| |
| /* pngrtran.c - transforms the data in a row for PNG readers |
| * |
| * Copyright (c) 2018-2019 Cosmin Truta |
| * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson |
| * Copyright (c) 1996-1997 Andreas Dilger |
| * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc. |
| * |
| * This code is released under the libpng license. |
| * For conditions of distribution and use, see the disclaimer |
| * and license in png.h |
| * |
| * This file contains 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_ARM_NEON_IMPLEMENTATION |
| # if PNG_ARM_NEON_IMPLEMENTATION == 1 |
| # define PNG_ARM_NEON_INTRINSICS_AVAILABLE |
| # if defined(_MSC_VER) && !defined(__clang__) && defined(_M_ARM64) |
| # include <arm64_neon.h> |
| # else |
| # include <arm_neon.h> |
| # endif |
| # endif |
| #endif |
| |
| #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"); |
| /* FALLTHROUGH */ |
| case PNG_CRC_ERROR_QUIT: /* Error/quit */ |
| |
| case PNG_CRC_DEFAULT: |
| default: |
| png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; |
| break; |
| } |
| |
| /* Tell libpng how we react to CRC errors in ancillary chunks */ |
| switch (ancil_action) |
| { |
| case PNG_CRC_NO_CHANGE: /* Leave setting as is */ |
| break; |
| |
| case PNG_CRC_WARN_USE: /* Warn/use data */ |
| png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; |
| png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE; |
| break; |
| |
| case PNG_CRC_QUIET_USE: /* Quiet/use data */ |
| png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; |
| png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE | |
| PNG_FLAG_CRC_ANCILLARY_NOWARN; |
| break; |
| |
| case PNG_CRC_ERROR_QUIT: /* Error/quit */ |
| png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; |
| png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN; |
| break; |
| |
| case PNG_CRC_WARN_DISCARD: /* Warn/discard data */ |
| |
| case PNG_CRC_DEFAULT: |
| default: |
| png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; |
| break; |
| } |
| } |
| |
| #ifdef PNG_READ_TRANSFORMS_SUPPORTED |
| /* Is it OK to set a transformation now? Only if png_start_read_image or |
| * png_read_update_info have not been called. It is not necessary for the IHDR |
| * to have been read in all cases; the need_IHDR parameter allows for this |
| * check too. |
| */ |
| static int |
| png_rtran_ok(png_structrp png_ptr, int need_IHDR) |
| { |
| if (png_ptr != NULL) |
| { |
| if ((png_ptr->flags & PNG_FLAG_ROW_INIT) != 0) |
| png_app_error(png_ptr, |
| "invalid after png_start_read_image or png_read_update_info"); |
| |
| else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0) |
| png_app_error(png_ptr, "invalid before the PNG header has been read"); |
| |
| else |
| { |
| /* Turn on failure to initialize correctly for all transforms. */ |
| png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED; |
| |
| return 1; /* Ok */ |
| } |
| } |
| |
| return 0; /* no png_error possible! */ |
| } |
| #endif |
| |
| #ifdef PNG_READ_BACKGROUND_SUPPORTED |
| /* Handle alpha and tRNS via a background color */ |
| void PNGFAPI |
| png_set_background_fixed(png_structrp png_ptr, |
| png_const_color_16p background_color, int background_gamma_code, |
| int need_expand, png_fixed_point background_gamma) |
| { |
| png_debug(1, "in png_set_background_fixed"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0 || background_color == NULL) |
| return; |
| |
| if (background_gamma_code == PNG_BACKGROUND_GAMMA_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 != 0) |
| 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) == 0) |
| return; |
| |
| png_ptr->transformations |= PNG_SCALE_16_TO_8; |
| } |
| #endif |
| |
| #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED |
| /* Chop 16-bit depth files to 8-bit depth */ |
| void PNGAPI |
| png_set_strip_16(png_structrp png_ptr) |
| { |
| png_debug(1, "in png_set_strip_16"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| png_ptr->transformations |= PNG_16_TO_8; |
| } |
| #endif |
| |
| #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED |
| void PNGAPI |
| png_set_strip_alpha(png_structrp png_ptr) |
| { |
| png_debug(1, "in png_set_strip_alpha"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| png_ptr->transformations |= PNG_STRIP_ALPHA; |
| } |
| #endif |
| |
| #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED) |
| static png_fixed_point |
| translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma, |
| int is_screen) |
| { |
| /* Check for flag values. The main reason for having the old Mac value as a |
| * flag is that it is pretty near impossible to work out what the correct |
| * value is from Apple documentation - a working Mac system is needed to |
| * discover the value! |
| */ |
| if (output_gamma == PNG_DEFAULT_sRGB || |
| output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB) |
| { |
| /* If there is no sRGB support this just sets the gamma to the standard |
