Mercurial > mm7
view lib/libpng/pngrtran.c @ 2407:378e5732ba38
Слияние
| author | Ritor1 |
|---|---|
| date | Wed, 09 Jul 2014 18:19:54 +0600 |
| parents | 6e178010fc29 |
| children |
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/* pngrtran.c - transforms the data in a row for PNG readers * * Last changed in libpng 1.6.10 [March 6, 2014] * Copyright (c) 1998-2014 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" #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 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) 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) || background_color == NULL) return; if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN) { png_warning(png_ptr, "Application must supply a known background gamma"); 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_byte)(background_gamma_code); if (need_expand) png_ptr->transformations |= PNG_BACKGROUND_EXPAND; else png_ptr->transformations &= ~PNG_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)) 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)) 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)) 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) 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) 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 *= PNG_FP_1; /* This preserves -1 and -2 exactly: */ output_gamma = floor(output_gamma + .5); if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN) png_fixed_error(png_ptr, "gamma value"); return (png_fixed_point)output_gamma; } # 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)) 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) { /* 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->transformations &= ~PNG_BACKGROUND_EXPAND; if (png_ptr->transformations & PNG_COMPOSE) 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)) return; png_ptr->transformations |= PNG_QUANTIZE; if (!full_quantize) { 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_byte)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_byte)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) break; } /* Swap the palette around, and set up a table, if necessary */ if (full_quantize) { 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_byte)i; png_ptr->quantize_index[i] = (png_byte)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_byte)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_byte)i; png_ptr->palette_to_index[i] = (png_byte)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_byte)i; t->right = (png_byte)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) { 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_byte)num_new_palette; png_ptr->palette_to_index[num_new_palette] = (png_byte)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_uint_16)num_palette; if (full_quantize) { 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_byte)d; png_ptr->palette_lookup[d_index] = (png_byte)i; } } } } } png_free(png_ptr, distance); } } #endif /* PNG_READ_QUANTIZE_SUPPORTED */ #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)) 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_SUPPORTED */ #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)) 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)) 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)) 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)) return; png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); } #endif /* defined(PNG_READ_EXPAND_SUPPORTED) */ #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)) 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)) 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)) 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_uint_16)(((png_uint_32)red*32768)/100000); green_int = (png_uint_16)(((png_uint_32)green*32768)/100000); png_ptr->rgb_to_gray_red_coeff = red_int; png_ptr->rgb_to_gray_green_coeff = green_int; png_ptr->rgb_to_gray_coefficients_set = 1; } 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. */ /*For the moment 'png_init_palette_transformations' and * 'png_init_rgb_transformations' only do some flag canceling optimizations. * The intent is that these two routines should have palette or rgb operations * extracted from 'png_init_read_transformations'. */ static void /* PRIVATE */ png_init_palette_transformations(png_structrp png_ptr) { /* Called to handle the (input) palette case. In png_do_read_transformations * the first step is to expand the palette if requested, so this code must * take care to only make changes that are invariant with respect to the * palette expansion, or only do them if there is no expansion. * * STRIP_ALPHA has already been handled in the caller (by setting num_trans * to 0.) */ 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; i<png_ptr->num_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) { /* 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) png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND); } #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED) /* png_set_background handling - deals with the complexity of whether the * background color is in the file format or the screen format in the case * where an 'expand' will happen. */ /* The following code cannot be entered in the alpha pre-multiplication case * because PNG_BACKGROUND_EXPAND is cancelled below. */ if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) && (png_ptr->transformations & PNG_EXPAND)) { { png_ptr->background.red = png_ptr->palette[png_ptr->background.index].red; png_ptr->background.green = png_ptr->palette[png_ptr->background.index].green; png_ptr->background.blue = png_ptr->palette[png_ptr->background.index].blue; #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED if (png_ptr->transformations & PNG_INVERT_ALPHA) { if (!(png_ptr->transformations & PNG_EXPAND_tRNS)) { /* Invert the alpha channel (in tRNS) unless the pixels are * going to be expanded, in which case leave it for later */ int i, istop = png_ptr->num_trans; for (i=0; i<istop; i++) png_ptr->trans_alpha[i] = (png_byte)(255 - png_ptr->trans_alpha[i]); } } #endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */ } } /* background expand and (therefore) no alpha association. */ #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */ } 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) { /* 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) png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND); } #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED) /* png_set_background handling - deals with the complexity of whether the * background color is in the file format or the screen format in the case * where an 'expand' will happen. */ /* The following code cannot be entered in the alpha pre-multiplication case * because PNG_BACKGROUND_EXPAND is cancelled below. */ if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) && (png_ptr->transformations & PNG_EXPAND) && !(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) /* i.e., GRAY or GRAY_ALPHA */ { { /* Expand background and tRNS chunks */ int gray = png_ptr->background.gray; int trans_gray = png_ptr->trans_color.gray; switch (png_ptr->bit_depth) { case 1: gray *= 0xff; trans_gray *= 0xff; break; case 2: gray *= 0x55; trans_gray *= 0x55; break; case 4: gray *= 0x11; trans_gray *= 0x11; break; default: case 8: /* FALL THROUGH (Already 8 bits) */ case 16: /* Already a full 16 bits */ break; } png_ptr->background.red = png_ptr->background.green = png_ptr->background.blue = (png_uint_16)gray; if (!(png_ptr->transformations & PNG_EXPAND_tRNS)) { png_ptr->trans_color.red = png_ptr->trans_color.green = png_ptr->trans_color.blue = (png_uint_16)trans_gray; } } } /* background expand and (therefore) no alpha association. */ #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */ } 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) 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_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_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) && !