/* pngrtran.c - transforms the data in a row for PNG readers | |
* | |
* Last changed in libpng 1.6.2 [April 25, 2013] | |
* Copyright (c) 1998-2013 Glenn Randers-Pehrson | |
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) | |
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) | |
* | |
* This code is released under the libpng license. | |
* For conditions of distribution and use, see the disclaimer | |
* and license in png.h | |
* | |
* This file contains functions optionally called by an application | |
* in order to tell libpng how to handle data when reading a PNG. | |
* Transformations that are used in both reading and writing are | |
* in pngtrans.c. | |
*/ | |
#include "pngpriv.h" | |
#ifdef PNG_READ_SUPPORTED | |
/* Set the action on getting a CRC error for an ancillary or critical chunk. */ | |
void PNGAPI | |
png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action) | |
{ | |
png_debug(1, "in png_set_crc_action"); | |
if (png_ptr == NULL) | |
return; | |
/* Tell libpng how we react to CRC errors in critical chunks */ | |
switch (crit_action) | |
{ | |
case PNG_CRC_NO_CHANGE: /* Leave setting as is */ | |
break; | |
case PNG_CRC_WARN_USE: /* Warn/use data */ | |
png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; | |
png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE; | |
break; | |
case PNG_CRC_QUIET_USE: /* Quiet/use data */ | |
png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; | |
png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE | | |
PNG_FLAG_CRC_CRITICAL_IGNORE; | |
break; | |
case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */ | |
png_warning(png_ptr, | |
"Can't discard critical data on CRC error"); | |
case PNG_CRC_ERROR_QUIT: /* Error/quit */ | |
case PNG_CRC_DEFAULT: | |
default: | |
png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK; | |
break; | |
} | |
/* Tell libpng how we react to CRC errors in ancillary chunks */ | |
switch (ancil_action) | |
{ | |
case PNG_CRC_NO_CHANGE: /* Leave setting as is */ | |
break; | |
case PNG_CRC_WARN_USE: /* Warn/use data */ | |
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; | |
png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE; | |
break; | |
case PNG_CRC_QUIET_USE: /* Quiet/use data */ | |
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; | |
png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE | | |
PNG_FLAG_CRC_ANCILLARY_NOWARN; | |
break; | |
case PNG_CRC_ERROR_QUIT: /* Error/quit */ | |
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; | |
png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN; | |
break; | |
case PNG_CRC_WARN_DISCARD: /* Warn/discard data */ | |
case PNG_CRC_DEFAULT: | |
default: | |
png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK; | |
break; | |
} | |
} | |
#ifdef PNG_READ_TRANSFORMS_SUPPORTED | |
/* Is it OK to set a transformation now? Only if png_start_read_image or | |
* png_read_update_info have not been called. It is not necessary for the IHDR | |
* to have been read in all cases, the parameter allows for this check too. | |
*/ | |
static int | |
png_rtran_ok(png_structrp png_ptr, int need_IHDR) | |
{ | |
if (png_ptr != NULL) | |
{ | |
if (png_ptr->flags & PNG_FLAG_ROW_INIT) | |
png_app_error(png_ptr, | |
"invalid after png_start_read_image or png_read_update_info"); | |
else if (need_IHDR && (png_ptr->mode & PNG_HAVE_IHDR) == 0) | |
png_app_error(png_ptr, "invalid before the PNG header has been read"); | |
else | |
{ | |
/* Turn on failure to initialize correctly for all transforms. */ | |
png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED; | |
return 1; /* Ok */ | |
} | |
} | |
return 0; /* no png_error possible! */ | |
} | |
#endif | |
#ifdef PNG_READ_BACKGROUND_SUPPORTED | |
/* Handle alpha and tRNS via a background color */ | |
void PNGFAPI | |
png_set_background_fixed(png_structrp png_ptr, | |
png_const_color_16p background_color, int background_gamma_code, | |