| * sRGB value. (This is a side effect of using this function!) |
| */ |
| # ifdef PNG_READ_sRGB_SUPPORTED |
| png_ptr->flags |= PNG_FLAG_ASSUME_sRGB; |
| # else |
| PNG_UNUSED(png_ptr) |
| # endif |
| if (is_screen != 0) |
| output_gamma = PNG_GAMMA_sRGB; |
| else |
| output_gamma = PNG_GAMMA_sRGB_INVERSE; |
| } |
| |
| else if (output_gamma == PNG_GAMMA_MAC_18 || |
| output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18) |
| { |
| if (is_screen != 0) |
| output_gamma = PNG_GAMMA_MAC_OLD; |
| else |
| output_gamma = PNG_GAMMA_MAC_INVERSE; |
| } |
| |
| return output_gamma; |
| } |
| |
| # ifdef PNG_FLOATING_POINT_SUPPORTED |
| static png_fixed_point |
| convert_gamma_value(png_structrp png_ptr, double output_gamma) |
| { |
| /* The following silently ignores cases where fixed point (times 100,000) |
| * gamma values are passed to the floating point API. This is safe and it |
| * means the fixed point constants work just fine with the floating point |
| * API. The alternative would just lead to undetected errors and spurious |
| * bug reports. Negative values fail inside the _fixed API unless they |
| * correspond to the flag values. |
| */ |
| if (output_gamma > 0 && output_gamma < 128) |
| output_gamma *= 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) == 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: |
| * |
| * 1.6.x: changed from 0.07..3 to 0.01..100 (to accommodate the optimal 16-bit |
| * gamma of 36, and its reciprocal.) |
| */ |
| if (output_gamma < 1000 || output_gamma > 10000000) |
| png_error(png_ptr, "output gamma out of expected range"); |
| |
| /* The default file gamma is the inverse of the output gamma; the output |
| * gamma may be changed below so get the file value first: |
| */ |
| file_gamma = png_reciprocal(output_gamma); |
| |
| /* There are really 8 possibilities here, composed of any combination |
| * of: |
| * |
| * premultiply the color channels |
| * do not encode non-opaque pixels |
| * encode the alpha as well as the color channels |
| * |
| * The differences disappear if the input/output ('screen') gamma is 1.0, |
| * because then the encoding is a no-op and there is only the choice of |
| * premultiplying the color channels or not. |
| * |
| * png_set_alpha_mode and png_set_background interact because both use |
| * png_compose to do the work. Calling both is only useful when |
| * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along |
| * with a default gamma value. Otherwise PNG_COMPOSE must not be set. |
| */ |
| switch (mode) |
| { |
| case PNG_ALPHA_PNG: /* default: png standard */ |
| /* No compose, but it may be set by png_set_background! */ |
| png_ptr->transformations &= ~PNG_ENCODE_ALPHA; |
| png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; |
| break; |
| |
| case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */ |
| compose = 1; |
| png_ptr->transformations &= ~PNG_ENCODE_ALPHA; |
| png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; |
| /* The output is linear: */ |
| output_gamma = PNG_FP_1; |
| break; |
| |
| case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */ |
| compose = 1; |
| png_ptr->transformations &= ~PNG_ENCODE_ALPHA; |
| png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA; |
| /* output_gamma records the encoding of opaque pixels! */ |
| break; |
| |
| case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */ |
| compose = 1; |
| png_ptr->transformations |= PNG_ENCODE_ALPHA; |
| png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; |
| break; |
| |
| default: |
| png_error(png_ptr, "invalid alpha mode"); |
| } |
| |
| /* Only set the default gamma if the file gamma has not been set (this has |
| * the side effect that the gamma in a second call to png_set_alpha_mode will |
| * be ignored.) |
| */ |
| if (png_ptr->colorspace.gamma == 0) |
| { |
| png_ptr->colorspace.gamma = file_gamma; |
| png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; |
| } |
| |
| /* But always set the output gamma: */ |
| png_ptr->screen_gamma = output_gamma; |
| |
| /* Finally, if pre-multiplying, set the background fields to achieve the |
| * desired result. |
| */ |
| if (compose != 0) |
| { |
| /* And obtain alpha pre-multiplication by composing on black: */ |
| memset(&png_ptr->background, 0, (sizeof png_ptr->background)); |
| png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */ |
| png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE; |
| png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND; |
| |
| if ((png_ptr->transformations & PNG_COMPOSE) != 0) |
| png_error(png_ptr, |
| "conflicting calls to set alpha mode and background"); |
| |
| png_ptr->transformations |= PNG_COMPOSE; |
| } |
| } |
| |
| # ifdef PNG_FLOATING_POINT_SUPPORTED |
| void PNGAPI |
| png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma) |
| { |
| png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr, |
| output_gamma)); |
| } |
| # endif |
| #endif |
| |
| #ifdef PNG_READ_QUANTIZE_SUPPORTED |