(png_ptr->transformations & PNG_COMPOSE)) { /* Stripping the alpha channel happens immediately after the 'expand' * transformations, before all other transformation, so it cancels out * the alpha handling. It has the side effect negating the effect of * PNG_EXPAND_tRNS too: */ png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | 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)) { 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) png_colorspace_set_rgb_coefficients(png_ptr); #endif #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED) /* Detect gray background and attempt to enable optimization for * gray --> RGB case. * * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or * RGB_ALPHA (in which case need_expand is superfluous anyway), the * background color might actually be gray yet not be flagged as such. * This is not a problem for the current code, which uses * PNG_BACKGROUND_IS_GRAY only to decide when to do the * png_do_gray_to_rgb() transformation. * * TODO: this code needs to be revised to avoid the complexity and * interdependencies. The color type of the background should be recorded in * png_set_background, along with the bit depth, then the code has a record * of exactly what color space the background is currently in. */ if (png_ptr->transformations & PNG_BACKGROUND_EXPAND) { /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if * the file was grayscale the background value is gray. */ if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) png_ptr->mode |= PNG_BACKGROUND_IS_GRAY; } else if (png_ptr->transformations & PNG_COMPOSE) { /* PNG_COMPOSE: png_set_background was called with need_expand false, * so the color is in the color space of the output or png_set_alpha_mode * was called and the color is black. Ignore RGB_TO_GRAY because that * happens before GRAY_TO_RGB. */ if (png_ptr->transformations & PNG_GRAY_TO_RGB) { if (png_ptr->background.red == png_ptr->background.green && png_ptr->background.red == png_ptr->background.blue) { png_ptr->mode |= PNG_BACKGROUND_IS_GRAY; png_ptr->background.gray = png_ptr->background.red; } } } #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */ #endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED */ /* 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 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) png_init_palette_transformations(png_ptr); else png_init_rgb_transformations(png_ptr); #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \ defined(PNG_READ_EXPAND_16_SUPPORTED) if ((png_ptr->transformations & PNG_EXPAND_16) && (png_ptr->transformations & PNG_COMPOSE) && !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) && png_ptr->bit_depth != 16) { /* TODO: fix this. Because the expand_16 operation is after the compose * handling the background color must be 8, not 16, bits deep, but the * application will supply a 16-bit value so reduce it here. * * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at * present, so that case is ok (until do_expand_16 is moved.) * * NOTE: this discards the low 16 bits of the user supplied background * color, but until expand_16 works properly there is no choice! */ # define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x)) CHOP(png_ptr->background.red); CHOP(png_ptr->background.green); CHOP(png_ptr->background.blue); CHOP(png_ptr->background.gray); # undef CHOP } #endif /* PNG_READ_BACKGROUND_SUPPORTED && PNG_READ_EXPAND_16_SUPPORTED */ #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \ (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \ defined(PNG_READ_STRIP_16_TO_8_SUPPORTED)) if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) && (png_ptr->transformations & PNG_COMPOSE) && !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) && png_ptr->bit_depth == 16) { /* On the other hand, if a 16-bit file is to be reduced to 8-bits per * component this will also happen after PNG_COMPOSE and so the background * color must be pre-expanded here. * * TODO: fix this too. */ png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257); png_ptr->background.green = (png_uint_16)(png_ptr->background.green * 257); png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257); png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257); } #endif /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the * background support (see the comments in scripts/pnglibconf.dfa), this * allows pre-multiplication of the alpha channel to be implemented as * compositing on black. This is probably sub-optimal and has been done in * 1.5.4 betas simply to enable external critique and testing (i.e. to * implement the new API quickly, without lots of internal changes.) */ #ifdef PNG_READ_GAMMA_SUPPORTED # ifdef PNG_READ_BACKGROUND_SUPPORTED /* Includes ALPHA_MODE */ png_ptr->background_1 = png_ptr->background; # endif /* 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) || ((png_ptr->transformations & PNG_RGB_TO_GRAY) && (png_gamma_significant(png_ptr->colorspace.gamma) || png_gamma_significant(png_ptr->screen_gamma))) || ((png_ptr->transformations & PNG_COMPOSE) && (png_gamma_significant(png_ptr->colorspace.gamma) || png_gamma_significant(png_ptr->screen_gamma) # ifdef PNG_READ_BACKGROUND_SUPPORTED || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE && png_gamma_significant(png_ptr->background_gamma)) # endif )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) && png_gamma_significant(png_ptr->screen_gamma)) ) { png_build_gamma_table(png_ptr, png_ptr->bit_depth); #ifdef PNG_READ_BACKGROUND_SUPPORTED if (png_ptr->transformations & PNG_COMPOSE) { /* 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) png_warning(png_ptr, "libpng does not support gamma+background+rgb_to_gray"); if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { /* We don't get to here unless there is a tRNS chunk with non-opaque * entries - see the checking code at the start of this function. */ png_color back, back_1; png_colorp palette = png_ptr->palette; int num_palette = png_ptr->num_palette; int i; if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE) { back.red = png_ptr->gamma_table[png_ptr->background.red]; back.green = png_ptr->gamma_table[png_ptr->background.green]; back.blue = png_ptr->gamma_table[png_ptr->background.blue]; back_1.red = png_ptr->gamma_to_1[png_ptr->background.red]; back_1.green = png_ptr->gamma_to_1[png_ptr->background.green]; back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue]; } else { png_fixed_point g, gs; switch (png_ptr->background_gamma_type) { case PNG_BACKGROUND_GAMMA_SCREEN: g = (png_ptr->screen_gamma); gs = PNG_FP_1; break; case PNG_BACKGROUND_GAMMA_FILE: g = png_reciprocal(png_ptr->colorspace.gamma); gs = png_reciprocal2(png_ptr->colorspace.gamma, png_ptr->screen_gamma); break; case PNG_BACKGROUND_GAMMA_UNIQUE: g = png_reciprocal(png_ptr->background_gamma); gs = png_reciprocal2(png_ptr->background_gamma, png_ptr->screen_gamma); break; default: g = PNG_FP_1; /* back_1 */ gs = PNG_FP_1; /* back */ break; } if (png_gamma_significant(gs)) { back.red = png_gamma_8bit_correct(png_ptr->background.red, gs); back.green = png_gamma_8bit_correct(png_ptr->background.green, gs); back.blue = png_gamma_8bit_correct(png_ptr->background.blue, gs); } else { back.red = (png_byte)png_ptr->background.red; back.green = (png_byte)png_ptr->background.green; back.blue = (png_byte)png_ptr->background.blue; } if (png_gamma_significant(g)) { back_1.red = png_gamma_8bit_correct(png_ptr->background.red, g); back_1.green = png_gamma_8bit_correct( png_ptr->background.green, g); back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue, g); } else { back_1.red = (png_byte)png_ptr->background.red; back_1.green = (png_byte)png_ptr->background.green; back_1.blue = (png_byte)png_ptr->background.blue; } } for (i = 0; i < num_palette; i++) { if (i < (int)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_byte v, w; v = png_ptr->gamma_to_1[palette[i].red]; png_composite(w, v, png_ptr->trans_alpha[i], back_1.red); palette[i].red = png_ptr->gamma_from_1[w]; v = png_ptr->gamma_to_1[palette[i].green]; png_composite(w, v, png_ptr->trans_alpha[i], back_1.green); palette[i].green = png_ptr->gamma_from_1[w]; v = png_ptr->gamma_to_1[palette[i].blue]; png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue); palette[i].blue = png_ptr->gamma_from_1[w]; } } else { 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 */ /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */ else /* color_type != PNG_COLOR_TYPE_PALETTE */ { int gs_sig, g_sig; png_fixed_point g = PNG_FP_1; /* Correction to linear */ png_fixed_point gs = PNG_FP_1; /* Correction to screen */ switch (png_ptr->background_gamma_type) { case PNG_BACKGROUND_GAMMA_SCREEN: g = png_ptr->screen_gamma; /* gs = PNG_FP_1; */ break; case PNG_BACKGROUND_GAMMA_FILE: g = png_reciprocal(png_ptr->colorspace.gamma); gs = png_reciprocal2(png_ptr->colorspace.gamma, png_ptr->screen_gamma); break; case PNG_BACKGROUND_GAMMA_UNIQUE: g = png_reciprocal(png_ptr->background_gamma); gs = png_reciprocal2(png_ptr->background_gamma, png_ptr->screen_gamma); break; default: png_error(png_ptr, "invalid background gamma type"); } g_sig = png_gamma_significant(g); gs_sig = png_gamma_significant(gs); if (g_sig) png_ptr->background_1.gray = png_gamma_correct(png_ptr, png_ptr->background.gray, g); if (gs_sig) png_ptr->background.gray = png_gamma_correct(png_ptr, png_ptr->background.gray, gs); if ((png_ptr->background.red != png_ptr->background.green) || (png_ptr->background.red != png_ptr->background.blue) || (png_ptr->background.red != png_ptr->background.gray)) { /* RGB or RGBA with color background */ if (g_sig) { png_ptr->background_1.red = png_gamma_correct(png_ptr, png_ptr->background.red, g); png_ptr->background_1.green = png_gamma_correct(png_ptr, png_ptr->background.green, g); png_ptr->background_1.blue = png_gamma_correct(png_ptr, png_ptr->background.blue, g); } if (gs_sig) { png_ptr->background.red = png_gamma_correct(png_ptr, png_ptr->background.red, gs); png_ptr->background.green = png_gamma_correct(png_ptr, png_ptr->background.green, gs); png_ptr->background.blue = png_gamma_correct(png_ptr, png_ptr->background.blue, gs); } } else { /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */ png_ptr->background_1.red = png_ptr->background_1.green = png_ptr->background_1.blue = png_ptr->background_1.gray; png_ptr->background.red = png_ptr->background.green = png_ptr->background.blue = png_ptr->background.gray; } /* The background is now in screen gamma: */ png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN; } /* color_type != PNG_COLOR_TYPE_PALETTE */ }/* png_ptr->transformations & PNG_BACKGROUND */ else /* Transformation does not include PNG_BACKGROUND */ #endif /* PNG_READ_BACKGROUND_SUPPORTED */ 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. */ 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 /* PNG_READ_GAMMA_SUPPORTED */ #ifdef PNG_READ_BACKGROUND_SUPPORTED /* No GAMMA transformation (see the hanging else 4 lines above) */ if ((png_ptr->transformations & PNG_COMPOSE) && (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_byte)png_ptr->background.red; back.green = (png_byte)png_ptr->background.green; back.blue = (png_byte)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 /* PNG_READ_BACKGROUND_SUPPORTED */ #ifdef PNG_READ_SHIFT_SUPPORTED if ((png_ptr->transformations & PNG_SHIFT) && !(png_ptr->transformations & PNG_EXPAND) && (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; i<istop; ++i) { int component = png_ptr->palette[i].red; component >>= shift; png_ptr->palette[i].red = (png_byte)component; } shift = 8 - png_ptr->sig_bit.green; if (shift > 0 && shift < 8) for (i=0; i<istop; ++i) { int component = png_ptr->palette[i].green; component >>= shift; png_ptr->palette[i].green = (png_byte)component; } shift = 8 - png_ptr->sig_bit.blue; if (shift > 0 && shift < 8) for (i=0; i<istop; ++i) { int component = png_ptr->palette[i].blue; component >>= shift; png_ptr->palette[i].blue = (png_byte)component; } } #endif /* PNG_READ_SHIFT_SUPPORTED */ } /* 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) { 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) { if (png_ptr->transformations & PNG_EXPAND_tRNS) 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) 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) info_ptr->bit_depth = 8; # endif # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED if (png_ptr->transformations & PNG_16_TO_8) 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_SUPPORTED */ } #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED if (png_ptr->transformations & PNG_GRAY_TO_RGB) info_ptr->color_type = (png_byte)(info_ptr->color_type | PNG_COLOR_MASK_COLOR); #endif #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED if (png_ptr->transformations & PNG_RGB_TO_GRAY) info_ptr->color_type = (png_byte)(info_ptr->color_type & ~PNG_COLOR_MASK_COLOR); #endif #ifdef PNG_READ_QUANTIZE_SUPPORTED if (png_ptr->transformations & PNG_QUANTIZE) { if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) || (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) && png_ptr->palette_lookup && 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 && 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) && (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) info_ptr->channels = 3; else info_ptr->channels = 1; #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED if (png_ptr->transformations & PNG_STRIP_ALPHA) { info_ptr->color_type = (png_byte)(info_ptr->color_type & ~PNG_COLOR_MASK_ALPHA); info_ptr->num_trans = 0; } #endif if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA) info_ptr->channels++; #ifdef PNG_READ_FILLER_SUPPORTED /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */ if ((png_ptr->transformations & PNG_FILLER) && ((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) 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) { 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_byte)(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) return; #endif } #ifdef PNG_READ_PACK_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_row_infop row_info, png_bytep row) { png_debug(1, "in png_do_unpack"); if (row_info->bit_depth < 8) { png_uint_32 i; png_uint_32 row_width=row_info->width; switch (row_info->bit_depth) { case 1: { png_bytep sp = row + (png_size_t)((row_width - 1) >> 3); png_bytep dp = row + (png_size_t)row_width - 1; png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07); for (i = 0; i < row_width; i++) { *dp = (png_byte)((*sp >> shift) & 0x01); if (shift == 7) { shift = 0; sp--; } else shift++; dp--; } break; } case 2: { png_bytep sp = row + (png_size_t)((row_width - 1) >> 2); png_bytep dp = row + (png_size_t)row_width - 1; png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1); for (i = 0; i < row_width; i++) { *dp = (png_byte)((*sp >> shift) & 0x03); if (shift == 6) { shift = 0; sp--; } else shift += 2; dp--; } break; } case 4: { png_bytep sp = row + (png_size_t)((row_width - 1) >> 1); png_bytep dp = row + (png_size_t)row_width - 1; png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2); for (i = 0; i < row_width; i++) { *dp = (png_byte)((*sp >> shift) & 0x0f); if (shift == 4) { shift = 0; sp--; } else shift = 4; dp--; } break; } default: break; } row_info->bit_depth = 8; row_info->pixel_depth = (png_byte)(8 * row_info->channels); row_info->rowbytes = row_width * row_info->channels; } } #endif #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_row_infop row_info, png_bytep row, png_const_color_8p sig_bits) { int color_type; png_debug(1, "in png_do_unshift"); /* The palette case has already been handled in the _init routine. */ color_type = row_info->color_type; if (color_type != PNG_COLOR_TYPE_PALETTE) { int shift[4]; int channels = 0; int bit_depth = row_info->bit_depth; if (color_type & PNG_COLOR_MASK_COLOR) { shift[channels++] = bit_depth - sig_bits->red; shift[channels++] = bit_depth - sig_bits->green; shift[channels++] = bit_depth - sig_bits->blue; } else { shift[channels++] = bit_depth - sig_bits->gray; } if (color_type & PNG_COLOR_MASK_ALPHA) { shift[channels++] = bit_depth - sig_bits->alpha; } { 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) return; } switch (bit_depth) { default: /* Must be 1bpp gray: should not be here! */ /* NOTREACHED */ break; case 2: /* Must be 2bpp gray */ /* assert(channels == 1 && shift[0] == 1) */ { png_bytep bp = row; png_bytep bp_end = bp + row_info->rowbytes; while (bp < bp_end) { int b = (*bp >> 1) & 0x55; *bp++ = (png_byte)b; } break; } case 4: /* Must be 4bpp gray */ /* assert(channels == 1) */ { png_bytep bp = row; png_bytep bp_end = bp + row_info->rowbytes; int gray_shift = shift[0]; int mask = 0xf >> gray_shift; mask |= mask << 4; while (bp < bp_end) { int b = (*bp >> gray_shift) & mask; *bp++ = (png_byte)b; } break; } case 8: /* Single byte components, G, GA, RGB, RGBA */ { png_bytep bp = row; png_bytep bp_end = bp + row_info->rowbytes; int channel = 0; while (bp < bp_end) { int b = *bp >> shift[channel]; if (++channel >= channels) channel = 0; *bp++ = (png_byte)b; } break; } #ifdef PNG_READ_16BIT_SUPPORTED case 16: /* Double byte components, G, GA, RGB, RGBA */ { png_bytep bp = row; png_bytep bp_end = bp + row_info->rowbytes; int