + y*step_row;
3826 png_uint_16p end_row = outrow + width * outchannels;
3828 /* Read the row, which is packed: */
3829 png_read_row(png_ptr, png_voidcast(png_bytep,
3830 display->local_row), NULL);
3831 inrow = png_voidcast(png_const_uint_16p, display->local_row);
3833 /* Now do the pre-multiplication on each pixel in this row.
3836 for (; outrow < end_row; outrow += stepx)
3838 png_uint_32 component = inrow[0];
3839 png_uint_16 alpha = inrow[1];
3841 if (alpha > 0) /* else 0 */
3843 if (alpha < 65535) /* else just use component */
3854 outrow[swap_alpha] = (png_uint_16)component;
3855 if (preserve_alpha != 0)
3856 outrow[1 ^ swap_alpha] = alpha;
3858 inrow += 2; /* components and alpha channel */
3867 png_error(png_ptr, "unexpected bit depth");
3874 /* The guts of png_image_finish_read as a png_safe_execute callback. */
3876 png_image_read_direct(png_voidp argument)
3878 png_image_read_control *display = png_voidcast(png_image_read_control*,
3880 png_imagep image = display->image;
3881 png_structrp png_ptr = image->opaque->png_ptr;
3882 png_inforp info_ptr = image->opaque->info_ptr;
3884 png_uint_32 format = image->format;
3885 int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
3886 int do_local_compose = 0;
3887 int do_local_background = 0; /* to avoid double gamma correction bug */
3890 /* Add transforms to ensure the correct output format is produced then check
3891 * that the required implementation support is there. Always expand; always
3892 * need 8 bits minimum, no palette and expanded tRNS.
3894 png_set_expand(png_ptr);
3896 /* Now check the format to see if it was modified. */
3898 png_uint_32 base_format = png_image_format(png_ptr) &
3899 ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
3900 png_uint_32 change = format ^ base_format;
3901 png_fixed_point output_gamma;
3902 int mode; /* alpha mode */
3904 /* Do this first so that we have a record if rgb to gray is happening. */
3905 if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
3907 /* gray<->color transformation required. */
3908 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3909 png_set_gray_to_rgb(png_ptr);
3913 /* libpng can't do both rgb to gray and
3914 * background/pre-multiplication if there is also significant gamma
3915 * correction, because both operations require linear colors and
3916 * the code only supports one transform doing the gamma correction.
3917 * Handle this by doing the pre-multiplication or background
3918 * operation in this code, if necessary.
3920 * TODO: fix this by rewriting pngrtran.c (!)
3922 * For the moment (given that fixing this in pngrtran.c is an
3923 * enormous change) 'do_local_background' is used to indicate that
3924 * the problem exists.
3926 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3927 do_local_background = 1/*maybe*/;
3929 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
3930 PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
3933 change &= ~PNG_FORMAT_FLAG_COLOR;
3936 /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
3939 png_fixed_point input_gamma_default;
3941 if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3942 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
3943 input_gamma_default = PNG_GAMMA_LINEAR;
3945 input_gamma_default = PNG_DEFAULT_sRGB;
3947 /* Call png_set_alpha_mode to set the default for the input gamma; the
3948 * output gamma is set by a second call below.
3950 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
3955 /* If there *is* an alpha channel in the input it must be multiplied
3956 * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
3958 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3959 mode = PNG_ALPHA_STANDARD; /* associated alpha */
3962 mode = PNG_ALPHA_PNG;
3964 output_gamma = PNG_GAMMA_LINEAR;
3969 mode = PNG_ALPHA_PNG;
3970 output_gamma = PNG_DEFAULT_sRGB;
3973 if ((change & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0)
3975 mode = PNG_ALPHA_OPTIMIZED;
3976 change &= ~PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
3979 /* If 'do_local_background' is set check for the presence of gamma
3980 * correction; this is part of the work-round for the libpng bug
3983 * TODO: fix libpng and remove this.
3985 if (do_local_background != 0)
3987 png_fixed_point gtest;
3989 /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
3990 * gamma correction, the screen gamma hasn't been set on png_struct
3991 * yet; it's set below. png_struct::gamma, however, is set to the
3994 if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma,
3995 PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
3996 do_local_background = 0;
3998 else if (mode == PNG_ALPHA_STANDARD)
4000 do_local_background = 2/*required*/;
4001 mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
4004 /* else leave as 1 for the checks below */
4007 /* If the bit-depth changes then handle that here. */
4008 if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
4010 if (linear != 0 /*16-bit output*/)
4011 png_set_expand_16(png_ptr);
4013 else /* 8-bit output */
4014 png_set_scale_16(png_ptr);
4016 change &= ~PNG_FORMAT_FLAG_LINEAR;
4019 /* Now the background/alpha channel changes. */
4020 if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
4022 /* Removing an alpha channel requires composition for the 8-bit
4023 * formats; for the 16-bit it is already done, above, by the
4024 * pre-multiplication and the channel just needs to be stripped.
4026 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
4028 /* If RGB->gray is happening the alpha channel must be left and the
4029 * operation completed locally.
