| Quellcodebibliothek Statistik Leitseite products/Sources/formale Sprachen/C/Firefox/media/libpng/ (Firefox Browser Version 153.0.1©) Datei vom 27.6.2026 mit Größe 142 kB |
|
Bilddatei pngread.c Sprache: C |
|||||||||||||||
|
/* pngread.c - read a PNG file * * Copyright (c) 2018-2026 Cosmin Truta * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson * Copyright (c) 1996-1997 Andreas Dilger * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc. * * This code is released under the libpng license. * For conditions of distribution and use, see the disclaimer * and license in png.h * * This file contains routines that an application calls directly to * read a PNG file or stream. */ #include "pngpriv.h" #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED) # include <errno.h> #endif #ifdef PNG_READ_SUPPORTED /* Create a PNG structure for reading, and allocate any memory needed. */ PNG_FUNCTION(png_structp,PNGAPI png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn), PNG_ALLOCATED) { #ifndef PNG_USER_MEM_SUPPORTED png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, error_fn, warn_fn, NULL, NULL, NULL); #else return png_create_read_struct_2(user_png_ver, error_ptr, error_fn, warn_fn, NULL, NULL, NULL); } /* Alternate create PNG structure for reading, and allocate any memory * needed. */ PNG_FUNCTION(png_structp,PNGAPI png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn), PNG_ALLOCATED) { png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr, error_fn, warn_fn, mem_ptr, malloc_fn, free_fn); #endif /* USER_MEM */ if (png_ptr != NULL) { png_ptr->mode = PNG_IS_READ_STRUCT; /* Added in libpng-1.6.0; this can be used to detect a read structure if * required (it will be zero in a write structure.) */ # ifdef PNG_SEQUENTIAL_READ_SUPPORTED png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE; # endif # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN; /* In stable builds only warn if an application error can be completely * handled. */ # if PNG_RELEASE_BUILD png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN; # endif # endif /* TODO: delay this, it can be done in png_init_io (if the app doesn't * do it itself) avoiding setting the default function if it is not * required. */ png_set_read_fn(png_ptr, NULL, NULL); } return png_ptr; } #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* Read the information before the actual image data. This has been * changed in v0.90 to allow reading a file that already has the magic * bytes read from the stream. You can tell libpng how many bytes have * been read from the beginning of the stream (up to the maximum of 8) * via png_set_sig_bytes(), and we will only check the remaining bytes * here. The application can then have access to the signature bytes we * read if it is determined that this isn't a valid PNG file. */ void PNGAPI png_read_info(png_structrp png_ptr, png_inforp info_ptr) { #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED int keep; #endif png_debug(1, "in png_read_info"); if (png_ptr == NULL || info_ptr == NULL) return; /* Read and check the PNG file signature. */ png_read_sig(png_ptr, info_ptr); for (;;) { png_uint_32 length = png_read_chunk_header(png_ptr); png_uint_32 chunk_name = png_ptr->chunk_name; /* IDAT logic needs to happen here to simplify getting the two flags * right. */ if (chunk_name == png_IDAT) { if ((png_ptr->mode & PNG_HAVE_IHDR) == 0) png_chunk_error(png_ptr, "Missing IHDR before IDAT"); else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && (png_ptr->mode & PNG_HAVE_PLTE) == 0) png_chunk_error(png_ptr, "Missing PLTE before IDAT"); else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0) png_chunk_benign_error(png_ptr, "Too many IDATs found"); png_ptr->mode |= PNG_HAVE_IDAT; } else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0) { png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT; png_ptr->mode |= PNG_AFTER_IDAT; } if (chunk_name == png_IHDR) png_handle_chunk(png_ptr, info_ptr, length); else if (chunk_name == png_IEND) png_handle_chunk(png_ptr, info_ptr, length); #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) { png_handle_unknown(png_ptr, info_ptr, length, keep); if (chunk_name == png_PLTE) png_ptr->mode |= PNG_HAVE_PLTE; else if (chunk_name == png_IDAT) { png_ptr->idat_size = 0; /* It has been consumed */ break; } } #endif else if (chunk_name == png_IDAT) { #ifdef PNG_READ_APNG_SUPPORTED png_have_info(png_ptr, info_ptr); #endif png_ptr->idat_size = length; break; } #ifdef PNG_READ_APNG_SUPPORTED else if (chunk_name == png_acTL) png_handle_acTL(png_ptr, info_ptr, length); else if (chunk_name == png_fcTL) png_handle_fcTL(png_ptr, info_ptr, length); else if (chunk_name == png_fdAT) png_handle_fdAT(png_ptr, info_ptr, length); #endif else png_handle_chunk(png_ptr, info_ptr, length); } } #endif /* SEQUENTIAL_READ */ #ifdef PNG_READ_APNG_SUPPORTED void PNGAPI png_read_frame_head(png_structp png_ptr, png_infop info_ptr) { png_byte have_chunk_after_DAT; /* after IDAT or after fdAT */ png_debug(0, "Reading frame head"); if ((png_ptr->mode & PNG_HAVE_acTL) == 0) png_error(png_ptr, "attempt to png_read_frame_head() but " "no acTL present"); /* do nothing for the main IDAT */ if (png_ptr->num_frames_read == 0) return; png_read_reset(png_ptr); png_ptr->flags &= ~PNG_FLAG_ROW_INIT; png_ptr->mode &= ~PNG_HAVE_fcTL; have_chunk_after_DAT = 0; for (;;) { png_uint_32 length = png_read_chunk_header(png_ptr); if (png_ptr->chunk_name == png_IDAT) { /* discard trailing IDATs for the first frame */ if (have_chunk_after_DAT != 0 || png_ptr->num_frames_read > 1) png_error(png_ptr, "png_read_frame_head(): out of place IDAT"); png_crc_finish(png_ptr, length); } else if (png_ptr->chunk_name == png_fcTL) { png_handle_fcTL(png_ptr, info_ptr, length); have_chunk_after_DAT = 1; } else if (png_ptr->chunk_name == png_fdAT) { png_ensure_sequence_number(png_ptr, length); /* discard trailing fdATs for frames other than the first */ if (have_chunk_after_DAT == 0 && png_ptr->num_frames_read > 1) png_crc_finish(png_ptr, length - 4); else if (png_ptr->mode & PNG_HAVE_fcTL) { png_ptr->idat_size = length - 4; png_ptr->mode |= PNG_HAVE_IDAT; break; } else png_error(png_ptr, "png_read_frame_head(): out of place fdAT"); } else { png_warning(png_ptr, "Skipped (ignored) a chunk " "between APNG chunks"); png_crc_finish(png_ptr, length); } } } #endif /* READ_APNG */ /* Optional call to update the users info_ptr structure */ void PNGAPI png_read_update_info(png_structrp png_ptr, png_inforp info_ptr) { png_debug(1, "in png_read_update_info"); if (png_ptr != NULL) { if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) { png_read_start_row(png_ptr); # ifdef PNG_READ_TRANSFORMS_SUPPORTED png_read_transform_info(png_ptr, info_ptr); # else PNG_UNUSED(info_ptr) # endif } /* New in 1.6.0 this avoids the bug of doing the initializations twice */ else png_app_error(png_ptr, "png_read_update_info/png_start_read_image: duplicate call"); } } #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* Initialize palette, background, etc, after transformations * are set, but before any reading takes place. This allows * the user to obtain a gamma-corrected palette, for example. * If the user doesn't call this, we will do it ourselves. */ void PNGAPI png_start_read_image(png_structrp png_ptr) { png_debug(1, "in png_start_read_image"); if (png_ptr != NULL) { if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) png_read_start_row(png_ptr); /* New in 1.6.0 this avoids the bug of doing the initializations twice */ else png_app_error(png_ptr, "png_start_read_image/png_read_update_info: duplicate call"); } } #endif /* SEQUENTIAL_READ */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED #ifdef PNG_MNG_FEATURES_SUPPORTED /* Undoes intrapixel differencing, * NOTE: this is apparently only supported in the 'sequential' reader. */ static void png_do_read_intrapixel(png_row_infop row_info, png_bytep row) { png_debug(1, "in png_do_read_intrapixel"); if ( (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0) { int bytes_per_pixel; png_uint_32 row_width = row_info->width; if (row_info->bit_depth == 8) { png_bytep rp; png_uint_32 i; if (row_info->color_type == PNG_COLOR_TYPE_RGB) bytes_per_pixel = 3; else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) bytes_per_pixel = 4; else return; for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) { *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff); *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff); } } else if (row_info->bit_depth == 16) { png_bytep rp; png_uint_32 i; if (row_info->color_type == PNG_COLOR_TYPE_RGB) bytes_per_pixel = 6; else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) bytes_per_pixel = 8; else return; for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) { png_uint_32 s0 = (png_uint_32)(*(rp ) << 8) | *(rp + 1); png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3); png_uint_32 s2 = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5); png_uint_32 red = (s0 + s1 + 65536) & 0xffff; png_uint_32 blue = (s2 + s1 + 65536) & 0xffff; *(rp ) = (png_byte)((red >> 8) & 0xff); *(rp + 1) = (png_byte)(red & 0xff); *(rp + 4) = (png_byte)((blue >> 8) & 0xff); *(rp + 5) = (png_byte)(blue & 0xff); } } } } #endif /* MNG_FEATURES */ void PNGAPI png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row) { png_row_info row_info; if (png_ptr == NULL) return; png_debug2(1, "in png_read_row (row %lu, pass %d)", (unsigned long)png_ptr->row_number, png_ptr->pass); /* png_read_start_row sets the information (in particular iwidth) for this * interlace pass. */ if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) png_read_start_row(png_ptr); /* 1.5.6: row_info moved out of png_struct to a local here. */ row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */ row_info.color_type = png_ptr->color_type; row_info.bit_depth = png_ptr->bit_depth; row_info.channels = png_ptr->channels; row_info.pixel_depth = png_ptr->pixel_depth; row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width); #ifdef PNG_WARNINGS_SUPPORTED if (png_ptr->row_number == 0 && png_ptr->pass == 0) { /* Check for transforms that have been set but were defined out */ #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED) if ((png_ptr->transformations & PNG_INVERT_MONO) != 0) png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED) if ((png_ptr->transformations & PNG_FILLER) != 0) png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \ !defined(PNG_READ_PACKSWAP_SUPPORTED) if ((png_ptr->transformations & PNG_PACKSWAP) != 0) png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED) if ((png_ptr->transformations & PNG_PACK) != 0) png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED) if ((png_ptr->transformations & PNG_SHIFT) != 0) png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED) if ((png_ptr->transformations & PNG_BGR) != 0) png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined"); #endif #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED) if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0) png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined"); #endif } #endif /* WARNINGS */ #ifdef PNG_READ_INTERLACING_SUPPORTED /* If interlaced and we do not need a new row, combine row and return. * Notice that the pixels we have from previous rows have been transformed * already; we can only combine like with like (transformed or * untransformed) and, because of the libpng API for interlaced images, this * means we must transform before de-interlacing. */ if (png_ptr->interlaced != 0 && (png_ptr->transformations & PNG_INTERLACE) != 0) { switch (png_ptr->pass) { case 0: if (png_ptr->row_number & 0x07) { if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, 1/*display*/); png_read_finish_row(png_ptr); return; } break; case 1: if ((png_ptr->row_number & 0x07) || png_ptr->width < 5) { if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, 1/*display*/); png_read_finish_row(png_ptr); return; } break; case 2: if ((png_ptr->row_number & 0x07) != 4) { if (dsp_row != NULL && (png_ptr->row_number & 4)) png_combine_row(png_ptr, dsp_row, 1/*display*/); png_read_finish_row(png_ptr); return; } break; case 3: if ((png_ptr->row_number & 3) || png_ptr->width < 3) { if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, 1/*display*/); png_read_finish_row(png_ptr); return; } break; case 4: if ((png_ptr->row_number & 3) != 2) { if (dsp_row != NULL && (png_ptr->row_number & 2)) png_combine_row(png_ptr, dsp_row, 1/*display*/); png_read_finish_row(png_ptr); return; } break; case 5: if ((png_ptr->row_number & 1) || png_ptr->width < 2) { if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, 1/*display*/); png_read_finish_row(png_ptr); return; } break; default: case 6: if ((png_ptr->row_number & 1) == 0) { png_read_finish_row(png_ptr); return; } break; } } #endif if ((png_ptr->mode & PNG_HAVE_IDAT) == 0) png_error(png_ptr, "Invalid attempt to read row data"); /* Fill the row with IDAT data: */ png_ptr->row_buf[0]=255; /* to force error if no data was found */ png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1); if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE) { if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST) png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1, png_ptr->prev_row + 1, png_ptr->row_buf[0]); else png_error(png_ptr, "bad adaptive filter value"); } /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before * 1.5.6, while the buffer really is this big in current versions of libpng * it may not be in the future, so this was changed just to copy the * interlaced count: */ memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1); #ifdef PNG_MNG_FEATURES_SUPPORTED if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 && (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING)) { /* Intrapixel differencing */ png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1); } #endif #ifdef PNG_READ_TRANSFORMS_SUPPORTED if (png_ptr->transformations # ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED || png_ptr->num_palette_max >= 0 # endif ) png_do_read_transformations(png_ptr, &row_info); #endif /* The transformed pixel depth should match the depth now in row_info. */ if (png_ptr->transformed_pixel_depth == 0) { png_ptr->transformed_pixel_depth = row_info.pixel_depth; if (row_info.pixel_depth > png_ptr->maximum_pixel_depth) png_error(png_ptr, "sequential row overflow"); } else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth) png_error(png_ptr, "internal sequential row size calculation error"); #ifdef PNG_READ_INTERLACING_SUPPORTED /* Expand interlaced rows to full size */ if (png_ptr->interlaced != 0 && (png_ptr->transformations & PNG_INTERLACE) != 0) { if (png_ptr->pass < 6) png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations); if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, 1/*display*/); if (row != NULL) png_combine_row(png_ptr, row, 0/*row*/); } else #endif { if (row != NULL) png_combine_row(png_ptr, row, -1/*ignored*/); if (dsp_row != NULL) png_combine_row(png_ptr, dsp_row, -1/*ignored*/); } png_read_finish_row(png_ptr); if (png_ptr->read_row_fn != NULL) (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass); } #endif /* SEQUENTIAL_READ */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* Read one or more rows of image data. If the image is interlaced, * and png_set_interlace_handling() has been called, the rows need to * contain the contents of the rows from the previous pass. If the * image has alpha or transparency, and png_handle_alpha()[*] has been * called, the rows contents must be initialized to the contents of the * screen. * * "row" holds the actual image, and pixels are placed in it * as they arrive. If the image is displayed after each pass, it will * appear to "sparkle" in. "display_row" can be used to display a * "chunky" progressive image, with finer detail added as it becomes * available. If you do not want this "chunky" display, you may pass * NULL for display_row. If you do not want the sparkle display, and * you have not called png_handle_alpha(), you may pass NULL for rows. * If you have called png_handle_alpha(), and the image has either an * alpha channel or a transparency chunk, you must provide a buffer for * rows. In this case, you do not have to provide a display_row buffer * also, but you may. If the image is not interlaced, or if you have * not called png_set_interlace_handling(), the display_row buffer will * be ignored, so pass NULL to it. * * [*] png_handle_alpha() does not exist yet, as of this version of libpng */ void PNGAPI png_read_rows(png_structrp png_ptr, png_bytepp row, png_bytepp display_row, png_uint_32 num_rows) { png_uint_32 i; png_bytepp rp; png_bytepp dp; png_debug(1, "in png_read_rows"); if (png_ptr == NULL) return; rp = row; dp = display_row; if (rp != NULL && dp != NULL) for (i = 0; i < num_rows; i++) { png_bytep rptr = *rp++; png_bytep dptr = *dp++; png_read_row(png_ptr, rptr, dptr); } else if (rp != NULL) for (i = 0; i < num_rows; i++) { png_bytep rptr = *rp; png_read_row(png_ptr, rptr, NULL); rp++; } else if (dp != NULL) for (i = 0; i < num_rows; i++) { png_bytep dptr = *dp; png_read_row(png_ptr, NULL, dptr); dp++; } } #endif /* SEQUENTIAL_READ */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* Read the entire image. If the image has an alpha channel or a tRNS * chunk, and you have called png_handle_alpha()[*], you will need to * initialize the image to the current image that PNG will be overlaying. * We set the num_rows again here, in case it was incorrectly set in * png_read_start_row() by a call to png_read_update_info() or * png_start_read_image() if png_set_interlace_handling() wasn't called * prior to either of these functions like it should have been. You can * only call this function once. If you desire to have an image for * each pass of a interlaced image, use png_read_rows() instead. * * [*] png_handle_alpha() does not exist yet, as of this version of libpng */ void PNGAPI png_read_image(png_structrp png_ptr, png_bytepp image) { png_uint_32 i, image_height; int pass, j; png_bytepp rp; png_debug(1, "in png_read_image"); if (png_ptr == NULL) return; #ifdef PNG_READ_INTERLACING_SUPPORTED if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) { pass = png_set_interlace_handling(png_ptr); /* And make sure transforms are initialized. */ png_start_read_image(png_ptr); } else { if (png_ptr->interlaced != 0 && (png_ptr->transformations & PNG_INTERLACE) == 0) { /* Caller called png_start_read_image or png_read_update_info without * first turning on the PNG_INTERLACE transform. We can fix this here, * but the caller should do it! */ png_warning(png_ptr, "Interlace handling should be turned on when " "using png_read_image"); /* Make sure this is set correctly */ png_ptr->num_rows = png_ptr->height; } /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in * the above error case. */ pass = png_set_interlace_handling(png_ptr); } #else if (png_ptr->interlaced) png_error(png_ptr, "Cannot read interlaced image -- interlace handler disabled"); pass = 1; #endif image_height=png_ptr->height; for (j = 0; j < pass; j++) { rp = image; for (i = 0; i < image_height; i++) { png_read_row(png_ptr, *rp, NULL); rp++; } } } #endif /* SEQUENTIAL_READ */ #ifdef PNG_SEQUENTIAL_READ_SUPPORTED /* Read the end of the PNG file. Will not read past the end of the * file, will verify the end is accurate, and will read any comments * or time information at the end of the file, if info is not NULL. */ void PNGAPI png_read_end(png_structrp png_ptr, png_inforp info_ptr) { #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED int keep; #endif png_debug(1, "in png_read_end"); if (png_ptr == NULL) return; /* If png_read_end is called in the middle of reading the rows there may * still be pending IDAT data and an owned zstream. Deal with this here. */ #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0) #endif png_read_finish_IDAT(png_ptr); #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED /* Report invalid palette index; added at libpng-1.5.10 */ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE && png_ptr->num_palette_max >= png_ptr->num_palette) png_benign_error(png_ptr, "Read palette index exceeding num_palette"); #endif do { png_uint_32 length = png_read_chunk_header(png_ptr); png_uint_32 chunk_name = png_ptr->chunk_name; if (chunk_name != png_IDAT) { /* These flags must be set consistently for all non-IDAT chunks, * including the unknown chunks. */ png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT | PNG_AFTER_IDAT; } if (chunk_name == png_IEND) png_handle_chunk(png_ptr, info_ptr, length); else if (chunk_name == png_IHDR) png_handle_chunk(png_ptr, info_ptr, length); else if (info_ptr == NULL) png_crc_finish(png_ptr, length); #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0) { if (chunk_name == png_IDAT) { if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0) png_benign_error(png_ptr, ".Too many IDATs found"); } png_handle_unknown(png_ptr, info_ptr, length, keep); if (chunk_name == png_PLTE) png_ptr->mode |= PNG_HAVE_PLTE; } #endif else if (chunk_name == png_IDAT) { /* Zero length IDATs are legal after the last IDAT has been * read, but not after other chunks have been read. 1.6 does not * always read all the deflate data; specifically it cannot be relied * upon to read the Adler32 at the end. If it doesn't ignore IDAT * chunks which are longer than zero as well: */ if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED)) || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0) png_benign_error(png_ptr, "..Too many IDATs found"); png_crc_finish(png_ptr, length); } else png_handle_chunk(png_ptr, info_ptr, length); } while ((png_ptr->mode & PNG_HAVE_IEND) == 0); } #endif /* SEQUENTIAL_READ */ /* Free all memory used in the read struct */ static void png_read_destroy(png_structrp png_ptr) { png_debug(1, "in png_read_destroy"); #ifdef PNG_READ_GAMMA_SUPPORTED png_destroy_gamma_table(png_ptr); #endif png_free(png_ptr, png_ptr->big_row_buf); png_ptr->big_row_buf = NULL; png_free(png_ptr, png_ptr->big_prev_row); png_ptr->big_prev_row = NULL; png_free(png_ptr, png_ptr->read_buffer); png_ptr->read_buffer = NULL; #ifdef PNG_READ_QUANTIZE_SUPPORTED png_free(png_ptr, png_ptr->palette_lookup); png_ptr->palette_lookup = NULL; png_free(png_ptr, png_ptr->quantize_index); png_ptr->quantize_index = NULL; #endif /* png_ptr->palette is always independently allocated (not aliased * with info_ptr->palette), so free it unconditionally. */ png_free(png_ptr, png_ptr->palette); png_ptr->palette = NULL; #if defined(PNG_tRNS_SUPPORTED) || \ defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) /* png_ptr->trans_alpha is always independently allocated (not aliased * with info_ptr->trans_alpha), so free it unconditionally. */ png_free(png_ptr, png_ptr->trans_alpha); png_ptr->trans_alpha = NULL; #endif inflateEnd(&png_ptr->zstream); #ifdef PNG_PROGRESSIVE_READ_SUPPORTED png_free(png_ptr, png_ptr->save_buffer); png_ptr->save_buffer = NULL; #endif #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \ defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) png_free(png_ptr, png_ptr->unknown_chunk.data); png_ptr->unknown_chunk.data = NULL; #endif #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED png_free(png_ptr, png_ptr->chunk_list); png_ptr->chunk_list = NULL; #endif #if defined(PNG_READ_EXPAND_SUPPORTED) && \ (defined(PNG_ARM_NEON_IMPLEMENTATION) || \ defined(PNG_RISCV_RVV_IMPLEMENTATION)) png_free(png_ptr, png_ptr->riffled_palette); png_ptr->riffled_palette = NULL; #endif /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error * callbacks are still set at this point. They are required to complete the * destruction of the png_struct itself. */ } /* Free all memory used by the read */ void PNGAPI png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr) { png_structrp png_ptr = NULL; png_debug(1, "in png_destroy_read_struct"); if (png_ptr_ptr != NULL) png_ptr = *png_ptr_ptr; if (png_ptr == NULL) return; /* libpng 1.6.0: use the API to destroy info structs to ensure consistent * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API. * The extra was, apparently, unnecessary yet this hides memory leak bugs. */ png_destroy_info_struct(png_ptr, end_info_ptr_ptr); png_destroy_info_struct(png_ptr, info_ptr_ptr); *png_ptr_ptr = NULL; png_read_destroy(png_ptr); png_destroy_png_struct(png_ptr); } void PNGAPI png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn) { if (png_ptr == NULL) return; png_ptr->read_row_fn = read_row_fn; } #ifdef PNG_SEQUENTIAL_READ_SUPPORTED #ifdef PNG_INFO_IMAGE_SUPPORTED void PNGAPI png_read_png(png_structrp png_ptr, png_inforp info_ptr, int transforms, png_voidp params) { png_debug(1, "in png_read_png"); if (png_ptr == NULL || info_ptr == NULL) return; /* png_read_info() gives us all of the information from the * PNG file before the first IDAT (image data chunk). */ png_read_info(png_ptr, info_ptr); if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep))) png_error(png_ptr, "Image is too high to process with png_read_png()"); /* -------------- image transformations start here ------------------- */ /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM * is not implemented. This will only happen in de-configured (non-default) * libpng builds. The results can be unexpected - png_read_png may return * short or mal-formed rows because the transform is skipped. */ /* Tell libpng to strip 16-bit/color files down to 8 bits per color. */ if ((transforms & PNG_TRANSFORM_SCALE_16) != 0) /* Added at libpng-1.5.4. "strip_16" produces the same result that it * did in earlier versions, while "scale_16" is now more accurate. */ #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED png_set_scale_16(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported"); #endif /* If both SCALE and STRIP are required pngrtran will effectively cancel the * latter by doing SCALE first. This is ok and allows apps not to check for * which is supported to get the right answer. */ if ((transforms & PNG_TRANSFORM_STRIP_16) != 0) #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED png_set_strip_16(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported"); #endif /* Strip alpha bytes from the input data without combining with * the background (not recommended). */ if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0) #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED png_set_strip_alpha(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported"); #endif /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single * byte into separate bytes (useful for paletted and grayscale images). */ if ((transforms & PNG_TRANSFORM_PACKING) != 0) #ifdef PNG_READ_PACK_SUPPORTED png_set_packing(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported"); #endif /* Change the order of packed pixels to least significant bit first * (not useful if you are using png_set_packing). */ if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0) #ifdef PNG_READ_PACKSWAP_SUPPORTED png_set_packswap(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported"); #endif /* Expand paletted colors into true RGB triplets * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel * Expand paletted or RGB images with transparency to full alpha * channels so the data will be available as RGBA quartets. */ if ((transforms & PNG_TRANSFORM_EXPAND) != 0) #ifdef PNG_READ_EXPAND_SUPPORTED png_set_expand(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported"); #endif /* We don't handle