int need_expand, png_fixed_point background_gamma) | |
{ | |
png_debug(1, "in png_set_background_fixed"); | |
if (!png_rtran_ok(png_ptr, 0) || background_color == NULL) | |
return; | |
if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN) | |
{ | |
png_warning(png_ptr, "Application must supply a known background gamma"); | |
return; | |
} | |
png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA; | |
png_ptr->transformations &= ~PNG_ENCODE_ALPHA; | |
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; | |
png_ptr->background = *background_color; | |
png_ptr->background_gamma = background_gamma; | |
png_ptr->background_gamma_type = (png_byte)(background_gamma_code); | |
if (need_expand) | |
png_ptr->transformations |= PNG_BACKGROUND_EXPAND; | |
else | |
png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND; | |
} | |
# ifdef PNG_FLOATING_POINT_SUPPORTED | |
void PNGAPI | |
png_set_background(png_structrp png_ptr, | |
png_const_color_16p background_color, int background_gamma_code, | |
int need_expand, double background_gamma) | |
{ | |
png_set_background_fixed(png_ptr, background_color, background_gamma_code, | |
need_expand, png_fixed(png_ptr, background_gamma, "png_set_background")); | |
} | |
# endif /* FLOATING_POINT */ | |
#endif /* READ_BACKGROUND */ | |
/* Scale 16-bit depth files to 8-bit depth. If both of these are set then the | |
* one that pngrtran does first (scale) happens. This is necessary to allow the | |
* TRANSFORM and API behavior to be somewhat consistent, and it's simpler. | |
*/ | |
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED | |
void PNGAPI | |
png_set_scale_16(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_set_scale_16"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
png_ptr->transformations |= PNG_SCALE_16_TO_8; | |
} | |
#endif | |
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED | |
/* Chop 16-bit depth files to 8-bit depth */ | |
void PNGAPI | |
png_set_strip_16(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_set_strip_16"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
png_ptr->transformations |= PNG_16_TO_8; | |
} | |
#endif | |
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED | |
void PNGAPI | |
png_set_strip_alpha(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_set_strip_alpha"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
png_ptr->transformations |= PNG_STRIP_ALPHA; | |
} | |
#endif | |
#if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED) | |
static png_fixed_point | |
translate_gamma_flags(png_structrp png_ptr, png_fixed_point output_gamma, | |
int is_screen) | |
{ | |
/* Check for flag values. The main reason for having the old Mac value as a | |
* flag is that it is pretty near impossible to work out what the correct | |
* value is from Apple documentation - a working Mac system is needed to | |
* discover the value! | |
*/ | |
if (output_gamma == PNG_DEFAULT_sRGB || | |
output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB) | |
{ | |
/* If there is no sRGB support this just sets the gamma to the standard | |
* sRGB value. (This is a side effect of using this function!) | |
*/ | |
# ifdef PNG_READ_sRGB_SUPPORTED | |
png_ptr->flags |= PNG_FLAG_ASSUME_sRGB; | |
# else | |
PNG_UNUSED(png_ptr) | |
# endif | |
if (is_screen) | |
output_gamma = PNG_GAMMA_sRGB; | |
else | |
output_gamma = PNG_GAMMA_sRGB_INVERSE; | |
} | |
else if (output_gamma == PNG_GAMMA_MAC_18 || | |
output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18) | |
{ | |
if (is_screen) | |
output_gamma = PNG_GAMMA_MAC_OLD; | |
else | |
output_gamma = PNG_GAMMA_MAC_INVERSE; | |
} | |
return output_gamma; | |
} | |
# ifdef PNG_FLOATING_POINT_SUPPORTED | |
static png_fixed_point | |
convert_gamma_value(png_structrp png_ptr, double output_gamma) | |
{ | |
/* The following silently ignores cases where fixed point (times 100,000) | |
* gamma values are passed to the floating point API. This is safe and it | |
