/* pngrtran.c - transforms the data in a row for PNG readers * * Last changed in libpng 1.7.0 [(PENDING RELEASE)] * Copyright (c) 1998-2015 Glenn Randers-Pehrson * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.88 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 functions optionally called by an application * in order to tell libpng how to handle data when reading a PNG. * Transformations that are used in both reading and writing are * in pngtrans.c. */ #include "pngpriv.h" #define PNG_SRC_FILE PNG_SRC_FILE_pngrtran #ifdef PNG_READ_SUPPORTED /* Set the action on getting a CRC error for an ancillary or critical chunk. */ void PNGAPI png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action) { png_debug(1, "in png_set_crc_action"); if (png_ptr == NULL) return; /* Tell libpng how we react to CRC errors in critical chunks */ switch (crit_action) { case PNG_CRC_NO_CHANGE: /* Leave setting as is */ break; case PNG_CRC_WARN_USE: /* Warn/use data */ png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE; break; case PNG_CRC_QUIET_USE: /* Quiet/use data */ png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE | PNG_FLAG_CRC_CRITICAL_IGNORE; break; case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */ png_warning(png_ptr, "Can't discard critical data on CRC error"); case PNG_CRC_ERROR_QUIT: /* Error/quit */ case PNG_CRC_DEFAULT: default: png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; break; } /* Tell libpng how we react to CRC errors in ancillary chunks */ switch (ancil_action) { case PNG_CRC_NO_CHANGE: /* Leave setting as is */ break; case PNG_CRC_WARN_USE: /* Warn/use data */ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE; break; case PNG_CRC_QUIET_USE: /* Quiet/use data */ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN; break; case PNG_CRC_ERROR_QUIT: /* Error/quit */ png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN; break; case PNG_CRC_WARN_DISCARD: /* Warn/discard data */ case PNG_CRC_DEFAULT: default: png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; break; } } #ifdef PNG_READ_TRANSFORMS_SUPPORTED /* Is it OK to set a transformation now? Only if png_start_read_image or * png_read_update_info have not been called. It is not necessary for the IHDR * to have been read in all cases; the need_IHDR parameter allows for this * check too. */ static int png_rtran_ok(png_structrp png_ptr, int need_IHDR) { if (png_ptr != NULL) { if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0) png_app_error(png_ptr, "invalid after png_start_read_image or png_read_update_info"); else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0) png_app_error(png_ptr, "invalid before the PNG header has been read"); else { /* Turn on failure to initialize correctly for all transforms. */ png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED; return 1; /* Ok */ } } return 0; /* no png_error possible! */ } #endif #ifdef PNG_READ_BACKGROUND_SUPPORTED /* Handle alpha and tRNS via a background color */ void PNGFAPI png_set_background_fixed(png_structrp png_ptr, png_const_color_16p background_color, int background_gamma_code, int need_expand, png_fixed_point background_gamma) { png_debug(1, "in png_set_background_fixed"); if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL) return; if (background_gamma_code != PNG_BACKGROUND_GAMMA_SCREEN && background_gamma_code != PNG_BACKGROUND_GAMMA_FILE && background_gamma_code != PNG_BACKGROUND_GAMMA_UNIQUE) { png_app_error(png_ptr, "invalid gamma type"); return; } png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA; png_ptr->transformations &= ~PNG_ENCODE_ALPHA; png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; png_ptr->background = *background_color; png_ptr->background_gamma = background_gamma; png_ptr->background_gamma_type = png_check_byte(png_ptr, background_gamma_code); if (need_expand != 0) png_ptr->flags |= PNG_FLAG_BACKGROUND_EXPAND; else png_ptr->flags &= ~PNG_FLAG_BACKGROUND_EXPAND; } # ifdef PNG_FLOATING_POINT_SUPPORTED void PNGAPI png_set_background(png_structrp png_ptr, png_const_color_16p background_color, int background_gamma_code, int need_expand, double background_gamma) { png_set_background_fixed(png_ptr, background_color, background_gamma_code, need_expand, png_fixed(png_ptr, background_gamma, "png_set_background")); } # endif /* FLOATING_POINT */ #endif /* READ_BACKGROUND */ /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the * one that pngrtran does first (scale) happens. This is necessary to allow the * TRANSFORM and API behavior to be somewhat consistent, and it's simpler. */ #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED void PNGAPI png_set_scale_16(png_structrp png_ptr) { png_debug(1, "in png_set_scale_16"); if (png_rtran_ok(png_ptr, 0) == 0) return; png_ptr->transformations |= PNG_SCALE_16_TO_8; } #endif #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED /* Chop 16-bit depth files to 8-bit depth */ void PNGAPI png_set_strip_16(png_structrp png_ptr) { png_debug(1, "in png_set_strip_16"); if (png_rtran_ok(png_ptr, 0) == 0) return; png_ptr->transformations |= PNG_16_TO_8; } #endif #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED void PNGAPI png_set_strip_alpha(png_structrp png_ptr) { png_debug(1, "in png_set_strip_alpha"); if (png_rtran_ok(png_ptr, 0) == 0) return; png_ptr->transformations |= PNG_STRIP_ALPHA; } #endif #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED) static png_fixed_point translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma, int is_screen) { /* Check for flag values. The main reason for having the old Mac value as a * flag is that it is pretty near impossible to work out what the correct * value is from Apple documentation - a working Mac system is needed to * discover the value! */ if (output_gamma == PNG_DEFAULT_sRGB || output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB) { /* If there is no sRGB support this just sets the gamma to the standard * sRGB value. (This is a side effect of using this function!) */ # ifdef PNG_READ_sRGB_SUPPORTED png_ptr->flags |= PNG_FLAG_ASSUME_sRGB; # else PNG_UNUSED(png_ptr) # endif if (is_screen != 0) output_gamma = PNG_GAMMA_sRGB; else output_gamma = PNG_GAMMA_sRGB_INVERSE; } else if (output_gamma == PNG_GAMMA_MAC_18 || output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18) { if (is_screen != 0) output_gamma = PNG_GAMMA_MAC_OLD; else output_gamma = PNG_GAMMA_MAC_INVERSE; } return output_gamma; } # ifdef PNG_FLOATING_POINT_SUPPORTED static png_fixed_point convert_gamma_value(png_structrp png_ptr, double output_gamma) { /* The following silently ignores cases where fixed point (times 100,000) * gamma values are passed to the floating point API. This is safe and it * means the fixed point constants work just fine with the floating point * API. The alternative would just lead to undetected errors and spurious * bug reports. Negative values fail inside the _fixed API unless they * correspond to the flag values. */ if (output_gamma < 0 || output_gamma > 128) output_gamma *= .00001; return png_fixed(png_ptr, output_gamma, "gamma value"); } # endif #endif /* READ_ALPHA_MODE || READ_GAMMA */ #ifdef PNG_READ_ALPHA_MODE_SUPPORTED void PNGFAPI png_set_alpha_mode_fixed(png_structrp png_ptr, int mode, png_fixed_point output_gamma) { int compose = 0; png_fixed_point file_gamma; png_debug(1, "in png_set_alpha_mode"); if (png_rtran_ok(png_ptr, 0) == 0) return; output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/); /* Validate the value to ensure it is in a reasonable range. The value * is expected to be 1 or greater, but this range test allows for some * viewing correction values. The intent is to weed out users of this API * who use the inverse of the gamma value accidentally! Since some of these * values are reasonable this may have to be changed. */ if (output_gamma < 70000 || output_gamma > 300000) png_error(png_ptr, "output gamma out of expected range"); /* The default file gamma is the inverse of the output gamma; the output * gamma may be changed below so get the file value first: */ file_gamma = png_reciprocal(output_gamma); /* There are really 8 possibilities here, composed of any combination * of: * * premultiply the color channels * do not encode non-opaque pixels * encode the alpha as well as the color channels * * The differences disappear if the input/output ('screen') gamma is 1.0, * because then the encoding is a no-op and there is only the choice of * premultiplying the color channels or not. * * png_set_alpha_mode and png_set_background interact because both use * png_compose to do the work. Calling both is only useful when * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along * with a default gamma value. Otherwise PNG_COMPOSE must not be set. */ switch (mode) { case PNG_ALPHA_PNG: /* default: png standard */ /* No compose, but it may be set by png_set_background! */ png_ptr->transformations &= ~PNG_ENCODE_ALPHA; png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; break; case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */ compose = 1; png_ptr->transformations &= ~PNG_ENCODE_ALPHA; png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; /* The output is linear: */ output_gamma = PNG_FP_1; break; case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */ compose = 1; png_ptr->transformations &= ~PNG_ENCODE_ALPHA; png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA; /* output_gamma records the encoding of opaque pixels! */ break; case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */ compose = 1; png_ptr->transformations |= PNG_ENCODE_ALPHA; png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; break; default: png_error(png_ptr, "invalid alpha mode"); } /* Only set the default gamma if the file gamma has not been set (this has * the side effect that the gamma in a second call to png_set_alpha_mode will * be ignored.) */ if (png_ptr->colorspace.gamma == 0) { png_ptr->colorspace.gamma = file_gamma; png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; } /* But always set the output gamma: */ png_ptr->screen_gamma = output_gamma; /* Finally, if pre-multiplying, set the background fields to achieve the * desired result. */ if (compose != 0) { /* And obtain alpha pre-multiplication by composing on black: */ memset(&png_ptr->background, 0, (sizeof png_ptr->background)); png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */ png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE; png_ptr->flags &= ~PNG_FLAG_BACKGROUND_EXPAND; if ((png_ptr->transformations & PNG_COMPOSE) != 0) png_error(png_ptr, "conflicting calls to set alpha mode and background"); png_ptr->transformations |= PNG_COMPOSE; } } # ifdef PNG_FLOATING_POINT_SUPPORTED void PNGAPI png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma) { png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr, output_gamma)); } # endif #endif #ifdef PNG_READ_QUANTIZE_SUPPORTED /* Dither file to 8-bit. Supply a palette, the current number * of elements in the palette, the maximum number of elements * allowed, and a histogram if possible. If the current number * of colors is greater then the maximum number, the palette will be * modified to fit in the maximum number. "full_quantize" indicates * whether we need a quantizing cube set up for RGB images, or if we * simply are reducing the number of colors in a paletted image. */ typedef struct png_dsort_struct { struct png_dsort_struct * next; png_byte left; png_byte right; } png_dsort; typedef png_dsort * png_dsortp; typedef png_dsort * * png_dsortpp; void PNGAPI png_set_quantize(png_structrp png_ptr, png_colorp palette, int num_palette, int maximum_colors, png_const_uint_16p histogram, int full_quantize) { png_debug(1, "in png_set_quantize"); if (png_rtran_ok(png_ptr, 0) == 0) return; png_ptr->transformations |= PNG_QUANTIZE; if (full_quantize == 0) { int i; png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_palette * (sizeof (png_byte)))); for (i = 0; i < num_palette; i++) png_ptr->quantize_index[i] = png_check_byte(png_ptr, i); } if (num_palette > maximum_colors) { if (histogram != NULL) { /* This is easy enough, just throw out the least used colors. * Perhaps not the best solution, but good enough. */ int i; /* Initialize an array to sort colors */ png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_palette * (sizeof (png_byte)))); /* Initialize the quantize_sort array */ for (i = 0; i < num_palette; i++) png_ptr->quantize_sort[i] = png_check_byte(png_ptr, i); /* Find the least used palette entries by starting a * bubble sort, and running it until we have sorted * out enough colors. Note that we don't care about * sorting all the colors, just finding which are * least used. */ for (i = num_palette - 1; i >= maximum_colors; i--) { int done; /* To stop early if the list is pre-sorted */ int j; done = 1; for (j = 0; j < i; j++) { if (histogram[png_ptr->quantize_sort[j]] < histogram[png_ptr->quantize_sort[j + 1]]) { png_byte t; t = png_ptr->quantize_sort[j]; png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1]; png_ptr->quantize_sort[j + 1] = t; done = 0; } } if (done != 0) break; } /* Swap the palette around, and set up a table, if necessary */ if (full_quantize != 0) { int j = num_palette; /* Put all the useful colors within the max, but don't * move the others. */ for (i = 0; i < maximum_colors; i++) { if ((int)png_ptr->quantize_sort[i] >= maximum_colors) { do j--; while ((int)png_ptr->quantize_sort[j] >= maximum_colors); palette[i] = palette[j]; } } } else { int j = num_palette; /* Move all the used colors inside the max limit, and * develop a translation table. */ for (i = 0; i < maximum_colors; i++) { /* Only move the colors we need to */ if ((int)png_ptr->quantize_sort[i] >= maximum_colors) { png_color tmp_color; do j--; while ((int)png_ptr->quantize_sort[j] >= maximum_colors); tmp_color = palette[j]; palette[j] = palette[i]; palette[i] = tmp_color; /* Indicate where the color went */ png_ptr->quantize_index[j] = png_check_byte(png_ptr, i); png_ptr->quantize_index[i] = png_check_byte(png_ptr, j); } } /* Find closest color for those colors we are not using */ for (i = 0; i < num_palette; i++) { if ((int)png_ptr->quantize_index[i] >= maximum_colors) { int min_d, k, min_k, d_index; /* Find the closest color to one we threw out */ d_index = png_ptr->quantize_index[i]; min_d = PNG_COLOR_DIST(palette[d_index], palette[0]); for (k = 1, min_k = 0; k < maximum_colors; k++) { int d; d = PNG_COLOR_DIST(palette[d_index], palette[k]); if (d < min_d) { min_d = d; min_k = k; } } /* Point to closest color */ png_ptr->quantize_index[i] = png_check_byte(png_ptr, min_k); } } } png_free(png_ptr, png_ptr->quantize_sort); png_ptr->quantize_sort = NULL; } else { /* This is much harder to do simply (and quickly). Perhaps * we need to go through a median cut routine, but those * don't always behave themselves with only a few colors * as input. So we will just find the closest two colors, * and throw out one of them (chosen somewhat randomly). * [We don't understand this at all, so if someone wants to * work on improving it, be our guest - AED, GRP] */ int i; int max_d; int num_new_palette; png_dsortp t; png_dsortpp hash; t = NULL; /* Initialize palette index arrays */ png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_palette * (sizeof (png_byte)))); png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_palette * (sizeof (png_byte)))); /* Initialize the sort array */ for (i = 0; i < num_palette; i++) { png_ptr->index_to_palette[i] = png_check_byte(png_ptr, i); png_ptr->palette_to_index[i] = png_check_byte(png_ptr, i); } hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 * (sizeof (png_dsortp)))); num_new_palette = num_palette; /* Initial wild guess at how far apart the farthest pixel * pair we will be eliminating will be. Larger * numbers mean more areas will be allocated, Smaller * numbers run the risk of not saving enough data, and * having to do this all over again. * * I have not done extensive checking on this number. */ max_d = 96; while (num_new_palette > maximum_colors) { for (i = 0; i < num_new_palette - 1; i++) { int j; for (j = i + 1; j < num_new_palette; j++) { int d; d = PNG_COLOR_DIST(palette[i], palette[j]); if (d <= max_d) { t = (png_dsortp)png_malloc_warn(png_ptr, (png_uint_32)(sizeof (png_dsort))); if (t == NULL) break; t->next = hash[d]; t->left = png_check_byte(png_ptr, i); t->right = png_check_byte(png_ptr, j); hash[d] = t; } } if (t == NULL) break; } if (t != NULL) for (i = 0; i <= max_d; i++) { if (hash[i] != NULL) { png_dsortp p; for (p = hash[i]; p; p = p->next) { if ((int)png_ptr->index_to_palette[p->left] < num_new_palette && (int)png_ptr->index_to_palette[p->right] < num_new_palette) { int j, next_j; if (num_new_palette & 0x01) { j = p->left; next_j = p->right; } else { j = p->right; next_j = p->left; } num_new_palette--; palette[png_ptr->index_to_palette[j]] = palette[num_new_palette]; if (full_quantize == 0) { int k; for (k = 0; k < num_palette; k++) { if (png_ptr->quantize_index[k] == png_ptr->index_to_palette[j]) png_ptr->quantize_index[k] = png_ptr->index_to_palette[next_j]; if ((int)png_ptr->quantize_index[k] == num_new_palette) png_ptr->quantize_index[k] = png_ptr->index_to_palette[j]; } } png_ptr->index_to_palette[png_ptr->palette_to_index [num_new_palette]] = png_ptr->index_to_palette[j]; png_ptr->palette_to_index[png_ptr->index_to_palette[j]] = png_ptr->palette_to_index[num_new_palette]; png_ptr->index_to_palette[j] = png_check_byte(png_ptr, num_new_palette); png_ptr->palette_to_index[num_new_palette] = png_check_byte(png_ptr, j); } if (num_new_palette <= maximum_colors) break; } if (num_new_palette <= maximum_colors) break; } } for (i = 0; i < 769; i++) { if (hash[i] != NULL) { png_dsortp p = hash[i]; while (p) { t = p->next; png_free(png_ptr, p); p = t; } } hash[i] = 0; } max_d += 96; } png_free(png_ptr, hash); png_free(png_ptr, png_ptr->palette_to_index); png_free(png_ptr, png_ptr->index_to_palette); png_ptr->palette_to_index = NULL; png_ptr->index_to_palette = NULL; } num_palette = maximum_colors; } if (png_ptr->palette == NULL) { png_ptr->palette = palette; } png_ptr->num_palette = png_check_u16(png_ptr, num_palette); if (full_quantize != 0) { int i; png_bytep distance; int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS; int num_red = (1 << PNG_QUANTIZE_RED_BITS); int num_green = (1 << PNG_QUANTIZE_GREEN_BITS); int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS); png_size_t num_entries = ((png_size_t)1 << total_bits); png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr, (png_uint_32)(num_entries * (sizeof (png_byte)))); distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries * (sizeof (png_byte)))); memset(distance, 0xff, num_entries * (sizeof (png_byte))); for (i = 0; i < num_palette; i++) { int ir, ig, ib; int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS)); int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS)); int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS)); for (ir = 0; ir < num_red; ir++) { /* int dr = abs(ir - r); */ int dr = ((ir > r) ? ir - r : r - ir); int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS + PNG_QUANTIZE_GREEN_BITS)); for (ig = 0; ig < num_green; ig++) { /* int dg = abs(ig - g); */ int dg = ((ig > g) ? ig - g : g - ig); int dt = dr + dg; int dm = ((dr > dg) ? dr : dg); int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS); for (ib = 0; ib < num_blue; ib++) { int d_index = index_g | ib; /* int db = abs(ib - b); */ int db = ((ib > b) ? ib - b : b - ib); int dmax = ((dm > db) ? dm : db); int d = dmax + dt + db; if (d < (int)distance[d_index]) { distance[d_index] = png_check_byte(png_ptr, d); png_ptr->palette_lookup[d_index] = png_check_byte(png_ptr, i); } } } } } png_free(png_ptr, distance); } } #endif /* READ_QUANTIZE */ #ifdef PNG_READ_GAMMA_SUPPORTED void PNGFAPI png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma, png_fixed_point file_gamma) { png_debug(1, "in png_set_gamma_fixed"); if (png_rtran_ok(png_ptr, 0) == 0) return; /* New in libpng-1.5.4 - reserve particular negative values as flags. */ scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/); file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/); /* Checking the gamma values for being >0 was added in 1.5.4 along with the * premultiplied alpha support; this actually hides an undocumented feature * of the previous implementation which allowed gamma processing to be * disabled in background handling. There is no evidence (so far) that this * was being used; however, png_set_background itself accepted and must still * accept '0' for the gamma value it takes, because it isn't always used. * * Since this is an API change (albeit a very minor one that removes an * undocumented API feature) the following checks were only enabled in * libpng-1.6.0. */ if (file_gamma <= 0) png_error(png_ptr, "invalid file gamma in png_set_gamma"); if (scrn_gamma <= 0) png_error(png_ptr, "invalid screen gamma in png_set_gamma"); /* Set the gamma values unconditionally - this overrides the value in the PNG * file if a gAMA chunk was present. png_set_alpha_mode provides a * different, easier, way to default the file gamma. */ png_ptr->colorspace.gamma = file_gamma; png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; png_ptr->screen_gamma = scrn_gamma; } # ifdef PNG_FLOATING_POINT_SUPPORTED void PNGAPI png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma) { png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma), convert_gamma_value(png_ptr, file_gamma)); } # endif /* FLOATING_POINT */ #endif /* READ_GAMMA */ #ifdef PNG_READ_EXPAND_SUPPORTED /* Expand paletted images to RGB, expand grayscale images of * less than 8-bit depth to 8-bit depth, and expand tRNS chunks * to alpha channels. */ void PNGAPI png_set_expand(png_structrp png_ptr) { png_debug(1, "in png_set_expand"); if (png_rtran_ok(png_ptr, 0) == 0) return; png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); } /* GRR 19990627: the following three functions currently are identical * to png_set_expand(). However, it is entirely reasonable that someone * might wish to expand an indexed image to RGB but *not* expand a single, * fully transparent palette entry to a full alpha channel--perhaps instead * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace * the transparent color with a particular RGB value, or drop tRNS entirely. * IOW, a future version of the library may make the transformations flag * a bit more fine-grained, with separate bits for each of these three * functions. * * More to the point, these functions make it obvious what libpng will be * doing, whereas "expand" can (and does) mean any number of things. * * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified * to expand only the sample depth but not to expand the tRNS to alpha * and its name was changed to png_set_expand_gray_1_2_4_to_8(). */ /* Expand paletted images to RGB. */ void PNGAPI png_set_palette_to_rgb(png_structrp png_ptr) { png_debug(1, "in png_set_palette_to_rgb"); if (png_rtran_ok(png_ptr, 0) == 0) return; png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); } /* Expand grayscale images of less than 8-bit depth to 8 bits. */ void PNGAPI png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr) { png_debug(1, "in png_set_expand_gray_1_2_4_to_8"); if (png_rtran_ok(png_ptr, 0) == 0) return; png_ptr->transformations |= PNG_EXPAND; } /* Expand tRNS chunks to alpha channels. */ void PNGAPI png_set_tRNS_to_alpha(png_structrp png_ptr) { png_debug(1, "in png_set_tRNS_to_alpha"); if (png_rtran_ok(png_ptr, 0) == 0) return; png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); } #endif /* READ_EXPAND */ #ifdef PNG_READ_EXPAND_16_SUPPORTED /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise * it may not work correctly.) */ void PNGAPI png_set_expand_16(png_structrp png_ptr) { png_debug(1, "in png_set_expand_16"); if (png_rtran_ok(png_ptr, 0) == 0) return; png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS); } #endif #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED void PNGAPI png_set_gray_to_rgb(png_structrp png_ptr) { png_debug(1, "in png_set_gray_to_rgb"); if (png_rtran_ok(png_ptr, 0) == 0) return; /* Because rgb must be 8 bits or more: */ png_set_expand_gray_1_2_4_to_8(png_ptr); png_ptr->transformations |= PNG_GRAY_TO_RGB; } #endif #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED void PNGFAPI png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action, png_fixed_point red, png_fixed_point green) { png_debug(1, "in png_set_rgb_to_gray"); /* Need the IHDR here because of the check on color_type below. */ /* TODO: fix this */ if (png_rtran_ok(png_ptr, 1) == 0) return; switch (error_action) { case PNG_ERROR_ACTION_NONE: png_ptr->transformations |= PNG_RGB_TO_GRAY; break; case PNG_ERROR_ACTION_WARN: png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN; break; case PNG_ERROR_ACTION_ERROR: png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR; break; default: png_error(png_ptr, "invalid error action to rgb_to_gray"); break; } if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) #ifdef PNG_READ_EXPAND_SUPPORTED png_ptr->transformations |= PNG_EXPAND; #else { /* Make this an error in 1.6 because otherwise the application may assume * that it just worked and get a memory overwrite. */ png_error(png_ptr, "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED"); /* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */ } #endif { if (red >= 0 && green >= 0 && red + green <= PNG_FP_1) { png_uint_16 red_int, green_int; /* NOTE: this calculation does not round, but this behavior is retained * for consistency; the inaccuracy is very small. The code here always * overwrites the coefficients, regardless of whether they have been * defaulted or set already. */ red_int = png_check_u16(png_ptr, ((png_uint_32)/*SAFE*/red*32768)/100000); green_int = png_check_u16(png_ptr, ((png_uint_32)/*SAFE*/green*32768)/100000); png_ptr->rgb_to_gray_red_coeff = red_int; png_ptr->rgb_to_gray_green_coeff = green_int; # if defined(PNG_COLORS_SPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED) png_ptr->colorspace.flags |= PNG_COLORSPACE_RGB_TO_GRAY_SET; # endif } else { if (red >= 0 && green >= 0) png_app_warning(png_ptr, "ignoring out of range rgb_to_gray coefficients"); /* Use the defaults, from the cHRM chunk if set, else the historical * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See * png_do_rgb_to_gray for more discussion of the values. In this case * the coefficients are not marked as 'set' and are not overwritten if * something has already provided a default. */ if (png_ptr->rgb_to_gray_red_coeff == 0 && png_ptr->rgb_to_gray_green_coeff == 0) { png_ptr->rgb_to_gray_red_coeff = 6968; png_ptr->rgb_to_gray_green_coeff = 23434; /* png_ptr->rgb_to_gray_blue_coeff = 2366; */ } } } } #ifdef PNG_FLOATING_POINT_SUPPORTED /* Convert a RGB image to a grayscale of the same width. This allows us, * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image. */ void PNGAPI png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red, double green) { png_set_rgb_to_gray_fixed(png_ptr, error_action, png_fixed(png_ptr, red, "rgb to gray red coefficient"), png_fixed(png_ptr, green, "rgb to gray green coefficient")); } #endif /* FLOATING POINT */ #endif /* RGB_TO_GRAY */ #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \ defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) void PNGAPI png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr read_user_transform_fn) { png_debug(1, "in png_set_read_user_transform_fn"); #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED png_ptr->transformations |= PNG_USER_TRANSFORM; png_ptr->read_user_transform_fn = read_user_transform_fn; #endif } #endif #ifdef PNG_READ_TRANSFORMS_SUPPORTED #ifdef PNG_READ_GAMMA_SUPPORTED /* In the case of gamma transformations only do transformations on images where * the [file] gamma and screen_gamma are not close reciprocals, otherwise it * slows things down slightly, and also needlessly introduces small errors. */ static int /* PRIVATE */ png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma) { /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma * correction as a difference of the overall transform from 1.0 * * We want to compare the threshold with s*f - 1, if we get * overflow here it is because of wacky gamma values so we * turn on processing anyway. */ png_fixed_point gtest; return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) || png_gamma_significant(gtest); } #endif /* Initialize everything needed for the read. This includes modifying * the palette. */ #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ defined(PNG_READ_ALPHA_MODE_SUPPORTED) static void gamma_correct_background(png_const_structrp png_ptr, unsigned int value, unsigned int depth, png_uint_16p backgroundp, png_uint_16p background_1p, png_fixed_point gamma_correct, png_fixed_point gamma_to_1) { switch (depth) { case 8: if (gamma_correct != PNG_FP_1) *backgroundp = png_gamma_8bit_correct(png_ptr, value, gamma_correct); else *backgroundp = png_check_u16(png_ptr, value); if (gamma_to_1 != PNG_FP_1) *background_1p = png_gamma_16bit_correct(png_ptr, value*257, gamma_to_1); else *background_1p = png_check_u16(png_ptr, value*257); return; case 16: if (gamma_correct != PNG_FP_1) *backgroundp = png_gamma_16bit_correct(png_ptr, value, gamma_correct); else *backgroundp = png_check_u16(png_ptr, value); if (gamma_to_1 != PNG_FP_1) *background_1p = png_gamma_16bit_correct(png_ptr, value, gamma_to_1); else *background_1p = png_check_u16(png_ptr, value); return; default: /* Low bit depth gray levels; do no harm. */ break; } *backgroundp = png_check_u16(png_ptr, value); *background_1p = 0; /* should not be used */ } static void /* PRIVATE */ png_init_background_transformations(png_structrp png_ptr) /* Set the png_ptr->background and png_ptr->background_1 members correctly * for the bit depth and format. */ { /* png_ptr->background is only assigned by png_set_background and * png_set_alpha_mode (which just zeros out the fields.) png_set_background * can set the PNG_FLAG_BACKGROUND_EXPAND flag if the input value is in the * file format, for example if it comes from a bKGD chunk. * * Under some circumstances deficiencies in the current libpng code mean that * the bit depth of the values must differ from the final bit depth; the bit * depth has to match that at which the processing of the image pixels * happens and this is not always the final bit depth. This is fixed up * here. * * First find the required depth. */ unsigned int bit_depth, required_bit_depth; unsigned int color_type = png_ptr->color_type; const png_uint_32 transform = png_ptr->transformations; const int need_expand = (png_ptr->flags & PNG_FLAG_BACKGROUND_EXPAND) != 0; if (color_type & PNG_COLOR_MASK_PALETTE) required_bit_depth = bit_depth = 8; else { required_bit_depth = bit_depth = png_ptr->bit_depth; /* But not PNG_EXPAND_16 at present because it happens after the compose * operation where the background is used! */ if (bit_depth < 8 && (transform & PNG_EXPAND) != 0) required_bit_depth = 8; } /* bit_depth and color_type now refer to the original file data and * required_bit_depth is correct for the processing libpng does, however it * does not necessarily match the output the application gets, fix that and * the color type here: */ if (need_expand == 0) { /* The background bit_depth and color_type need correcting */ if ((transform & PNG_EXPAND) != 0) color_type &= ~PNG_COLOR_MASK_PALETTE; /* The RGB<->gray transformations do the to gray operation first, then the * from gray. */ if ((transform & PNG_RGB_TO_GRAY) != 0) color_type &= ~PNG_COLOR_MASK_COLOR; if ((transform & PNG_GRAY_TO_RGB) != 0) color_type |= PNG_COLOR_MASK_COLOR; bit_depth = required_bit_depth; /* The expansion to 16 bits and the scaling back from 16 bits per * component to only 8 happens after the background processing (at * present) so these transforms only affect the screen value, not the * required value. Note that the 16_TO_8 conversions happen before the 8 * to 16 one, so in theory both could occur - the order of the tests below * must be correct! * * TODO: Note that the second of these changes cause an input 16-bit * background value to be temporarily crushed to 8-bits per component, * losing precision. This is a bug and should be fixed. */ if (bit_depth == 16 && (transform & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) != 0) bit_depth = 8; if (bit_depth == 8 && (color_type & PNG_COLOR_MASK_PALETTE) == 0 && (transform & PNG_EXPAND_16) != 0) bit_depth = 16; } /* Double check the input value: when 'need_expand' is false the app is * providing a background value for us an it should have 'bit_depth' data in * it. Unfortunately this may not be the case; we can't check in * png_set_background because we don't know what transforms the app will end * up asking for, so we have to check here. Prior to 1.7.0 no check was * performed and the result could potentially be garbage. */ if (bit_depth < 16) /* Else range changes always succeed */ { if (color_type == PNG_COLOR_TYPE_PALETTE) { /* If the PNG is indexed and the need_expand flag was true the * background color is a palette index and this index must be in range. * If, however, need_expand is false the background is an RGB value and * it must be in the 8 bit range. This duplicates the tests below, * but this code will probably all disappear in the very near future; * it is just way to error prone. */ if (need_expand) { if (png_ptr->background.index >= png_ptr->num_palette || png_ptr->palette != NULL) png_app_error(png_ptr, "background has invalid palette index"); } else if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) { if (png_ptr->background.gray > 255) png_app_error(png_ptr, "palette background gray value out of range"); } else if (png_ptr->background.red > 255 || png_ptr->background.green > 255 || png_ptr->background.blue > 255) png_app_error(png_ptr, "palette background RGB value out of range"); } else { const unsigned int mask = ~((1U << bit_depth) - 1); if ((color_type & PNG_COLOR_MASK_COLOR) != 0) { if ((png_ptr->background.red & mask) != 0 || (png_ptr->background.green & mask) != 0 || (png_ptr->background.blue & mask) != 0) png_app_error(png_ptr, "background RGB value out of range"); } else if ((png_ptr->background.gray & mask) != 0) png_app_error(png_ptr, "background gray value out of range"); } } /* Now make the background have the correct format. This involves reading the * correct fields from png_ptr->background, adjusting the bit depth of the * result and potentially gamma correcting the value then calculating the * png_ptr->background_1 values too. */ { unsigned int mult = 1; png_fixed_point gamma_to_1, gamma_correct; switch (png_ptr->background_gamma_type) { case PNG_BACKGROUND_GAMMA_SCREEN: gamma_to_1 = png_ptr->screen_gamma; gamma_correct = PNG_FP_1; break; case PNG_BACKGROUND_GAMMA_FILE: gamma_to_1 = png_reciprocal(png_ptr->colorspace.gamma); gamma_correct = png_reciprocal2(png_ptr->colorspace.gamma, png_ptr->screen_gamma); break; case PNG_BACKGROUND_GAMMA_UNIQUE: gamma_to_1 = png_reciprocal(png_ptr->background_gamma); gamma_correct = png_reciprocal2(png_ptr->background_gamma, png_ptr->screen_gamma); break; default: gamma_to_1 = PNG_FP_1; gamma_correct = PNG_FP_1; break; } # define CORRECT(v, c)\ gamma_correct_background(png_ptr, (v)*mult, bit_depth,\ &png_ptr->background.c, &png_ptr->background_1.c,\ gamma_correct, gamma_to_1);\ if (bit_depth > required_bit_depth)\ png_ptr->background.c =\ png_check_u16(png_ptr, PNG_DIV257(png_ptr->background.c)) /* The multiplier 'mult' scales the values to 'required_depth', * 'bit_depth' is the depth of the resultant values. */ while (bit_depth < required_bit_depth) mult += mult << bit_depth, bit_depth <<= 1; /* In the event that this still leaves the background bit depth greater * than the libpng required depth scale the values back to the 8-bit * range, the test below verifies that this is correct. */ affirm(bit_depth <= required_bit_depth || (bit_depth == 16 && required_bit_depth == 8)); if ((color_type & PNG_COLOR_MASK_COLOR) != 0) { png_ptr->flags &= ~PNG_FLAG_BACKGROUND_IS_GRAY; /* checked below */ /* If need_expand was passed to png_set_background the background value * was in the file format, therefore if the file is a palette file the * background will have been an index into the palette. Notice that if * need_expand was false then the color is RGB even if the output still * has a palette. */ if (need_expand && (color_type & PNG_COLOR_MASK_PALETTE) != 0) { unsigned int background_index = png_ptr->background.index; if (background_index < png_ptr->num_palette && png_ptr->palette != NULL) { /* In fact 'mult' is always 1 at present in this case */ CORRECT(png_ptr->palette[background_index].red, red); CORRECT(png_ptr->palette[background_index].green, green); CORRECT(png_ptr->palette[background_index].blue, blue); } else { png_app_error(png_ptr, "out of range background index"); memset(&png_ptr->background, 0, sizeof png_ptr->background); memset(&png_ptr->background_1, 0, sizeof png_ptr->background_1); } } else { CORRECT(png_ptr->background.red, red); CORRECT(png_ptr->background.green, green); CORRECT(png_ptr->background.blue, blue); } if (png_ptr->background.red == png_ptr->background.blue && png_ptr->background.red == png_ptr->background.green) { png_ptr->flags |= PNG_FLAG_BACKGROUND_IS_GRAY; png_ptr->background.gray = png_ptr->background.red; png_ptr->background_1.gray = png_ptr->background_1.red; } else png_ptr->background.gray = png_ptr->background_1.gray = 0; } else { png_ptr->flags |= PNG_FLAG_BACKGROUND_IS_GRAY; CORRECT(png_ptr->background.gray, gray); png_ptr->background.red = png_ptr->background.green = png_ptr->background.blue = png_ptr->background.gray; png_ptr->background_1.red = png_ptr->background_1.green = png_ptr->background_1.blue = png_ptr->background_1.gray; } # undef CORRECT } } #endif /* READ_BACKGROUND || READ_ALPHA_MODE */ static void /* PRIVATE */ png_init_palette_transformations(png_structrp png_ptr) { int input_has_alpha = 0; int input_has_transparency = 0; if (png_ptr->num_trans > 0) { int i; /* Ignore if all the entries are opaque (unlikely!) */ for (i=0; inum_trans; ++i) { if (png_ptr->trans_alpha[i] == 255) continue; else if (png_ptr->trans_alpha[i] == 0) input_has_transparency = 1; else { input_has_transparency = 1; input_has_alpha = 1; break; } } } /* If no alpha we can optimize. */ if (input_has_alpha == 0) { /* Any alpha means background and associative alpha processing is * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA * and ENCODE_ALPHA are irrelevant. */ png_ptr->transformations &= ~PNG_ENCODE_ALPHA; png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; if (input_has_transparency == 0) png_ptr->transformations &= ~PNG_COMPOSE; } } static void /* PRIVATE */ png_init_rgb_transformations(png_structrp png_ptr) { /* Added to libpng-1.5.4: check the color type to determine whether there * is any alpha or transparency in the image and simply cancel the * background and alpha mode stuff if there isn't. */ int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0; int input_has_transparency = png_ptr->num_trans > 0; /* If no alpha we can optimize. */ if (input_has_alpha == 0) { /* Any alpha means background and associative alpha processing is * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA * and ENCODE_ALPHA are irrelevant. */ # ifdef PNG_READ_ALPHA_MODE_SUPPORTED png_ptr->transformations &= ~PNG_ENCODE_ALPHA; png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; # endif if (input_has_transparency == 0) png_ptr->transformations &= ~PNG_COMPOSE; } } void /* PRIVATE */ png_init_read_transformations(png_structrp png_ptr) { png_debug(1, "in png_init_read_transformations"); /* This internal function is called from png_read_start_row in pngrutil.c * and it is called before the 'rowbytes' calculation is done, so the code * in here can change or update the transformations flags. * * First do updates that do not depend on the details of the PNG image data * being processed. */ #ifdef PNG_READ_GAMMA_SUPPORTED /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds * png_set_alpha_mode and this is another source for a default file gamma so * the test needs to be performed later - here. In addition prior to 1.5.4 * the tests were repeated for the PALETTE color type here - this is no * longer necessary (and doesn't seem to have been necessary before.) */ { /* The following temporary indicates if overall gamma correction is * required. */ int gamma_correction = 0; if (png_ptr->colorspace.gamma != 0) /* has been set */ { if (png_ptr->screen_gamma != 0) /* screen set too */ gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma, png_ptr->screen_gamma); else /* Assume the output matches the input; a long time default behavior * of libpng, although the standard has nothing to say about this. */ png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma); } else if (png_ptr->screen_gamma != 0) /* The converse - assume the file matches the screen, note that this * perhaps undesireable default can (from 1.5.4) be changed by calling * png_set_alpha_mode (even if the alpha handling mode isn't required * or isn't changed from the default.) */ png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma); else /* neither are set */ /* Just in case the following prevents any processing - file and screen * are both assumed to be linear and there is no way to introduce a * third gamma value other than png_set_background with 'UNIQUE', and, * prior to 1.5.4 */ png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1; /* We have a gamma value now. */ png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; /* Now turn the gamma transformation on or off as appropriate. Notice * that PNG_GAMMA just refers to the file->screen correction. Alpha * composition may independently cause gamma correction because it needs * linear data (e.g. if the file has a gAMA chunk but the screen gamma * hasn't been specified.) In any case this flag may get turned off in * the code immediately below if the transform can be handled outside the * row loop. */ if (gamma_correction != 0) png_ptr->transformations |= PNG_GAMMA; else png_ptr->transformations &= ~PNG_GAMMA; } #endif /* Certain transformations have the effect of preventing other * transformations that happen afterward in png_do_read_transformations; * resolve the interdependencies here. From the code of * png_do_read_transformations the order is: * * 1) PNG_EXPAND (including PNG_EXPAND_tRNS) * 2) PNG_STRIP_ALPHA (if no compose) * 3) PNG_RGB_TO_GRAY * 4) PNG_GRAY_TO_RGB iff !PNG_FLAG_BACKGROUND_IS_GRAY * 5) PNG_COMPOSE * 6) PNG_GAMMA * 7) PNG_STRIP_ALPHA (if compose) * 8) PNG_ENCODE_ALPHA * 9) PNG_SCALE_16_TO_8 * 10) PNG_16_TO_8 * 11) PNG_QUANTIZE (converts to palette) * 12) PNG_EXPAND_16 * 13) PNG_GRAY_TO_RGB iff PNG_FLAG_BACKGROUND_IS_GRAY * 14) PNG_INVERT_MONO * 15) PNG_INVERT_ALPHA * 16) PNG_SHIFT * 17) PNG_PACK * 18) PNG_BGR * 19) PNG_PACKSWAP * 20) PNG_FILLER (includes PNG_ADD_ALPHA) * 21) PNG_SWAP_ALPHA * 22) PNG_SWAP_BYTES * 23) PNG_USER_TRANSFORM [must be last] */ #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0) { if ((png_ptr->transformations & PNG_FILLER) == 0) png_ptr->transformations &= ~(PNG_INVERT_ALPHA|PNG_SWAP_ALPHA); if ((png_ptr->transformations & PNG_COMPOSE) == 0) { /* Stripping the alpha channel happens immediately after the 'expand' * transformations, before all other transformations, so it cancels out * the alpha handling. It has the side effect negating the effect of * PNG_EXPAND_tRNS too: */ png_ptr->transformations &= ~(PNG_ENCODE_ALPHA | PNG_EXPAND_tRNS); png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen * so transparency information would remain just so long as it wasn't * expanded. This produces unexpected API changes if the set of things * that do PNG_EXPAND_tRNS changes (perfectly possible