background color or gamma transformation or quantizing. */ /* Invert monochrome files to have 0 as white and 1 as black */ if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0) #ifdef PNG_READ_INVERT_SUPPORTED png_set_invert_mono(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported"); #endif /* If you want to shift the pixel values from the range [0,255] or * [0,65535] to the original [0,7] or [0,31], or whatever range the * colors were originally in: */ if ((transforms & PNG_TRANSFORM_SHIFT) != 0) #ifdef PNG_READ_SHIFT_SUPPORTED if ((info_ptr->valid & PNG_INFO_sBIT) != 0) png_set_shift(png_ptr, &info_ptr->sig_bit); #else png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported"); #endif /* Flip the RGB pixels to BGR (or RGBA to BGRA) */ if ((transforms & PNG_TRANSFORM_BGR) != 0) #ifdef PNG_READ_BGR_SUPPORTED png_set_bgr(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported"); #endif /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0) #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED png_set_swap_alpha(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported"); #endif /* Swap bytes of 16-bit files to least significant byte first */ if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0) #ifdef PNG_READ_SWAP_SUPPORTED png_set_swap(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported"); #endif /* Added at libpng-1.2.41 */ /* Invert the alpha channel from opacity to transparency */ if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0) #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED png_set_invert_alpha(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported"); #endif /* Added at libpng-1.2.41 */ /* Expand grayscale image to RGB */ if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0) #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED png_set_gray_to_rgb(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported"); #endif /* Added at libpng-1.5.4 */ if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0) #ifdef PNG_READ_EXPAND_16_SUPPORTED png_set_expand_16(png_ptr); #else png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported"); #endif /* We don't handle adding filler bytes */ /* We use png_read_image and rely on that for interlace handling, but we also * call png_read_update_info therefore must turn on interlace handling now: */ (void)png_set_interlace_handling(png_ptr); /* Optional call to gamma correct and add the background to the palette * and update info structure. REQUIRED if you are expecting libpng to * update the palette for you (i.e., you selected such a transform above). */ png_read_update_info(png_ptr, info_ptr); /* -------------- image transformations end here ------------------- */ png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0); if (info_ptr->row_pointers == NULL) { png_uint_32 iptr; info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr, info_ptr->height * (sizeof (png_bytep)))); for (iptr=0; iptr<info_ptr->height; iptr++) info_ptr->row_pointers[iptr] = NULL; info_ptr->free_me |= PNG_FREE_ROWS; for (iptr = 0; iptr < info_ptr->height; iptr++) info_ptr->row_pointers[iptr] = png_voidcast(png_bytep, png_malloc(png_ptr, info_ptr->rowbytes)); } png_read_image(png_ptr, info_ptr->row_pointers); info_ptr->valid |= PNG_INFO_IDAT; /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */ png_read_end(png_ptr, info_ptr); PNG_UNUSED(params) } #endif /* INFO_IMAGE */ #endif /* SEQUENTIAL_READ */ #ifdef PNG_SIMPLIFIED_READ_SUPPORTED /* SIMPLIFIED READ * * This code currently relies on the sequential reader, though it could easily * be made to work with the progressive one. */ /* Arguments to png_image_finish_read: */ /* Encoding of PNG data (used by the color-map code) */ # define P_NOTSET 0 /* File encoding not yet known */ # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */ # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */ # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */ # define P_LINEAR8 4 /* 8-bit linear: only from a file value */ /* Color-map processing: after libpng has run on the PNG image further * processing may be needed to convert the data to color-map indices. */ #define PNG_CMAP_NONE 0 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */ #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */ #define PNG_CMAP_RGB 3 /* Process RGB data */ #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */ /* The following document where the background is for each processing case. */ #define PNG_CMAP_NONE_BACKGROUND 256 #define PNG_CMAP_GA_BACKGROUND 231 #define PNG_CMAP_TRANS_BACKGROUND 254 #define PNG_CMAP_RGB_BACKGROUND 256 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216 typedef struct { /* Arguments */ png_imagep image; png_voidp buffer; png_int_32 row_stride; png_voidp colormap; png_const_colorp background; /* Instance variables */ png_voidp local_row; png_voidp first_row; ptrdiff_t row_step; /* step between rows */ int file_encoding; /* E_ values above */ png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */ int colormap_processing; /* PNG_CMAP_ values above */ } png_image_read_control; /* Do all the *safe* initialization - 'safe' means that png_error won't be * called, so setting up the jmp_buf is not required. This means that anything * called from here must *not* call png_malloc - it has to call png_malloc_warn * instead so that control is returned safely back to this routine. */ static int png_image_read_init(png_imagep image) { if (image->opaque == NULL) { png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image, png_safe_error, png_safe_warning); /* And set the rest of the structure to NULL to ensure that the various * fields are consistent. */ memset(image, 0, (sizeof *image)); image->version = PNG_IMAGE_VERSION; if (png_ptr != NULL) { png_infop info_ptr = png_create_info_struct(png_ptr); if (info_ptr != NULL) { png_controlp control = png_voidcast(png_controlp, png_malloc_warn(png_ptr, (sizeof *control))); if (control != NULL) { memset(control, 0, (sizeof *control)); control->png_ptr = png_ptr; control->info_ptr = info_ptr; control->for_write = 0; image->opaque = control; return 1; } /* Error clean up */ png_destroy_info_struct(png_ptr, &info_ptr); } png_destroy_read_struct(&png_ptr, NULL, NULL); } return png_image_error(image, "png_image_read: out of memory"); } return png_image_error(image, "png_image_read: opaque pointer not NULL"); } /* Utility to find the base format of a PNG file from a png_struct. */ static png_uint_32 png_image_format(png_structrp png_ptr) { png_uint_32 format = 0; if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) format |= PNG_FORMAT_FLAG_COLOR; if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) format |= PNG_FORMAT_FLAG_ALPHA; /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS * sets the png_struct fields; that's all we are interested in here. The * precise interaction with an app call to png_set_tRNS and PNG file reading * is unclear. */ else if (png_ptr->num_trans > 0) format |= PNG_FORMAT_FLAG_ALPHA; if (png_ptr->bit_depth == 16) format |= PNG_FORMAT_FLAG_LINEAR; if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0) format |= PNG_FORMAT_FLAG_COLORMAP; return format; } static int chromaticities_match_sRGB(const png_xy *xy) { # define sRGB_TOLERANCE 1000 static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */ { /* color x y */ /* red */ 64000, 33000, /* green */ 30000, 60000, /* blue */ 15000, 6000, /* white */ 31270, 32900 }; if (PNG_OUT_OF_RANGE(xy->whitex, sRGB_xy.whitex,sRGB_TOLERANCE) || PNG_OUT_OF_RANGE(xy->whitey, sRGB_xy.whitey,sRGB_TOLERANCE) || PNG_OUT_OF_RANGE(xy->redx, sRGB_xy.redx, sRGB_TOLERANCE) || PNG_OUT_OF_RANGE(xy->redy, sRGB_xy.redy, sRGB_TOLERANCE) || PNG_OUT_OF_RANGE(xy->greenx, sRGB_xy.greenx,sRGB_TOLERANCE) || PNG_OUT_OF_RANGE(xy->greeny, sRGB_xy.greeny,sRGB_TOLERANCE) || PNG_OUT_OF_RANGE(xy->bluex, sRGB_xy.bluex, sRGB_TOLERANCE) || PNG_OUT_OF_RANGE(xy->bluey, sRGB_xy.bluey, sRGB_TOLERANCE)) return 0; return 1; } /* Is the given gamma significantly different from sRGB? The test is the same * one used in pngrtran.c when deciding whether to do gamma correction. The * arithmetic optimizes the division by using the fact that the inverse of the * file sRGB gamma is 2.2 */ static int png_gamma_not_sRGB(png_fixed_point g) { /* 1.6.47: use the same sanity checks as used in pngrtran.c */ if (g < PNG_LIB_GAMMA_MIN || g > PNG_LIB_GAMMA_MAX) return 0; /* Includes the uninitialized value 0 */ return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */); } /* Do the main body of a 'png_image_begin_read' function; read the PNG file * header and fill in all the information. This is executed in a safe context, * unlike the init routine above. */ static int png_image_is_not_sRGB(png_const_structrp png_ptr) { /* Does the colorspace **not** match sRGB? The flag is only set if the * answer can be determined reliably. * * png_struct::chromaticities always exists since the simplified API * requires rgb-to-gray. The mDCV, cICP and cHRM chunks may all set it to * a non-sRGB value, so it needs to be checked but **only** if one of * those chunks occurred in the file. */ /* Highest priority: check to be safe. */ if (png_has_chunk(png_ptr, cICP) || png_has_chunk(png_ptr, mDCV)) return !chromaticities_match_sRGB(&png_ptr->chromaticities); /* If the image is marked as sRGB then it is... */ if (png_has_chunk(png_ptr, sRGB)) return 0; /* Last stop: cHRM, must check: */ if (png_has_chunk(png_ptr, cHRM)) return !chromaticities_match_sRGB(&png_ptr->chromaticities); /* Else default to sRGB */ return 0; } static int png_image_read_header(png_voidp argument) { png_imagep image = png_voidcast(png_imagep, argument); png_structrp png_ptr = image->opaque->png_ptr; png_inforp info_ptr = image->opaque->info_ptr; #ifdef PNG_BENIGN_ERRORS_SUPPORTED png_set_benign_errors(png_ptr, 1/*warn*/); #endif png_read_info(png_ptr, info_ptr); /* Do this the fast way; just read directly out of png_struct. */ image->width = png_ptr->width; image->height = png_ptr->height; { png_uint_32 format = png_image_format(png_ptr); image->format = format; /* Greyscale images don't (typically) have colour space information and * using it is pretty much impossible, so use sRGB for grayscale (it * doesn't matter r==g==b so the transform is irrelevant.) */ if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && png_image_is_not_sRGB(png_ptr)) image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB; } /* We need the maximum number of entries regardless of the format the * application sets here. */ { png_uint_32 cmap_entries; switch (png_ptr->color_type) { case PNG_COLOR_TYPE_GRAY: cmap_entries = 1U << png_ptr->bit_depth; break; case PNG_COLOR_TYPE_PALETTE: cmap_entries = (png_uint_32)png_ptr->num_palette; break; default: cmap_entries = 256; break; } if (cmap_entries > 256) cmap_entries = 256; image->colormap_entries = cmap_entries; } return 1; } #ifdef PNG_STDIO_SUPPORTED int PNGAPI png_image_begin_read_from_stdio(png_imagep image, FILE *file) { if (image != NULL && image->version == PNG_IMAGE_VERSION) { if (file != NULL) { if (png_image_read_init(image) != 0) { /* This is slightly evil, but png_init_io doesn't do anything other * than this and we haven't changed the standard IO functions so * this saves a 'safe' function. */ image->opaque->png_ptr->io_ptr = file; return png_safe_execute(image, png_image_read_header, image); } } else return png_image_error(image, "png_image_begin_read_from_stdio: invalid argument"); } else if (image != NULL) return png_image_error(image, "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION"); return 0; } int PNGAPI png_image_begin_read_from_file(png_imagep image, const char *file_name) { if (image != NULL && image->version == PNG_IMAGE_VERSION) { if (file_name != NULL) { FILE *fp = fopen(file_name, "rb"); if (fp != NULL) { if (png_image_read_init(image) != 0) { image->opaque->png_ptr->io_ptr = fp; image->opaque->owned_file = 1; return png_safe_execute(image, png_image_read_header, image); } /* Clean up: just the opened file. */ (void)fclose(fp); } else return png_image_error(image, strerror(errno)); } else return png_image_error(image, "png_image_begin_read_from_file: invalid argument"); } else if (image != NULL) return png_image_error(image, "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION"); return 0; } #endif /* STDIO */ static void PNGCBAPI png_image_memory_read(png_structp png_ptr, png_bytep out, size_t need) { if (png_ptr != NULL) { png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr); if (image != NULL) { png_controlp cp = image->opaque; if (cp != NULL) { png_const_bytep memory = cp->memory; size_t size = cp->size; if (memory != NULL && size >= need) { memcpy(out, memory, need); cp->memory = memory + need; cp->size = size - need; return; } png_error(png_ptr, "read beyond end of data"); } } png_error(png_ptr, "invalid memory read"); } } int PNGAPI png_image_begin_read_from_memory(png_imagep image, png_const_voidp memory, size_t size) { if (image != NULL && image->version == PNG_IMAGE_VERSION) { if (memory != NULL && size > 0) { if (png_image_read_init(image) != 0) { /* Now set the IO functions to read from the memory buffer and * store it into io_ptr. Again do this in-place to avoid calling a * libpng function that requires error handling. */ image->opaque->memory = png_voidcast(png_const_bytep, memory); image->opaque->size = size; image->opaque->png_ptr->io_ptr = image; image->opaque->png_ptr->read_data_fn = png_image_memory_read; return png_safe_execute(image, png_image_read_header, image); } } else return png_image_error(image, "png_image_begin_read_from_memory: invalid argument"); } else if (image != NULL) return png_image_error(image, "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION"); return 