* means the fixed point constants work just fine with the floating point | |
* API. The alternative would just lead to undetected errors and spurious | |
* bug reports. Negative values fail inside the _fixed API unless they | |
* correspond to the flag values. | |
*/ | |
if (output_gamma > 0 && output_gamma < 128) | |
output_gamma *= PNG_FP_1; | |
/* This preserves -1 and -2 exactly: */ | |
output_gamma = floor(output_gamma + .5); | |
if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN) | |
png_fixed_error(png_ptr, "gamma value"); | |
return (png_fixed_point)output_gamma; | |
} | |
# endif | |
#endif /* READ_ALPHA_MODE || READ_GAMMA */ | |
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED | |
void PNGFAPI | |
png_set_alpha_mode_fixed(png_structrp png_ptr, int mode, | |
png_fixed_point output_gamma) | |
{ | |
int compose = 0; | |
png_fixed_point file_gamma; | |
png_debug(1, "in png_set_alpha_mode"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/); | |
/* Validate the value to ensure it is in a reasonable range. The value | |
* is expected to be 1 or greater, but this range test allows for some | |
* viewing correction values. The intent is to weed out users of this API | |
* who use the inverse of the gamma value accidentally! Since some of these | |
* values are reasonable this may have to be changed. | |
*/ | |
if (output_gamma < 70000 || output_gamma > 300000) | |
png_error(png_ptr, "output gamma out of expected range"); | |
/* The default file gamma is the inverse of the output gamma; the output | |
* gamma may be changed below so get the file value first: | |
*/ | |
file_gamma = png_reciprocal(output_gamma); | |
/* There are really 8 possibilities here, composed of any combination | |
* of: | |
* | |
* premultiply the color channels | |
* do not encode non-opaque pixels | |
* encode the alpha as well as the color channels | |
* | |
* The differences disappear if the input/output ('screen') gamma is 1.0, | |
* because then the encoding is a no-op and there is only the choice of | |
* premultiplying the color channels or not. | |
* | |
* png_set_alpha_mode and png_set_background interact because both use | |
* png_compose to do the work. Calling both is only useful when | |
* png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along | |
* with a default gamma value. Otherwise PNG_COMPOSE must not be set. | |
*/ | |
switch (mode) | |
{ | |
case PNG_ALPHA_PNG: /* default: png standard */ | |
/* No compose, but it may be set by png_set_background! */ | |
png_ptr->transformations &= ~PNG_ENCODE_ALPHA; | |
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; | |
break; | |
case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */ | |
compose = 1; | |
png_ptr->transformations &= ~PNG_ENCODE_ALPHA; | |
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; | |
/* The output is linear: */ | |
output_gamma = PNG_FP_1; | |
break; | |
case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */ | |
compose = 1; | |
png_ptr->transformations &= ~PNG_ENCODE_ALPHA; | |
png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA; | |
/* output_gamma records the encoding of opaque pixels! */ | |
break; | |
case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */ | |
compose = 1; | |
png_ptr->transformations |= PNG_ENCODE_ALPHA; | |
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; | |
break; | |
default: | |
png_error(png_ptr, "invalid alpha mode"); | |
} | |
/* Only set the default gamma if the file gamma has not been set (this has | |
* the side effect that the gamma in a second call to png_set_alpha_mode will | |
* be ignored.) | |
*/ | |
if (png_ptr->colorspace.gamma == 0) | |
{ | |
png_ptr->colorspace.gamma = file_gamma; | |
png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; | |
} | |
/* But always set the output gamma: */ | |
png_ptr->screen_gamma = output_gamma; | |
/* Finally, if pre-multiplying, set the background fields to achieve the | |
* desired result. | |
*/ | |