4031 * TODO: fix libpng and remove this.
4033 if (do_local_background != 0)
4034 do_local_background = 2/*required*/;
4036 /* 16-bit output: just remove the channel */
4037 else if (linear != 0) /* compose on black (well, pre-multiply) */
4038 png_set_strip_alpha(png_ptr);
4040 /* 8-bit output: do an appropriate compose */
4041 else if (display->background != NULL)
4045 c.index = 0; /*unused*/
4046 c.red = display->background->red;
4047 c.green = display->background->green;
4048 c.blue = display->background->blue;
4049 c.gray = display->background->green;
4051 /* This is always an 8-bit sRGB value, using the 'green' channel
4052 * for gray is much better than calculating the luminance here;
4053 * we can get off-by-one errors in that calculation relative to
4054 * the app expectations and that will show up in transparent
4057 png_set_background_fixed(png_ptr, &c,
4058 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
4059 0/*gamma: not used*/);
4062 else /* compose on row: implemented below. */
4064 do_local_compose = 1;
4065 /* This leaves the alpha channel in the output, so it has to be
4066 * removed by the code below. Set the encoding to the 'OPTIMIZE'
4067 * one so the code only has to hack on the pixels that require
4070 mode = PNG_ALPHA_OPTIMIZED;
4074 else /* output needs an alpha channel */
4076 /* This is tricky because it happens before the swap operation has
4077 * been accomplished; however, the swap does *not* swap the added
4078 * alpha channel (weird API), so it must be added in the correct
4081 png_uint_32 filler; /* opaque filler */
4090 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
4091 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
4093 where = PNG_FILLER_BEFORE;
4094 change &= ~PNG_FORMAT_FLAG_AFIRST;
4099 where = PNG_FILLER_AFTER;
4101 png_set_add_alpha(png_ptr, filler, where);
4104 /* This stops the (irrelevant) call to swap_alpha below. */
4105 change &= ~PNG_FORMAT_FLAG_ALPHA;
4108 /* Now set the alpha mode correctly; this is always done, even if there is
4109 * no alpha channel in either the input or the output because it correctly
4110 * sets the output gamma.
4112 png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
4114 # ifdef PNG_FORMAT_BGR_SUPPORTED
4115 if ((change & PNG_FORMAT_FLAG_BGR) != 0)
4117 /* Check only the output format; PNG is never BGR; don't do this if
4118 * the output is gray, but fix up the 'format' value in that case.
4120 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
4121 png_set_bgr(png_ptr);
4124 format &= ~PNG_FORMAT_FLAG_BGR;
4126 change &= ~PNG_FORMAT_FLAG_BGR;
4130 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
4131 if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
4133 /* Only relevant if there is an alpha channel - it's particularly
4134 * important to handle this correctly because do_local_compose may
4135 * be set above and then libpng will keep the alpha channel for this
4138 if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
4140 /* Disable this if doing a local background,
4141 * TODO: remove this when local background is no longer required.
4143 if (do_local_background != 2)
4144 png_set_swap_alpha(png_ptr);
4148 format &= ~PNG_FORMAT_FLAG_AFIRST;
4150 change &= ~PNG_FORMAT_FLAG_AFIRST;
4154 /* If the *output* is 16-bit then we need to check for a byte-swap on this
4159 png_uint_16 le = 0x0001;
4161 if ((*(png_const_bytep) & le) != 0)
4162 png_set_swap(png_ptr);
4165 /* If change is not now 0 some transformation is missing - error out. */
4167 png_error(png_ptr, "png_read_image: unsupported transformation");
4170 PNG_SKIP_CHUNKS(png_ptr);
4172 /* Update the 'info' structure and make sure the result is as required; first
4173 * make sure to turn on the interlace handling if it will be required
4174 * (because it can't be turned on *after* the call to png_read_update_info!)
4176 * TODO: remove the do_local_background fixup below.
4178 if (do_local_compose == 0 && do_local_background != 2)
4179 passes = png_set_interlace_handling(png_ptr);
4181 png_read_update_info(png_ptr, info_ptr);
4184 png_uint_32 info_format = 0;
4186 if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
4187 info_format |= PNG_FORMAT_FLAG_COLOR;
4189 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4191 /* do_local_compose removes this channel below. */
4192 if (do_local_compose == 0)
4194 /* do_local_background does the same if required. */
4195 if (do_local_background != 2 ||
4196 (format & PNG_FORMAT_FLAG_ALPHA) != 0)
4197 info_format |= PNG_FORMAT_FLAG_ALPHA;
4201 else if (do_local_compose != 0) /* internal error */
4202 png_error(png_ptr, "png_image_read: alpha channel lost");
4204 if ((format & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) {
4205 info_format |= PNG_FORMAT_FLAG_ASSOCIATED_ALPHA;
4208 if (info_ptr->bit_depth == 16)
4209 info_format |= PNG_FORMAT_FLAG_LINEAR;
4211 #ifdef PNG_FORMAT_BGR_SUPPORTED
4212 if ((png_ptr->transformations & PNG_BGR) != 0)
4213 info_format |= PNG_FORMAT_FLAG_BGR;
4216 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
4217 if (do_local_background == 2)
4219 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
4220 info_format |= PNG_FORMAT_FLAG_AFIRST;
4223 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
4224 ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
4225 (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
4227 if (do_local_background == 2)
4228 png_error(png_ptr, "unexpected alpha swap transformation");
4230 info_format |= PNG_FORMAT_FLAG_AFIRST;
4234 /* This is actually an internal error. */
4235 if (info_format != format)
4236 png_error(png_ptr, "png_read_image: invalid transformations");
4239 /* Now read the rows. If do_local_compose is set then it is necessary to use
4240 * a local row buffer. The output will be GA, RGBA or BGRA and must be
4241 * converted to G, RGB or BGR as appropriate. The 'local_row' member of the
4242 * display acts as a flag.