0; } /* Utility function to skip chunks that are not used by the simplified image * read functions and an appropriate macro to call it. */ #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED static void png_image_skip_unused_chunks(png_structrp png_ptr) { /* Prepare the reader to ignore all recognized chunks whose data will not * be used, i.e., all chunks recognized by libpng except for those * involved in basic image reading: * * IHDR, PLTE, IDAT, IEND * * Or image data handling: * * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT. * * This provides a small performance improvement and eliminates any * potential vulnerability to security problems in the unused chunks. * * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored * too. This allows the simplified API to be compiled without iCCP support. */ { static const png_byte chunks_to_process[] = { 98, 75, 71, 68, '\0', /* bKGD */ 99, 72, 82, 77, '\0', /* cHRM */ 99, 73, 67, 80, '\0', /* cICP */ 103, 65, 77, 65, '\0', /* gAMA */ 109, 68, 67, 86, '\0', /* mDCV */ 115, 66, 73, 84, '\0', /* sBIT */ 115, 82, 71, 66, '\0', /* sRGB */ }; /* Ignore unknown chunks and all other chunks except for the * IHDR, PLTE, tRNS, IDAT, and IEND chunks. */ png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER, NULL, -1); /* But do not ignore image data handling chunks */ png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT, chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5); } } # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p) #else # define PNG_SKIP_CHUNKS(p) ((void)0) #endif /* HANDLE_AS_UNKNOWN */ /* The following macro gives the exact rounded answer for all values in the * range 0..255 (it actually divides by 51.2, but the rounding still generates * the correct numbers 0..5 */ #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8) /* Utility functions to make particular color-maps */ static void set_file_encoding(png_image_read_control *display) { png_structrp png_ptr = display->image->opaque->png_ptr; png_fixed_point g = png_resolve_file_gamma(png_ptr); /* PNGv3: the result may be 0 however the 'default_gamma' should have been * set before this is called so zero is an error: */ if (g == 0) png_error(png_ptr, "internal: default gamma not set"); if (png_gamma_significant(g) != 0) { if (png_gamma_not_sRGB(g) != 0) { display->file_encoding = P_FILE; display->gamma_to_linear = png_reciprocal(g); } else display->file_encoding = P_sRGB; } else display->file_encoding = P_LINEAR8; } static unsigned int decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding) { if (encoding == P_FILE) /* double check */ encoding = display->file_encoding; if (encoding == P_NOTSET) /* must be the file encoding */ { set_file_encoding(display); encoding = display->file_encoding; } switch (encoding) { case P_FILE: value = png_gamma_16bit_correct(value*257, display->gamma_to_linear); break; case P_sRGB: value = png_sRGB_table[value]; break; case P_LINEAR: break; case P_LINEAR8: value *= 257; break; #ifdef __GNUC__ default: png_error(display->image->opaque->png_ptr, "unexpected encoding (internal error)"); #endif } return value; } static png_uint_32 png_colormap_compose(png_image_read_control *display, png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha, png_uint_32 background, int encoding) { /* The file value is composed on the background, the background has the given * encoding and so does the result, the file is encoded with P_FILE and the * file and alpha are 8-bit values. The (output) encoding will always be * P_LINEAR or P_sRGB. */ png_uint_32 f = decode_gamma(display, foreground, foreground_encoding); png_uint_32 b = decode_gamma(display, background, encoding); /* The alpha is always an 8-bit value (it comes from the palette), the value * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires. */ f = f * alpha + b * (255-alpha); if (encoding == P_LINEAR) { /* Scale to 65535; divide by 255, approximately (in fact this is extremely * accurate, it divides by 255.00000005937181414556, with no overflow.) */ f *= 257; /* Now scaled by 65535 */ f += f >> 16; f = (f+32768) >> 16; } else /* P_sRGB */ f = PNG_sRGB_FROM_LINEAR(f); return f; } /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must * be 8-bit. */ static void png_create_colormap_entry(png_image_read_control *display, png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue, png_uint_32 alpha, int encoding) { png_imagep image = display->image; int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ? P_LINEAR : P_sRGB; int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 && (red != green || green != blue); if (ip > 255) png_error(image->opaque->png_ptr, "color-map index out of range"); /* Update the cache with whether the file gamma is significantly different * from sRGB. */ if (encoding == P_FILE) { if (display->file_encoding == P_NOTSET) set_file_encoding(display); /* Note that the cached value may be P_FILE too, but if it is then the * gamma_to_linear member has been set. */ encoding = display->file_encoding; } if (encoding == P_FILE) { png_fixed_point g = display->gamma_to_linear; red = png_gamma_16bit_correct(red*257, g); green = png_gamma_16bit_correct(green*257, g); blue = png_gamma_16bit_correct(blue*257, g); if (convert_to_Y != 0 || output_encoding == P_LINEAR) { alpha *= 257; encoding = P_LINEAR; } else { red = PNG_sRGB_FROM_LINEAR(red * 255); green = PNG_sRGB_FROM_LINEAR(green * 255); blue = PNG_sRGB_FROM_LINEAR(blue * 255); encoding = P_sRGB; } } else if (encoding == P_LINEAR8) { /* This encoding occurs quite frequently in test cases because PngSuite * includes a gAMA 1.0 chunk with most images. */ red *= 257; green *= 257; blue *= 257; alpha *= 257; encoding = P_LINEAR; } else if (encoding == P_sRGB && (convert_to_Y != 0 || output_encoding == P_LINEAR)) { /* The values are 8-bit sRGB values, but must be converted to 16-bit * linear. */ red = png_sRGB_table[red]; green = png_sRGB_table[green]; blue = png_sRGB_table[blue]; alpha *= 257; encoding = P_LINEAR; } /* This is set if the color isn't gray but the output is. */ if (encoding == P_LINEAR) { if (convert_to_Y != 0) { /* NOTE: these values are copied from png_do_rgb_to_gray */ png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green + (png_uint_32)2366 * blue; if (output_encoding == P_LINEAR) y = (y + 16384) >> 15; else { /* y is scaled by 32768, we need it scaled by 255: */ y = (y + 128) >> 8; y *= 255; y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7); alpha = PNG_DIV257(alpha); encoding = P_sRGB; } blue = red = green = y; } else if (output_encoding == P_sRGB) { red = PNG_sRGB_FROM_LINEAR(red * 255); green = PNG_sRGB_FROM_LINEAR(green * 255); blue = PNG_sRGB_FROM_LINEAR(blue * 255); alpha = PNG_DIV257(alpha); encoding = P_sRGB; } } if (encoding != output_encoding) png_error(image->opaque->png_ptr, "bad encoding (internal error)"); /* Store the value. */ { # ifdef PNG_FORMAT_AFIRST_SUPPORTED int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 && (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; # else # define afirst 0 # endif # ifdef PNG_FORMAT_BGR_SUPPORTED int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0; # else # define bgr 0 # endif if (output_encoding == P_LINEAR) { png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap); entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); /* The linear 16-bit values must be pre-multiplied by the alpha channel * value, if less than 65535 (this is, effectively, composite on black * if the alpha channel is removed.) */ switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) { case 4: entry[afirst ? 0 : 3] = (png_uint_16)alpha; /* FALLTHROUGH */ case 3: if (alpha < 65535) { if (alpha > 0) { blue = (blue * alpha + 32767U)/65535U; green = (green * alpha + 32767U)/65535U; red = (red * alpha + 32767U)/65535U; } else red = green = blue = 0; } entry[afirst + (2 ^ bgr)] = (png_uint_16)blue; entry[afirst + 1] = (png_uint_16)green; entry[afirst + bgr] = (png_uint_16)red; break; case 2: entry[1 ^ afirst] = (png_uint_16)alpha; /* FALLTHROUGH */ case 1: if (alpha < 65535) { if (alpha > 0) green = (green * alpha + 32767U)/65535U; else green = 0; } entry[afirst] = (png_uint_16)green; break; default: break; } } else /* output encoding is P_sRGB */ { png_bytep entry = png_voidcast(png_bytep, display->colormap); entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format); switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format)) { case 4: entry[afirst ? 0 : 3] = (png_byte)alpha; /* FALLTHROUGH */ case 3: entry[afirst + (2 ^ bgr)] = (png_byte)blue; entry[afirst + 1] = (png_byte)green; entry[afirst + bgr] = (png_byte)red; break; case 2: entry[1 ^ afirst] = (png_byte)alpha; /* FALLTHROUGH */ case 1: entry[afirst] = (png_byte)green; break; default: break; } } # ifdef afirst # undef afirst # endif # ifdef bgr # undef bgr # endif } } static int make_gray_file_colormap(png_image_read_control *display) { unsigned int i; for (i=0; i<256; ++i) png_create_colormap_entry(display, i, i, i, i, 255, P_FILE); return (int)i; } static int make_gray_colormap(png_image_read_control *display) { unsigned int i; for (i=0; i<256; ++i) png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB); return (int)i; } #define PNG_GRAY_COLORMAP_ENTRIES 256 static int make_ga_colormap(png_image_read_control *display) { unsigned int i, a; /* Alpha is retained, the output will be a color-map with entries * selected by six levels of alpha. One transparent entry, 6 gray * levels for all the intermediate alpha values, leaving 230 entries * for the opaque grays. The color-map entries are the six values * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the * relevant entry. * * if (alpha > 229) // opaque * { * // The 231 entries are selected to make the math below work: * base = 0; * entry = (231 * gray + 128) >> 8; * } * else if (alpha < 26) // transparent * { * base = 231; * entry = 0; * } * else // partially opaque * { * base = 226 + 6 * PNG_DIV51(alpha); * entry = PNG_DIV51(gray); * } */ i = 0; while (i < 231) { unsigned int gray = (i * 256 + 115) / 231; png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB); } /* 255 is used here for the component values for consistency with the code * that undoes premultiplication in pngwrite.c. */ png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB); for (a=1; a<5; ++a) { unsigned int g; for (g=0; g<6; ++g) png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51, P_sRGB); } return (int)i; } #define PNG_GA_COLORMAP_ENTRIES 256 static int make_rgb_colormap(png_image_read_control *display) { unsigned int i, r; /* Build a 6x6x6 opaque RGB cube */ for (i=r=0; r<6; ++r) { unsigned int g; for (g=0; g<6; ++g) { unsigned int b; for (b=0; b<6; ++b) png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255, P_sRGB); } } return (int)i; } #define PNG_RGB_COLORMAP_ENTRIES 216 /* Return a palette index to the above palette given three 8-bit sRGB values. */ #define PNG_RGB_INDEX(r,g,b) \ ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b))) static int png_image_read_colormap(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_structrp png_ptr = image->opaque->png_ptr; png_uint_32 output_format = image->format; int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ? P_LINEAR : P_sRGB; unsigned int cmap_entries; unsigned int output_processing; /* Output processing option */ unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */ /* Background information; the background color and the index of this color * in the color-map if it exists (else 256). */ unsigned int background_index = 256; png_uint_32 back_r, back_g, back_b; /* Flags to accumulate things that need to be done to the input. */ int expand_tRNS = 0; /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is * very difficult to do, the results look awful, and it is difficult to see * what possible use it is because the application can't control the * color-map. */ if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 || png_ptr->num_trans > 0) /* alpha in input */ && ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */) { if (output_encoding == P_LINEAR) /* compose on black */ back_b = back_g = back_r = 0; else if (display->background == NULL /* no way to remove it */) png_error(png_ptr, "background color must be supplied to remove alpha/transparency"); /* Get a copy of the background color (this avoids repeating the checks * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the * output format. */ else { back_g = display->background->green; if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0) { back_r = display->background->red; back_b = display->background->blue; } else back_b = back_r = back_g; } } else if (output_encoding == P_LINEAR) back_b = back_r = back_g = 65535; else back_b = back_r = back_g = 255; /* Default the input file gamma if required - this is necessary because * libpng assumes that if no gamma information is present the data is in the * output format, but the simplified API deduces the gamma from the input * format. The 'default' gamma value is also set by png_set_alpha_mode, but * this is happening before any such call, so: * * TODO: should be an internal API and all this code should be copied into a * single common gamma+colorspace file. */ if (png_ptr->bit_depth == 16 && (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) png_ptr->default_gamma = PNG_GAMMA_LINEAR; else png_ptr->default_gamma = PNG_GAMMA_sRGB_INVERSE; /* Decide what to do based on the PNG color type of the input data. The * utility function png_create_colormap_entry deals with most aspects of the * output transformations; this code works out how to produce bytes of * color-map entries from the original format. */ switch (png_ptr->color_type) { case PNG_COLOR_TYPE_GRAY: if (png_ptr->bit_depth <= 8) { /* There at most 256 colors in the output, regardless of * transparency. */ unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0; cmap_entries = 1U << png_ptr->bit_depth; if (cmap_entries > image->colormap_entries) png_error(png_ptr, "gray[8] color-map: too few entries"); step = 255 / (cmap_entries - 1); output_processing = PNG_CMAP_NONE; /* If there is a tRNS chunk then this either selects a transparent * value or, if the output has no alpha, the background color. */ if (png_ptr->num_trans > 0) { trans = png_ptr->trans_color.gray; if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) back_alpha = output_encoding == P_LINEAR ? 