channel = 0; while (bp < bp_end) { int value = (bp[0] << 8) + bp[1]; value >>= shift[channel]; if (++channel >= channels) channel = 0; *bp++ = (png_byte)(value >> 8); *bp++ = (png_byte)(value & 0xff); } break; } #endif } } } #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_row_infop row_info, png_bytep row) { png_debug(1, "in png_do_scale_16_to_8"); if (row_info->bit_depth == 16) { png_bytep sp = row; /* source */ png_bytep dp = row; /* destination */ png_bytep ep = sp + row_info->rowbytes; /* 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 += (((int)*sp++ - tmp + 128) * 65535) >> 24; *dp++ = (png_byte)tmp; } row_info->bit_depth = 8; row_info->pixel_depth = (png_byte)(8 * row_info->channels); row_info->rowbytes = row_info->width * row_info->channels; } } #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_row_infop row_info, png_bytep row) { png_debug(1, "in png_do_chop"); if (row_info->bit_depth == 16) { png_bytep sp = row; /* source */ png_bytep dp = row; /* destination */ png_bytep ep = sp + row_info->rowbytes; /* end+1 */ while (sp < ep) { *dp++ = *sp; sp += 2; /* skip low byte */ } row_info->bit_depth = 8; row_info->pixel_depth = (png_byte)(8 * row_info->channels); row_info->rowbytes = row_info->width * row_info->channels; } } #endif #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED static void png_do_read_swap_alpha(png_row_infop row_info, png_bytep row) { png_debug(1, "in png_do_read_swap_alpha"); { png_uint_32 row_width = row_info->width; if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) { /* This converts from RGBA to ARGB */ if (row_info->bit_depth == 8) { png_bytep sp = row + row_info->rowbytes; png_bytep dp = sp; png_byte save; png_uint_32 i; for (i = 0; i < row_width; i++) { save = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = save; } } #ifdef PNG_READ_16BIT_SUPPORTED /* This converts from RRGGBBAA to AARRGGBB */ else { png_bytep sp = row + row_info->rowbytes; png_bytep dp = sp; png_byte save[2]; png_uint_32 i; for (i = 0; i < row_width; i++) { save[0] = *(--sp); save[1] = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = save[0]; *(--dp) = save[1]; } } #endif } else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) { /* This converts from GA to AG */ if (row_info->bit_depth == 8) { png_bytep sp = row + row_info->rowbytes; png_bytep dp = sp; png_byte save; png_uint_32 i; for (i = 0; i < row_width; i++) { save = *(--sp); *(--dp) = *(--sp); *(--dp) = save; } } #ifdef PNG_READ_16BIT_SUPPORTED /* This converts from GGAA to AAGG */ else { png_bytep sp = row + row_info->rowbytes; png_bytep dp = sp; png_byte save[2]; png_uint_32 i; for (i = 0; i < row_width; i++) { save[0] = *(--sp); save[1] = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = save[0]; *(--dp) = save[1]; } } #endif } } } #endif #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED static void png_do_read_invert_alpha(png_row_infop row_info, png_bytep row) { png_uint_32 row_width; png_debug(1, "in png_do_read_invert_alpha"); row_width = row_info->width; if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) { if (row_info->bit_depth == 8) { /* This inverts the alpha channel in RGBA */ png_bytep sp = row + row_info->rowbytes; png_bytep dp = sp; png_uint_32 i; for (i = 0; i < row_width; i++) { *(--dp) = (png_byte)(255 - *(--sp)); /* This does nothing: *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); We can replace it with: */ sp-=3; dp=sp; } } #ifdef PNG_READ_16BIT_SUPPORTED /* This inverts the alpha channel in RRGGBBAA */ else { png_bytep sp = row + row_info->rowbytes; png_bytep dp = sp; png_uint_32 i; for (i = 0; i < row_width; i++) { *(--dp) = (png_byte)(255 - *(--sp)); *(--dp) = (png_byte)(255 - *(--sp)); /* This does nothing: *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); We can replace it with: */ sp-=6; dp=sp; } } #endif } else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) { if (row_info->bit_depth == 8) { /* This inverts the alpha channel in GA */ png_bytep sp = row + row_info->rowbytes; png_bytep dp = sp; png_uint_32 i; for (i = 0; i < row_width; i++) { *(--dp) = (png_byte)(255 - *(--sp)); *(--dp) = *(--sp); } } #ifdef PNG_READ_16BIT_SUPPORTED else { /* This inverts the alpha channel in GGAA */ png_bytep sp = row + row_info->rowbytes; png_bytep dp = sp; png_uint_32 i; for (i = 0; i < row_width; i++) { *(--dp) = (png_byte)(255 - *(--sp)); *(--dp) = (png_byte)(255 - *(--sp)); /* *(--dp) = *(--sp); *(--dp) = *(--sp); */ sp-=2; dp=sp; } } #endif } } #endif #ifdef PNG_READ_FILLER_SUPPORTED /* Add filler channel if we have RGB color */ static void png_do_read_filler(png_row_infop row_info, png_bytep row, png_uint_32 filler, png_uint_32 flags) { png_uint_32 i; png_uint_32 row_width = row_info->width; #ifdef PNG_READ_16BIT_SUPPORTED png_byte hi_filler = (png_byte)((filler>>8) & 0xff); #endif png_byte lo_filler = (png_byte)(filler & 0xff); png_debug(1, "in png_do_read_filler"); if ( row_info->color_type == PNG_COLOR_TYPE_GRAY) { if (row_info->bit_depth == 8) { if (flags & PNG_FLAG_FILLER_AFTER) { /* This changes the data from G to GX */ png_bytep sp = row + (png_size_t)row_width; png_bytep dp = sp + (png_size_t)row_width; for (i = 1; i < row_width; i++) { *(--dp) = lo_filler; *(--dp) = *(--sp); } *(--dp) = lo_filler; row_info->channels = 2; row_info->pixel_depth = 16; row_info->rowbytes = row_width * 2; } else { /* This changes the data from G to XG */ png_bytep sp = row + (png_size_t)row_width; png_bytep dp = sp + (png_size_t)row_width; for (i = 0; i < row_width; i++) { *(--dp) = *(--sp); *(--dp) = lo_filler; } row_info->channels = 2; row_info->pixel_depth = 16; row_info->rowbytes = row_width * 2; } } #ifdef PNG_READ_16BIT_SUPPORTED else if (row_info->bit_depth == 16) { if (flags & PNG_FLAG_FILLER_AFTER) { /* This changes the data from GG to GGXX */ png_bytep sp = row + (png_size_t)row_width * 2; png_bytep dp = sp + (png_size_t)row_width * 2; for (i = 1; i < row_width; i++) { *(--dp) = hi_filler; *(--dp) = lo_filler; *(--dp) = *(--sp); *(--dp) = *(--sp); } *(--dp) = hi_filler; *(--dp) = lo_filler; row_info->channels = 2; row_info->pixel_depth = 32; row_info->rowbytes = row_width * 4; } else { /* This changes the data from GG to XXGG */ png_bytep sp = row + (png_size_t)row_width * 2; png_bytep dp = sp + (png_size_t)row_width * 2; for (i = 0; i < row_width; i++) { *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = hi_filler; *(--dp) = lo_filler; } row_info->channels = 2; row_info->pixel_depth = 32; row_info->rowbytes = row_width * 4; } } #endif } /* COLOR_TYPE == GRAY */ else if (row_info->color_type == PNG_COLOR_TYPE_RGB) { if (row_info->bit_depth == 8) { if (flags & PNG_FLAG_FILLER_AFTER) { /* This changes the data from RGB to RGBX */ png_bytep sp = row + (png_size_t)row_width * 3; png_bytep dp = sp + (png_size_t)row_width; for (i = 1; i < row_width; i++) { *(--dp) = lo_filler; *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); } *(--dp) = lo_filler; row_info->channels = 4; row_info->pixel_depth = 32; row_info->rowbytes = row_width * 4; } else { /* This changes the data from RGB to XRGB */ png_bytep sp = row + (png_size_t)row_width * 3; png_bytep dp = sp + (png_size_t)row_width; for (i = 0; i < row_width; i++) { *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = lo_filler; } row_info->channels = 4; row_info->pixel_depth = 32; row_info->rowbytes = row_width * 4; } } #ifdef PNG_READ_16BIT_SUPPORTED else if (row_info->bit_depth == 16) { if (flags & PNG_FLAG_FILLER_AFTER) { /* This changes the data from RRGGBB to RRGGBBXX */ png_bytep sp = row + (png_size_t)row_width * 6; png_bytep dp = sp + (png_size_t)row_width * 2; for (i = 1; i < row_width; i++) { *(--dp) = hi_filler; *(--dp) = lo_filler; *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); } *(--dp) = hi_filler; *(--dp) = lo_filler; row_info->channels = 4; row_info->pixel_depth = 64; row_info->rowbytes = row_width * 8; } else { /* This changes the data from RRGGBB to XXRRGGBB */ png_bytep sp = row + (png_size_t)row_width * 6; png_bytep dp = sp + (png_size_t)row_width * 2; for (i = 0; i < row_width; i++) { *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = *(--sp); *(--dp) = hi_filler; *(--dp) = lo_filler; } row_info->channels = 4; row_info->pixel_depth = 64; row_info->rowbytes = row_width * 8; } } #endif } /* COLOR_TYPE == RGB */ } #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_row_infop row_info, png_bytep row) { png_uint_32 i; png_uint_32 row_width = row_info->width; png_debug(1, "in png_do_gray_to_rgb"); if (row_info->bit_depth >= 8 && !