| /* Dither file to 8-bit. Supply a palette, the current number |
| * of elements in the palette, the maximum number of elements |
| * allowed, and a histogram if possible. If the current number |
| * of colors is greater than the maximum number, the palette will be |
| * modified to fit in the maximum number. "full_quantize" indicates |
| * whether we need a quantizing cube set up for RGB images, or if we |
| * simply are reducing the number of colors in a paletted image. |
| */ |
| |
| typedef struct png_dsort_struct |
| { |
| struct png_dsort_struct * next; |
| png_byte left; |
| png_byte right; |
| } png_dsort; |
| typedef png_dsort * png_dsortp; |
| typedef png_dsort * * png_dsortpp; |
| |
| void PNGAPI |
| png_set_quantize(png_structrp png_ptr, png_colorp palette, |
| int num_palette, int maximum_colors, png_const_uint_16p histogram, |
| int full_quantize) |
| { |
| png_debug(1, "in png_set_quantize"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| png_ptr->transformations |= PNG_QUANTIZE; |
| |
| if (full_quantize == 0) |
| { |
| int i; |
| |
| png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr, |
| (png_alloc_size_t)((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_alloc_size_t)((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 != 0) |
| break; |
| } |
| |
| /* Swap the palette around, and set up a table, if necessary */ |
| if (full_quantize != 0) |
| { |
| int j = num_palette; |
| |
| /* Put all the useful colors within the max, but don't |
| * move the others. |
| */ |
| for (i = 0; i < maximum_colors; i++) |
| { |
| if ((int)png_ptr->quantize_sort[i] >= maximum_colors) |
| { |
| do |
| j--; |
| while ((int)png_ptr->quantize_sort[j] >= maximum_colors); |
| |
| palette[i] = palette[j]; |
| } |
| } |
| } |
| else |
| { |
| int j = num_palette; |
| |
| /* Move all the used colors inside the max limit, and |
| * develop a translation table. |
| */ |
| for (i = 0; i < maximum_colors; i++) |
| { |
| /* Only move the colors we need to */ |
| if ((int)png_ptr->quantize_sort[i] >= maximum_colors) |
| { |
| png_color tmp_color; |
| |
| do |
| j--; |
| while ((int)png_ptr->quantize_sort[j] >= maximum_colors); |
| |
| tmp_color = palette[j]; |
| palette[j] = palette[i]; |
| palette[i] = tmp_color; |
| /* Indicate where the color went */ |
| png_ptr->quantize_index[j] = (png_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_alloc_size_t)((png_uint_32)num_palette * |
| (sizeof (png_byte)))); |
| png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr, |
| (png_alloc_size_t)((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_alloc_size_t)(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_alloc_size_t)(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 == 0) |
| { |
| int k; |
| |
| for (k = 0; k < num_palette; k++) |
| { |
| if (png_ptr->quantize_index[k] == |
| png_ptr->index_to_palette[j]) |
| png_ptr->quantize_index[k] = |
| png_ptr->index_to_palette[next_j]; |
| |
| if ((int)png_ptr->quantize_index[k] == |
| num_new_palette) |
| png_ptr->quantize_index[k] = |
| png_ptr->index_to_palette[j]; |
| } |
| } |
| |
| png_ptr->index_to_palette[png_ptr->palette_to_index |
| [num_new_palette]] = png_ptr->index_to_palette[j]; |
| |
| png_ptr->palette_to_index[png_ptr->index_to_palette[j]] |
| = png_ptr->palette_to_index[num_new_palette]; |
| |
| png_ptr->index_to_palette[j] = |
| (png_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 != 0) |
| { |
| int i; |
| png_bytep distance; |
| int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS + |
| PNG_QUANTIZE_BLUE_BITS; |
| int num_red = (1 << PNG_QUANTIZE_RED_BITS); |
| int num_green = (1 << PNG_QUANTIZE_GREEN_BITS); |
| int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS); |
| size_t num_entries = ((size_t)1 << total_bits); |
| |
| png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr, |
| (png_alloc_size_t)(num_entries * (sizeof (png_byte)))); |
| |
| distance = (png_bytep)png_malloc(png_ptr, (png_alloc_size_t)(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 /* READ_QUANTIZE */ |
| |
| #ifdef PNG_READ_GAMMA_SUPPORTED |
| void PNGFAPI |
| png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma, |
| png_fixed_point file_gamma) |
| { |
| png_debug(1, "in png_set_gamma_fixed"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| /* New in libpng-1.5.4 - reserve particular negative values as flags. */ |
| scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/); |
| file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/); |
| |
| /* Checking the gamma values for being >0 was added in 1.5.4 along with the |
| * premultiplied alpha support; this actually hides an undocumented feature |
| * of the previous implementation which allowed gamma processing to be |
| * disabled in background handling. There is no evidence (so far) that this |
| * was being used; however, png_set_background itself accepted and must still |
| * accept '0' for the gamma value it takes, because it isn't always used. |
| * |