65535 : 255; } /* png_create_colormap_entry just takes an RGBA and writes the * corresponding color-map entry using the format from 'image', * including the required conversion to sRGB or linear as * appropriate. The input values are always either sRGB (if the * gamma correction flag is 0) or 0..255 scaled file encoded values * (if the function must gamma correct them). */ for (i=val=0; i<cmap_entries; ++i, val += step) { /* 'i' is a file value. While this will result in duplicated * entries for 8-bit non-sRGB encoded files it is necessary to * have non-gamma corrected values to do tRNS handling. */ if (i != trans) png_create_colormap_entry(display, i, val, val, val, 255, P_FILE/*8-bit with file gamma*/); /* Else this entry is transparent. The colors don't matter if * there is an alpha channel (back_alpha == 0), but it does no * harm to pass them in; the values are not set above so this * passes in white. * * NOTE: this preserves the full precision of the application * supplied background color when it is used. */ else png_create_colormap_entry(display, i, back_r, back_g, back_b, back_alpha, output_encoding); } /* We need libpng to preserve the original encoding. */ data_encoding = P_FILE; /* The rows from libpng, while technically gray values, are now also * color-map indices; however, they may need to be expanded to 1 * byte per pixel. This is what png_set_packing does (i.e., it * unpacks the bit values into bytes.) */ if (png_ptr->bit_depth < 8) png_set_packing(png_ptr); } else /* bit depth is 16 */ { /* The 16-bit input values can be converted directly to 8-bit gamma * encoded values; however, if a tRNS chunk is present 257 color-map * entries are required. This means that the extra entry requires * special processing; add an alpha channel, sacrifice gray level * 254 and convert transparent (alpha==0) entries to that. * * Use libpng to chop the data to 8 bits. Convert it to sRGB at the * same time to minimize quality loss. If a tRNS chunk is present * this means libpng must handle it too; otherwise it is impossible * to do the exact match on the 16-bit value. * * If the output has no alpha channel *and* the background color is * gray then it is possible to let libpng handle the substitution by * ensuring that the corresponding gray level matches the background * color exactly. */ data_encoding = P_sRGB; if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) png_error(png_ptr, "gray[16] color-map: too few entries"); cmap_entries = (unsigned int)make_gray_colormap(display); if (png_ptr->num_trans > 0) { unsigned int back_alpha; if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) back_alpha = 0; else { if (back_r == back_g && back_g == back_b) { /* Background is gray; no special processing will be * required. */ png_color_16 c; png_uint_32 gray = back_g; if (output_encoding == P_LINEAR) { gray = PNG_sRGB_FROM_LINEAR(gray * 255); /* And make sure the corresponding palette entry * matches. */ png_create_colormap_entry(display, gray, back_g, back_g, back_g, 65535, P_LINEAR); } /* The background passed to libpng, however, must be the * sRGB value. */ c.index = 0; /*unused*/ c.gray = c.red = c.green = c.blue = (png_uint_16)gray; /* NOTE: does this work without expanding tRNS to alpha? * It should be the color->gray case below apparently * doesn't. */ png_set_background_fixed(png_ptr, &c, PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 0/*gamma: not used*/); output_processing = PNG_CMAP_NONE; break; } #ifdef __COVERITY__ /* Coverity claims that output_encoding cannot be 2 (P_LINEAR) * here. */ back_alpha = 255; #else back_alpha = output_encoding == P_LINEAR ? 65535 : 255; #endif } /* output_processing means that the libpng-processed row will be * 8-bit GA and it has to be processing to single byte color-map * values. Entry 254 is replaced by either a completely * transparent entry or by the background color at full * precision (and the background color is not a simple gray * level in this case.) */ expand_tRNS = 1; output_processing = PNG_CMAP_TRANS; background_index = 254; /* And set (overwrite) color-map entry 254 to the actual * background color at full precision. */ png_create_colormap_entry(display, 254, back_r, back_g, back_b, back_alpha, output_encoding); } else output_processing = PNG_CMAP_NONE; } break; case PNG_COLOR_TYPE_GRAY_ALPHA: /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum * of 65536 combinations. If, however, the alpha channel is to be * removed there are only 256 possibilities if the background is gray. * (Otherwise there is a subset of the 65536 possibilities defined by * the triangle between black, white and the background color.) * * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to * worry about tRNS matching - tRNS is ignored if there is an alpha * channel. */ data_encoding = P_sRGB; if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) { if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) png_error(png_ptr, "gray+alpha color-map: too few entries"); cmap_entries = (unsigned int)make_ga_colormap(display); background_index = PNG_CMAP_GA_BACKGROUND; output_processing = PNG_CMAP_GA; } else /* alpha is removed */ { /* Alpha must be removed as the PNG data is processed when the * background is a color because the G and A channels are * independent and the vector addition (non-parallel vectors) is a * 2-D problem. * * This can be reduced to the same algorithm as above by making a * colormap containing gray levels (for the opaque grays), a * background entry (for a transparent pixel) and a set of four six * level color values, one set for each intermediate alpha value. * See the comments in make_ga_colormap for how this works in the * per-pixel processing. * * If the background is gray, however, we only need a 256 entry gray * level color map. It is sufficient to make the entry generated * for the background color be exactly the color specified. */ if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 || (back_r == back_g && back_g == back_b)) { /* Background is gray; no special processing will be required. */ png_color_16 c; png_uint_32 gray = back_g; if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) png_error(png_ptr, "gray-alpha color-map: too few entries"); cmap_entries = (unsigned int)make_gray_colormap(display); if (output_encoding == P_LINEAR) { gray = PNG_sRGB_FROM_LINEAR(gray * 255); /* And make sure the corresponding palette entry matches. */ png_create_colormap_entry(display, gray, back_g, back_g, back_g, 65535, P_LINEAR); } /* The background passed to libpng, however, must be the sRGB * value. */ c.index = 0; /*unused*/ c.gray = c.red = c.green = c.blue = (png_uint_16)gray; png_set_background_fixed(png_ptr, &c, PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 0/*gamma: not used*/); output_processing = PNG_CMAP_NONE; } else { png_uint_32 i, a; /* This is the same as png_make_ga_colormap, above, except that * the entries are all opaque. */ if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) png_error(png_ptr, "ga-alpha color-map: too few entries"); i = 0; while (i < 231) { png_uint_32 gray = (i * 256 + 115) / 231; png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB); } /* NOTE: this preserves the full precision of the application * background color. */ background_index = i; png_create_colormap_entry(display, i++, back_r, back_g, back_b, #ifdef __COVERITY__ /* Coverity claims that output_encoding * cannot be 2 (P_LINEAR) here. */ 255U, #else output_encoding == P_LINEAR ? 65535U : 255U, #endif output_encoding); /* For non-opaque input composite on the sRGB background - this * requires inverting the encoding for each component. The input * is still converted to the sRGB encoding because this is a * reasonable approximate to the logarithmic curve of human * visual sensitivity, at least over the narrow range which PNG * represents. Consequently 'G' is always sRGB encoded, while * 'A' is linear. We need the linear background colors. */ if (output_encoding == P_sRGB) /* else already linear */ { /* This may produce a value not exactly matching the * background, but that's ok because these numbers are only * used when alpha != 0 */ back_r = png_sRGB_table[back_r]; back_g = png_sRGB_table[back_g]; back_b = png_sRGB_table[back_b]; } for (a=1; a<5; ++a) { unsigned int g; /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled * by an 8-bit alpha value (0..255). */ png_uint_32 alpha = 51 * a; png_uint_32 back_rx = (255-alpha) * back_r; png_uint_32 back_gx = (255-alpha) * back_g; png_uint_32 back_bx = (255-alpha) * back_b; for (g=0; g<6; ++g) { png_uint_32 gray = png_sRGB_table[g*51] * alpha; png_create_colormap_entry(display, i++, PNG_sRGB_FROM_LINEAR(gray + back_rx), PNG_sRGB_FROM_LINEAR(gray + back_gx), PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB); } } cmap_entries = i; output_processing = PNG_CMAP_GA; } } break; case PNG_COLOR_TYPE_RGB: case PNG_COLOR_TYPE_RGB_ALPHA: /* Exclude the case where the output is gray; we can always handle this * with the cases above. */ if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0) { /* The color-map will be grayscale, so we may as well convert the * input RGB values to a simple grayscale and use the grayscale * code above. * * NOTE: calling this apparently damages the recognition of the * transparent color in background color handling; call * png_set_tRNS_to_alpha before png_set_background_fixed. */ png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1, -1); data_encoding = P_sRGB; /* The output will now be one or two 8-bit gray or gray+alpha * channels. The more complex case arises when the input has alpha. */ if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || png_ptr->num_trans > 0) && (output_format & PNG_FORMAT_FLAG_ALPHA) != 0) { /* Both input and output have an alpha channel, so no background * processing is required; just map the GA bytes to the right * color-map entry. */ expand_tRNS = 1; if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries) png_error(png_ptr, "rgb[ga] color-map: too few entries"); cmap_entries = (unsigned int)make_ga_colormap(display); background_index = PNG_CMAP_GA_BACKGROUND; output_processing = PNG_CMAP_GA; } else { const png_fixed_point gamma = png_resolve_file_gamma(png_ptr); /* Either the input or the output has no alpha channel, so there * will be no non-opaque pixels in the color-map; it will just be * grayscale. */ if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries) png_error(png_ptr, "rgb[gray] color-map: too few entries"); /* Ideally this code would use libpng to do the gamma correction, * but if an input alpha channel is to be removed we will hit the * libpng bug in gamma+compose+rgb-to-gray (the double gamma * correction bug). Fix this by dropping the gamma correction in * this case and doing it in the palette; this will result in * duplicate palette entries, but that's better than the * alternative of double gamma correction. * * NOTE: PNGv3: check the resolved result of all the potentially * different colour space chunks. */ if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || png_ptr->num_trans > 0) && png_gamma_not_sRGB(gamma) != 0) { cmap_entries = (unsigned int)make_gray_file_colormap(display); data_encoding = P_FILE; } else cmap_entries = (unsigned int)make_gray_colormap(display); /* But if the input has alpha or transparency it must be removed */ if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || png_ptr->num_trans > 0) { png_color_16 c; png_uint_32 gray = back_g; /* We need to ensure that the application background exists in * the colormap and that completely transparent pixels map to * it. Achieve this simply by ensuring that the entry * selected for the background really is the background color. */ if (data_encoding == P_FILE) /* from the fixup above */ { /* The app supplied a gray which is in output_encoding, we * need to convert it to a value of the input (P_FILE) * encoding then set this palette entry to the required * output encoding. */ if (output_encoding == P_sRGB) gray = png_sRGB_table[gray]; /* now P_LINEAR */ gray = PNG_DIV257(png_gamma_16bit_correct(gray, gamma)); /* now P_FILE */ /* And make sure the corresponding palette entry contains * exactly the required sRGB value. */ png_create_colormap_entry(display, gray, back_g, back_g, back_g, 0/*unused*/, output_encoding); } else if (output_encoding == P_LINEAR) { gray = PNG_sRGB_FROM_LINEAR(gray * 255); /* And make sure the corresponding palette entry matches. */ png_create_colormap_entry(display, gray, back_g, back_g, back_g, 0/*unused*/, P_LINEAR); } /* The background passed to libpng, however, must be the * output (normally sRGB) value. */ c.index = 0; /*unused*/ c.gray = c.red = c.green = c.blue = (png_uint_16)gray; /* NOTE: the following is apparently a bug in libpng. Without * it the transparent color recognition in * png_set_background_fixed seems to go wrong. */ expand_tRNS = 1; png_set_background_fixed(png_ptr, &c, PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 0/*gamma: not used*/); } output_processing = PNG_CMAP_NONE; } } else /* output is color */ { /* We could use png_quantize here so long as