(row_info->color_type & PNG_COLOR_MASK_COLOR)) { if (row_info->color_type == PNG_COLOR_TYPE_GRAY) { if (row_info->bit_depth == 8) { /* This changes G to RGB */ png_bytep sp = row + (png_size_t)row_width - 1; png_bytep dp = sp + (png_size_t)row_width * 2; for (i = 0; i < row_width; i++) { *(dp--) = *sp; *(dp--) = *sp; *(dp--) = *(sp--); } } else { /* This changes GG to RRGGBB */ png_bytep sp = row + (png_size_t)row_width * 2 - 1; png_bytep dp = sp + (png_size_t)row_width * 4; for (i = 0; i < row_width; i++) { *(dp--) = *sp; *(dp--) = *(sp - 1); *(dp--) = *sp; *(dp--) = *(sp - 1); *(dp--) = *(sp--); *(dp--) = *(sp--); } } } else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) { if (row_info->bit_depth == 8) { /* This changes GA to RGBA */ png_bytep sp = row + (png_size_t)row_width * 2 - 1; png_bytep dp = sp + (png_size_t)row_width * 2; for (i = 0; i < row_width; i++) { *(dp--) = *(sp--); *(dp--) = *sp; *(dp--) = *sp; *(dp--) = *(sp--); } } else { /* This changes GGAA to RRGGBBAA */ png_bytep sp = row + (png_size_t)row_width * 4 - 1; png_bytep dp = sp + (png_size_t)row_width * 4; for (i = 0; i < row_width; i++) { *(dp--) = *(sp--); *(dp--) = *(sp--); *(dp--) = *sp; *(dp--) = *(sp - 1); *(dp--) = *sp; *(dp--) = *(sp - 1); *(dp--) = *(sp--); *(dp--) = *(sp--); } } } row_info->channels = (png_byte)(row_info->channels + 2); row_info->color_type |= PNG_COLOR_MASK_COLOR; row_info->pixel_depth = (png_byte)(row_info->channels * row_info->bit_depth); row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); } } #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 * <http://www.inforamp.net/~poynton/> (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): * <http://www.poynton.com/notes/colour_and_gamma/> * 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_structrp png_ptr, png_row_infop row_info, png_bytep row) { int rgb_error = 0; png_debug(1, "in png_do_rgb_to_gray"); if (!(row_info->color_type & PNG_COLOR_MASK_PALETTE) && (row_info->color_type & PNG_COLOR_MASK_COLOR)) { 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->color_type & PNG_COLOR_MASK_ALPHA) != 0; if (row_info->bit_depth == 8) { #ifdef PNG_READ_GAMMA_SUPPORTED /* 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_bytep sp = row; png_bytep dp = row; 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) { red = png_ptr->gamma_to_1[red]; green = png_ptr->gamma_to_1[green]; blue = png_ptr->gamma_to_1[blue]; rgb_error |= 1; *(dp++) = png_ptr->gamma_from_1[ (rc*red + gc*green + bc*blue + 16384)>>15]; } 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) *(dp++) = *(sp++); } } else #endif { png_bytep sp = row; png_bytep dp = row; 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; /* NOTE: this is the historical approach which simply * truncates the results. */ *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15); } else *(dp++) = red; if (have_alpha) *(dp++) = *(sp++); } } } else /* RGB bit_depth == 16 */ { #ifdef PNG_READ_GAMMA_SUPPORTED if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL) { png_bytep sp = row; png_bytep dp = row; png_uint_32 i; for (i = 0; i < row_width; i++) { png_uint_16 red, green, blue, w; red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; if (red == green && red == blue) { if (png_ptr->gamma_16_table != NULL) w = png_ptr->gamma_16_table[(red&0xff) >> png_ptr->gamma_shift][red>>8]; else w = red; } else { png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff) >> png_ptr->gamma_shift][red>>8]; png_uint_16 green_1 = png_ptr->gamma_16_to_1[(green&0xff) >> png_ptr->gamma_shift][green>>8]; png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff) >> png_ptr->gamma_shift][blue>>8]; png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1 + bc*blue_1 + 16384)>>15); w = png_ptr->gamma_16_from_1[(gray16&0xff) >> png_ptr->gamma_shift][gray16 >> 8]; rgb_error |= 1; } *(dp++) = (png_byte)((w>>8) & 0xff); *(dp++) = (png_byte)(w & 0xff); if (have_alpha) { *(dp++) = *(sp++); *(dp++) = *(sp++); } } } else #endif { png_bytep sp = row; png_bytep dp = row; png_uint_32 i; for (i = 0; i < row_width; i++) { png_uint_16 red, green, blue, gray16; red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; 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. */ gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >> 15); *(dp++) = (png_byte)((gray16>>8) & 0xff); *(dp++) = (png_byte)(gray16 & 0xff); if (have_alpha) { *(dp++) = *(sp++); *(dp++) = *(sp++); } } } } row_info->channels = (png_byte)(row_info->channels - 2); row_info->color_type = (png_byte)(row_info->color_type & ~PNG_COLOR_MASK_COLOR); row_info->pixel_depth = (png_byte)(row_info->channels * row_info->bit_depth); row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); } 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_row_infop row_info, png_bytep row, png_structrp png_ptr) { #ifdef PNG_READ_GAMMA_SUPPORTED png_const_bytep gamma_table = png_ptr->gamma_table; png_const_bytep gamma_from_1 = png_ptr->gamma_from_1; png_const_bytep gamma_to_1 = png_ptr->gamma_to_1; png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table; png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1; png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1; int gamma_shift = png_ptr->gamma_shift; int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0; #endif png_bytep sp; png_uint_32 i; png_uint_32 row_width = row_info->width; int shift; png_debug(1, "in png_do_compose"); { switch (row_info->color_type) { case PNG_COLOR_TYPE_GRAY: { switch (row_info->bit_depth) { case 1: { sp = row; shift = 7; for (i = 0; i < row_width; i++) { if ((png_uint_16)((*sp >> shift) & 0x01) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0x7f7f >> (7 - shift)); tmp |= png_ptr->background.gray << shift; *sp = (png_byte)(tmp & 0xff); } if (!shift) { shift = 7; sp++; } else shift--; } break; } case 2: { #ifdef PNG_READ_GAMMA_SUPPORTED if (gamma_table != NULL) { sp = row; shift = 6; for (i = 0; i < row_width; i++) { if ((png_uint_16)((*sp >> shift) & 0x03) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0x3f3f >> (6 - shift)); tmp |= png_ptr->background.gray << shift; *sp = (png_byte)(tmp & 0xff); } else { unsigned int p = (*sp >> shift) & 0x03; unsigned int g = (gamma_table [p | (p << 2) | (p << 4) | (p << 6)] >> 6) & 0x03; unsigned int tmp = *sp & (0x3f3f >> (6 - shift)); tmp |= g << shift; *sp = (png_byte)(tmp & 0xff); } if (!shift) { shift = 6; sp++; } else shift -= 2; } } else #endif { sp = row; shift = 6; for (i = 0; i < row_width; i++) { if ((png_uint_16)((*sp >> shift) & 0x03) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0x3f3f >> (6 - shift)); tmp |= png_ptr->background.gray << shift; *sp = (png_byte)(tmp & 0xff); } if (!shift) { shift = 6; sp++; } else shift -= 2; } } break; } case 4: { #ifdef PNG_READ_GAMMA_SUPPORTED if (gamma_table != NULL) { sp = row; shift = 4; for (i = 0; i < row_width; i++) { if ((png_uint_16)((*sp >> shift) & 0x0f) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0xf0f >> (4 - shift)); tmp |= png_ptr->background.gray << shift; *sp = (png_byte)(tmp & 0xff); } else { unsigned int p = (*sp >> shift) & 0x0f; unsigned int g = (gamma_table[p | (p << 4)] >> 4) & 0x0f; unsigned int tmp = *sp & (0xf0f >> (4 - shift)); tmp |= g << shift; *sp = (png_byte)(tmp & 0xff); } if (!shift) { shift = 4; sp++; } else shift -= 4; } } else #endif { sp = row; shift = 4; for (i = 0; i < row_width; i++) { if ((png_uint_16)((*sp >> shift) & 0x0f) == png_ptr->trans_color.gray) { unsigned int tmp = *sp & (0xf0f >> (4 - shift)); tmp |= png_ptr->background.gray << shift; *sp = (png_byte)(tmp & 0xff); } if (!shift) { shift = 4; sp++; } else shift -= 4; } } break; } case 8: { #ifdef PNG_READ_GAMMA_SUPPORTED if (gamma_table != NULL) { sp = row; for (i = 0; i < row_width; i++, sp++) { if (*sp == png_ptr->trans_color.gray) *sp = (png_byte)png_ptr->background.gray; else *sp = gamma_table[*sp]; } } else #endif { sp = row; for (i = 0; i < row_width; i++, sp++) { if (*sp == png_ptr->trans_color.gray) *sp = (png_byte)png_ptr->background.gray; } } break; } case 16: { #ifdef PNG_READ_GAMMA_SUPPORTED if (gamma_16 != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 2) { png_uint_16 v; v = (png_uint_16)(((*sp) << 8) + *(sp + 1)); if (v == png_ptr->trans_color.gray) { /* Background is already in screen gamma */ *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff); *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff); } else { v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); } } } else #endif { sp = row; for (i = 0; i < row_width; i++, sp += 2) { png_uint_16 v; v = (png_uint_16)(((*sp) << 8) + *(sp + 1)); if (v == png_ptr->trans_color.gray) { *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff); *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff); } } } break; } default: break; } break; } case PNG_COLOR_TYPE_RGB: { if (row_info->bit_depth == 8) { #ifdef PNG_READ_GAMMA_SUPPORTED 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_byte)png_ptr->background.red; *(sp + 1) = (png_byte)png_ptr->background.green; *(sp + 2) = (png_byte)png_ptr->background.blue; } else { *sp = gamma_table[*sp]; *(sp + 1) = gamma_table[*(sp + 1)]; *(sp + 2) = gamma_table[*(sp + 2)]; } } } else #endif { 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_byte)png_ptr->background.red; *(sp + 1) = (png_byte)png_ptr->background.green; *(sp + 2) = (png_byte)png_ptr->background.blue; } } } } else /* if (row_info->bit_depth == 16) */ { #ifdef PNG_READ_GAMMA_SUPPORTED if (gamma_16 != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 6) { png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1)); png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8) + *(sp + 3)); png_uint_16 b = (png_uint_16)(((*(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_byte)((png_ptr->background.red >> 8) & 0xff); *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff); *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff); *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff); *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); } else { png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)]; *(sp + 2) = (png_byte)((v >> 8) & 0xff); *(sp + 3) = (png_byte)(v & 0xff); v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)]; *(sp + 4) = (png_byte)((v >> 8) & 0xff); *(sp + 5) = (png_byte)(v & 0xff); } } } else #endif { sp = row; for (i = 0; i < row_width; i++, sp += 6) { png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1)); png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8) + *(sp + 3)); png_uint_16 b = (png_uint_16)(((*(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)((png_ptr->background.red >> 8) & 0xff); *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff); *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff); *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff); *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); } } } } break; } case PNG_COLOR_TYPE_GRAY_ALPHA: { if (row_info->bit_depth == 8) { #ifdef PNG_READ_GAMMA_SUPPORTED if (gamma_to_1 != NULL && gamma_from_1 != NULL && gamma_table != NULL) { sp = row; for (i = 0; i < row_width; i++, sp += 2) { png_uint_16 a = *(sp + 1); if (a == 0xff) *sp = gamma_table[*sp]; else if (a == 0) { /* Background is already in screen gamma */ *sp = (png_byte)png_ptr->background.gray; } else { png_byte v, w; v = gamma_to_1[*sp]; png_composite(w, v, a, png_ptr->background_1.gray); if (!optimize) w = gamma_from_1[w]; *sp = w; } } } else #endif { sp = row; for (i = 0; i < row_width; i++, sp += 2) { png_byte a = *(sp + 1); if (a == 0) *sp = (png_byte)png_ptr->background.gray; else if (a < 0xff) png_composite(*sp, *sp, a, png_ptr->background.gray); } } } else /* if (png_ptr->bit_depth == 16) */ { #ifdef PNG_READ_GAMMA_SUPPORTED 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_uint_16)(((*(sp + 2)) << 8) + *(sp + 3)); if (a == (png_uint_16)0xffff) { png_uint_16 v; v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); } else if (a == 0) { /* Background is already in screen gamma */ *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff); *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff); } else { png_uint_16 g, v, w; g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp]; png_composite_16(v, g, a, png_ptr->background_1.gray); if (optimize) w = v; else w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8]; *sp = (png_byte)((w >> 8) & 0xff); *(sp + 1) = (png_byte)(w & 0xff); } } } else #endif { sp = row; for (i = 0; i < row_width; i++, sp += 4) { png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8) + *(sp + 3)); if (a == 0) { *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff); *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff); } else if (a < 0xffff) { png_uint_16 g, v; g = (png_uint_16)(((*sp) << 8) + *(sp + 1)); png_composite_16(v, g, a, png_ptr->background.gray); *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); } } } } break; } case PNG_COLOR_TYPE_RGB_ALPHA: { if (row_info->bit_depth == 8) { #ifdef PNG_READ_GAMMA_SUPPORTED 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_byte)png_ptr->background.red; *(sp + 1) = (png_byte)png_ptr->background.green; *(sp + 2) = (png_byte)png_ptr->background.blue; } else { png_byte v, w; v = gamma_to_1[*sp]; png_composite(w, v, a, png_ptr->background_1.red); if (!optimize) w = gamma_from_1[w]; *sp = w; v = gamma_to_1[*(sp + 1)]; png_composite(w, v, a, png_ptr->background_1.green); if (!optimize) w = gamma_from_1[w]; *(sp + 1) = w; v = gamma_to_1[*(sp + 2)]; png_composite(w, v, a, png_ptr->background_1.blue); if (!optimize) w = gamma_from_1[w]; *(sp + 2) = w; } } } else #endif { sp = row; for (i = 0; i < row_width; i++, sp += 4) { png_byte a = *(sp + 3); if (a == 0) { *sp = (png_byte)png_ptr->background.red; *(sp + 1) = (png_byte)png_ptr->background.green; *(sp + 2) = (png_byte)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) */ { #ifdef PNG_READ_GAMMA_SUPPORTED 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_uint_16)(((png_uint_16)(*(sp + 6)) << 8) + (png_uint_16)(*(sp + 7))); if (a == (png_uint_16)0xffff) { png_uint_16 v; v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)]; *(sp + 2) = (png_byte)((v >> 8) & 0xff); *(sp + 3) = (png_byte)(v & 0xff); v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)]; *(sp + 4) = (png_byte)((v >> 8) & 0xff); *(sp + 5) = (png_byte)(v & 0xff); } else if (a == 0) { /* Background is already in screen gamma */ *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff); *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff); *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff); *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); } else { png_uint_16 v, w; v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp]; png_composite_16(w, v, a, png_ptr->background_1.red); if (!optimize) w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8]; *sp = (png_byte)((w >> 8) & 0xff); *(sp + 1) = (png_byte)(w & 0xff); v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)]; png_composite_16(w, v, a, png_ptr->background_1.green); if (!optimize) w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8]; *(sp + 2) = (png_byte)((w >> 8) & 0xff); *(sp + 3) = (png_byte)(w & 0xff); v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)]; png_composite_16(w, v, a, png_ptr->background_1.blue); if (!optimize) w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8]; *(sp + 4) = (png_byte)((w >> 8) & 0xff); *(sp + 5) = (png_byte)(w & 0xff); } } } else #endif { sp = row; for (i = 0; i < row_width; i++, sp += 8) { png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6)) << 8) + (png_uint_16)(*(sp + 7))); if (a == 0) { *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff); *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff); *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff); *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); } else if (a < 0xffff) { png_uint_16 v; png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1)); png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8) + *(sp + 3)); png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8) + *(sp + 5)); png_composite_16(v, r, a, png_ptr->background.red); *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); png_composite_16(v, g, a, png_ptr->background.green); *(sp + 2) = (png_byte)((v >> 8) & 0xff); *(sp + 3) = (png_byte)(v & 0xff); png_composite_16(v, b, a, png_ptr->background.blue); *(sp + 4) = (png_byte)((v >> 8) & 0xff); *(sp + 5) = (png_byte)(v & 0xff); } } } } break; } default: break; } } } #endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_READ_ALPHA_MODE_SUPPORTED */ #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_row_infop row_info, png_bytep row, png_structrp png_ptr) { png_const_bytep gamma_table = png_ptr->gamma_table; png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table; int gamma_shift = png_ptr->gamma_shift; png_bytep sp; png_uint_32 i; png_uint_32 row_width=row_info->width; png_debug(1, "in png_do_gamma"); if (((row_info->bit_depth <= 8 && gamma_table != NULL) || (row_info->bit_depth == 16 && gamma_16_table != NULL))) { switch (row_info->color_type) { case PNG_COLOR_TYPE_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 + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); sp += 2; v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); sp += 2; v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); sp += 2; } } break; } case PNG_COLOR_TYPE_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 = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); sp += 2; v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); sp += 2; v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); sp += 4; } } break; } case PNG_COLOR_TYPE_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 = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); sp += 4; } } break; } case PNG_COLOR_TYPE_GRAY: { if (row_info->bit_depth == 2) { sp = row; for (i = 0; i < row_width; i += 4) { int a = *sp & 0xc0; int b = *sp & 0x30; int c = *sp & 0x0c; int d = *sp & 0x03; *sp = (png_byte)( ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)| ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)| ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)| ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) )); sp++; } } if (row_info->bit_depth == 4) { sp = row; for (i = 0; i < row_width; i += 2) { int msb = *sp & 0xf0; int lsb = *sp & 0x0f; *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0) | (((int)gamma_table[(lsb << 4) | lsb]) >> 4)); sp++; } } else if (row_info->bit_depth == 8) { sp = row; for (i = 0; i < row_width; i++) { *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 = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; *sp = (png_byte)((v >> 8) & 0xff); *(sp + 1) = (png_byte)(v & 0xff); 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_row_infop row_info, png_bytep row, png_structrp png_ptr) { png_uint_32 row_width = row_info->width; png_debug(1, "in png_do_encode_alpha"); if (row_info->color_type & PNG_COLOR_MASK_ALPHA) { if (row_info->bit_depth == 8) { PNG_CONST png_bytep table = png_ptr->gamma_from_1; if (table != NULL) { PNG_CONST int step = (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2; /* The alpha channel is the last component: */ row += step - 1; for (; row_width > 0; --row_width, row += step) *row = table[*row]; return; } } else if (row_info->bit_depth == 16) { PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1; PNG_CONST int gamma_shift = png_ptr->gamma_shift; if (table != NULL) { PNG_CONST int step = (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4; /* The alpha channel is the last component: */ row += step - 2; for (; row_width > 0; --row_width, row += step) { png_uint_16 v; v = table[*(row + 1) >> gamma_shift][*row]; *row = (png_byte)((v >> 8) & 0xff); *(row + 1) = (png_byte)(v & 0xff); } return; } } } /* Only get to here if called with a weird row_info; no harm has been done, * so just issue a warning. */ png_warning(png_ptr, "png_do_encode_alpha: unexpected call"); } #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_row_infop row_info, png_bytep row, png_const_colorp palette, png_const_bytep trans_alpha, int num_trans) { int shift, value; png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width=row_info->width; png_debug(1, "in png_do_expand_palette"); if (row_info->color_type == PNG_COLOR_TYPE_PALETTE) { if (row_info->bit_depth < 8) { switch (row_info->bit_depth) { case 1: { sp = row + (png_size_t)((row_width - 1) >> 3); dp = row + (png_size_t)row_width - 1; shift = 7 - (int)((row_width + 7) & 0x07); for (i = 0; i < row_width; i++) { if ((*sp >> shift) & 0x01) *dp = 1; else *dp = 0; if (shift == 7) { shift = 0; sp--; } else shift++; dp--; } break; } case 2: { sp = row + (png_size_t)((row_width - 1) >> 2); dp = row + (png_size_t)row_width - 1; shift = (int)((3 - ((row_width + 3) & 0x03)) << 1); for (i = 0; i < row_width; i++) { value = (*sp >> shift) & 0x03; *dp = (png_byte)value; if (shift == 6) { shift = 0; sp--; } else shift += 2; dp--; } break; } case 4: { sp = row + (png_size_t)((row_width - 1) >> 1); dp = row + (png_size_t)row_width - 1; shift = (int)((row_width & 0x01) << 2); for (i = 0; i < row_width; i++) { value = (*sp >> shift) & 0x0f; *dp = (png_byte)value; if (shift == 4) { shift = 0; sp--; } else shift += 4; dp--; } break; } default: break; } row_info->bit_depth = 8; row_info->pixel_depth = 8; row_info->rowbytes = row_width; } if (row_info->bit_depth == 8) { { if (num_trans > 0) { sp = row + (png_size_t)row_width - 1; dp = row + (png_size_t)(row_width << 2) - 1; for (i = 0; i < row_width; i++) { if ((int)(*sp) >= num_trans) *dp-- = 0xff; else *dp-- = trans_alpha[*sp]; *dp-- = palette[*sp].blue; *dp-- = palette[*sp].green; *dp-- = palette[*sp].red; sp--; } row_info->bit_depth = 8; row_info->pixel_depth = 32; row_info->rowbytes = row_width * 4; row_info->color_type = 6; row_info->channels = 4; } else { sp = row + (png_size_t)row_width - 1; dp = row + (png_size_t)(row_width * 3) - 1; for (i = 0; i < row_width; i++) { *dp-- = palette[*sp].blue; *dp-- = palette[*sp].green; *dp-- = palette[*sp].red; sp--; } row_info->bit_depth = 8; row_info->pixel_depth = 24; row_info->rowbytes = row_width * 3; row_info->color_type = 2; row_info->channels = 3; } } } } } /* 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_row_infop row_info, png_bytep row, png_const_color_16p trans_color) { int shift, value; png_bytep sp, dp; png_uint_32 i; png_uint_32 row_width=row_info->width; png_debug(1, "in png_do_expand"); { if (row_info->color_type == PNG_COLOR_TYPE_GRAY) { unsigned int gray = trans_color ? trans_color->gray : 0; if (row_info->bit_depth < 8) { switch (row_info->bit_depth) { case 1: { gray = (gray & 0x01) * 0xff; sp = row + (png_size_t)((row_width - 1) >> 3); dp = row + (png_size_t)row_width - 1; shift = 7 - (int)((row_width + 7) & 0x07); for (i = 0; i < row_width; i++) { if ((*sp >> shift) & 0x01) *dp = 0xff; else *dp = 0; if (shift == 7) { shift = 0; sp--; } else shift++; dp--; } break; } case 2: { gray = (gray & 0x03) * 0x55; sp = row + (png_size_t)((row_width - 1) >> 2); dp = row + (png_size_t)row_width - 1; shift = (int)((3 - ((row_width + 3) & 0x03)) << 1); for (i = 0; i < row_width; i++) { value = (*sp >> shift) & 0x03; *dp = (png_byte)(value | (value << 2) | (value << 4) | (value << 6)); if (shift == 6) { shift = 0; sp--; } else shift += 2; dp--; } break; } case 4: { gray = (gray & 0x0f) * 0x11; sp = row + (png_size_t)((row_width - 1) >> 1); dp = row + (png_size_t)row_width - 1; shift = (int)((1 - ((row_width + 1) & 0x01)) << 2); for (i = 0; i < row_width; i++) { value = (*sp >> shift) & 0x0f; *dp = (png_byte)(value | (value << 4)); if (shift == 4) { shift = 0; sp--; } else shift = 4; dp--; } break; } default: break; } row_info->bit_depth = 8; row_info->pixel_depth = 8; row_info->rowbytes = row_width; } if (trans_color != NULL) { if (row_info->bit_depth == 8) { gray = gray & 0xff; sp = row + (png_size_t)row_width - 1; dp = row + (png_size_t)(row_width << 1) - 1; for (i = 0; i < row_width; i++) { if (*sp == gray) *dp-- = 0; else *dp-- = 0xff; *dp-- = *sp--; } } else if (row_info->bit_depth == 16) { unsigned int gray_high = (gray >> 8) & 0xff; unsigned int gray_low = gray & 0xff; sp = row + row_info->rowbytes - 1; dp = row + (row_info->rowbytes << 1) - 1; for (i = 0; i < row_width; i++) { if (*(sp - 1) == gray_high && *(sp) == gray_low) { *dp-- = 0; *dp-- = 0; } else { *dp-- = 0xff; *dp-- = 0xff; } *dp-- = *sp--; *dp-- = *sp--; } } row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA; row_info->channels = 2; row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1); row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); } } else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_color) { if (row_info->bit_depth == 8) { png_byte red = (png_byte)(trans_color->red & 0xff); png_byte green = (png_byte)(trans_color->green & 0xff); png_byte blue = (png_byte)(trans_color->blue & 0xff); sp = row + (png_size_t)row_info->rowbytes - 1; dp = row + (png_size_t)(row_width << 2) - 1; for (i = 0; i < row_width; i++) { if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue) *dp-- = 0; else *dp-- = 