| * Since this is an API change (albeit a very minor one that removes an |
| * undocumented API feature) the following checks were only enabled in |
| * libpng-1.6.0. |
| */ |
| if (file_gamma <= 0) |
| png_error(png_ptr, "invalid file gamma in png_set_gamma"); |
| |
| if (scrn_gamma <= 0) |
| png_error(png_ptr, "invalid screen gamma in png_set_gamma"); |
| |
| /* Set the gamma values unconditionally - this overrides the value in the PNG |
| * file if a gAMA chunk was present. png_set_alpha_mode provides a |
| * different, easier, way to default the file gamma. |
| */ |
| png_ptr->colorspace.gamma = file_gamma; |
| png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; |
| png_ptr->screen_gamma = scrn_gamma; |
| } |
| |
| # ifdef PNG_FLOATING_POINT_SUPPORTED |
| void PNGAPI |
| png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma) |
| { |
| png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma), |
| convert_gamma_value(png_ptr, file_gamma)); |
| } |
| # endif /* FLOATING_POINT */ |
| #endif /* READ_GAMMA */ |
| |
| #ifdef PNG_READ_EXPAND_SUPPORTED |
| /* Expand paletted images to RGB, expand grayscale images of |
| * less than 8-bit depth to 8-bit depth, and expand tRNS chunks |
| * to alpha channels. |
| */ |
| void PNGAPI |
| png_set_expand(png_structrp png_ptr) |
| { |
| png_debug(1, "in png_set_expand"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); |
| } |
| |
| /* GRR 19990627: the following three functions currently are identical |
| * to png_set_expand(). However, it is entirely reasonable that someone |
| * might wish to expand an indexed image to RGB but *not* expand a single, |
| * fully transparent palette entry to a full alpha channel--perhaps instead |
| * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace |
| * the transparent color with a particular RGB value, or drop tRNS entirely. |
| * IOW, a future version of the library may make the transformations flag |
| * a bit more fine-grained, with separate bits for each of these three |
| * functions. |
| * |
| * More to the point, these functions make it obvious what libpng will be |
| * doing, whereas "expand" can (and does) mean any number of things. |
| * |
| * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified |
| * to expand only the sample depth but not to expand the tRNS to alpha |
| * and its name was changed to png_set_expand_gray_1_2_4_to_8(). |
| */ |
| |
| /* Expand paletted images to RGB. */ |
| void PNGAPI |
| png_set_palette_to_rgb(png_structrp png_ptr) |
| { |
| png_debug(1, "in png_set_palette_to_rgb"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); |
| } |
| |
| /* Expand grayscale images of less than 8-bit depth to 8 bits. */ |
| void PNGAPI |
| png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr) |
| { |
| png_debug(1, "in png_set_expand_gray_1_2_4_to_8"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| png_ptr->transformations |= PNG_EXPAND; |
| } |
| |
| /* Expand tRNS chunks to alpha channels. */ |
| void PNGAPI |
| png_set_tRNS_to_alpha(png_structrp png_ptr) |
| { |
| png_debug(1, "in png_set_tRNS_to_alpha"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); |
| } |
| #endif /* READ_EXPAND */ |
| |
| #ifdef PNG_READ_EXPAND_16_SUPPORTED |
| /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise |
| * it may not work correctly.) |
| */ |
| void PNGAPI |
| png_set_expand_16(png_structrp png_ptr) |
| { |
| png_debug(1, "in png_set_expand_16"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS); |
| } |
| #endif |
| |
| #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED |
| void PNGAPI |
| png_set_gray_to_rgb(png_structrp png_ptr) |
| { |
| png_debug(1, "in png_set_gray_to_rgb"); |
| |
| if (png_rtran_ok(png_ptr, 0) == 0) |
| return; |
| |
| /* Because rgb must be 8 bits or more: */ |
| png_set_expand_gray_1_2_4_to_8(png_ptr); |
| png_ptr->transformations |= PNG_GRAY_TO_RGB; |
| } |
| #endif |
| |
| #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED |
| void PNGFAPI |
| png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action, |
| png_fixed_point red, png_fixed_point green) |
| { |
| png_debug(1, "in png_set_rgb_to_gray"); |
| |
| /* Need the IHDR here because of the check on color_type below. */ |
| /* TODO: fix this */ |
| if (png_rtran_ok(png_ptr, 1) == 0) |
| return; |
| |
| switch (error_action) |
| { |
| case PNG_ERROR_ACTION_NONE: |
| png_ptr->transformations |= PNG_RGB_TO_GRAY; |
| break; |
| |
| case PNG_ERROR_ACTION_WARN: |
| png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN; |
| break; |
| |
| case PNG_ERROR_ACTION_ERROR: |
| png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR; |
| break; |
| |
| default: |
| png_error(png_ptr, "invalid error action to rgb_to_gray"); |
| } |
| |
| 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 == 0) |
| { |
| /* Any alpha means background and associative alpha processing is |
| * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA |
| * and ENCODE_ALPHA are irrelevant. |