there is no transparent * color or alpha; png_quantize ignores alpha. Easier overall just * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube. * Consequently we always want libpng to produce sRGB data. */ data_encoding = P_sRGB; /* Is there any transparency or alpha? */ if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA || png_ptr->num_trans > 0) { /* Is there alpha in the output too? If so all four channels are * processed into a special RGB cube with alpha support. */ if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0) { png_uint_32 r; if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) png_error(png_ptr, "rgb+alpha color-map: too few entries"); cmap_entries = (unsigned int)make_rgb_colormap(display); /* Add a transparent entry. */ png_create_colormap_entry(display, cmap_entries, 255, 255, 255, 0, P_sRGB); /* This is stored as the background index for the processing * algorithm. */ background_index = cmap_entries++; /* Add 27 r,g,b entries each with alpha 0.5. */ for (r=0; r<256; r = (r << 1) | 0x7f) { png_uint_32 g; for (g=0; g<256; g = (g << 1) | 0x7f) { png_uint_32 b; /* This generates components with the values 0, 127 and * 255 */ for (b=0; b<256; b = (b << 1) | 0x7f) png_create_colormap_entry(display, cmap_entries++, r, g, b, 128, P_sRGB); } } expand_tRNS = 1; output_processing = PNG_CMAP_RGB_ALPHA; } else { /* Alpha/transparency must be removed. The background must * exist in the color map (achieved by setting adding it after * the 666 color-map). If the standard processing code will * pick up this entry automatically that's all that is * required; libpng can be called to do the background * processing. */ unsigned int sample_size = PNG_IMAGE_SAMPLE_SIZE(output_format); png_uint_32 r, g, b; /* sRGB background */ if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries) png_error(png_ptr, "rgb-alpha color-map: too few entries"); cmap_entries = (unsigned int)make_rgb_colormap(display); png_create_colormap_entry(display, cmap_entries, back_r, back_g, back_b, 0/*unused*/, output_encoding); if (output_encoding == P_LINEAR) { r = PNG_sRGB_FROM_LINEAR(back_r * 255); g = PNG_sRGB_FROM_LINEAR(back_g * 255); b = PNG_sRGB_FROM_LINEAR(back_b * 255); } else { r = back_r; g = back_g; b = back_b; } /* Compare the newly-created color-map entry with the one the * PNG_CMAP_RGB algorithm will use. If the two entries don't * match, add the new one and set this as the background * index. */ if (memcmp((png_const_bytep)display->colormap + sample_size * cmap_entries, (png_const_bytep)display->colormap + sample_size * PNG_RGB_INDEX(r,g,b), sample_size) != 0) { /* The background color must be added. */ background_index = cmap_entries++; /* Add 27 r,g,b entries each with created by composing with * the background at alpha 0.5. */ for (r=0; r<256; r = (r << 1) | 0x7f) { for (g=0; g<256; g = (g << 1) | 0x7f) { /* This generates components with the values 0, 127 * and 255 */ for (b=0; b<256; b = (b << 1) | 0x7f) png_create_colormap_entry(display, cmap_entries++, png_colormap_compose(display, r, P_sRGB, 128, back_r, output_encoding), png_colormap_compose(display, g, P_sRGB, 128, back_g, output_encoding), png_colormap_compose(display, b, P_sRGB, 128, back_b, output_encoding), 0/*unused*/, output_encoding); } } expand_tRNS = 1; output_processing = PNG_CMAP_RGB_ALPHA; } else /* background color is in the standard color-map */ { png_color_16 c; c.index = 0; /*unused*/ c.red = (png_uint_16)back_r; c.gray = c.green = (png_uint_16)back_g; c.blue = (png_uint_16)back_b; png_set_background_fixed(png_ptr, &c, PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 0/*gamma: not used*/); output_processing = PNG_CMAP_RGB; } } } else /* no alpha or transparency in the input */ { /* Alpha in the output is irrelevant, simply map the opaque input * pixels to the 6x6x6 color-map. */ if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries) png_error(png_ptr, "rgb color-map: too few entries"); cmap_entries = (unsigned int)make_rgb_colormap(display); output_processing = PNG_CMAP_RGB; } } break; case PNG_COLOR_TYPE_PALETTE: /* It's already got a color-map. It may be necessary to eliminate the * tRNS entries though. */ { unsigned int num_trans = png_ptr->num_trans; png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL; png_const_colorp colormap = png_ptr->palette; int do_background = trans != NULL && (output_format & PNG_FORMAT_FLAG_ALPHA) == 0; unsigned int i; /* Just in case: */ if (trans == NULL) num_trans = 0; output_processing = PNG_CMAP_NONE; data_encoding = P_FILE; /* Don't change from color-map indices */ cmap_entries = (unsigned int)png_ptr->num_palette; if (cmap_entries > 256) cmap_entries = 256; if (cmap_entries > (unsigned int)image->colormap_entries) png_error(png_ptr, "palette color-map: too few entries"); for (i=0; i < cmap_entries; ++i) { if (do_background != 0 && i < num_trans && trans[i] < 255) { if (trans[i] == 0) png_create_colormap_entry(display, i, back_r, back_g, back_b, 0, output_encoding); else { /* Must compose the PNG file color in the color-map entry * on the sRGB color in 'back'. */ png_create_colormap_entry(display, i, png_colormap_compose(display, colormap[i].red, P_FILE, trans[i], back_r, output_encoding), png_colormap_compose(display, colormap[i].green, P_FILE, trans[i], back_g, output_encoding), png_colormap_compose(display, colormap[i].blue, P_FILE, trans[i], back_b, output_encoding), output_encoding == P_LINEAR ? trans[i] * 257U : trans[i], output_encoding); } } else png_create_colormap_entry(display, i, colormap[i].red, colormap[i].green, colormap[i].blue, i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/); } /* The PNG data may have indices packed in fewer than 8 bits, it * must be expanded if so. */ if (png_ptr->bit_depth < 8) png_set_packing(png_ptr); } break; default: png_error(png_ptr, "invalid PNG color type"); /*NOT REACHED*/ } /* Now deal with the output processing */ if (expand_tRNS != 0 && png_ptr->num_trans > 0 && (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0) png_set_tRNS_to_alpha(png_ptr); switch (data_encoding) { case P_sRGB: /* Change to 8-bit sRGB */ png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB); /* FALLTHROUGH */ case P_FILE: if (png_ptr->bit_depth > 8) png_set_scale_16(png_ptr); break; #ifdef __GNUC__ default: png_error(png_ptr, "bad data option (internal error)"); #endif } if (cmap_entries > 256 || cmap_entries > image->colormap_entries) png_error(png_ptr, "color map overflow (BAD internal error)"); image->colormap_entries = cmap_entries; /* Double check using the recorded background index */ switch (output_processing) { case PNG_CMAP_NONE: if (background_index != PNG_CMAP_NONE_BACKGROUND) goto bad_background; break; case PNG_CMAP_GA: if (background_index != PNG_CMAP_GA_BACKGROUND) goto bad_background; break; case PNG_CMAP_TRANS: if (background_index >= cmap_entries || background_index != PNG_CMAP_TRANS_BACKGROUND) goto bad_background; break; case PNG_CMAP_RGB: if (background_index != PNG_CMAP_RGB_BACKGROUND) goto bad_background; break; case PNG_CMAP_RGB_ALPHA: if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND) goto bad_background; break; default: png_error(png_ptr, "bad processing option (internal error)"); bad_background: png_error(png_ptr, "bad background index (internal error)"); } display->colormap_processing = (int)output_processing; return 1/*ok*/; } /* The final part of the color-map read called from png_image_finish_read. */ static int png_image_read_and_map(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_structrp png_ptr = image->opaque->png_ptr; int passes; /* Called when the libpng data must be transformed into the color-mapped * form. There is a local row buffer in display->local and this routine must * do the interlace handling. */ switch (png_ptr->interlaced) { case PNG_INTERLACE_NONE: passes = 1; break; case PNG_INTERLACE_ADAM7: passes = PNG_INTERLACE_ADAM7_PASSES; break; default: png_error(png_ptr, "unknown interlace type"); } { png_uint_32 height = image->height; png_uint_32 width = image->width; int proc = display->colormap_processing; png_bytep first_row = png_voidcast(png_bytep, display->first_row); ptrdiff_t row_step = display->row_step; int pass; for (pass = 0; pass < passes; ++pass) { unsigned int startx, stepx, stepy; png_uint_32 y; if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) { /* The row may be empty for a short image: */ if (PNG_PASS_COLS(width, pass) == 0) continue; startx = PNG_PASS_START_COL(pass); stepx = PNG_PASS_COL_OFFSET(pass); y = PNG_PASS_START_ROW(pass); stepy = PNG_PASS_ROW_OFFSET(pass); } else { y = 0; startx = 0; stepx = stepy = 1; } for (; y<height; y += stepy) { png_bytep inrow = png_voidcast(png_bytep, display->local_row); png_bytep outrow = first_row + y * row_step; png_const_bytep row_end = outrow + width; /* Read the libpng data into the temporary buffer. */ png_read_row(png_ptr, inrow, NULL); /* Now process the row according to the processing option, note * that the caller verifies that the format of the libpng output * data is as required. */ outrow += startx; switch (proc) { case PNG_CMAP_GA: for (; outrow < row_end; outrow += stepx) { /* The data is always in the PNG order */ unsigned int gray = *inrow++; unsigned int alpha = *inrow++; unsigned int entry; /* NOTE: this code is copied as a comment in * make_ga_colormap above. Please update the * comment if you change this code! */ if (alpha > 229) /* opaque */ { entry = (231 * gray + 128) >> 8; } else if (alpha < 26) /* transparent */ { entry = 231; } else /* partially opaque */ { entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray); } *outrow = (png_byte)entry; } break; case PNG_CMAP_TRANS: for (; outrow < row_end; outrow += stepx) { png_byte gray = *inrow++; png_byte alpha = *inrow++; if (alpha == 0) *outrow = PNG_CMAP_TRANS_BACKGROUND; else if (gray != PNG_CMAP_TRANS_BACKGROUND) *outrow = gray; else *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1); } break; case PNG_CMAP_RGB: for (; outrow < row_end; outrow += stepx) { *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]); inrow += 3; } break; case PNG_CMAP_RGB_ALPHA: for (; outrow < row_end; outrow += stepx) { unsigned int alpha = inrow[3]; /* Because the alpha entries only hold alpha==0.5 values * split the processing at alpha==0.25 (64) and 0.75 * (196). */ if (alpha >= 196) *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]); else if (alpha < 64) *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND; else { /* Likewise there are three entries for each of r, g * and b. We could select the entry by popcount on * the top two bits on those architectures that * support it, this is what the code below does, * crudely. */ unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1; /* Here are how the values map: * * 0x00 .. 0x3f -> 0 * 0x40 .. 0xbf -> 1 * 0xc0 .. 0xff -> 2 * * So, as above with the explicit alpha checks, the * breakpoints are at 64 and 196. */ if (inrow[0] & 0x80) back_i += 9; /* red */ if (inrow[0] & 0x40) back_i += 9; if (inrow[1] & 0x80) back_i += 3; /* green */ if (inrow[1] & 0x40) back_i += 3; if (inrow[2] & 0x80) back_i += 1; /* blue */ if (inrow[2] & 0x40) back_i += 1; *outrow = (png_byte)back_i; } inrow += 4; } break; default: break; } } } } return 1; } static int png_image_read_colormapped(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_controlp control = image->opaque; png_structrp png_ptr = control->png_ptr; png_inforp info_ptr = control->info_ptr; int passes = 0; /* As a flag */ PNG_SKIP_CHUNKS(png_ptr); /* Update the 'info' structure and make sure the result is as required; first * make sure to turn on the interlace handling if it will be required * (because it can't be turned on *after* the call to png_read_update_info!) */ if (display->colormap_processing == PNG_CMAP_NONE) passes = png_set_interlace_handling(png_ptr); png_read_update_info(png_ptr, info_ptr); /* The expected output can be deduced from the colormap_processing option. */ switch (display->colormap_processing) { case PNG_CMAP_NONE: /* Output must be one channel and one byte per pixel, the output * encoding can be anything. */ if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE || info_ptr->color_type == PNG_COLOR_TYPE_GRAY) && info_ptr->bit_depth == 8) break; goto bad_output; case PNG_CMAP_TRANS: case PNG_CMAP_GA: /* Output must be two channels and the 'G' one must be sRGB, the latter * can be checked with an exact number because it should have been set * to this number above! */ if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA && info_ptr->bit_depth == 8 && png_ptr->screen_gamma == PNG_GAMMA_sRGB && image->colormap_entries == 256) break; goto bad_output; case PNG_CMAP_RGB: /* Output must be 8-bit sRGB encoded RGB */ if (info_ptr->color_type == PNG_COLOR_TYPE_RGB && info_ptr->bit_depth == 8 && png_ptr->screen_gamma == PNG_GAMMA_sRGB && image->colormap_entries == 216) break; goto bad_output; case PNG_CMAP_RGB_ALPHA: /* Output must be 8-bit sRGB encoded RGBA */ if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA && info_ptr->bit_depth == 8 && png_ptr->screen_gamma == PNG_GAMMA_sRGB && image->colormap_entries == 244 /* 216 + 1 + 27 */) break; goto bad_output; default: bad_output: png_error(png_ptr, "bad color-map processing (internal error)"); } /* Now read the rows. Do this here if it is possible to read directly into * the output buffer, otherwise allocate a local row buffer of the maximum * size libpng requires and call the relevant processing routine safely. */ { png_voidp first_row = display->buffer; ptrdiff_t row_step = display->row_stride; /* The following adjustment is to ensure that calculations are correct, * regardless whether row_step is positive or negative. */ if (row_step < 0) { char *ptr = png_voidcast(char*, first_row); ptr += (image->height-1) * (-row_step); first_row = png_voidcast(png_voidp, ptr); } display->first_row = first_row; display->row_step = row_step; } if (passes == 0) { int result; png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); display->local_row = row; result = png_safe_execute(image, png_image_read_and_map, display); display->local_row = NULL; png_free(png_ptr, row); return result; } else { ptrdiff_t row_step = display->row_step; while (--passes >= 0) { png_uint_32 y = image->height; png_bytep row = png_voidcast(png_bytep, display->first_row); for (; y > 0; --y) { png_read_row(png_ptr, row, NULL); row += row_step; } } return 1; } } /* Row reading for interlaced 16-to-8 bit depth conversion with local buffer. */ static int png_image_read_direct_scaled(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_structrp png_ptr = image->opaque->png_ptr; png_inforp info_ptr = image->opaque->info_ptr; png_bytep local_row = png_voidcast(png_bytep, display->local_row); png_bytep first_row = png_voidcast(png_bytep, display->first_row); ptrdiff_t row_step = display->row_step; size_t row_bytes = png_get_rowbytes(png_ptr, info_ptr); int passes; /* Handle interlacing. */ switch (png_ptr->interlaced) { case PNG_INTERLACE_NONE: passes = 1; break; case PNG_INTERLACE_ADAM7: passes = PNG_INTERLACE_ADAM7_PASSES; break; default: png_error(png_ptr, "unknown interlace type"); } /* Read each pass using local_row as intermediate buffer. */ while (--passes >= 0) { png_uint_32 y = image->height; png_bytep output_row = first_row; for (; y > 0; --y) { /* Read into local_row (gets transformed 8-bit data). */ png_read_row(png_ptr, local_row, NULL); /* Copy from local_row to user buffer. * Use row_bytes (i.e. the actual size in bytes of the row data) for * copying into output_row. Use row_step for advancing output_row, * to respect the caller's stride for padding or negative (bottom-up) * layouts. */ memcpy(output_row, local_row, row_bytes); output_row += row_step; } } return 1; } /* Just the row reading part of png_image_read. */ static int png_image_read_composite(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_structrp png_ptr = image->opaque->png_ptr; int passes; switch (png_ptr->interlaced) { case PNG_INTERLACE_NONE: passes = 1; break; case PNG_INTERLACE_ADAM7: passes = PNG_INTERLACE_ADAM7_PASSES; break; default: png_error(png_ptr, "unknown interlace type"); } { png_uint_32 height = image->height; png_uint_32 width = image->width; ptrdiff_t row_step = display->row_step; unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1; int optimize_alpha = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0; int pass; for (pass = 0; pass < passes; ++pass) { unsigned int startx, stepx, stepy; png_uint_32 y; if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) { /* The row may be empty for a short image: */ if (PNG_PASS_COLS(width, pass) == 0) continue; startx = PNG_PASS_START_COL(pass) * channels; stepx = PNG_PASS_COL_OFFSET(pass) * channels; y = PNG_PASS_START_ROW(pass); stepy = PNG_PASS_ROW_OFFSET(pass); } else { y = 0; startx = 0; stepx = channels; stepy = 1; } for (; y<height; y += stepy) { png_bytep inrow = png_voidcast(png_bytep, display->local_row); png_bytep outrow; png_const_bytep row_end; /* Read the row, which is packed: */ png_read_row(png_ptr, inrow, NULL); outrow = png_voidcast(png_bytep, display->first_row); outrow += y * row_step; row_end = outrow + width * channels; /* Now do the composition on each pixel in this row. */ outrow += startx; for (; outrow < row_end; outrow += stepx) { png_byte alpha = inrow[channels]; if (alpha > 0) /* else no change to the output */ { unsigned int c; for (c=0; c<channels; ++c) { png_uint_32 component = inrow[c]; if (alpha < 255) /* else just use component */ { if (optimize_alpha != 0) { /* This is PNG_OPTIMIZED_ALPHA, the component value * is a linear 8-bit value. Combine this with the * current outrow[c] value which is sRGB encoded. * Arithmetic here is 16-bits to preserve the output * values correctly. */ component *= 257*255; /* =65535 */ component += (255-alpha)*png_sRGB_table[outrow[c]]; /* Clamp to the valid range to defend against * unforeseen cases where the data might be sRGB * instead of linear premultiplied. * (Belt-and-suspenders for CVE-2025-66293.) */ if (component > 255*65535) component = 255*65535; /* So 'component' is scaled by 255*65535 and is * therefore appropriate for the sRGB-to-linear * conversion table. */ component = PNG_sRGB_FROM_LINEAR(component); } else { /* Compositing was already done on the palette * entries. The data is sRGB premultiplied on black. * Composite with the background in sRGB space. * This is not gamma-correct, but matches what was * done to the palette. */ png_uint_32 background = outrow[c]; component += ((255-alpha) * background + 127) / 255; if (component > 255) component = 255; } } outrow[c] = (png_byte)component; } } inrow += channels+1; /* components and alpha channel */ } } } } return 1; } /* The do_local_background case; called when all the following transforms are to * be done: * * PNG_RGB_TO_GRAY * PNG_COMPOSITE * PNG_GAMMA * * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and * PNG_COMPOSITE code performs gamma correction, so we get double gamma * correction. The fix-up is to prevent the PNG_COMPOSITE operation from * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha * row and handles the removal or pre-multiplication of the alpha channel. */ static int png_image_read_background(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_structrp png_ptr = image->opaque->png_ptr; png_inforp info_ptr = image->opaque->info_ptr; png_uint_32 height = image->height; png_uint_32 width = image->width; int pass, passes; /* Double check the convoluted logic below. We expect to get here with * libpng doing rgb to gray and gamma correction but background processing * left to the png_image_read_background function. The rows libpng produce * might be 8 or 16-bit but should always have two channels; gray plus alpha. */ if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) png_error(png_ptr, "lost rgb to gray"); if ((png_ptr->transformations & PNG_COMPOSE) != 0) png_error(png_ptr, "unexpected compose"); if (png_get_channels(png_ptr, info_ptr) != 2) png_error(png_ptr, "lost/gained channels"); /* Expect the 8-bit case to always remove the alpha channel */ if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 && (image->format & PNG_FORMAT_FLAG_ALPHA) != 0) png_error(png_ptr, "unexpected 8-bit transformation"); switch (png_ptr->interlaced) { case PNG_INTERLACE_NONE: passes = 1; break; case PNG_INTERLACE_ADAM7: passes = PNG_INTERLACE_ADAM7_PASSES; break; default: png_error(png_ptr, "unknown interlace type"); } /* Use direct access to info_ptr here because otherwise the simplified API * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is * checking the value after libpng expansions, not the original value in the * PNG. */ switch (info_ptr->bit_depth) { case 8: /* 8-bit sRGB gray values with an alpha channel; the alpha channel is * to be removed by composing on a background: either the row if * display->background is NULL or display->background->green if not. * Unlike the code above ALPHA_OPTIMIZED has *not* been done. */ { png_bytep first_row = png_voidcast(png_bytep, display->first_row); ptrdiff_t row_step = display->row_step; for (pass = 0; pass < passes; ++pass) { unsigned int startx, stepx, stepy; png_uint_32 y; if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) { /* The row may be empty for a short image: */ if (PNG_PASS_COLS(width, pass) == 0) continue; startx = PNG_PASS_START_COL(pass); stepx = PNG_PASS_COL_OFFSET(pass); y = PNG_PASS_START_ROW(pass); stepy = PNG_PASS_ROW_OFFSET(pass); } else { y = 0; startx = 0; stepx = stepy = 1; } if (display->background == NULL) { for (; y<height; y += stepy) { png_bytep inrow = png_voidcast(png_bytep, display->local_row); png_bytep outrow = first_row + y * row_step; png_const_bytep row_end = outrow + width; /* Read the row, which is packed: */ png_read_row(png_ptr, inrow, NULL); /* Now do the composition on each pixel in this row. */ outrow += startx; for (; outrow < row_end; outrow += stepx) { png_byte alpha = inrow[1]; if (alpha > 0) /* else no change to the output */ { png_uint_32 component = inrow[0]; if (alpha < 255) /* else just use component */ { /* Since PNG_OPTIMIZED_ALPHA was not set it is * necessary to invert the sRGB transfer * function and multiply the alpha out. */ component = png_sRGB_table[component] * alpha; component += png_sRGB_table[outrow[0]] * (255-alpha); component = PNG_sRGB_FROM_LINEAR(component); } outrow[0] = (png_byte)component; } inrow += 2; /* gray and alpha channel */ } } } else /* constant background value */ { png_byte background8 = display->background->green; png_uint_16 background = png_sRGB_table[background8]; for (; y<height; y += stepy) { png_bytep inrow = png_voidcast(png_bytep, display->local_row); png_bytep outrow = first_row + y * row_step; png_const_bytep row_end = outrow + width; /* Read the row, which is packed: */ png_read_row(png_ptr, inrow, NULL); /* Now do the composition on each pixel in this row. */ outrow += startx; for (; outrow < row_end; outrow += stepx) { png_byte alpha = inrow[1]; if (alpha > 0) /* else use background */ { png_uint_32 component = inrow[0]; if (alpha < 255) /* else just use component */ { component = png_sRGB_table[component] * alpha; component += background * (255-alpha); component = PNG_sRGB_FROM_LINEAR(component); } outrow[0] = (png_byte)component; } else outrow[0] = background8; inrow += 2; /* gray and alpha channel */ } } } } } break; case 16: /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must * still be done and, maybe, the alpha channel removed. This code also * handles the alpha-first option. */ { png_uint_16p first_row = png_voidcast(png_uint_16p, display->first_row); /* The division by two is safe because the caller passed in a * stride which was multiplied by 2 (below) to get row_step. */ ptrdiff_t row_step = display->row_step / 2; unsigned int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0; unsigned int outchannels = 1U+preserve_alpha; int swap_alpha = 0; # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED if (preserve_alpha != 0 && (image->format & PNG_FORMAT_FLAG_AFIRST) != 0) swap_alpha = 1; # endif for (pass = 0; pass < passes; ++pass) { unsigned int startx, stepx, stepy; png_uint_32 y; /* The 'x' start and step are adjusted to output components here. */ if (png_ptr->interlaced == PNG_INTERLACE_ADAM7) { /* The row may be empty for a short image: */ if (PNG_PASS_COLS(width, pass) == 0) continue; startx = PNG_PASS_START_COL(pass) * outchannels; stepx = PNG_PASS_COL_OFFSET(pass) * outchannels; y = PNG_PASS_START_ROW(pass); stepy = PNG_PASS_ROW_OFFSET(pass); } else { y = 0; startx = 0; stepx = outchannels; stepy = 1; } for (; y<height; y += stepy) { png_const_uint_16p inrow; png_uint_16p outrow = first_row + y * row_step; png_uint_16p row_end = outrow + width * outchannels; /* Read the row, which is packed: */ png_read_row(png_ptr, png_voidcast(png_bytep, display->local_row), NULL); inrow = png_voidcast(png_const_uint_16p, display->local_row); /* Now do the pre-multiplication on each pixel in this row. */ outrow += startx; for (; outrow < row_end; outrow += stepx) { png_uint_32 component = inrow[0]; png_uint_16 alpha = inrow[1]; if (alpha > 0) /* else 0 */ { if (alpha < 65535) /* else just use component */ { component *= alpha; component += 32767; component /= 65535; } } else component = 0; outrow[swap_alpha] = (png_uint_16)component; if (preserve_alpha != 0) outrow[1 ^ swap_alpha] = alpha; inrow += 2; /* components and alpha channel */ } } } } break; #ifdef __GNUC__ default: png_error(png_ptr, "unexpected bit depth"); #endif } return 1; } /* The guts of png_image_finish_read as a png_safe_execute callback. */ static int png_image_read_direct(png_voidp argument) { png_image_read_control *display = png_voidcast(png_image_read_control*, argument); png_imagep image = display->image; png_structrp png_ptr = image->opaque->png_ptr; png_inforp info_ptr = image->opaque->info_ptr; png_uint_32 format = image->format; int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0; int do_local_compose = 0; int do_local_background = 0; /* to avoid double gamma correction bug */ int do_local_scale = 0; /* for interlaced 16-to-8 bit conversion */ int passes = 0; /* Add transforms to ensure the correct output format is produced then check * that the required implementation support is there. Always expand; always * need 8 bits minimum, no palette and expanded tRNS. */ png_set_expand(png_ptr); /* Now check the format to see if it was modified. */ { png_uint_32 base_format = png_image_format(png_ptr) & ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */; png_uint_32 change = format ^ base_format; png_fixed_point output_gamma; int mode; /* alpha mode */ /* Do this first so that we have a record if rgb to gray is happening. */ if ((change & PNG_FORMAT_FLAG_COLOR) != 0) { /* gray<->color transformation required. */ if ((format & PNG_FORMAT_FLAG_COLOR) != 0) png_set_gray_to_rgb(png_ptr); else { /* libpng can't do both rgb to gray and * background/pre-multiplication if there is also significant gamma * correction, because both operations require linear colors and * the code only supports one transform doing the gamma correction. * Handle this by doing the pre-multiplication or background * operation in this code, if necessary. * * TODO: fix this by rewriting pngrtran.c (!) * * For the moment (given that fixing this in pngrtran.c is an * enormous change) 'do_local_background' is used to indicate that * the problem exists. */ if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) do_local_background = 