if (compose) | |
{ | |
/* And obtain alpha pre-multiplication by composing on black: */ | |
memset(&png_ptr->background, 0, (sizeof png_ptr->background)); | |
png_ptr->background_gamma = png_ptr->colorspace.gamma; /* just in case */ | |
png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE; | |
png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND; | |
if (png_ptr->transformations & PNG_COMPOSE) | |
png_error(png_ptr, | |
"conflicting calls to set alpha mode and background"); | |
png_ptr->transformations |= PNG_COMPOSE; | |
} | |
} | |
# ifdef PNG_FLOATING_POINT_SUPPORTED | |
void PNGAPI | |
png_set_alpha_mode(png_structrp png_ptr, int mode, double output_gamma) | |
{ | |
png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr, | |
output_gamma)); | |
} | |
# endif | |
#endif | |
#ifdef PNG_READ_QUANTIZE_SUPPORTED | |
/* Dither file to 8-bit. Supply a palette, the current number | |
* of elements in the palette, the maximum number of elements | |
* allowed, and a histogram if possible. If the current number | |
* of colors is greater then the maximum number, the palette will be | |
* modified to fit in the maximum number. "full_quantize" indicates | |
* whether we need a quantizing cube set up for RGB images, or if we | |
* simply are reducing the number of colors in a paletted image. | |
*/ | |
typedef struct png_dsort_struct | |
{ | |
struct png_dsort_struct * next; | |
png_byte left; | |
png_byte right; | |
} png_dsort; | |
typedef png_dsort * png_dsortp; | |
typedef png_dsort * * png_dsortpp; | |
void PNGAPI | |
png_set_quantize(png_structrp png_ptr, png_colorp palette, | |
int num_palette, int maximum_colors, png_const_uint_16p histogram, | |
int full_quantize) | |
{ | |
png_debug(1, "in png_set_quantize"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
png_ptr->transformations |= PNG_QUANTIZE; | |
if (!full_quantize) | |
{ | |
int i; | |
png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr, | |
(png_uint_32)(num_palette * (sizeof (png_byte)))); | |
for (i = 0; i < num_palette; i++) | |
png_ptr->quantize_index[i] = (png_byte)i; | |
} | |
if (num_palette > maximum_colors) | |
{ | |
if (histogram != NULL) | |
{ | |
/* This is easy enough, just throw out the least used colors. | |
* Perhaps not the best solution, but good enough. | |
*/ | |
int i; | |
/* Initialize an array to sort colors */ | |
png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr, | |
(png_uint_32)(num_palette * (sizeof (png_byte)))); | |
/* Initialize the quantize_sort array */ | |
for (i = 0; i < num_palette; i++) | |
png_ptr->quantize_sort[i] = (png_byte)i; | |
/* Find the least used palette entries by starting a | |
* bubble sort, and running it until we have sorted | |
* out enough colors. Note that we don't care about | |
* sorting all the colors, just finding which are | |
* least used. | |
*/ | |
for (i = num_palette - 1; i >= maximum_colors; i--) | |
{ | |
int done; /* To stop early if the list is pre-sorted */ | |
int j; | |
done = 1; | |
for (j = 0; j < i; j++) | |
{ | |
if (histogram[png_ptr->quantize_sort[j]] | |
< histogram[png_ptr->quantize_sort[j + 1]]) | |
{ | |
png_byte t; | |
t = png_ptr->quantize_sort[j]; | |
png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1]; | |
png_ptr->quantize_sort[j + 1] = t; | |
done = 0; | |
} | |
} | |
if (done) | |
break; | |
} | |
/* Swap the palette around, and set up a table, if necessary */ | |
if (full_quantize) | |
{ | |
int j = num_palette; | |
/* Put all the useful colors within the max, but don't | |
* move the others. | |
*/ | |
for (i = 0; i < maximum_colors; i++) | |
{ | |
if ((int)png_ptr->quantize_sort[i] >= maximum_colors) | |
{ | |
do | |
j--; | |
while ((int)png_ptr->quantize_sort[j] >= maximum_colors); | |
palette[i] = palette[j]; | |
} | |
} | |
} | |
else | |
{ | |
int j = num_palette; | |
/* Move all the used colors inside the max limit, and | |
* develop a translation table. | |
*/ | |
for (i = 0; i < maximum_colors; i++) | |