| */ |
| png_ptr->transformations &= ~PNG_ENCODE_ALPHA; |
| png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; |
| |
| if (input_has_transparency == 0) |
| png_ptr->transformations &= ~(PNG_COMPOSE | 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) != 0 && |
| (png_ptr->transformations & PNG_EXPAND) != 0) |
| { |
| { |
| 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) != 0) |
| { |
| if ((png_ptr->transformations & PNG_EXPAND_tRNS) == 0) |
| { |
| /* 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 /* READ_INVERT_ALPHA */ |
| } |
| } /* background expand and (therefore) no alpha association. */ |
| #endif /* READ_EXPAND && READ_BACKGROUND */ |
| } |
| |
| static void /* PRIVATE */ |
| png_init_rgb_transformations(png_structrp png_ptr) |
| { |
| /* Added to libpng-1.5.4: check the color type to determine whether there |
| * is any alpha or transparency in the image and simply cancel the |
| * background and alpha mode stuff if there isn't. |
| */ |
| int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0; |
| int input_has_transparency = png_ptr->num_trans > 0; |
| |
| /* If no alpha we can optimize. */ |
| if (input_has_alpha == 0) |
| { |
| /* Any alpha means background and associative alpha processing is |
| * required, however if the alpha is 0 or 1 throughout OPTIMIZE_ALPHA |
| * and ENCODE_ALPHA are irrelevant. |
| */ |
| # ifdef PNG_READ_ALPHA_MODE_SUPPORTED |
| png_ptr->transformations &= ~PNG_ENCODE_ALPHA; |
| png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; |
| # endif |
| |
| if (input_has_transparency == 0) |
| png_ptr->transformations &= ~(PNG_COMPOSE | 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) != 0 && |
| (png_ptr->transformations & PNG_EXPAND) != 0 && |
| (png_ptr->color_type & PNG_COLOR_MASK_COLOR) == 0) |
| /* 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: |
| /* FALLTHROUGH */ /* (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) == 0) |
| { |
| 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 /* READ_EXPAND && READ_BACKGROUND */ |
| } |
| |
| 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 undesirable default can (from 1.5.4) be changed by calling |
| * png_set_alpha_mode (even if the alpha handling mode isn't required |
| * or isn't changed from the default.) |
| */ |
| png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma); |
| |
| else /* neither are set */ |
| /* Just in case the following prevents any processing - file and screen |
| * are both assumed to be linear and there is no way to introduce a |
| * third gamma value other than png_set_background with 'UNIQUE', and, |
| * prior to 1.5.4 |
| */ |
| png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1; |
| |
| /* We have a gamma value now. */ |
| png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; |
| |
| /* Now turn the gamma transformation on or off as appropriate. Notice |
| * that PNG_GAMMA just refers to the file->screen correction. Alpha |
| * composition may independently cause gamma correction because it needs |
| * linear data (e.g. if the file has a gAMA chunk but the screen gamma |
| * hasn't been specified.) In any case this flag may get turned off in |
| * the code immediately below if the transform can be handled outside the |
| * row loop. |
| */ |
| if (gamma_correction != 0) |
| png_ptr->transformations |= PNG_GAMMA; |
| |
| else |
| png_ptr->transformations &= ~PNG_GAMMA; |
| } |
| #endif |
| |
| /* Certain transformations have the effect of preventing other |
| * transformations that happen afterward in png_do_read_transformations; |
| * resolve the interdependencies here. From the code of |
| * png_do_read_transformations the order is: |
| * |
| * 1) PNG_EXPAND (including PNG_EXPAND_tRNS) |
| * 2) PNG_STRIP_ALPHA (if no compose) |
| * 3) PNG_RGB_TO_GRAY |
| * 4) PNG_GRAY_TO_RGB iff !PNG_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) != 0 && |
| (png_ptr->transformations & PNG_COMPOSE) == 0) |
| { |
| /* 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) == 0) |
| { |
| png_ptr->transformations &= ~PNG_ENCODE_ALPHA; |
| png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; |
| } |
| #endif |
| |
| #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED |
| /* Make sure the coefficients for the rgb to gray conversion are set |
| * appropriately. |
| */ |
| if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) |
| png_colorspace_set_rgb_coefficients(png_ptr); |
| #endif |
| |
| #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) != 0) |
| { |
| /* 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) == 0) |
| png_ptr->mode |= PNG_BACKGROUND_IS_GRAY; |
| } |
| |
| else if ((png_ptr->transformations & PNG_COMPOSE) != 0) |
| { |
| /* 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) != 0) |
| { |
| 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 /* READ_EXPAND && READ_BACKGROUND */ |
| #endif /* READ_GRAY_TO_RGB */ |
| |
| /* 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) != 0 && |