0xff; *dp-- = *sp--; *dp-- = *sp--; *dp-- = *sp--; } } else if (row_info->bit_depth == 16) { png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff); png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff); png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff); png_byte red_low = (png_byte)(trans_color->red & 0xff); png_byte green_low = (png_byte)(trans_color->green & 0xff); png_byte blue_low = (png_byte)(trans_color->blue & 0xff); sp = row + row_info->rowbytes - 1; dp = row + (png_size_t)(row_width << 3) - 1; for (i = 0; i < row_width; i++) { if (*(sp - 5) == red_high && *(sp - 4) == red_low && *(sp - 3) == green_high && *(sp - 2) == green_low && *(sp - 1) == blue_high && *(sp ) == blue_low) { *dp-- = 0; *dp-- = 0; } else { *dp-- = 0xff; *dp-- = 0xff; } *dp-- = *sp--; *dp-- = *sp--; *dp-- = *sp--; *dp-- = *sp--; *dp-- = *sp--; *dp-- = *sp--; } } row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA; row_info->channels = 4; row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2); row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); } } } #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_row_infop row_info, png_bytep row) { if (row_info->bit_depth == 8 && row_info->color_type != PNG_COLOR_TYPE_PALETTE) { /* The row 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_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */ png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */ while (dp > sp) dp[-2] = dp[-1] = *--sp, dp -= 2; row_info->rowbytes *= 2; row_info->bit_depth = 16; row_info->pixel_depth = (png_byte)(row_info->channels * 16); } } #endif #ifdef PNG_READ_QUANTIZE_SUPPORTED static void png_do_quantize(png_row_infop row_info, png_bytep row, png_const_bytep palette_lookup, png_const_bytep quantize_lookup) { 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) { if (row_info->color_type == PNG_COLOR_TYPE_RGB && 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->color_type = PNG_COLOR_TYPE_PALETTE; row_info->channels = 1; row_info->pixel_depth = row_info->bit_depth; row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); } else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA && 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->color_type = PNG_COLOR_TYPE_PALETTE; row_info->channels = 1; row_info->pixel_depth = row_info->bit_depth; row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); } else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE && quantize_lookup) { sp = row; for (i = 0; i < row_width; i++, sp++) { *sp = quantize_lookup[*sp]; } } } } #endif /* PNG_READ_QUANTIZE_SUPPORTED */ /* 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) { png_debug(1, "in png_do_read_transformations"); if (png_ptr->row_buf == NULL) { /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this * error is incredibly rare and incredibly easy to debug without this * information. */ png_error(png_ptr, "NULL row buffer"); } /* 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)) { /* 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, "Uninitialized row"); } #ifdef PNG_READ_EXPAND_SUPPORTED if (png_ptr->transformations & PNG_EXPAND) { if (row_info->color_type == PNG_COLOR_TYPE_PALETTE) { png_do_expand_palette(row_info, png_ptr->row_buf + 1, png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans); } else { if (png_ptr->num_trans && (png_ptr->transformations & PNG_EXPAND_tRNS)) png_do_expand(row_info, png_ptr->row_buf + 1, &(png_ptr->trans_color)); else png_do_expand(row_info, png_ptr->row_buf + 1, NULL); } } #endif #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_STRIP_ALPHA) && !(png_ptr->transformations & PNG_COMPOSE) && (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA || row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)) png_do_strip_channel(row_info, 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) { int rgb_error = png_do_rgb_to_gray(png_ptr, row_info, png_ptr->row_buf + 1); if (rgb_error) { 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) && !(png_ptr->mode & PNG_BACKGROUND_IS_GRAY)) png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1); #endif #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ defined(PNG_READ_ALPHA_MODE_SUPPORTED) if (png_ptr->transformations & PNG_COMPOSE) png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr); #endif #ifdef PNG_READ_GAMMA_SUPPORTED if ((png_ptr->transformations & PNG_GAMMA) && #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED /* Because RGB_TO_GRAY does the gamma transform. */ !(png_ptr->transformations & PNG_RGB_TO_GRAY) && #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.) */ !((png_ptr->transformations & PNG_COMPOSE) && ((png_ptr->num_trans != 0) || (png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) && #endif /* Because png_init_read_transformations transforms the palette, unless * RGB_TO_GRAY will do the transform. */ (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)) png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr); #endif #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED if ((png_ptr->transformations & PNG_STRIP_ALPHA) && (png_ptr->transformations & PNG_COMPOSE) && (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA || row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)) png_do_strip_channel(row_info, 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) && (row_info->color_type & PNG_COLOR_MASK_ALPHA)) png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr); #endif #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED if (png_ptr->transformations & PNG_SCALE_16_TO_8) png_do_scale_16_to_8(row_info, 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) png_do_chop(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_QUANTIZE_SUPPORTED if (png_ptr->transformations & PNG_QUANTIZE) { png_do_quantize(row_info, png_ptr->row_buf + 1, png_ptr->palette_lookup, png_ptr->quantize_index); if (row_info->rowbytes == 0) png_error(png_ptr, "png_do_quantize returned rowbytes=0"); } #endif /* PNG_READ_QUANTIZE_SUPPORTED */ #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) png_do_expand_16(row_info, 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) && (png_ptr->mode & PNG_BACKGROUND_IS_GRAY)) png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_INVERT_SUPPORTED if (png_ptr->transformations & PNG_INVERT_MONO) png_do_invert(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED if (png_ptr->transformations & PNG_INVERT_ALPHA) png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_SHIFT_SUPPORTED if (png_ptr->transformations & PNG_SHIFT) png_do_unshift(row_info, png_ptr->row_buf + 1, &(png_ptr->shift)); #endif #ifdef PNG_READ_PACK_SUPPORTED if (png_ptr->transformations & PNG_PACK) png_do_unpack(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED /* Added at libpng-1.5.10 */ if (row_info->color_type == PNG_COLOR_TYPE_PALETTE && png_ptr->num_palette_max >= 0) png_do_check_palette_indexes(png_ptr, row_info); #endif #ifdef PNG_READ_BGR_SUPPORTED if (png_ptr->transformations & PNG_BGR) png_do_bgr(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_PACKSWAP_SUPPORTED if (png_ptr->transformations & PNG_PACKSWAP) png_do_packswap(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_FILLER_SUPPORTED if (png_ptr->transformations & PNG_FILLER) png_do_read_filler(row_info, png_ptr->row_buf + 1, (png_uint_32)png_ptr->filler, png_ptr->flags); #endif #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED if (png_ptr->transformations & PNG_SWAP_ALPHA) png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1); #endif #ifdef PNG_READ_16BIT_SUPPORTED #ifdef PNG_READ_SWAP_SUPPORTED if (png_ptr->transformations & PNG_SWAP_BYTES) png_do_swap(row_info, png_ptr->row_buf + 1); #endif #endif #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED if (png_ptr->transformations & PNG_USER_TRANSFORM) { if (png_ptr->read_user_transform_fn != NULL) (*(png_ptr->read_user_transform_fn)) /* User read transform function */ (png_ptr, /* png_ptr */ row_info, /* 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) row_info->bit_depth = png_ptr->user_transform_depth; if (png_ptr->user_transform_channels) row_info->channels = png_ptr->user_transform_channels; #endif row_info->pixel_depth = (png_byte)(row_info->bit_depth * row_info->channels); row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width); } #endif } #endif /* PNG_READ_TRANSFORMS_SUPPORTED */ #endif /* PNG_READ_SUPPORTED */