{ | |
/* Only move the colors we need to */ | |
if ((int)png_ptr->quantize_sort[i] >= maximum_colors) | |
{ | |
png_color tmp_color; | |
do | |
j--; | |
while ((int)png_ptr->quantize_sort[j] >= maximum_colors); | |
tmp_color = palette[j]; | |
palette[j] = palette[i]; | |
palette[i] = tmp_color; | |
/* Indicate where the color went */ | |
png_ptr->quantize_index[j] = (png_byte)i; | |
png_ptr->quantize_index[i] = (png_byte)j; | |
} | |
} | |
/* Find closest color for those colors we are not using */ | |
for (i = 0; i < num_palette; i++) | |
{ | |
if ((int)png_ptr->quantize_index[i] >= maximum_colors) | |
{ | |
int min_d, k, min_k, d_index; | |
/* Find the closest color to one we threw out */ | |
d_index = png_ptr->quantize_index[i]; | |
min_d = PNG_COLOR_DIST(palette[d_index], palette[0]); | |
for (k = 1, min_k = 0; k < maximum_colors; k++) | |
{ | |
int d; | |
d = PNG_COLOR_DIST(palette[d_index], palette[k]); | |
if (d < min_d) | |
{ | |
min_d = d; | |
min_k = k; | |
} | |
} | |
/* Point to closest color */ | |
png_ptr->quantize_index[i] = (png_byte)min_k; | |
} | |
} | |
} | |
png_free(png_ptr, png_ptr->quantize_sort); | |
png_ptr->quantize_sort = NULL; | |
} | |
else | |
{ | |
/* This is much harder to do simply (and quickly). Perhaps | |
* we need to go through a median cut routine, but those | |
* don't always behave themselves with only a few colors | |
* as input. So we will just find the closest two colors, | |
* and throw out one of them (chosen somewhat randomly). | |
* [We don't understand this at all, so if someone wants to | |
* work on improving it, be our guest - AED, GRP] | |
*/ | |
int i; | |
int max_d; | |
int num_new_palette; | |
png_dsortp t; | |
png_dsortpp hash; | |
t = NULL; | |
/* Initialize palette index arrays */ | |
png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr, | |
(png_uint_32)(num_palette * (sizeof (png_byte)))); | |
png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr, | |
(png_uint_32)(num_palette * (sizeof (png_byte)))); | |
/* Initialize the sort array */ | |
for (i = 0; i < num_palette; i++) | |
{ | |
png_ptr->index_to_palette[i] = (png_byte)i; | |
png_ptr->palette_to_index[i] = (png_byte)i; | |
} | |
hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 * | |
(sizeof (png_dsortp)))); | |
num_new_palette = num_palette; | |
/* Initial wild guess at how far apart the farthest pixel | |
* pair we will be eliminating will be. Larger | |
* numbers mean more areas will be allocated, Smaller | |
* numbers run the risk of not saving enough data, and | |
* having to do this all over again. | |
* | |
* I have not done extensive checking on this number. | |
*/ | |
max_d = 96; | |
while (num_new_palette > maximum_colors) | |
{ | |
for (i = 0; i < num_new_palette - 1; i++) | |
{ | |
int j; | |
for (j = i + 1; j < num_new_palette; j++) | |
{ | |
int d; | |
d = PNG_COLOR_DIST(palette[i], palette[j]); | |
if (d <= max_d) | |
{ | |
t = (png_dsortp)png_malloc_warn(png_ptr, | |
(png_uint_32)(sizeof (png_dsort))); | |
if (t == NULL) | |
break; | |
t->next = hash[d]; | |
t->left = (png_byte)i; | |
t->right = (png_byte)j; | |
hash[d] = t; | |
} | |
} | |
if (t == NULL) | |
break; | |
} | |
if (t != NULL) | |
for (i = 0; i <= max_d; i++) | |
{ | |
if (hash[i] != NULL) | |
{ | |
png_dsortp p; | |
for (p = hash[i]; p; p = p->next) | |
{ | |
if ((int)png_ptr->index_to_palette[p->left] | |
< num_new_palette && | |
(int)png_ptr->index_to_palette[p->right] | |
< num_new_palette) | |
{ | |
int j, next_j; | |
if (num_new_palette & 0x01) | |
{ | |
j = p->left; | |
next_j = p->right; | |
} | |
else | |
{ | |
j = p->right; | |
next_j = p->left; | |
} | |
num_new_palette--; | |
palette[png_ptr->index_to_palette[j]] | |
= palette[num_new_palette]; | |
if (!full_quantize) | |
{ | |
int k; | |
for (k = 0; k < num_palette; k++) | |
{ | |
if (png_ptr->quantize_index[k] == | |
png_ptr->index_to_palette[j]) | |
png_ptr->quantize_index[k] = | |
png_ptr->index_to_palette[next_j]; | |