| (png_ptr->transformations & PNG_COMPOSE) != 0 && |
| (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 && |
| 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 /* READ_BACKGROUND && READ_EXPAND_16 */ |
| |
| #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)) != 0 && |
| (png_ptr->transformations & PNG_COMPOSE) != 0 && |
| (png_ptr->transformations & PNG_BACKGROUND_EXPAND) == 0 && |
| 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) != 0 || |
| ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0 && |
| (png_gamma_significant(png_ptr->colorspace.gamma) != 0 || |
| png_gamma_significant(png_ptr->screen_gamma) != 0)) || |
| ((png_ptr->transformations & PNG_COMPOSE) != 0 && |
| (png_gamma_significant(png_ptr->colorspace.gamma) != 0 || |
| png_gamma_significant(png_ptr->screen_gamma) != 0 |
| # ifdef PNG_READ_BACKGROUND_SUPPORTED |
| || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE && |
| png_gamma_significant(png_ptr->background_gamma) != 0) |
| # endif |
| )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) != 0 && |
| png_gamma_significant(png_ptr->screen_gamma) != 0)) |
| { |
| png_build_gamma_table(png_ptr, png_ptr->bit_depth); |
| |
| #ifdef PNG_READ_BACKGROUND_SUPPORTED |
| if ((png_ptr->transformations & PNG_COMPOSE) != 0) |
| { |
| /* Issue a warning about this combination: because RGB_TO_GRAY is |
| * optimized to do the gamma transform if present yet do_background has |
| * to do the same thing if both options are set a |
| * double-gamma-correction happens. This is true in all versions of |
| * libpng to date. |
| */ |
| if ((png_ptr->transformations & PNG_RGB_TO_GRAY) != 0) |
| png_warning(png_ptr, |
| "libpng does not support gamma+background+rgb_to_gray"); |
| |
| if ((png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) != 0) |
| { |
| /* 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) != 0) |
| { |
| 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) != 0) |
| { |
| 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 != 0) |
| png_ptr->background_1.gray = png_gamma_correct(png_ptr, |
| png_ptr->background.gray, g); |
| |
| if (gs_sig != 0) |
| 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 != 0) |
| { |
| 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 != 0) |
| { |
| 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 /* READ_BACKGROUND */ |
| if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE |
| #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED |
| /* RGB_TO_GRAY needs to have non-gamma-corrected values! */ |
| && ((png_ptr->transformations & PNG_EXPAND) == 0 || |
| (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) |
| #endif |
| ) |
| { |
| png_colorp palette = png_ptr->palette; |
| int num_palette = png_ptr->num_palette; |
| int i; |
| |
| /* NOTE: there are other transformations that should probably be in |
| * here too. |
| */ |
| for (i = 0; i < num_palette; i++) |
| { |
| palette[i].red = png_ptr->gamma_table[palette[i].red]; |
| palette[i].green = png_ptr->gamma_table[palette[i].green]; |
| palette[i].blue = png_ptr->gamma_table[palette[i].blue]; |
| } |
| |
| /* Done the gamma correction. */ |
| png_ptr->transformations &= ~PNG_GAMMA; |
| } /* color_type == PALETTE && !PNG_BACKGROUND transformation */ |
| } |
| #ifdef PNG_READ_BACKGROUND_SUPPORTED |
| else |
| #endif |
| #endif /* READ_GAMMA */ |
| |
| #ifdef PNG_READ_BACKGROUND_SUPPORTED |
| /* No GAMMA transformation (see the hanging else 4 lines above) */ |
| if ((png_ptr->transformations & PNG_COMPOSE) != 0 && |
| (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)) |
| { |
| int i; |
| int istop = (int)png_ptr->num_trans; |
| png_color back; |
| png_colorp palette = png_ptr->palette; |
| |
| back.red = (png_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 /* READ_BACKGROUND */ |
| |
| #ifdef PNG_READ_SHIFT_SUPPORTED |
| if ((png_ptr->transformations & PNG_SHIFT) != 0 && |
| (png_ptr->transformations & PNG_EXPAND) == 0 && |
| (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)) |
| { |
| int i; |
| int istop = png_ptr->num_palette; |
| int shift = 8 - png_ptr->sig_bit.red; |
| |
| png_ptr->transformations &= ~PNG_SHIFT; |
| |
| /* significant bits can be in the range 1 to 7 for a meaningful 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 /* READ_SHIFT */ |
| } |
| |
| /* Modify the info structure to reflect the transformations. The |
| * info should be updated so a PNG file could be written with it, |
| * assuming the transformations result in valid PNG data. |
| */ |
| void /* PRIVATE */ |
| png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr) |
| { |
| png_debug(1, "in png_read_transform_info"); |
| |
| #ifdef PNG_READ_EXPAND_SUPPORTED |
| if ((png_ptr->transformations & PNG_EXPAND) != 0) |
| { |
| if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) |
| { |
| /* This check must match what actually happens in |
| * png_do_expand_palette; if it ever checks the tRNS chunk to see if |