given the * documentation - which says ask for what you want, accept what you * get.) This makes the behavior consistent from 1.5.4: */ png_ptr->num_trans = 0; } } #endif /* STRIP_ALPHA supported, no COMPOSE */ #ifdef PNG_READ_ALPHA_MODE_SUPPORTED /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA * settings will have no effect. */ if (png_gamma_significant(png_ptr->screen_gamma) == 0) { png_ptr->transformations &= ~PNG_ENCODE_ALPHA; png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; } #endif #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED /* Make sure the coefficients for the rgb to gray conversion are set * appropriately. */ if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) png_colorspace_set_rgb_coefficients(png_ptr); #endif if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) png_init_palette_transformations(png_ptr); else png_init_rgb_transformations(png_ptr); #ifdef PNG_READ_BACKGROUND_SUPPORTED /* Set up the background information if required. It is only used if * PNG_COMPOSE is specified. */ if ((png_ptr->transformations & PNG_COMPOSE) != 0) png_init_background_transformations(png_ptr); #endif /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations * can be performed directly on the palette, and some (such as rgb to gray) * can be optimized inside the palette. This is particularly true of the * composite (background and alpha) stuff, which can be pretty much all done * in the palette even if the result is expanded to RGB or gray afterward. * * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and * earlier and the palette stuff is actually handled on the first row. This * leads to the reported bug that the palette returned by png_get_PLTE is not * updated. */ #if 0 /* NYI */ png_do_palette_transformations(png_ptr); #endif #ifdef PNG_READ_GAMMA_SUPPORTED /* This needs to change - in the palette image case a whole set of tables are * built when it would be quicker to just calculate the correct value for * each palette entry directly. Also, the test is too tricky - why check * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction * the gamma tables will not be built even if composition is required on a * gamma encoded value. * * In 1.5.4 this is addressed below by an additional check on the individual * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the * tables. */ if ((png_ptr->transformations & PNG_GAMMA) != 0 || ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 && (png_gamma_significant(png_ptr->colorspace.gamma) != 0 || png_gamma_significant(png_ptr->screen_gamma) != 0)) || ((png_ptr->transformations & PNG_COMPOSE) != 0 && (png_gamma_significant(png_ptr->colorspace.gamma) != 0 || png_gamma_significant(png_ptr->screen_gamma) != 0 # ifdef PNG_READ_BACKGROUND_SUPPORTED || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE && png_gamma_significant(png_ptr->background_gamma) != 0) # endif )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 && png_gamma_significant(png_ptr->screen_gamma) != 0) ) { png_build_gamma_tables(png_ptr, png_ptr->bit_depth); #ifdef PNG_READ_BACKGROUND_SUPPORTED if ((png_ptr->transformations & PNG_COMPOSE) != 0) { /* Issue a warning about this combination: because RGB_TO_GRAY is * optimized to do the gamma transform if present yet do_background has * to do the same thing if both options are set a * double-gamma-correction happens. This is true in all versions of * libpng to date. */ if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) png_warning(png_ptr, "libpng does not support gamma+background+rgb_to_gray"); if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0) { unsigned int i, num_palette = png_ptr->num_palette; png_color back; png_color_16 back_1 = png_ptr->background_1; png_colorp palette = png_ptr->palette; back.red = png_check_byte(png_ptr, png_ptr->background.red); back.green = png_check_byte(png_ptr, png_ptr->background.green); back.blue = png_check_byte(png_ptr, png_ptr->background.blue); for (i = 0; i < num_palette; i++) { if (i < png_ptr->num_trans && png_ptr->trans_alpha[i] != 0xff) { if (png_ptr->trans_alpha[i] == 0) { palette[i] = back; } else /* if (png_ptr->trans_alpha[i] != 0xff) */ { png_uint_16 v, w; unsigned int alpha = png_ptr->trans_alpha[i] * 257U; unsigned int shift = png_ptr->gamma_shift; unsigned int add = (shift > 0 ? 1U<<(shift-1) : 0); if (png_ptr->gamma_to_1 != NULL) { v = png_ptr->gamma_to_1[palette[i].red]; png_composite_16(w, v, alpha, back_1.red); palette[i].red = png_ptr->gamma_from_1[(w+add)>>shift]; v = png_ptr->gamma_to_1[palette[i].green]; png_composite_16(w, v, alpha, back_1.green); palette[i].green = png_ptr->gamma_from_1[(w+add)>>shift]; v = png_ptr->gamma_to_1[palette[i].blue]; png_composite_16(w, v, alpha, back_1.blue); palette[i].blue = png_ptr->gamma_from_1[(w+add)>>shift]; } } } else if (png_ptr->gamma_table != NULL) { palette[i].red = png_ptr->gamma_table[palette[i].red]; palette[i].green = png_ptr->gamma_table[palette[i].green]; palette[i].blue = png_ptr->gamma_table[palette[i].blue]; } } /* Prevent the transformations being done again. * * NOTE: this is highly dubious; it removes the transformations in * place. This seems inconsistent with the general treatment of the * transformations elsewhere. */ png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA); } /* color_type == PNG_COLOR_TYPE_PALETTE */ }/* png_ptr->transformations & PNG_BACKGROUND */ else /* Transformation does not include PNG_BACKGROUND */ #endif /* READ_BACKGROUND */ if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED /* RGB_TO_GRAY needs to have non-gamma-corrected values! */ && ((png_ptr->transformations & PNG_EXPAND) == 0 || (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) #endif ) { png_colorp palette = png_ptr->palette; int num_palette = png_ptr->num_palette; int i; /* NOTE: there are other transformations that should probably be in * here too. */ if (png_ptr->gamma_table != NULL) { for (i = 0; i < num_palette; i++) { palette[i].red = png_ptr->gamma_table[palette[i].red]; palette[i].green = png_ptr->gamma_table[palette[i].green]; palette[i].blue = png_ptr->gamma_table[palette[i].blue]; } } /* Done the gamma correction. */ png_ptr->transformations &= ~PNG_GAMMA; } /* color_type == PALETTE && !PNG_BACKGROUND transformation */ } #ifdef PNG_READ_BACKGROUND_SUPPORTED else #endif #endif /* READ_GAMMA */ #ifdef PNG_READ_BACKGROUND_SUPPORTED /* No GAMMA transformation (see the hanging else 4 lines above) */ if ((png_ptr->transformations & PNG_COMPOSE) != 0 && (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)) { int i; int istop = (int)png_ptr->num_trans; png_color back; png_colorp palette = png_ptr->palette; back.red = png_check_byte(png_ptr, png_ptr->background.red); back.green = png_check_byte(png_ptr, png_ptr->background.green); back.blue = png_check_byte(png_ptr, png_ptr->background.blue); for (i = 0; i < istop; i++) { if (png_ptr->trans_alpha[i] == 0) { palette[i] = back; } else if (png_ptr->trans_alpha[i] != 0xff) { /* The png_composite() macro is defined in png.h */ png_composite(palette[i].red, palette[i].red, png_ptr->trans_alpha[i], back.red); png_composite(palette[i].green, palette[i].green, png_ptr->trans_alpha[i], back.green); png_composite(palette[i].blue, palette[i].blue, png_ptr->trans_alpha[i], back.blue); } } png_ptr->transformations &= ~PNG_COMPOSE; } #endif /* READ_BACKGROUND */ #ifdef PNG_READ_SHIFT_SUPPORTED if ((png_ptr->transformations & PNG_SHIFT) != 0 && (png_ptr->transformations & PNG_EXPAND) == 0 && (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)) { int i; int istop = png_ptr->num_palette; int shift = 8 - png_ptr->sig_bit.red; png_ptr->transformations &= ~PNG_SHIFT; /* significant bits can be in the range 1 to 7 for a meaninful result, if * the number of significant bits is 0 then no shift is done (this is an * error condition which is silently ignored.) */ if (shift > 0 && shift < 8) for (i=0; ipalette[i].red; component >>= shift; png_ptr->palette[i].red = png_check_byte(png_ptr, component); } shift = 8 - png_ptr->sig_bit.green; if (shift > 0 && shift < 8) for (i=0; ipalette[i].green; component >>= shift; png_ptr->palette[i].green = png_check_byte(png_ptr, component); } shift = 8 - png_ptr->sig_bit.blue; if (shift > 0 && shift < 8) for (i=0; ipalette[i].blue; component >>= shift; png_ptr->palette[i].blue = png_check_byte(png_ptr, component); } } #endif /* READ_SHIFT */ } /* Modify the info structure to reflect the transformations. The * info should be updated so a PNG file could be written with it, * assuming the transformations result in valid PNG data. */ void /* PRIVATE */ png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr) { png_debug(1, "in png_read_transform_info"); #ifdef PNG_READ_EXPAND_SUPPORTED if ((png_ptr->transformations & PNG_EXPAND) != 0) { if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { /* This check must match what actually happens in * png_do_expand_palette; if it ever checks the tRNS chunk to see if * it is all opaque we must do the same (at present it does not.) */ if (png_ptr->num_trans > 0) info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA; else info_ptr->color_type = PNG_COLOR_TYPE_RGB; info_ptr->bit_depth = 8; info_ptr->num_trans = 0; if (png_ptr->palette == NULL) png_error (png_ptr, "Palette is NULL in indexed image"); } else { if (png_ptr->num_trans != 0) { if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0) info_ptr->color_type |= PNG_COLOR_MASK_ALPHA; } if (info_ptr->bit_depth < 8) info_ptr->bit_depth = 8; info_ptr->num_trans = 0; } } #endif #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ defined(PNG_READ_ALPHA_MODE_SUPPORTED) /* The following is almost certainly wrong unless the background value is in * the screen space! */ if ((png_ptr->transformations & PNG_COMPOSE) != 0) info_ptr->background = png_ptr->background; #endif #ifdef PNG_READ_GAMMA_SUPPORTED /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4), * however it seems that the code in png_init_read_transformations, which has * been called before this from png_read_update_info->png_read_start_row * sometimes does the gamma transform and cancels the flag. * * TODO: this looks wrong; the info_ptr should end up with a gamma equal to * the screen_gamma value. The following probably results in weirdness if * the info_ptr is used by the app after the rows have been read. */ info_ptr->colorspace.gamma = png_ptr->colorspace.gamma; #endif if (info_ptr->bit_depth == 16) { # ifdef PNG_READ_16BIT_SUPPORTED # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0) info_ptr->bit_depth = 8; # endif # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED if ((png_ptr->transformations & PNG_16_TO_8) != 0) info_ptr->bit_depth = 8; # endif # else /* No 16 bit support: force chopping 16-bit input down to 8, in this case * the app program can chose if both APIs are available by setting the * correct scaling to use. */ # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED /* For compatibility with previous versions use the strip method by * default. This code works because if PNG_SCALE_16_TO_8 is already * set the code below will do that in preference to the chop. */ png_ptr->transformations |= PNG_16_TO_8; info_ptr->bit_depth = 8; # else # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED png_ptr->transformations |= PNG_SCALE_16_TO_8; info_ptr->bit_depth = 8; # else CONFIGURATION ERROR: you must enable at least one 16 to 8 method # endif # endif #endif /* !READ_16BIT */ } #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0) info_ptr->color_type = png_check_byte(png_ptr, info_ptr->color_type | PNG_COLOR_MASK_COLOR); #endif #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) info_ptr->color_type = png_check_byte(png_ptr, info_ptr->color_type & ~PNG_COLOR_MASK_COLOR); #endif #ifdef PNG_READ_QUANTIZE_SUPPORTED if ((png_ptr->transformations & PNG_QUANTIZE) != 0) { if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) || (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) && png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8) { info_ptr->color_type = PNG_COLOR_TYPE_PALETTE; } } #endif #ifdef PNG_READ_EXPAND_16_SUPPORTED if ((png_ptr->transformations & PNG_EXPAND_16) != 0 && info_ptr->bit_depth == 8 && info_ptr->color_type != PNG_COLOR_TYPE_PALETTE) { info_ptr->bit_depth = 16; } #endif #ifdef PNG_READ_PACK_SUPPORTED if ((png_ptr->transformations & PNG_PACK) != 0 && (info_ptr->bit_depth < 8)) info_ptr->bit_depth = 8; #endif if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) info_ptr->channels = 1; else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) info_ptr->channels = 3; else info_ptr->channels = 1; #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0) { info_ptr->color_type = png_check_byte(png_ptr, info_ptr->color_type & ~PNG_COLOR_MASK_ALPHA); info_ptr->num_trans = 0; } #endif if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) info_ptr->channels++; #ifdef PNG_READ_FILLER_SUPPORTED /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */ if ((png_ptr->transformations & PNG_FILLER) != 0 && (info_ptr->color_type == PNG_COLOR_TYPE_RGB || info_ptr->color_type == PNG_COLOR_TYPE_GRAY)) { info_ptr->channels++; /* If adding a true alpha channel not just filler */ if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0) info_ptr->color_type |= PNG_COLOR_MASK_ALPHA; } #endif #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \ defined(PNG_READ_USER_TRANSFORM_SUPPORTED) if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0) { if (info_ptr->bit_depth < png_ptr->user_transform_depth) info_ptr->bit_depth = png_ptr->user_transform_depth; if (info_ptr->channels < png_ptr->user_transform_channels) info_ptr->channels = png_ptr->user_transform_channels; } #endif info_ptr->pixel_depth = png_check_byte(png_ptr, info_ptr->channels * info_ptr->bit_depth); info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width); /* Adding in 1.5.4: cache the above value in png_struct so that we can later * check in png_rowbytes that the user buffer won't get overwritten. Note * that the field is not always set - if png_read_update_info isn't called * the application has to either not do any transforms or get the calculation * right itself. */ png_ptr->info_rowbytes = info_ptr->rowbytes; #ifndef PNG_READ_EXPAND_SUPPORTED if (png_ptr != NULL) return; #endif } #if defined (PNG_READ_PACK_SUPPORTED) || defined (PNG_READ_EXPAND_SUPPORTED) /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel, * without changing the actual values. Thus, if you had a row with * a bit depth of 1, you would end up with bytes that only contained * the numbers 0 or 1. If you would rather they contain 0 and 255, use * png_do_shift() after this. */ static void png_do_unpack(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_unpack"); # define png_ptr row_info->png_ptr if (row_info->bit_depth < 8) { switch (row_info->bit_depth) { case 1: { png_const_bytep sp = row + png_transform_rowbytes(row_info) - 1; /* Because we copy from the last pixel down the shift required * at the start is 8-pixels_in_last_byte, which is just: */ unsigned int shift = 0x7 & -row_info->width; png_bytep dp; row_info->flags |= PNG_BITS_SHIFTED; row_info->bit_depth = 8; dp = row + png_transform_rowbytes(row_info); while (dp > row) { *--dp = (*sp >> shift) & 0x01; shift = 0x7 & (shift+1); if (shift == 0) --sp; } debug(dp == row && shift == 0 && sp == row-1); break; } case 2: { png_const_bytep sp = row + png_transform_rowbytes(row_info) - 1; unsigned int shift = 7 & -(row_info->width << 1); png_bytep dp; row_info->flags |= PNG_BITS_SHIFTED; row_info->bit_depth = 8; dp = row + png_transform_rowbytes(row_info); while (dp > row) { *--dp = (*sp >> shift) & 0x03; shift = 0x7 & (shift+2); if (shift == 0) --sp; } debug(dp == row && shift == 0 && sp == row-1); break; } case 4: { png_const_bytep sp = row + png_transform_rowbytes(row_info) - 1; unsigned int shift = 7 & -(row_info->width << 2); png_bytep dp; row_info->flags |= PNG_BITS_SHIFTED; row_info->bit_depth = 8; dp = row + png_transform_rowbytes(row_info); while (dp > row) { *--dp = (*sp >> shift) & 0x0f; shift = 0x7 & (shift+4); if (shift == 0) --sp; } debug(dp == row && shift == 0 && sp == row-1); break; } default: break; } } # undef png_ptr } #endif /* READ_PACK || READ_EXPAND */ #ifdef PNG_READ_SHIFT_SUPPORTED /* Reverse the effects of png_do_shift. This routine merely shifts the * pixels back to their significant bits values. Thus, if you have * a row of bit depth 8, but only 5 are significant, this will shift * the values back to 0 through 31. */ static void png_do_unshift(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_unshift"); /* The palette case has already been handled in the _init routine. */ if (!