if ((int)png_ptr->quantize_index[k] == | |
num_new_palette) | |
png_ptr->quantize_index[k] = | |
png_ptr->index_to_palette[j]; | |
} | |
} | |
png_ptr->index_to_palette[png_ptr->palette_to_index | |
[num_new_palette]] = png_ptr->index_to_palette[j]; | |
png_ptr->palette_to_index[png_ptr->index_to_palette[j]] | |
= png_ptr->palette_to_index[num_new_palette]; | |
png_ptr->index_to_palette[j] = | |
(png_byte)num_new_palette; | |
png_ptr->palette_to_index[num_new_palette] = | |
(png_byte)j; | |
} | |
if (num_new_palette <= maximum_colors) | |
break; | |
} | |
if (num_new_palette <= maximum_colors) | |
break; | |
} | |
} | |
for (i = 0; i < 769; i++) | |
{ | |
if (hash[i] != NULL) | |
{ | |
png_dsortp p = hash[i]; | |
while (p) | |
{ | |
t = p->next; | |
png_free(png_ptr, p); | |
p = t; | |
} | |
} | |
hash[i] = 0; | |
} | |
max_d += 96; | |
} | |
png_free(png_ptr, hash); | |
png_free(png_ptr, png_ptr->palette_to_index); | |
png_free(png_ptr, png_ptr->index_to_palette); | |
png_ptr->palette_to_index = NULL; | |
png_ptr->index_to_palette = NULL; | |
} | |
num_palette = maximum_colors; | |
} | |
if (png_ptr->palette == NULL) | |
{ | |
png_ptr->palette = palette; | |
} | |
png_ptr->num_palette = (png_uint_16)num_palette; | |
if (full_quantize) | |
{ | |
int i; | |
png_bytep distance; | |
int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS + | |
PNG_QUANTIZE_BLUE_BITS; | |
int num_red = (1 << PNG_QUANTIZE_RED_BITS); | |
int num_green = (1 << PNG_QUANTIZE_GREEN_BITS); | |
int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS); | |
png_size_t num_entries = ((png_size_t)1 << total_bits); | |
png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr, | |
(png_uint_32)(num_entries * (sizeof (png_byte)))); | |
distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries * | |
(sizeof (png_byte)))); | |
memset(distance, 0xff, num_entries * (sizeof (png_byte))); | |
for (i = 0; i < num_palette; i++) | |
{ | |
int ir, ig, ib; | |
int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS)); | |
int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS)); | |
int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS)); | |
for (ir = 0; ir < num_red; ir++) | |
{ | |
/* int dr = abs(ir - r); */ | |
int dr = ((ir > r) ? ir - r : r - ir); | |
int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS + | |
PNG_QUANTIZE_GREEN_BITS)); | |
for (ig = 0; ig < num_green; ig++) | |
{ | |
/* int dg = abs(ig - g); */ | |
int dg = ((ig > g) ? ig - g : g - ig); | |
int dt = dr + dg; | |
int dm = ((dr > dg) ? dr : dg); | |
int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS); | |
for (ib = 0; ib < num_blue; ib++) | |
{ | |
int d_index = index_g | ib; | |
/* int db = abs(ib - b); */ | |
int db = ((ib > b) ? ib - b : b - ib); | |
int dmax = ((dm > db) ? dm : db); | |
int d = dmax + dt + db; | |
if (d < (int)distance[d_index]) | |
{ | |
distance[d_index] = (png_byte)d; | |
png_ptr->palette_lookup[d_index] = (png_byte)i; | |
} | |
} | |
} | |
} | |
} | |
png_free(png_ptr, distance); | |
} | |
} | |
#endif /* PNG_READ_QUANTIZE_SUPPORTED */ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
void PNGFAPI | |
png_set_gamma_fixed(png_structrp png_ptr, png_fixed_point scrn_gamma, | |
png_fixed_point file_gamma) | |
{ | |
png_debug(1, "in png_set_gamma_fixed"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
/* New in libpng-1.5.4 - reserve particular negative values as flags. */ | |
scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/); | |
file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/); | |
/* Checking the gamma values for being >0 was added in 1.5.4 along with the | |
* premultiplied alpha support; this actually hides an undocumented feature | |
* of the previous implementation which allowed gamma processing to be | |
* disabled in background handling. There is no evidence (so far) that this | |
* was being used; however, png_set_background itself accepted and must still | |