| * it is all opaque we must do the same (at present it does not.) |
| */ |
| if (png_ptr->num_trans > 0) |
| info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA; |
| |
| else |
| info_ptr->color_type = PNG_COLOR_TYPE_RGB; |
| |
| info_ptr->bit_depth = 8; |
| info_ptr->num_trans = 0; |
| |
| if (png_ptr->palette == NULL) |
| png_error (png_ptr, "Palette is NULL in indexed image"); |
| } |
| else |
| { |
| if (png_ptr->num_trans != 0) |
| { |
| if ((png_ptr->transformations & PNG_EXPAND_tRNS) != 0) |
| info_ptr->color_type |= PNG_COLOR_MASK_ALPHA; |
| } |
| if (info_ptr->bit_depth < 8) |
| info_ptr->bit_depth = 8; |
| |
| info_ptr->num_trans = 0; |
| } |
| } |
| #endif |
| |
| #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ |
| defined(PNG_READ_ALPHA_MODE_SUPPORTED) |
| /* The following is almost certainly wrong unless the background value is in |
| * the screen space! |
| */ |
| if ((png_ptr->transformations & PNG_COMPOSE) != 0) |
| info_ptr->background = png_ptr->background; |
| #endif |
| |
| #ifdef PNG_READ_GAMMA_SUPPORTED |
| /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4), |
| * however it seems that the code in png_init_read_transformations, which has |
| * been called before this from png_read_update_info->png_read_start_row |
| * sometimes does the gamma transform and cancels the flag. |
| * |
| * TODO: this looks wrong; the info_ptr should end up with a gamma equal to |
| * the screen_gamma value. The following probably results in weirdness if |
| * the info_ptr is used by the app after the rows have been read. |
| */ |
| info_ptr->colorspace.gamma = png_ptr->colorspace.gamma; |
| #endif |
| |
| if (info_ptr->bit_depth == 16) |
| { |
| # ifdef PNG_READ_16BIT_SUPPORTED |
| # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED |
| if ((png_ptr->transformations & PNG_SCALE_16_TO_8) != 0) |
| info_ptr->bit_depth = 8; |
| # endif |
| |
| # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED |
| if ((png_ptr->transformations & PNG_16_TO_8) != 0) |
| info_ptr->bit_depth = 8; |
| # endif |
| |
| # else |
| /* No 16-bit support: force chopping 16-bit input down to 8, in this case |
| * the app program can chose if both APIs are available by setting the |
| * correct scaling to use. |
| */ |
| # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED |
| /* For compatibility with previous versions use the strip method by |
| * default. This code works because if PNG_SCALE_16_TO_8 is already |
| * set the code below will do that in preference to the chop. |
| */ |
| png_ptr->transformations |= PNG_16_TO_8; |
| info_ptr->bit_depth = 8; |
| # else |
| |
| # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED |
| png_ptr->transformations |= PNG_SCALE_16_TO_8; |
| info_ptr->bit_depth = 8; |
| # else |
| |
| CONFIGURATION ERROR: you must enable at least one 16 to 8 method |
| # endif |
| # endif |
| #endif /* !READ_16BIT */ |
| } |
| |
| #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED |
| if ((png_ptr->transformations & PNG_GRAY_TO_RGB) != 0) |
| info_ptr->color_type = (png_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) != 0) |
| 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) != 0) |
| { |
| if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) || |
| (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) && |
| png_ptr->palette_lookup != 0 && info_ptr->bit_depth == 8) |
| { |
| info_ptr->color_type = PNG_COLOR_TYPE_PALETTE; |
| } |
| } |
| #endif |
| |
| #ifdef PNG_READ_EXPAND_16_SUPPORTED |
| if ((png_ptr->transformations & PNG_EXPAND_16) != 0 && |
| info_ptr->bit_depth == 8 && |
| info_ptr->color_type != PNG_COLOR_TYPE_PALETTE) |
| { |
| info_ptr->bit_depth = 16; |
| } |
| #endif |
| |
| #ifdef PNG_READ_PACK_SUPPORTED |
| if ((png_ptr->transformations & PNG_PACK) != 0 && |
| (info_ptr->bit_depth < 8)) |
| info_ptr->bit_depth = 8; |
| #endif |
| |
| if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) |
| info_ptr->channels = 1; |
| |
| else if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0) |
| info_ptr->channels = 3; |
| |
| else |
| info_ptr->channels = 1; |
| |
| #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED |
| if ((png_ptr->transformations & PNG_STRIP_ALPHA) != 0) |
| { |
| info_ptr->color_type = (png_byte)(info_ptr->color_type & |
| ~PNG_COLOR_MASK_ALPHA); |
| info_ptr->num_trans = 0; |
| } |
| #endif |
| |
| if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0) |
| info_ptr->channels++; |
| |
| #ifdef PNG_READ_FILLER_SUPPORTED |
| /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */ |
| if ((png_ptr->transformations & PNG_FILLER) != 0 && |
| (info_ptr->color_type == PNG_COLOR_TYPE_RGB || |
| info_ptr->color_type == PNG_COLOR_TYPE_GRAY)) |
| { |
| info_ptr->channels++; |
| /* If adding a true alpha channel not just filler */ |
| if ((png_ptr->transformations & PNG_ADD_ALPHA) != 0) |
| info_ptr->color_type |= PNG_COLOR_MASK_ALPHA; |
| } |
| #endif |
| |