(row_info->flags & PNG_INDEXED)) { png_const_structrp png_ptr = row_info->png_ptr; unsigned int shift[4]; unsigned int channels = 0; unsigned int bit_depth = row_info->bit_depth; if (row_info->channels > 2) /* at least three channels: color */ { shift[channels++] = bit_depth - png_ptr->shift.red; shift[channels++] = bit_depth - png_ptr->shift.green; shift[channels++] = bit_depth - png_ptr->shift.blue; } else { shift[channels++] = bit_depth - png_ptr->shift.gray; } if (row_info->channels > channels) /* one more channel: alpha */ shift[channels++] = bit_depth - png_ptr->shift.alpha; debug(row_info->channels == channels); { unsigned int c, have_shift; for (c = have_shift = 0; c < channels; ++c) { /* A shift of more than the bit depth is an error condition but it * gets ignored here. */ if (shift[c] <= 0 || shift[c] >= bit_depth) shift[c] = 0; else have_shift = 1; } if (have_shift == 0) return; } switch (bit_depth) { default: /* Must be 1bpp gray: should not be here! */ impossible("unshift bit depth"); /* NOTREACHED */ break; case 2: /* Must be 2bpp gray */ debug(channels == 1 && shift[0] == 1); { png_bytep bp = row; png_bytep bp_end = bp + png_transform_rowbytes(row_info); while (bp < bp_end) *bp = (*bp >> 1) & 0x55, ++bp; row_info->flags |= PNG_BITS_SHIFTED; break; } case 4: /* Must be 4bpp gray */ debug(channels == 1); { png_bytep bp = row; png_bytep bp_end = bp + png_transform_rowbytes(row_info); unsigned int gray_shift = shift[0]; unsigned int mask = 0xf >> gray_shift; /* <= 4 bits */ mask |= mask << 4; /* <= 8 bits */ while (bp < bp_end) *bp = (png_byte)/*SAFE*/((*bp >> gray_shift) & mask), ++bp; row_info->flags |= PNG_BITS_SHIFTED; break; } case 8: /* Single byte components, G, GA, RGB, RGBA */ { png_bytep bp = row; png_bytep bp_end = bp + png_transform_rowbytes(row_info); unsigned int channel = 0; while (bp < bp_end) { *bp = (png_byte)/*SAFE*/(*bp >> shift[channel]), ++bp; if (++channel >= channels) channel = 0; } row_info->flags |= PNG_BITS_SHIFTED; break; } case 16: /* Double byte components, G, GA, RGB, RGBA */ { png_bytep bp = row; png_bytep bp_end = bp + png_transform_rowbytes(row_info); unsigned int channel = 0; while (bp < bp_end) { unsigned int value = bp[0]; value = (value << 8) + bp[1]; /* <= 16 bits */ value >>= shift[channel]; if (++channel >= channels) channel = 0; *bp++ = (png_byte)/*SAFE*/(value >> 8); *bp++ = PNG_BYTE(value); } row_info->flags |= PNG_BITS_SHIFTED; break; } } } } #endif #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED /* Scale rows of bit depth 16 down to 8 accurately */ static void png_do_scale_16_to_8(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_scale_16_to_8"); # define png_ptr row_info->png_ptr if (row_info->bit_depth == 16) { png_const_bytep sp = row; /* source */ png_bytep dp = row; /* destination */ png_bytep ep = dp + png_transform_rowbytes(row_info); /* end+1 */ while (sp < ep) { /* The input is an array of 16 bit components, these must be scaled to * 8 bits each. For a 16 bit value V the required value (from the PNG * specification) is: * * (V * 255) / 65535 * * This reduces to round(V / 257), or floor((V + 128.5)/257) * * Represent V as the two byte value vhi.vlo. Make a guess that the * result is the top byte of V, vhi, then the correction to this value * is: * * error = floor(((V-vhi.vhi) + 128.5) / 257) * = floor(((vlo-vhi) + 128.5) / 257) * * This can be approximated using integer arithmetic (and a signed * shift): * * error = (vlo-vhi+128) >> 8; * * The approximate differs from the exact answer only when (vlo-vhi) is * 128; it then gives a correction of +1 when the exact correction is * 0. This gives 128 errors. The exact answer (correct for all 16 bit * input values) is: * * error = (vlo-vhi+128)*65535 >> 24; * * An alternative arithmetic calculation which also gives no errors is: * * (V * 255 + 32895) >> 16 */ png_int_32 tmp = *sp++; /* must be signed! */ tmp += ((*sp++ - tmp + 128) * 65535) >> 24; *dp++ = png_check_byte(png_ptr, tmp); } row_info->bit_depth = 8; } # undef png_ptr } #endif #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED static void /* Simply discard the low byte. This was the default behavior prior * to libpng-1.5.4. */ png_do_chop(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_chop"); # define png_ptr row_info->png_ptr if (row_info->bit_depth == 16) { png_const_bytep sp = row; /* source */ png_const_bytep ep = sp + png_transform_rowbytes(row_info); /* end+1 */ png_bytep dp = row; /* destination */ while (sp < ep) { *dp++ = *sp; sp += 2; /* skip low byte */ } row_info->bit_depth = 8; } # undef png_ptr } #endif #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED static void png_do_read_swap_alpha(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_read_swap_alpha"); # define png_ptr row_info->png_ptr debug(!(row_info->flags & PNG_ALPHA_SWAPPED)); if (!(row_info->flags & PNG_INDEXED)) { if (row_info->channels == 4) { /* This converts from RGBA to ARGB */ if (row_info->bit_depth == 8) { png_bytep dp = row + png_transform_rowbytes(row_info); while (dp >= row+4/*safe*/) { png_byte alpha = *--dp; *dp = dp[-1], --dp; *dp = dp[-1], --dp; *dp = dp[-1], --dp; *dp = alpha; } debug(dp == row); row_info->flags |= PNG_ALPHA_SWAPPED; } /* This converts from RRGGBBAA to AARRGGBB */ else { png_bytep dp = row + png_transform_rowbytes(row_info); while (dp >= row+8/*safe*/) { png_byte alpha_last = *--dp; png_byte alpha_first = dp[-1]; /* dp points to the second alpha byte */ *dp = dp[-2], --dp; *dp = dp[-2], --dp; *dp = dp[-2], --dp; *dp = dp[-2], --dp; *dp = dp[-2], --dp; *dp = dp[-2], --dp; *dp = alpha_last, --dp; *dp = alpha_first; } debug(dp == row); row_info->flags |= PNG_ALPHA_SWAPPED; } } else if (row_info->channels == 2) { /* This converts from GA to AG */ if (row_info->bit_depth == 8) { png_bytep dp = row + png_transform_rowbytes(row_info); while (dp >= row+1/*safe*/) { png_byte alpha = *--dp; *dp = dp[-1], --dp; *dp = alpha; } debug(dp == row); row_info->flags ^= PNG_ALPHA_SWAPPED; } /* This converts from GGAA to AAGG */ else { png_bytep dp = row + png_transform_rowbytes(row_info); while (dp >= row+4/*safe*/) { png_byte alpha_last = *--dp; png_byte alpha_first = dp[-1]; /* dp points to the second alpha byte */ *dp = dp[-2], --dp; *dp = dp[-2], --dp; *dp = alpha_last, --dp; *dp = alpha_first; } debug(dp == row); row_info->flags ^= PNG_ALPHA_SWAPPED; } } } # undef png_ptr } #endif #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED static void png_do_read_invert_alpha(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_read_invert_alpha"); # define png_ptr row_info->png_ptr debug(!(row_info->flags & PNG_ALPHA_SWAPPED)); if (row_info->channels == 4) { if (row_info->bit_depth == 8) { /* This inverts the fourth channel in RGBA */ png_bytep ep = row + png_transform_rowbytes(row_info); for (row += 3; row < ep; row += 4) *row ^= 0xff; row_info->flags ^= PNG_ALPHA_INVERTED; } #ifdef PNG_READ_16BIT_SUPPORTED /* This inverts the alpha channel in RRGGBBAA */ else { /* Need 2 bytes for each pixel, so subtract 1 from ep here: */ png_bytep ep = row + png_transform_rowbytes(row_info) - 1; for (row += 6; row < ep; row += 8) { row[0] ^= 0xff; row[1] ^= 0xff; } row_info->flags ^= PNG_ALPHA_INVERTED; } #endif } else if (row_info->channels == 2) { if (row_info->bit_depth == 8) { /* This inverts the alpha channel in GA */ png_bytep ep = row + png_transform_rowbytes(row_info); for (row += 1; row < ep; row += 2) *row ^= 0xff; row_info->flags ^= PNG_ALPHA_INVERTED; } #ifdef PNG_READ_16BIT_SUPPORTED else { /* This inverts the alpha channel in GGAA */ /* Need 2 bytes for each pixel, so subtract 1 from ep here: */ png_bytep ep = row + png_transform_rowbytes(row_info) - 1; for (row += 2; row < ep; row += 4) { row[0] ^= 0xff; row[1] ^= 0xff; } row_info->flags ^= PNG_ALPHA_INVERTED; } #endif } # undef png_ptr } #endif #ifdef PNG_READ_FILLER_SUPPORTED /* Add filler channel to 1 and 3 channel non-indexed data */ static void png_do_read_filler(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_read_filler"); /* TODO: remove these checks, this code will work on any number of * channels but, at present, png_set_filler relies on this function * not doing anything in inappropriate cases. */ if (!(row_info->flags & PNG_INDEXED) && (row_info->channels == 1 || row_info->channels == 3) && (row_info->bit_depth == 8 #ifdef PNG_READ_16BIT_SUPPORTED || row_info->bit_depth == 16 #endif )) { png_const_structrp png_ptr = row_info->png_ptr; png_bytep sp = row + png_transform_rowbytes(row_info); /*input*/ png_bytep dp; ++(row_info->channels); dp = row + png_transform_rowbytes(row_info); /*output*/ if (row_info->bit_depth == 8) { const png_byte fb = PNG_BYTE(png_ptr->filler); /* Add a filler before or after the current channels. */ if ((png_ptr->flags & PNG_FLAG_FILLER_AFTER) != 0) { if (row_info->channels == 2) { while (dp >= row+2) { *--dp = fb; *--dp = *--sp; } debug(dp == row && sp == row); } else /* channels == 4 */ { while (dp >= row+4) { *--dp = fb; *--dp = *--sp; *--dp = *--sp; *--dp = *--sp; } debug(dp == row && sp == row); } } else /* filler before */ { if (row_info->channels == 2) { while (dp >= row+2) { *--dp = *--sp; *--dp = fb; } debug(dp == row && sp == row); } else /* channels == 4 */ { while (dp >= row+4) { *--dp = *--sp; *--dp = *--sp; *--dp = *--sp; *--dp = fb; } debug(dp == row && sp == row); } } } # ifdef PNG_READ_16BIT_SUPPORTED else /* bit_depth == 16 */ { /* Two byte pixels values: */ const png_byte fb_first = PNG_BYTE(png_ptr->filler >> 8); const png_byte fb_last = PNG_BYTE(png_ptr->filler); /* Add a filler before or after the current channels. */ if ((png_ptr->flags & PNG_FLAG_FILLER_AFTER) != 0) { if (row_info->channels == 2) { while (dp >= row+4) { /* 2 channel bytes, 2 filler bytes */ *--dp = fb_last; *--dp = fb_first; *--dp = *--sp; *--dp = *--sp; } debug(sp == row && dp == row); } else /* channels == 4 */ { while (dp >= row+8) { /* 6 channel bytes, 2 filler bytes */ *--dp = fb_last; *--dp = fb_first; dp -= 6, sp -= 6; memmove(dp, sp, 6); } debug(sp == row && dp == row); } } else /* filler before */ { if (row_info->channels == 2) { while (dp >= row+4) { /* 2 channel bytes, 2 filler bytes */ *--dp = *--sp; *--dp = *--sp; *--dp = fb_last; *--dp = fb_first; } debug(sp == row && dp == row); } else /* channels == 4 */ { while (dp >= row+8) { /* 6 channel bytes, 2 filler bytes */ dp -= 6, sp -= 6; memmove(dp, sp, 6); *--dp = fb_last; *--dp = fb_first; } debug(sp == row && dp == row); } } if (!(png_ptr->transformations & PNG_ADD_ALPHA)) row_info->flags |= PNG_FILLER_IN_ALPHA; } # endif } } #endif #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED /* Expand grayscale files to RGB, with or without alpha */ static void png_do_gray_to_rgb(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_gray_to_rgb"); # define png_ptr row_info->png_ptr if (!(row_info->flags & PNG_INDEXED) && (row_info->bit_depth == 8 || row_info->bit_depth == 16) && (row_info->channels == 1 || row_info->channels == 2)) { png_bytep sp = row + png_transform_rowbytes(row_info); png_bytep dp; debug(!