1/*maybe*/; png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT); } change &= ~PNG_FORMAT_FLAG_COLOR; } /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise. */ { /* This is safe but should no longer be necessary as * png_ptr->default_gamma should have been set after the * info-before-IDAT was read in png_image_read_header. * * TODO: 1.8: remove this and see what happens. */ png_fixed_point input_gamma_default; if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 && (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0) input_gamma_default = PNG_GAMMA_LINEAR; else input_gamma_default = PNG_DEFAULT_sRGB; /* Call png_set_alpha_mode to set the default for the input gamma; the * output gamma is set by a second call below. */ png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default); } if (linear != 0) { /* If there *is* an alpha channel in the input it must be multiplied * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG. */ if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) mode = PNG_ALPHA_STANDARD; /* associated alpha */ else mode = PNG_ALPHA_PNG; output_gamma = PNG_GAMMA_LINEAR; } else { mode = PNG_ALPHA_PNG; output_gamma = PNG_DEFAULT_sRGB; } if ((change & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) { mode = PNG_ALPHA_OPTIMIZED; change &= ~PNG_FORMAT_FLAG_ASSOCIATED_ALPHA; } /* If 'do_local_background' is set check for the presence of gamma * correction; this is part of the work-round for the libpng bug * described above. * * TODO: fix libpng and remove this. */ if (do_local_background != 0) { png_fixed_point gtest; /* This is 'png_gamma_threshold' from pngrtran.c; the test used for * gamma correction, the screen gamma hasn't been set on png_struct * yet; it's set below. png_struct::gamma, however, is set to the * final value. */ if (png_muldiv(>est, output_gamma, png_resolve_file_gamma(png_ptr), PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0) do_local_background = 0; else if (mode == PNG_ALPHA_STANDARD) { do_local_background = 2/*required*/; mode = PNG_ALPHA_PNG; /* prevent libpng doing it */ } /* else leave as 1 for the checks below */ } /* If the bit-depth changes then handle that here. */ if ((change & PNG_FORMAT_FLAG_LINEAR) != 0) { if (linear != 0 /*16-bit output*/) png_set_expand_16(png_ptr); else /* 8-bit output */ { png_set_scale_16(png_ptr); /* For interlaced images, use local_row buffer to avoid overflow * in png_combine_row() which writes using IHDR bit-depth. */ if (png_ptr->interlaced != 0) do_local_scale = 1; } change &= ~PNG_FORMAT_FLAG_LINEAR; } /* Now the background/alpha channel changes. */ if ((change & PNG_FORMAT_FLAG_ALPHA) != 0) { /* Removing an alpha channel requires composition for the 8-bit * formats; for the 16-bit it is already done, above, by the * pre-multiplication and the channel just needs to be stripped. */ if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0) { /* If RGB->gray is happening the alpha channel must be left and the * operation completed locally. * * TODO: fix libpng and remove this. */ if (do_local_background != 0) do_local_background = 2/*required*/; /* 16-bit output: just remove the channel */ else if (linear != 0) /* compose on black (well, pre-multiply) */ png_set_strip_alpha(png_ptr); /* 8-bit output: do an appropriate compose */ else if (display->background != NULL) { png_color_16 c; c.index = 0; /*unused*/ c.red = display->background->red; c.green = display->background->green; c.blue = display->background->blue; c.gray = display->background->green; /* This is always an 8-bit sRGB value, using the 'green' channel * for gray is much better than calculating the luminance here; * we can get off-by-one errors in that calculation relative to * the app expectations and that will show up in transparent * pixels. */ png_set_background_fixed(png_ptr, &c, PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/, 0/*gamma: not used*/); } else /* compose on row: implemented below. */ { do_local_compose = 1; /* This leaves the alpha channel in the output, so it has to be * removed by the code below. Set the encoding to the 'OPTIMIZE' * one so the code only has to hack on the pixels that require * composition. */ mode = PNG_ALPHA_OPTIMIZED; } } else /* output needs an alpha channel */ { /* This is tricky because it happens before the swap operation has * been accomplished; however, the swap does *not* swap the added * alpha channel (weird API), so it must be added in the correct * place. */ png_uint_32 filler; /* opaque filler */ int where; if (linear != 0) filler = 65535; else filler = 255; #ifdef PNG_FORMAT_AFIRST_SUPPORTED if ((format & PNG_FORMAT_FLAG_AFIRST) != 0) { where = PNG_FILLER_BEFORE; change &= ~PNG_FORMAT_FLAG_AFIRST; } else #endif where = PNG_FILLER_AFTER; png_set_add_alpha(png_ptr, filler, where); } /* This stops the (irrelevant) call to swap_alpha below. */ change &= ~PNG_FORMAT_FLAG_ALPHA; } /* Now set the alpha mode correctly; this is always done, even if there is * no alpha channel in either the input or the output because it correctly * sets the output gamma. */ png_set_alpha_mode_fixed(png_ptr, mode, output_gamma); # ifdef PNG_FORMAT_BGR_SUPPORTED if ((change & PNG_FORMAT_FLAG_BGR) != 0) { /* Check only the output format; PNG is never BGR; don't do this if * the output is gray, but fix up the 'format' value in that case. */ if ((format & PNG_FORMAT_FLAG_COLOR) != 0) png_set_bgr(png_ptr); else format &= ~PNG_FORMAT_FLAG_BGR; change &= ~PNG_FORMAT_FLAG_BGR; } # endif # ifdef PNG_FORMAT_AFIRST_SUPPORTED if ((change & PNG_FORMAT_FLAG_AFIRST) != 0) { /* Only relevant if there is an alpha channel - it's particularly * important to handle this correctly because do_local_compose may * be set above and then libpng will keep the alpha channel for this * code to remove. */ if ((format & PNG_FORMAT_FLAG_ALPHA) != 0) { /* Disable this if doing a local background, * TODO: remove this when local background is no longer required. */ if (do_local_background != 2) png_set_swap_alpha(png_ptr); } else format &= ~PNG_FORMAT_FLAG_AFIRST; change &= ~PNG_FORMAT_FLAG_AFIRST; } # endif /* If the *output* is 16-bit then we need to check for a byte-swap on this * architecture. */ if (linear != 0) { png_uint_16 le = 0x0001; if ((*(png_const_bytep) & le) != 0) png_set_swap(png_ptr); } /* If change is not now 0 some transformation is missing - error out. */ if (change != 0) png_error(png_ptr, "png_read_image: unsupported transformation"); } PNG_SKIP_CHUNKS(png_ptr); /* Update the 'info' structure and make sure the result is as required; first * make sure to turn on the interlace handling if it will be required * (because it can't be turned on *after* the call to png_read_update_info!) * * TODO: remove the do_local_background fixup below. */ if (do_local_compose == 0 && do_local_background != 2) passes = png_set_interlace_handling(png_ptr); png_read_update_info(png_ptr, info_ptr); { png_uint_32 info_format = 0; if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) info_format |= PNG_FORMAT_FLAG_COLOR; if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) { /* do_local_compose removes this channel below. */ if (do_local_compose == 0) { /* do_local_background does the same if required. */ if (do_local_background != 2 || (format & PNG_FORMAT_FLAG_ALPHA) != 0) info_format |= PNG_FORMAT_FLAG_ALPHA; } } else if (do_local_compose != 0) /* internal error */ png_error(png_ptr, "png_image_read: alpha channel lost"); if ((format & PNG_FORMAT_FLAG_ASSOCIATED_ALPHA) != 0) { info_format |= PNG_FORMAT_FLAG_ASSOCIATED_ALPHA; } if (info_ptr->bit_depth == 16) info_format |= PNG_FORMAT_FLAG_LINEAR; #ifdef PNG_FORMAT_BGR_SUPPORTED if ((png_ptr->transformations & PNG_BGR) != 0) info_format |= PNG_FORMAT_FLAG_BGR; #endif #ifdef PNG_FORMAT_AFIRST_SUPPORTED if (do_local_background == 2) { if ((format & PNG_FORMAT_FLAG_AFIRST) != 0) info_format |= PNG_FORMAT_FLAG_AFIRST; } if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 || ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 && (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0)) { if (do_local_background == 2) png_error(png_ptr, "unexpected alpha swap transformation"); info_format |= PNG_FORMAT_FLAG_AFIRST; } # endif /* This is actually an internal error. */ if (info_format != format) png_error(png_ptr, "png_read_image: invalid transformations"); } /* Now read the rows. If do_local_compose is set then it is necessary to use * a local row buffer. The output will be GA, RGBA or BGRA and must be * converted to G, RGB or BGR as appropriate. The 'local_row' member of the * display acts as a flag. */ { png_voidp first_row = display->buffer; ptrdiff_t row_step = display->row_stride; if (linear != 0) row_step *= 2; /* The following adjustment is to ensure that calculations are correct, * regardless whether row_step is positive or negative. */ if (row_step < 0) { char *ptr = png_voidcast(char*, first_row); ptr += (image->height - 1) * (-row_step); first_row = png_voidcast(png_voidp, ptr); } display->first_row = first_row; display->row_step = row_step; } if (do_local_compose != 0) { int result; png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); display->local_row = row; result = png_safe_execute(image, png_image_read_composite, display); display->local_row = NULL; png_free(png_ptr, row); return result; } else if (do_local_background == 2) { int result; png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); display->local_row = row; result = png_safe_execute(image, png_image_read_background, display); display->local_row = NULL; png_free(png_ptr, row); return result; } else if (do_local_scale != 0) { /* For interlaced 16-to-8 conversion, use an intermediate row buffer * to avoid buffer overflows in png_combine_row. The local_row is sized * for the transformed (8-bit) output, preventing the overflow that would * occur if png_combine_row wrote 16-bit data directly to the user buffer. */ int result; png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr)); display->local_row = row; result = png_safe_execute(image, png_image_read_direct_scaled, display); display->local_row = NULL; png_free(png_ptr, row); return result; } else { ptrdiff_t row_step = display->row_step; while (--passes >= 0) { png_uint_32 y = image->height; png_bytep row = png_voidcast(png_bytep, display->first_row); for (; y > 0; --y) { png_read_row(png_ptr, row, NULL); row += row_step; } } return 1; } } int PNGAPI png_image_finish_read(png_imagep image, png_const_colorp background, void *buffer, png_int_32 row_stride, void *colormap) { if (image != NULL && image->version == PNG_IMAGE_VERSION) { /* Check for row_stride overflow. This check is not performed on the * original PNG format because it may not occur in the output PNG format * and libpng deals with the issues of reading the original. */ unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format); /* The following checks just the 'row_stride' calculation to ensure it * fits in a signed 32-bit value. Because channels/components can be * either 1 or 2 bytes in size the length of a row can still overflow 32 * bits; this is just to verify that the 'row_stride' argument can be * represented. */ if (image->width <= 0x7fffffffU/channels) /* no overflow */ { png_uint_32 check; png_uint_32 png_row_stride = image->width * channels; if (row_stride == 0) row_stride = (png_int_32)/*SAFE*/png_row_stride; if (row_stride < 0) check = -(png_uint_32)row_stride; else check = (png_uint_32)row_stride; /* This verifies 'check', the absolute value of the actual stride * passed in and detects overflow in the application calculation (i.e. * if the app did actually pass in a non-zero 'row_stride'. */ if (image->opaque != NULL && buffer != NULL && check >= png_row_stride) { /* Now check for overflow of the image buffer calculation; this * limits the whole image size to 32 bits for API compatibility with * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro. * * The PNG_IMAGE_BUFFER_SIZE macro is: * * (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride)) * * And the component size is always 1 or 2, so make sure that the * number of *bytes* that the application is saying are available * does actually fit into a 32-bit number. * * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE * will be changed to use png_alloc_size_t; bigger images can be * accommodated on 64-bit systems. */ if (image->height <= 0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check) { if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 || (image->colormap_entries > 0 && colormap != NULL)) { int result; png_image_read_control display; memset(&display, 0, (sizeof display)); display.image = image; display.buffer = buffer; display.row_stride = row_stride; display.colormap = colormap; display.background = background; display.local_row = NULL; /* Choose the correct 'end' routine; for the color-map case * all the setup has already been done. */ if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0) result = png_safe_execute(image, png_image_read_colormap, &display) && png_safe_execute(image, png_image_read_colormapped, &display); else result = png_safe_execute(image, png_image_read_direct, &display); png_image_free(image); return result; } else return png_image_error(image, "png_image_finish_read[color-map]: no color-map"); } else return png_image_error(image, "png_image_finish_read: image too large"); } else return png_image_error(image, "png_image_finish_read: invalid argument"); } else return png_image_error(image, "png_image_finish_read: row_stride too large"); } else if (image != NULL) return png_image_error(image, "png_image_finish_read: damaged PNG_IMAGE_VERSION"); return 0; } #endif /* SIMPLIFIED_READ */ #endif /* READ */
¤ Dauer der Verarbeitung: 0.207 Sekunden ¤*© Formatika GbR, Deutschland |
|
||||||||||||||
2026-10-11