4245 png_voidp first_row = display->buffer;
4246 ptrdiff_t row_bytes = display->row_stride;
4251 /* The following expression is designed to work correctly whether it gives
4252 * a signed or an unsigned result.
4256 char *ptr = png_voidcast(char*, first_row);
4257 ptr += (image->height-1) * (-row_bytes);
4258 first_row = png_voidcast(png_voidp, ptr);
4261 display->first_row = first_row;
4262 display->row_bytes = row_bytes;
4265 if (do_local_compose != 0)
4268 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4270 display->local_row = row;
4271 result = png_safe_execute(image, png_image_read_composite, display);
4272 display->local_row = NULL;
4273 png_free(png_ptr, row);
4278 else if (do_local_background == 2)
4281 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4283 display->local_row = row;
4284 result = png_safe_execute(image, png_image_read_background, display);
4285 display->local_row = NULL;
4286 png_free(png_ptr, row);
4293 png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
4295 while (--passes >= 0)
4297 png_uint_32 y = image->height;
4298 png_bytep row = png_voidcast(png_bytep, display->first_row);
4302 png_read_row(png_ptr, row, NULL);
4312 png_image_finish_read(png_imagep image, png_const_colorp background,
4313 void *buffer, png_int_32 row_stride, void *colormap)
4315 if (image != NULL && image->version == PNG_IMAGE_VERSION)
4317 /* Check for row_stride overflow. This check is not performed on the
4318 * original PNG format because it may not occur in the output PNG format
4319 * and libpng deals with the issues of reading the original.
4321 unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
4323 /* The following checks just the 'row_stride' calculation to ensure it
4324 * fits in a signed 32-bit value. Because channels/components can be
4325 * either 1 or 2 bytes in size the length of a row can still overflow 32
4326 * bits; this is just to verify that the 'row_stride' argument can be
4329 if (image->width <= 0x7fffffffU/channels) /* no overflow */
4332 png_uint_32 png_row_stride = image->width * channels;
4334 if (row_stride == 0)
4335 row_stride = (png_int_32)/*SAFE*/png_row_stride;
4338 check = (png_uint_32)(-row_stride);
4341 check = (png_uint_32)row_stride;
4343 /* This verifies 'check', the absolute value of the actual stride
4344 * passed in and detects overflow in the application calculation (i.e.
4345 * if the app did actually pass in a non-zero 'row_stride'.
4347 if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
4349 /* Now check for overflow of the image buffer calculation; this
4350 * limits the whole image size to 32 bits for API compatibility with
4351 * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
4353 * The PNG_IMAGE_BUFFER_SIZE macro is:
4355 * (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
4357 * And the component size is always 1 or 2, so make sure that the
4358 * number of *bytes* that the application is saying are available
4359 * does actually fit into a 32-bit number.
4361 * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE
4362 * will be changed to use png_alloc_size_t; bigger images can be
4363 * accommodated on 64-bit systems.
4365 if (image->height <=
4366 0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
4368 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
4369 (image->colormap_entries > 0 && colormap != NULL))
4372 png_image_read_control display;
4374 memset(&display, 0, (sizeof display));
4375 display.image = image;
4376 display.buffer = buffer;
4377 display.row_stride = row_stride;
4378 display.colormap = colormap;
4379 display.background = background;
4380 display.local_row = NULL;
4382 /* Choose the correct 'end' routine; for the color-map case
4383 * all the setup has already been done.
4385 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
4387 png_safe_execute(image,
4388 png_image_read_colormap, &display) &&
4389 png_safe_execute(image,
4390 png_image_read_colormapped, &display);
4394 png_safe_execute(image,
4395 png_image_read_direct, &display);
4397 png_image_free(image);
4402 return png_image_error(image,
4403 "png_image_finish_read[color-map]: no color-map");
4407 return png_image_error(image,
4408 "png_image_finish_read: image too large");
4412 return png_image_error(image,
4413 "png_image_finish_read: invalid argument");
4417 return png_image_error(image,
4418 "png_image_finish_read: row_stride too large");
4421 else if (image != NULL)
4422 return png_image_error(image,
4423 "png_image_finish_read: damaged PNG_IMAGE_VERSION");
4428 #endif /* SIMPLIFIED_READ */