(row_info->flags & PNG_ALPHA_SWAPPED)); row_info->channels += 2; dp = row + png_transform_rowbytes(row_info); if (row_info->channels == 3) { if (row_info->bit_depth == 8) { /* This changes G to RGB */ while (sp > row) { *--dp = *--sp; *--dp = *sp; *--dp = *sp; } debug(dp == row && sp == row); } else { /* This changes GG to RRGGBB */ while (sp > row) { const png_byte hi = *--sp; const png_byte lo = *--sp; *--dp = hi; *--dp = lo; *--dp = hi; *--dp = lo; /* it's off to work we go */ *--dp = hi; *--dp = lo; } debug(dp == row && sp == row); } } else { debug(row_info->channels == 4); if (row_info->bit_depth == 8) { /* This changes GA to RGBA */ while (sp > row) { *--dp = *--sp; /* A */ *--dp = *--sp; /* G -> B */ *--dp = *sp; /* G -> G */ *--dp = *sp; /* G -> R */ } debug(dp == row && sp == row); } else { /* This changes GGAA to RRGGBBAA */ while (sp > row) { *--dp = *--sp; *--dp = *--sp; /* A */ { const png_byte hi = *--sp; const png_byte lo = *--sp; *--dp = hi; *--dp = lo; *--dp = hi; *--dp = lo; *--dp = hi; *--dp = lo; } } debug(dp == row && sp == row); } } } # undef png_ptr } #endif #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED /* Reduce RGB files to grayscale, with or without alpha * using the equation given in Poynton's ColorFAQ of 1998-01-04 at * (THIS LINK IS DEAD June 2008 but * versions dated 1998 through November 2002 have been archived at * http://web.archive.org/web/20000816232553/http://www.inforamp.net/ * ~poynton/notes/colour_and_gamma/ColorFAQ.txt ) * Charles Poynton poynton at poynton.com * * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B * * which can be expressed with integers as * * Y = (6969 * R + 23434 * G + 2365 * B)/32768 * * Poynton's current link (as of January 2003 through July 2011): * * has changed the numbers slightly: * * Y = 0.2126*R + 0.7152*G + 0.0722*B * * which can be expressed with integers as * * Y = (6966 * R + 23436 * G + 2366 * B)/32768 * * Historically, however, libpng uses numbers derived from the ITU-R Rec 709 * end point chromaticities and the D65 white point. Depending on the * precision used for the D65 white point this produces a variety of different * numbers, however if the four decimal place value used in ITU-R Rec 709 is * used (0.3127,0.3290) the Y calculation would be: * * Y = (6968 * R + 23435 * G + 2366 * B)/32768 * * While this is correct the rounding results in an overflow for white, because * the sum of the rounded coefficients is 32769, not 32768. Consequently * libpng uses, instead, the closest non-overflowing approximation: * * Y = (6968 * R + 23434 * G + 2366 * B)/32768 * * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk * (including an sRGB chunk) then the chromaticities are used to calculate the * coefficients. See the chunk handling in pngrutil.c for more information. * * In all cases the calculation is to be done in a linear colorspace. If no * gamma information is available to correct the encoding of the original RGB * values this results in an implicit assumption that the original PNG RGB * values were linear. * * Other integer coefficents can be used via png_set_rgb_to_gray(). Because * the API takes just red and green coefficients the blue coefficient is * calculated to make the sum 32768. This will result in different rounding * to that used above. */ static int png_do_rgb_to_gray(png_transform_controlp row_info, png_bytep row) { int rgb_error = 0; png_debug(1, "in png_do_rgb_to_gray"); if (!(row_info->flags & PNG_INDEXED) && (row_info->channels == 3 || row_info->channels == 4)) { png_const_structrp png_ptr = row_info->png_ptr; PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff; PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff; PNG_CONST png_uint_32 bc = 32768 - rc - gc; PNG_CONST png_uint_32 row_width = row_info->width; PNG_CONST int have_alpha = row_info->channels == 4; png_bytep sp = row; png_bytep dp = row; /* NOTE: rc+gc+bc == 32768 and is a (png_uint_32) value, so the worst * case calculation below (for white) is: * * 32768*65535+16384 * * Which still fits in 32 (unsigned) bits, and: * * (32768*65535+16384) >> 15 * * is 65535 (always). Consequently the calculation below is marked * SAFE. Likewise for a png_byte value the maximum is 255. */ if (row_info->bit_depth == 8) { /* Notice that gamma to/from 1 are not necessarily inverses (if * there is an overall gamma correction). Prior to 1.5.5 this code * checked the linearized values for equality; this doesn't match * the documentation, the original values must be checked. */ if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL) { PNG_CONST unsigned int shift = 15 + png_ptr->gamma_shift; PNG_CONST png_uint_32 add = 1U << (shift-1); png_uint_32 i; for (i = 0; i < row_width; i++) { png_byte red = *(sp++); png_byte green = *(sp++); png_byte blue = *(sp++); if (red != green || red != blue) { /* gamma_to_1 is (png_uint_16[]) */ unsigned int red_1 = png_ptr->gamma_to_1[red]; unsigned int green_1 = png_ptr->gamma_to_1[green]; unsigned int blue_1 = png_ptr->gamma_to_1[blue]; rgb_error |= 1; *(dp++) = png_ptr->gamma_from_1[ /*SAFE*/(rc*red_1 + gc*green_1 + bc*blue_1 + add)>>shift]; } else { /* If there is no overall correction the table will not be * set. */ if (png_ptr->gamma_table != NULL) red = png_ptr->gamma_table[red]; *(dp++) = red; } if (have_alpha != 0) *(dp++) = *(sp++); } } else { png_uint_32 i; for (i = 0; i < row_width; i++) { png_byte red = *(sp++); png_byte green = *(sp++); png_byte blue = *(sp++); if (red != green || red != blue) { rgb_error |= 1; *(dp++) = (png_byte)/*SAFE*/ ((rc*red+gc*green+bc*blue+16384) >> 15); } else *(dp++) = red; if (have_alpha != 0) *(dp++) = *(sp++); } } } else /* RGB bit_depth == 16 */ { if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL) { unsigned int shift = png_ptr->gamma_shift; unsigned int add = (shift > 0 ? (1U << (shift-1)) : 0); png_uint_32 i; for (i = 0; i < row_width; i++) { unsigned int red, green, blue; png_uint_16 w; red = *sp++ << 8, red |= *sp++; green = *sp++ << 8, green |= *sp++; blue = *sp++ << 8, blue |= *sp++; if (red == green && red == blue) { if (png_ptr->gamma_16_table != NULL) w = png_ptr->gamma_16_table[/*SAFE*/(red+add) >> shift]; else w = (png_uint_16)/*SAFE*/red; } else { red = png_ptr->gamma_16_to_1[/*SAFE*/(red+add) >> shift]; green = png_ptr->gamma_16_to_1[/*SAFE*/(green+add) >> shift]; blue = png_ptr->gamma_16_to_1[/*SAFE*/(blue+add) >> shift]; w = png_ptr->gamma_16_from_1[/*SAFE*/ (((rc*red + gc*green + bc*blue + 16384)>>15)+add)>>shift]; rgb_error |= 1; } *(dp++) = (png_byte)/*SAFE*/(w>>8); *(dp++) = PNG_BYTE(w); if (have_alpha != 0) { *(dp++) = *(sp++); *(dp++) = *(sp++); } } } else { png_uint_32 i; for (i = 0; i < row_width; i++) { unsigned int red, green, blue, w; red = *sp++ << 8, red |= *sp++; green = *sp++ << 8, green |= *sp++; blue = *sp++ << 8, blue |= *sp++; if (red != green || red != blue) rgb_error |= 1; /* From 1.5.5 in the 16 bit case do the accurate conversion even * in the 'fast' case - this is because this is where the code * ends up when handling linear 16 bit data. */ w = (rc*red+gc*green+bc*blue+16384) >> 15; *(dp++) = (png_byte)/*SAFE*/(w>>8); *(dp++) = PNG_BYTE(w); if (have_alpha != 0) { *(dp++) = *(sp++); *(dp++) = *(sp++); } } } } row_info->channels -= 2; } return rgb_error; } #endif #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ defined(PNG_READ_ALPHA_MODE_SUPPORTED) /* Replace any alpha or transparency with the supplied background color. * "background" is already in the screen gamma, while "background_1" is * at a gamma of 1.0. Paletted files have already been taken care of. */ static void png_do_compose(png_transform_controlp row_info, png_bytep row) { png_const_structrp png_ptr = row_info->png_ptr; png_const_bytep gamma_table = png_ptr->gamma_table; png_const_bytep gamma_from_1 = png_ptr->gamma_from_1; png_const_uint_16p gamma_to_1 = png_ptr->gamma_to_1; png_const_uint_16p gamma_16 = png_ptr->gamma_16_table; png_const_uint_16p gamma_16_from_1 = png_ptr->gamma_16_from_1; png_const_uint_16p gamma_16_to_1 = png_ptr->gamma_16_to_1; PNG_CONST unsigned int shift = png_ptr->gamma_shift; PNG_CONST unsigned int add = (shift > 0 ? 1U<<(shift-1) : 0); PNG_CONST int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0; png_bytep sp; png_uint_32 i; png_uint_32 row_width = row_info->width; png_debug(1, "in png_do_compose"); if (!(row_info->flags & PNG_INDEXED)) { switch (row_info->channels) { case 1 /*GRAY*/: { switch (row_info->bit_depth) { case 1: { int bit_shift = 7; sp = row; for (i = 0; i < row_width; i++) { if (((*sp >> bit_shift) & 0x01) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0x7f7f >> (7 - bit_shift)); tmp |= png_ptr->background.gray << bit_shift; *sp = png_check_byte(png_ptr, tmp); } if (bit_shift == 0) { bit_shift = 7; sp++; } else bit_shift--; } break; } case 2: { #if 0 if (gamma_table != NULL) { int bit_shift = 6; sp = row; for (i = 0; i < row_width; i++) { if (((*sp >> bit_shift) & 0x03) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0x3f3f >> (6 - bit_shift)); tmp |= png_ptr->background.gray << bit_shift; *sp = png_check_byte(png_ptr, tmp); } else { unsigned int p = (*sp >> bit_shift) & 0x03; unsigned int g = (gamma_table [p | (p << 2) | (p << 4) | (p << 6)] >> 6) & 0x03; unsigned int tmp = *sp & (0x3f3f >> (6 - bit_shift)); tmp |= g << bit_shift; *sp = png_check_byte(png_ptr, tmp); } if (bit_shift == 0) { bit_shift = 6; sp++; } else bit_shift -= 2; } } else #endif { int bit_shift = 6; sp = row; for (i = 0; i < row_width; i++) { if (((*sp >> bit_shift) & 0x03) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0x3f3f >> (6 - bit_shift)); tmp |= png_ptr->background.gray << bit_shift; *sp = png_check_byte(png_ptr, tmp); } if (bit_shift == 0) { bit_shift = 6; sp++; } else bit_shift -= 2; } } break; } case 4: { #if 0 if (gamma_table != NULL) { int bit_shift = 4; sp = row; for (i = 0; i < row_width; i++) { if (((*sp >> bit_shift) & 0x0f) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0xf0f >> (4 - bit_shift)); tmp |= png_ptr->background.gray << bit_shift; *sp = png_check_byte(png_ptr, tmp); } else { unsigned int p = (*sp >> bit_shift) & 0x0f; unsigned int g = (gamma_table[p | (p << 4)] >> 4) & 0x0f; unsigned int tmp = *sp & (0xf0f >> (4 - bit_shift)); tmp |= g << bit_shift; *sp = png_check_byte(png_ptr, tmp); } if (bit_shift == 0) { bit_shift = 4; sp++; } else bit_shift -= 4; } } else #endif { int bit_shift = 4; sp = row; for (i = 0; i < row_width; i++) { if (((*sp >> bit_shift) & 0x0f) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0xf0f >> (4 - bit_shift)); tmp |= png_ptr->background.gray << bit_shift; *sp = png_check_byte(png_ptr, tmp); } if (bit_shift == 0) { bit_shift = 4; sp++; } else bit_shift -= 4; } } break; } case 8: { if (gamma_table != NULL) { sp = row; for (i = 0; i < row_width; i++, sp++) { if (*sp == png_ptr->trans_color.gray) *sp = png_check_byte(png_ptr, png_ptr->background.gray); else *sp = gamma_table[*sp]; } } else { sp = row; for (i = 0; i < row_width; i++, sp++) { if (*sp == png_ptr->trans_color.gray) *sp = png_check_byte(png_ptr, png_ptr->background.gray); } } break; } case 16: { if (gamma_16 != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 2) { png_uint_16 v; v = png_check_u16(png_ptr, ((*sp) << 8) + *(sp + 1)); if (v == png_ptr->trans_color.gray) { /* Background is already in screen gamma */ *sp = png_check_byte(png_ptr, png_ptr->background.gray >> 8); *(sp + 1) = PNG_BYTE(png_ptr->background.gray); } else { v = gamma_16[(v+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); } } } else { sp = row; for (i = 0; i < row_width; i++, sp += 2) { png_uint_16 v; v = png_check_u16(png_ptr, ((*sp) << 8) + *(sp + 1)); if (v == png_ptr->trans_color.gray) { *sp = png_check_byte(png_ptr, png_ptr->background.gray >> 8); *(sp + 1) = PNG_BYTE(png_ptr->background.gray); } } } break; } default: break; } break; } case 3 /*RGB*/: { if (row_info->bit_depth == 8) { if (gamma_table != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 3) { if (*sp == png_ptr->trans_color.red && *(sp + 1) == png_ptr->trans_color.green && *(sp + 2) == png_ptr->trans_color.blue) { *sp = png_check_byte(png_ptr, png_ptr->background.red); *(sp + 1) = png_check_byte(png_ptr, png_ptr->background.green); *(sp + 2) = png_check_byte(png_ptr, png_ptr->background.blue); } else { *sp = gamma_table[*sp]; *(sp + 1) = gamma_table[*(sp + 1)]; *(sp + 2) = gamma_table[*(sp + 2)]; } } } else { sp = row; for (i = 0; i < row_width; i++, sp += 3) { if (*sp == png_ptr->trans_color.red && *(sp + 1) == png_ptr->trans_color.green && *(sp + 2) == png_ptr->trans_color.blue) { *sp = png_check_byte(png_ptr, png_ptr->background.red); *(sp + 1) = png_check_byte(png_ptr, png_ptr->background.green); *(sp + 2) = png_check_byte(png_ptr, png_ptr->background.blue); } } } } else /* if (row_info->bit_depth == 16) */ { if (gamma_16 != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 6) { png_uint_16 r = png_check_u16(png_ptr, ((*sp) << 8) + *(sp + 1)); png_uint_16 g = png_check_u16(png_ptr, ((*(sp + 2)) << 8) + *(sp + 3)); png_uint_16 b = png_check_u16(png_ptr, ((*(sp + 4)) << 8) + *(sp + 5)); if (r == png_ptr->trans_color.red && g == png_ptr->trans_color.green && b == png_ptr->trans_color.blue) { /* Background is already in screen gamma */ *sp = png_check_byte(png_ptr, png_ptr->background.red >> 8); *(sp + 1) = PNG_BYTE(png_ptr->background.red); *(sp + 2) = png_check_byte(png_ptr, png_ptr->background.green >> 8); *(sp + 3) = PNG_BYTE(png_ptr->background.green); *(sp + 4) = png_check_byte(png_ptr, png_ptr->background.blue >> 8); *(sp + 5) = PNG_BYTE(png_ptr->background.blue); } else { png_uint_16 v = gamma_16[(r+add) >> shift]; *sp = (png_byte)/*SAFE*/(v >> 8); *(sp + 1) = PNG_BYTE(v); v = gamma_16[(g+add) >> shift]; *(sp + 2) = (png_byte)/*SAFE*/(v >> 8); *(sp + 3) = PNG_BYTE(v); v = gamma_16[(b+add) >> shift]; *(sp + 4) = (png_byte)/*SAFE*/(v >> 8); *(sp + 5) = PNG_BYTE(v); } } } else { sp = row; for (i = 0; i < row_width; i++, sp += 6) { unsigned int r = ((*sp) << 8) + *(sp + 1); unsigned int g = ((*(sp + 2)) << 8) + *(sp + 3); unsigned int b = ((*(sp + 4)) << 8) + *(sp + 5); if (r == png_ptr->trans_color.red && g == png_ptr->trans_color.green && b == png_ptr->trans_color.blue) { *sp = (png_byte)/*SAFE*/(png_ptr->background.red >> 8); *(sp + 1) = PNG_BYTE(png_ptr->background.red); *(sp + 2) = (png_byte)/*SAFE*/( png_ptr->background.green >> 8); *(sp + 3) = PNG_BYTE(png_ptr->background.green); *(sp + 4) = (png_byte)/*SAFE*/( png_ptr->background.blue >> 8); *(sp + 5) = PNG_BYTE(png_ptr->background.blue); /*UNTESTED*/ } } /*UNTESTED*/ } } break; } case 2 /*GRAY_ALPHA*/: { if (row_info->bit_depth == 8) { if (gamma_to_1 != NULL && gamma_from_1 != NULL && gamma_table != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 2) { unsigned int a = *(sp + 1); if (a == 0xff) *sp = gamma_table[*sp]; else if (a == 0) { /* Background is already in screen gamma */ *sp = png_check_byte(png_ptr, png_ptr->background.gray); } else { unsigned int v, w; v = gamma_to_1[*sp]; png_composite_16(w, v, 257*a, png_ptr->background_1.gray); if (optimize == 0) w = gamma_from_1[(w+add)>>shift]; else /* alpha pixels linear and approximate */ w = PNG_DIV257(w); *sp = png_check_byte(png_ptr, w); } } } else { sp = row; for (i = 0; i < row_width; i++, sp += 2) { png_byte a = *(sp + 1); if (a == 0) *sp = png_check_byte(png_ptr, png_ptr->background.gray); else if (a < 0xff) png_composite(*sp, *sp, a, png_ptr->background.gray); } } } else /* if (png_ptr->bit_depth == 16) */ { if (gamma_16 != NULL && gamma_16_from_1 != NULL && gamma_16_to_1 != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 4) { png_uint_16 a = png_check_u16(png_ptr, ((*(sp + 2)) << 8) + *(sp + 3)); if (a == 65535) { unsigned int v; v = gamma_16[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = (png_byte)/*SAFE*/(v >> 8); *(sp + 1) = PNG_BYTE(v); } else if (a == 0) { /* Background is already in screen gamma */ *sp = png_check_byte(png_ptr, png_ptr->background.gray >> 8); *(sp + 1) = PNG_BYTE(png_ptr->background.gray); } else { png_uint_16 g, v, w; g = gamma_16_to_1[((sp[0]<<8)+sp[1]+add) >> shift]; png_composite_16(v, g, a, png_ptr->background_1.gray); if (optimize == 0) w = gamma_16_from_1[(v+add) >> shift]; else w = v; *sp = png_check_byte(png_ptr, w >> 8); *(sp + 1) = PNG_BYTE(w); } } } else { sp = row; for (i = 0; i < row_width; i++, sp += 4) { png_uint_16 a = png_check_u16(png_ptr, ((*(sp + 2)) << 8) + *(sp + 3)); if (a == 0) { *sp = png_check_byte(png_ptr, png_ptr->background.gray >> 8); *(sp + 1) = PNG_BYTE(png_ptr->background.gray); } else if (a < 0xffff) { unsigned int g, v; g = ((*sp) << 8) + *(sp + 1); png_composite_16(v, g, a, png_ptr->background.gray); *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); } } } } break; } case 4 /*RGB_ALPHA*/: { if (row_info->bit_depth == 8) { if (gamma_to_1 != NULL && gamma_from_1 != NULL && gamma_table != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 4) { png_byte a = *(sp + 3); if (a == 0xff) { *sp = gamma_table[*sp]; *(sp + 1) = gamma_table[*(sp + 1)]; *(sp + 2) = gamma_table[*(sp + 2)]; } else if (a == 0) { /* Background is already in screen gamma */ *sp = png_check_byte(png_ptr, png_ptr->background.red); *(sp + 1) = png_check_byte(png_ptr, png_ptr->background.green); *(sp + 2) = png_check_byte(png_ptr, png_ptr->background.blue); } else { unsigned int v, w; unsigned int alpha = a * 257U; v = gamma_to_1[*sp]; png_composite_16(w, v, alpha, png_ptr->background_1.red); if (optimize == 0) w = gamma_from_1[(w+add)>>shift]; else w = PNG_DIV257(w); *sp = png_check_byte(png_ptr, w); v = gamma_to_1[*(sp + 1)]; png_composite_16(w, v, alpha, png_ptr->background_1.green); if (optimize == 0) w = gamma_from_1[(w+add)>>shift]; else w = PNG_DIV257(w); *(sp + 1) = png_check_byte(png_ptr, w); v = gamma_to_1[*(sp + 2)]; png_composite_16(w, v, alpha, png_ptr->background_1.blue); if (optimize == 0) w = gamma_from_1[(w+add)>>shift]; else w = PNG_DIV257(w); *(sp + 2) = png_check_byte(png_ptr, w); } } } else { sp = row; for (i = 0; i < row_width; i++, sp += 4) { png_byte a = *(sp + 3); if (a == 0) { *sp = png_check_byte(png_ptr, png_ptr->background.red); *(sp + 1) = png_check_byte(png_ptr, png_ptr->background.green); *(sp + 2) = png_check_byte(png_ptr, png_ptr->background.blue); } else if (a < 0xff) { png_composite(*sp, *sp, a, png_ptr->background.red); png_composite(*(sp + 1), *(sp + 1), a, png_ptr->background.green); png_composite(*(sp + 2), *(sp + 2), a, png_ptr->background.blue); } } } } else /* if (row_info->bit_depth == 16) */ { if (gamma_16 != NULL && gamma_16_from_1 != NULL && gamma_16_to_1 != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 8) { png_uint_16 a = png_check_u16(png_ptr, ((*(sp + 6)) << 8) + *(sp + 7)); if (a == 65535) { png_uint_16 v; v = gamma_16[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); v = gamma_16[((sp[2]<<8)+sp[3]+add) >> shift]; *(sp + 2) = png_check_byte(png_ptr, v >> 8); *(sp + 3) = PNG_BYTE(v); v = gamma_16[((sp[4]<<8)+sp[5]+add) >> shift]; *(sp + 4) = png_check_byte(png_ptr, v >> 8); *(sp + 5) = PNG_BYTE(v); } else if (a == 0) { /* Background is already in screen gamma */ *sp = png_check_byte(png_ptr, png_ptr->background.red >> 8); *(sp + 1) = PNG_BYTE(png_ptr->background.red); *(sp + 2) = png_check_byte(png_ptr, png_ptr->background.green >> 8); *(sp + 3) = PNG_BYTE(png_ptr->background.green); *(sp + 4) = png_check_byte(png_ptr, png_ptr->background.blue >> 8); *(sp + 5) = PNG_BYTE(png_ptr->background.blue); } else { png_uint_16 v, w; v = gamma_16_to_1[((sp[0]<<8)+sp[1]+add) >> shift]; png_composite_16(w, v, a, png_ptr->background_1.red); if (optimize == 0) w = gamma_16_from_1[(w+add) >> shift]; *sp = png_check_byte(png_ptr, w >> 8); *(sp + 1) = PNG_BYTE(w); v = gamma_16_to_1[((sp[2]<<8)+sp[3]+add) >> shift]; png_composite_16(w, v, a, png_ptr->background_1.green); if (optimize == 0) w = gamma_16_from_1[(w+add) >> shift]; *(sp + 2) = png_check_byte(png_ptr, w >> 8); *(sp + 3) = PNG_BYTE(w); v = gamma_16_to_1[((sp[4]<<8)+sp[5]+add) >> shift]; png_composite_16(w, v, a, png_ptr->background_1.blue); if (optimize == 0) w = gamma_16_from_1[(w+add) >> shift]; *(sp + 4) = png_check_byte(png_ptr, w >> 8); *(sp + 5) = PNG_BYTE(w); } } } else { sp = row; for (i = 0; i < row_width; i++, sp += 8) { png_uint_16 a = png_check_u16(png_ptr, ((*(sp + 6)) << 8) + *(sp + 7)); if (a == 0) { *sp = png_check_byte(png_ptr, png_ptr->background.red >> 8); *(sp + 1) = PNG_BYTE(png_ptr->background.red); *(sp + 2) = png_check_byte(png_ptr, png_ptr->background.green >> 8); *(sp + 3) = PNG_BYTE(png_ptr->background.green); *(sp + 4) = png_check_byte(png_ptr, png_ptr->background.blue >> 8); *(sp + 5) = PNG_BYTE(png_ptr->background.blue); } else if (a < 0xffff) { png_uint_16 v; png_uint_16 r = png_check_u16(png_ptr, ((*sp) << 8) + *(sp + 1)); png_uint_16 g = png_check_u16(png_ptr, ((*(sp + 2)) << 8) + *(sp + 3)); png_uint_16 b = png_check_u16(png_ptr, ((*(sp + 4)) << 8) + *(sp + 5)); png_composite_16(v, r, a, png_ptr->background.red); *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); png_composite_16(v, g, a, png_ptr->background.green); *(sp + 2) = png_check_byte(png_ptr, v >> 8); *(sp + 3) = PNG_BYTE(v); png_composite_16(v, b, a, png_ptr->background.blue); *(sp + 4) = png_check_byte(png_ptr, v >> 8); *(sp + 5) = PNG_BYTE(v); } } } } break; } default: break; } } } #endif /* READ_BACKGROUND || READ_ALPHA_MODE */ #ifdef PNG_READ_GAMMA_SUPPORTED /* Gamma correct the image, avoiding the alpha channel. Make sure * you do this after you deal with the transparency issue on grayscale * or RGB images. If your bit depth is 8, use gamma_table, if it * is 16, use gamma_16_table and gamma_shift. Build these with * build_gamma_table(). */ static void png_do_gamma(png_transform_controlp row_info, png_bytep row) { png_const_structrp png_ptr = row_info->png_ptr; png_const_bytep gamma_table = png_ptr->gamma_table; png_const_uint_16p gamma_16_table = png_ptr->gamma_16_table; int shift = png_ptr->gamma_shift; int add = (shift > 0 ? 1U << (shift-1) : 0); png_bytep sp; png_uint_32 i; png_uint_32 row_width=row_info->width; png_debug(1, "in png_do_gamma"); /* Prior to libpng 1.7.0 this code would attempt to gamma correct 2 and 4 bit * gray level values, the results are ridiculously inaccurate. In 1.7.0 the * code is removed and a warning is introduced to catch cases where an * application might actually try it. */ if (((row_info->bit_depth == 8 && gamma_table != NULL) || (row_info->bit_depth == 16 && gamma_16_table != NULL))) { if (!(row_info->flags & PNG_INDEXED)) switch (row_info->channels) { case 3 /*RGB*/: { if (row_info->bit_depth == 8) { sp = row; for (i = 0; i < row_width; i++) { *sp = gamma_table[*sp]; sp++; *sp = gamma_table[*sp]; sp++; *sp = gamma_table[*sp]; sp++; } } else /* if (row_info->bit_depth == 16) */ { sp = row; for (i = 0; i < row_width; i++) { png_uint_16 v; v = gamma_16_table[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); sp += 2; v = gamma_16_table[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); sp += 2; v = gamma_16_table[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); sp += 2; } } break; } case 4 /*RGB_ALPHA*/: { if (row_info->bit_depth == 8) { sp = row; for (i = 0; i < row_width; i++) { *sp = gamma_table[*sp]; sp++; *sp = gamma_table[*sp]; sp++; *sp = gamma_table[*sp]; sp++; sp++; } } else /* if (row_info->bit_depth == 16) */ { sp = row; for (i = 0; i < row_width; i++) { png_uint_16 v; v = gamma_16_table[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); sp += 2; v = gamma_16_table[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); sp += 2; v = gamma_16_table[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); sp += 4; } } break; } case 2 /*GRAY_ALPHA*/: { if (row_info->bit_depth == 8) { sp = row; for (i = 0; i < row_width; i++) { *sp = gamma_table[*sp]; sp += 2; } } else /* if (row_info->bit_depth == 16) */ { sp = row; for (i = 0; i < row_width; i++) { png_uint_16 v; v = gamma_16_table[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); sp += 4; } } break; } case 1 /*GRAY*/: { if (row_info->bit_depth == 8) { sp = row; for (i = 0; i < row_width; i++) { *sp = gamma_table[*sp]; sp++; } } else /*row_info->bit_depth == 16 */ { sp = row; for (i = 0; i < row_width; i++) { png_uint_16 v; v = gamma_16_table[((sp[0]<<8)+sp[1]+add) >> shift]; *sp = png_check_byte(png_ptr, v >> 8); *(sp + 1) = PNG_BYTE(v); sp += 2; } } break; } default: break; } } } #endif #ifdef PNG_READ_ALPHA_MODE_SUPPORTED /* Encode the alpha channel to the output gamma (the input channel is always * linear.) Called only with color types that have an alpha channel. Needs the * from_1 tables. */ static void png_do_encode_alpha(png_transform_controlp row_info, png_bytep row) { int step = row_info->channels; png_debug(1, "in png_do_encode_alpha"); if ((step == 2 || step == 4) && !(row_info->flags & PNG_INDEXED)) { png_const_structrp png_ptr = row_info->png_ptr; PNG_CONST unsigned int shift = png_ptr->gamma_shift; PNG_CONST unsigned int add = (shift > 0 ? 1U<<(shift-1) : 0); png_uint_32 row_width = row_info->width; if (row_info->bit_depth == 8) { PNG_CONST png_bytep gamma_from_1 = png_ptr->gamma_from_1; affirm(gamma_from_1 != NULL); { /* The alpha channel is the last component: */ row += step - 1; for (; row_width > 0; --row_width, row += step) *row = gamma_from_1[(257U**row+add)>>shift]; } } else if (row_info->bit_depth == 16) { PNG_CONST png_uint_16p gamma_16_from_1 = png_ptr->gamma_16_from_1; affirm(gamma_16_from_1 != NULL); { step *= 2; /* The alpha channel is the last component: */ row += step - 2; for (; row_width > 0; --row_width, row += step) { png_uint_16 v; v = gamma_16_from_1[((row[0]<<8)+row[1]+add) >> shift]; *row = png_check_byte(png_ptr, v >> 8); *(row + 1) = PNG_BYTE(v); } } } } } #endif #ifdef PNG_READ_EXPAND_SUPPORTED /* Expands a palette row to an RGB or RGBA row depending * upon whether you supply trans and num_trans. */ static void png_do_expand_palette(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_expand_palette"); if ((row_info->flags & PNG_INDEXED) && row_info->channels == 1) { png_const_structrp png_ptr = row_info->png_ptr; /* Unpack packed pixels into 1-per-byte: */ if (row_info->bit_depth < 8) { png_do_unpack(row_info, row); debug(row_info->flags & PNG_BITS_SHIFTED); row_info->flags &= ~PNG_BITS_SHIFTED; } affirm(row_info->bit_depth == 8); { /* 8-bit per index, unpack to RGB or RGBA */ png_const_colorp palette = png_ptr->palette; const int num_palette = png_ptr->num_palette; int num_trans = png_ptr->num_trans; int bad_index = 0; png_const_bytep sp = row + png_transform_rowbytes(row_info); png_bytep dp; if (num_trans > num_palette) num_trans = num_palette; /* 11.3.2.1: tRNS no longer than palette */ if (num_trans > 0) /* Unpack to RGBA */ { png_const_bytep trans_alpha = png_ptr->trans_alpha; row_info->channels = 4; dp = row + png_transform_rowbytes(row_info); while (dp >= row+4) { const int index = *--sp; if (index < num_trans) *--dp = trans_alpha[index]; else *--dp = 0xff; if (index < num_palette) { *--dp = palette[index].blue; *--dp = palette[index].green; *--dp = palette[index].red; } else { bad_index = index; *--dp = 0; /* default to black */ *--dp = 0; *--dp = 0; } } debug(dp == row && sp == row); } else /* Unpack to RGB */ { row_info->channels = 3; dp = row + png_transform_rowbytes(row_info); while (dp >= row+3) { const int index = *--sp; if (index < num_palette) { *--dp = palette[index].blue; *--dp = palette[index].green; *--dp = palette[index].red; } else { bad_index = index; *--dp = 0; /* default to black */ *--dp = 0; *--dp = 0; } } debug(sp == row && sp == row); } /* At this point we have squirted new RGB or RGBA values into * the row, this zaps all the error flags *and* PNG_INDEXED, * if a bad index we detected we record that (it's not a good idea * to output a warning on every row!) */ if (bad_index) row_info->flags = PNG_BAD_INDEX; else row_info->flags = 0; } } } /* Like do_unpack except that the packed data is expanded to the full 8-bit * range; scaled up. This is not a good thing to do on an indexed image; * the indices will be invalid. */ static void png_do_expand_channels(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_expand_channels"); # define png_ptr row_info->png_ptr debug(!(row_info->flags & PNG_BITS_SHIFTED)); if (row_info->bit_depth < 8) { switch (row_info->bit_depth) { case 1: { png_const_bytep sp = row + png_transform_rowbytes(row_info)-1; unsigned int shift = 0x7 & -row_info->width; png_bytep dp; row_info->bit_depth = 8; dp = row + png_transform_rowbytes(row_info); while (dp > row) { *--dp = (png_byte)/*SAFE*/(((*sp >> shift) & 0x01) * 255); shift = 0x7 & (shift+1); if (shift == 0) --sp; } debug(dp == row && shift == 0 && sp == row-1); break; } case 2: { png_const_bytep sp = row + png_transform_rowbytes(row_info)-1; unsigned int shift = 7 & -(row_info->width << 1); png_bytep dp; row_info->bit_depth = 8; dp = row + png_transform_rowbytes(row_info); while (dp > row) { *--dp = (png_byte)/*SAFE*/(((*sp >> shift) & 0x03) * 85); shift = 0x7 & (shift+2); if (shift == 0) --sp; } debug(dp == row && shift == 0 && sp == row-1); break; } case 4: { png_const_bytep sp = row + png_transform_rowbytes(row_info)-1; unsigned int shift = 7 & -(row_info->width << 2); png_bytep dp; row_info->bit_depth = 8; dp = row + png_transform_rowbytes(row_info); while (dp > row) { *--dp = (png_byte)/*SAFE*/(((*sp >> shift) & 0x0f) * 17); shift = 0x7 & (shift+4); if (shift == 0) --sp; } debug(dp == row && shift == 0 && sp == row-1); break; } default: break; } } # undef png_ptr } /* If the bit depth < 8, it is expanded to 8. Also, if the already * expanded transparency value is supplied, an alpha channel is built. */ static void png_do_expand(png_transform_controlp row_info, png_bytep row) { png_const_structrp png_ptr = row_info->png_ptr; png_debug(1, "in png_do_expand"); if (row_info->channels == 1 && !(row_info->flags & PNG_INDEXED)) { /* Grayscale (1 channel), tRNS expansion requires that the data * be expanded to 8-bit pixels and the tRNS 'gray' value is expanded * to match. ISO PNG 11.3.2.1 suggests that only the low order bits * are considered when the bit depth is less than 16. */ if (png_ptr->num_trans != 0 && (png_ptr->transformations & PNG_EXPAND_tRNS) != 0) { unsigned int gray = png_ptr->trans_color.gray; switch (row_info->bit_depth) { case 1: gray &= 0x1; gray |= gray << 1; /*FALL THROUGH*/ case 2: gray &= 0x3; gray |= gray << 2; /*FALL THROUGH*/ case 4: gray &= 0xf; gray |= gray << 4; png_do_expand_channels(row_info, row); affirm(row_info->bit_depth == 8); /*FALL THROUGH*/ case 8: gray &= 0xff; { png_const_bytep sp = row + png_transform_rowbytes(row_info); png_bytep dp; row_info->channels = 2; dp = row + png_transform_rowbytes(row_info); while (dp >= row+2) { const png_byte g = *--sp; *--dp = (g == gray) ? 