| #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \ |
| defined(PNG_READ_USER_TRANSFORM_SUPPORTED) |
| if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0) |
| { |
| if (png_ptr->user_transform_depth != 0) |
| info_ptr->bit_depth = png_ptr->user_transform_depth; |
| |
| if (png_ptr->user_transform_channels != 0) |
| 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 != NULL) |
| 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 + (size_t)((row_width - 1) >> 3); |
| png_bytep dp = row + (size_t)row_width - 1; |
| png_uint_32 shift = 7U - ((row_width + 7U) & 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 + (size_t)((row_width - 1) >> 2); |
| png_bytep dp = row + (size_t)row_width - 1; |
| png_uint_32 shift = ((3U - ((row_width + 3U) & 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 + (size_t)((row_width - 1) >> 1); |
| png_bytep dp = row + (size_t)row_width - 1; |
| png_uint_32 shift = ((1U - ((row_width + 1U) & 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) != 0) |
| { |
| 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) != 0) |
| { |
| 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 == 0) |
| 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; |
| } |
| 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_uint_32 row_width = row_info->width; |
| |
| png_debug(1, "in png_do_read_swap_alpha"); |
| |
| 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); |
| #endif |
| png_byte lo_filler = (png_byte)filler; |
| |
| 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) != 0) |
| { |
| /* This changes the data from G to GX */ |
| png_bytep sp = row + (size_t)row_width; |
| png_bytep dp = sp + (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 + (size_t)row_width; |
| png_bytep dp = sp + (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) != 0) |
| { |
| /* This changes the data from GG to GGXX */ |
| png_bytep sp = row + (size_t)row_width * 2; |
| png_bytep dp = sp + (size_t)row_width * 2; |
| for (i = 1; i < row_width; i++) |
| { |
| *(--dp) = lo_filler; |
| *(--dp) = hi_filler; |
| *(--dp) = *(--sp); |
| *(--dp) = *(--sp); |
| } |
| *(--dp) = lo_filler; |
| *(--dp) = hi_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 + (size_t)row_width * 2; |
| png_bytep dp = sp + (size_t)row_width * 2; |
| for (i = 0; i < row_width; i++) |
| { |
| *(--dp) = *(--sp); |
| *(--dp) = *(--sp); |
| *(--dp) = lo_filler; |
| *(--dp) = hi_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) != 0) |
| { |
| /* This changes the data from RGB to RGBX */ |
| png_bytep sp = row + (size_t)row_width * 3; |
| png_bytep dp = sp + (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 + (size_t)row_width * 3; |
| png_bytep dp = sp + (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) != 0) |
| { |
| /* This changes the data from RRGGBB to RRGGBBXX */ |
| png_bytep sp = row + (size_t)row_width * 6; |
| png_bytep dp = sp + (size_t)row_width * 2; |
| for (i = 1; i < row_width; i++) |
| { |
| *(--dp) = lo_filler; |
| *(--dp) = hi_filler; |
| *(--dp) = *(--sp); |
| *(--dp) = *(--sp); |
| *(--dp) = *(--sp); |
| *(--dp) = *(--sp); |
| *(--dp) = *(--sp); |
| *(--dp) = *(--sp); |
| } |
| *(--dp) = lo_filler; |
| *(--dp) = hi_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 + (size_t)row_width * 6; |
| png_bytep dp = sp + (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) = lo_filler; |
| *(--dp) = hi_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) == 0) |
| { |
| if (row_info->color_type == PNG_COLOR_TYPE_GRAY) |
| { |
| if (row_info->bit_depth == 8) |
| { |
| /* This changes G to RGB */ |
| png_bytep sp = row + (size_t)row_width - 1; |
| png_bytep dp = sp + (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 + (size_t)row_width * 2 - 1; |
| png_bytep dp = sp + (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 + (size_t)row_width * 2 - 1; |
| png_bytep dp = sp + (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 + (size_t)row_width * 4 - 1; |
| png_bytep dp = sp + (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 |
| * https://web.archive.org/web/20000816232553/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 coefficients 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) == 0 && |
| (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0) |
| { |
| png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff; |
| png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff; |
| png_uint_32 bc = 32768 - rc - gc; |
| png_uint_32 row_width = row_info->width; |
| 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 != 0) |
| *(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 != 0) |
| *(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; |
| png_byte hi,lo; |
| |
| hi=*(sp)++; lo=*(sp)++; red = (png_uint_16)((hi << 8) | (lo)); |
| hi=*(sp)++; lo=*(sp)++; green = (png_uint_16)((hi << 8) | (lo)); |
| hi=*(sp)++; lo=*(sp)++; blue = (png_uint_16)((hi << 8) | (lo)); |
| |
| 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 |