0 : 0xff; *--dp = g; } debug(dp == row && sp == row); } break; case 16: { png_const_bytep sp = row + png_transform_rowbytes(row_info); png_bytep dp; row_info->channels = 2; dp = row + png_transform_rowbytes(row_info); while (dp >= row+4) { dp -= 4; sp -= 2; { const unsigned int g = (sp[0] << 8) | sp[1]; dp[2] = dp[3] = (g == gray) ? 0 : 0xff; dp[1] = PNG_BYTE(g); dp[0] = PNG_BYTE(g >> 8); } } debug(dp == row && sp == row); } break; default: impossible("bit depth invalid"); } } else if (row_info->bit_depth < 8) /* but no tRNS */ png_do_expand_channels(row_info, row); } else if (row_info->channels == 3 && png_ptr->num_trans != 0 && (png_ptr->transformations & PNG_EXPAND_tRNS) != 0) { if (row_info->bit_depth == 8) { png_const_bytep sp = row + png_transform_rowbytes(row_info); png_bytep dp; png_uint_32 trans = ((((png_ptr->trans_color.blue & 0xff) << 8) | (png_ptr->trans_color.green & 0xff) ) << 8) | (png_ptr->trans_color.red & 0xff); row_info->channels = 4; dp = row + png_transform_rowbytes(row_info); while (dp >= row+4) { png_uint_32 pixel = *--sp; /* B */ pixel = (pixel << 8) | *--sp; /* G */ pixel = (pixel << 8) | *--sp; /* R */ *--dp = (pixel == trans) ? 0 : 0xff; *--dp = PNG_BYTE(pixel >> 16); /* B */ *--dp = PNG_BYTE(pixel >> 8); /* G */ *--dp = PNG_BYTE(pixel ); /* R */ } debug(dp == row && sp == row); } else if (row_info->bit_depth == 16) { /* The full 6 bytes of the input RRGGBB need to be compared against * the transparent color value. Allow the compiler to choose how to * do this by using the standard library routines. */ png_const_bytep sp = row + png_transform_rowbytes(row_info); png_bytep dp; png_byte trans[6]; trans[0] = PNG_BYTE(png_ptr->trans_color.red >> 8); trans[1] = PNG_BYTE(png_ptr->trans_color.red); trans[2] = PNG_BYTE(png_ptr->trans_color.green >> 8); trans[3] = PNG_BYTE(png_ptr->trans_color.green); trans[4] = PNG_BYTE(png_ptr->trans_color.blue >> 8); trans[5] = PNG_BYTE(png_ptr->trans_color.blue); row_info->channels = 4; dp = row + png_transform_rowbytes(row_info); while (dp >= row+8) { png_byte alpha; dp -= 8; sp -= 6; alpha = memcmp(trans, sp, 6) ? 0xff : 0; memmove(dp, sp, 6); dp[7] = dp[6] = alpha; } debug(dp == row && sp == row); } } } #endif #ifdef PNG_READ_EXPAND_16_SUPPORTED /* If the bit depth is 8 and the color type is not a palette type expand the * whole row to 16 bits. Has no effect otherwise. */ static void png_do_expand_16(png_transform_controlp row_info, png_bytep row) { png_debug(1, "in png_do_expand16"); # define png_ptr row_info->png_ptr if (row_info->bit_depth == 8 && !(row_info->flags & PNG_INDEXED)) { /* The rows have a sequence of bytes containing [0..255] and we need * to turn it into another row containing [0..65535], to do this we * calculate: * * (input / 255) * 65535 * * Which happens to be exactly input * 257 and this can be achieved * simply by byte replication in place (copying backwards). */ png_const_bytep sp = row + png_transform_rowbytes(row_info); png_bytep dp; row_info->bit_depth = 16; dp = row + png_transform_rowbytes(row_info); while (dp > sp) dp[-2] = dp[-1] = *--sp, dp -= 2; debug(dp == row && sp == row); } # undef png_ptr } #endif #ifdef PNG_READ_QUANTIZE_SUPPORTED static void png_do_quantize(png_transform_controlp row_info, png_bytep row) { png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width=row_info->width; png_debug(1, "in png_do_quantize"); if (row_info->bit_depth == 8) { png_const_bytep palette_lookup = row_info->png_ptr->palette_lookup; if (row_info->channels == 3 && palette_lookup) { int r, g, b, p; sp = row; dp = row; for (i = 0; i < row_width; i++) { r = *sp++; g = *sp++; b = *sp++; /* This looks real messy, but the compiler will reduce * it down to a reasonable formula. For example, with * 5 bits per color, we get: * p = (((r >> 3) & 0x1f) << 10) | * (((g >> 3) & 0x1f) << 5) | * ((b >> 3) & 0x1f); */ p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) & ((1 << PNG_QUANTIZE_RED_BITS) - 1)) << (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) | (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) & ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) << (PNG_QUANTIZE_BLUE_BITS)) | ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) & ((1 << PNG_QUANTIZE_BLUE_BITS) - 1)); *dp++ = palette_lookup[p]; } row_info->flags |= PNG_INDEXED; row_info->channels = 1; } else if (row_info->channels == 4 && palette_lookup != NULL) { int r, g, b, p; sp = row; dp = row; for (i = 0; i < row_width; i++) { r = *sp++; g = *sp++; b = *sp++; sp++; p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) & ((1 << PNG_QUANTIZE_RED_BITS) - 1)) << (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) | (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) & ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) << (PNG_QUANTIZE_BLUE_BITS)) | ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) & ((1 << PNG_QUANTIZE_BLUE_BITS) - 1)); *dp++ = palette_lookup[p]; } row_info->flags |= PNG_INDEXED; row_info->channels = 1; } else if (row_info->channels == 1 && (row_info->flags & PNG_INDEXED) && row_info->png_ptr->quantize_index != NULL) { png_const_bytep quantize_lookup = row_info->png_ptr->quantize_index; sp = row; for (i = 0; i < row_width; i++, sp++) { *sp = quantize_lookup[*sp]; } } } } #endif /* READ_QUANTIZE */ /* Transform the row. The order of transformations is significant, * and is very touchy. If you add a transformation, take care to * decide how it fits in with the other transformations here. */ void /* PRIVATE */ png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info_in) { png_transform_control display; png_debug(1, "in png_do_read_transformations"); affirm(png_ptr->row_buf != NULL); /* The following is debugging; prior to 1.5.4 the code was never compiled in; * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro * PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for * all transformations, however in practice the ROW_INIT always gets done on * demand, if necessary. */ if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 && (png_ptr->flags & PNG_FLAG_ROW_INIT) == 0) { /* Application has failed to call either png_read_start_image() or * png_read_update_info() after setting transforms that expand pixels. * This check added to libpng-1.2.19 (but not enabled until 1.5.4). */ png_error(png_ptr, "missing png_read_start_image or update_info"); } /* Ok, it looks genuine, set up the control structure from the supplied * row_info. */ png_init_transform_control(png_ptr, &display, row_info_in); #ifdef PNG_READ_EXPAND_SUPPORTED if ((png_ptr->transformations & PNG_EXPAND) != 0) { if (display.flags & PNG_INDEXED) png_do_expand_palette(&display, png_ptr->row_buf + 1); else png_do_expand(&display, png_ptr->row_buf + 1); } #endif #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 && (png_ptr->transformations & PNG_COMPOSE) == 0 && (display.channels == 4 || display.channels == 2)) png_do_strip_channel(&display, png_ptr->row_buf + 1, 0 /* at_start == false, because SWAP_ALPHA happens later */); #endif #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) { int rgb_error = png_do_rgb_to_gray(&display, png_ptr->row_buf + 1); if (rgb_error != 0) { png_ptr->rgb_to_gray_status=1; if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == PNG_RGB_TO_GRAY_WARN) png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel"); if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == PNG_RGB_TO_GRAY_ERR) png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel"); } } #endif /* From Andreas Dilger e-mail to png-implement, 26 March 1998: * * In most cases, the "simple transparency" should be done prior to doing * gray-to-RGB, or you will have to test 3x as many bytes to check if a * pixel is transparent. You would also need to make sure that the * transparency information is upgraded to RGB. * * To summarize, the current flow is: * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite * with background "in place" if transparent, * convert to RGB if necessary * - Gray + alpha -> composite with gray background and remove alpha bytes, * convert to RGB if necessary * * To support RGB backgrounds for gray images we need: * - Gray + simple transparency -> convert to RGB + simple transparency, * compare 3 or 6 bytes and composite with * background "in place" if transparent * (3x compare/pixel compared to doing * composite with gray bkgrnd) * - Gray + alpha -> convert to RGB + alpha, composite with background and * remove alpha bytes (3x float * operations/pixel compared with composite * on gray background) * * Greg's change will do this. The reason it wasn't done before is for * performance, as this increases the per-pixel operations. If we would check * in advance if the background was gray or RGB, and position the gray-to-RGB * transform appropriately, then it would save a lot of work/time. */ #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED /* If gray -> RGB, do so now only if background is non-gray; else do later * for performance reasons */ if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 && (png_ptr->flags & PNG_FLAG_BACKGROUND_IS_GRAY) == 0) png_do_gray_to_rgb(&display, png_ptr->row_buf + 1); #endif #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ defined(PNG_READ_ALPHA_MODE_SUPPORTED) if ((png_ptr->transformations & PNG_COMPOSE) != 0) png_do_compose(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_GAMMA_SUPPORTED if ((png_ptr->transformations & PNG_GAMMA) != 0 && #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED /* Because RGB_TO_GRAY does the gamma transform. */ (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0 && #endif #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ defined(PNG_READ_ALPHA_MODE_SUPPORTED) /* Because PNG_COMPOSE does the gamma transform if there is something to * do (if there is an alpha channel or transparency.) * WARNING: prior to 1.7.0 this was checking png_ptr->color_type, which * probably means that the gamma would get dropped if the alpha * channel was stripped yet PNG_COMPOSE was also set. */ !((png_ptr->transformations & PNG_COMPOSE) != 0 && (png_ptr->num_trans != 0 || display.channels == 2 || display.channels == 4)) && #endif /* Because png_init_read_transformations transforms the palette, unless * RGB_TO_GRAY will do the transform. Note that this does need to check * the original color type because the expand_palette call preceeds this * check. */ (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)) png_do_gamma(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0 && (png_ptr->transformations & PNG_COMPOSE) != 0 && (display.channels == 2 || display.channels == 4)) png_do_strip_channel(&display, png_ptr->row_buf + 1, 0 /* at_start == false, because SWAP_ALPHA happens later */); #endif #ifdef PNG_READ_ALPHA_MODE_SUPPORTED if ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 && (display.channels == 2 || display.channels == 4)) png_do_encode_alpha(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0) png_do_scale_16_to_8(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED /* There is no harm in doing both of these because only one has any effect, * by putting the 'scale' option first if the app asks for scale (either by * calling the API or in a TRANSFORM flag) this is what happens. */ if ((png_ptr->transformations & PNG_16_TO_8) != 0) png_do_chop(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_QUANTIZE_SUPPORTED if ((png_ptr->transformations & PNG_QUANTIZE) != 0) png_do_quantize(&display, png_ptr->row_buf + 1); #endif /* READ_QUANTIZE */ #ifdef PNG_READ_EXPAND_16_SUPPORTED /* Do the expansion now, after all the arithmetic has been done. Notice * that previous transformations can handle the PNG_EXPAND_16 flag if this * is efficient (particularly true in the case of gamma correction, where * better accuracy results faster!) */ if ((png_ptr->transformations & PNG_EXPAND_16) != 0) png_do_expand_16(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED /* NOTE: moved here in 1.5.4 (from much later in this list.) */ if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0 && (png_ptr->flags & PNG_FLAG_BACKGROUND_IS_GRAY) != 0) png_do_gray_to_rgb(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_INVERT_SUPPORTED if ((png_ptr->transformations & PNG_INVERT_MONO) != 0) png_do_invert(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0) png_do_read_invert_alpha(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_SHIFT_SUPPORTED if ((png_ptr->transformations & PNG_SHIFT) != 0) png_do_unshift(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_PACK_SUPPORTED if ((png_ptr->transformations & PNG_PACK) != 0) png_do_unpack(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED /* Added at libpng-1.5.10 */ if ((display.flags & PNG_INDEXED) != 0 && png_ptr->num_palette_max >= 0) png_do_check_palette_indexes(png_ptr, &display); #endif #ifdef PNG_READ_BGR_SUPPORTED if ((png_ptr->transformations & PNG_BGR) != 0) png_do_bgr(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_PACKSWAP_SUPPORTED if ((png_ptr->transformations & PNG_PACKSWAP) != 0) png_do_packswap(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_FILLER_SUPPORTED if ((png_ptr->transformations & PNG_FILLER) != 0) png_do_read_filler(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0) png_do_read_swap_alpha(&display, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_16BIT_SUPPORTED #ifdef PNG_READ_SWAP_SUPPORTED if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0) png_do_swap(&display, png_ptr->row_buf + 1); #endif #endif /* The user transform expects a png_row_info, and it would be inconvenient * to change this. */ png_end_transform_control(row_info_in, &display); #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0) { if (png_ptr->read_user_transform_fn != NULL) (*(png_ptr->read_user_transform_fn)) /* User read transform function */ (png_ptr, /* png_ptr */ row_info_in, /* row_info: */ /* png_uint_32 width; width of row */ /* png_size_t rowbytes; number of bytes in row */ /* png_byte color_type; color type of pixels */ /* png_byte bit_depth; bit depth of samples */ /* png_byte channels; number of channels (1-4) */ /* png_byte pixel_depth; bits per pixel (depth*channels) */ png_ptr->row_buf + 1); /* start of pixel data for row */ #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED if (png_ptr->user_transform_depth != 0) row_info_in->bit_depth = png_ptr->user_transform_depth; if (png_ptr->user_transform_channels != 0) row_info_in->channels = png_ptr->user_transform_channels; #endif row_info_in->pixel_depth = png_check_byte(png_ptr, row_info_in->bit_depth * row_info_in->channels); row_info_in->rowbytes = PNG_ROWBYTES(row_info_in->pixel_depth, row_info_in->width); } #endif } #endif /* READ_TRANSFORMS */ #endif /* READ */