* accept '0' for the gamma value it takes, because it isn't always used. | |
* | |
* Since this is an API change (albeit a very minor one that removes an | |
* undocumented API feature) the following checks were only enabled in | |
* libpng-1.6.0. | |
*/ | |
if (file_gamma <= 0) | |
png_error(png_ptr, "invalid file gamma in png_set_gamma"); | |
if (scrn_gamma <= 0) | |
png_error(png_ptr, "invalid screen gamma in png_set_gamma"); | |
/* Set the gamma values unconditionally - this overrides the value in the PNG | |
* file if a gAMA chunk was present. png_set_alpha_mode provides a | |
* different, easier, way to default the file gamma. | |
*/ | |
png_ptr->colorspace.gamma = file_gamma; | |
png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; | |
png_ptr->screen_gamma = scrn_gamma; | |
} | |
# ifdef PNG_FLOATING_POINT_SUPPORTED | |
void PNGAPI | |
png_set_gamma(png_structrp png_ptr, double scrn_gamma, double file_gamma) | |
{ | |
png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma), | |
convert_gamma_value(png_ptr, file_gamma)); | |
} | |
# endif /* FLOATING_POINT_SUPPORTED */ | |
#endif /* READ_GAMMA */ | |
#ifdef PNG_READ_EXPAND_SUPPORTED | |
/* Expand paletted images to RGB, expand grayscale images of | |
* less than 8-bit depth to 8-bit depth, and expand tRNS chunks | |
* to alpha channels. | |
*/ | |
void PNGAPI | |
png_set_expand(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_set_expand"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); | |
} | |
/* GRR 19990627: the following three functions currently are identical | |
* to png_set_expand(). However, it is entirely reasonable that someone | |
* might wish to expand an indexed image to RGB but *not* expand a single, | |
* fully transparent palette entry to a full alpha channel--perhaps instead | |
* convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace | |
* the transparent color with a particular RGB value, or drop tRNS entirely. | |
* IOW, a future version of the library may make the transformations flag | |
* a bit more fine-grained, with separate bits for each of these three | |
* functions. | |
* | |
* More to the point, these functions make it obvious what libpng will be | |
* doing, whereas "expand" can (and does) mean any number of things. | |
* | |
* GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified | |
* to expand only the sample depth but not to expand the tRNS to alpha | |
* and its name was changed to png_set_expand_gray_1_2_4_to_8(). | |
*/ | |
/* Expand paletted images to RGB. */ | |
void PNGAPI | |
png_set_palette_to_rgb(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_set_palette_to_rgb"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); | |
} | |
/* Expand grayscale images of less than 8-bit depth to 8 bits. */ | |
void PNGAPI | |
png_set_expand_gray_1_2_4_to_8(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_set_expand_gray_1_2_4_to_8"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
png_ptr->transformations |= PNG_EXPAND; | |
} | |
/* Expand tRNS chunks to alpha channels. */ | |
void PNGAPI | |
png_set_tRNS_to_alpha(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_set_tRNS_to_alpha"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS); | |
} | |
#endif /* defined(PNG_READ_EXPAND_SUPPORTED) */ | |
#ifdef PNG_READ_EXPAND_16_SUPPORTED | |
/* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise | |
* it may not work correctly.) | |
*/ | |
void PNGAPI | |
png_set_expand_16(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_set_expand_16"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS); | |
} | |
#endif | |
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED | |
void PNGAPI | |
png_set_gray_to_rgb(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_set_gray_to_rgb"); | |
if (!png_rtran_ok(png_ptr, 0)) | |
return; | |
/* Because rgb must be 8 bits or more: */ | |
png_set_expand_gray_1_2_4_to_8(png_ptr); | |
png_ptr->transformations |= PNG_GRAY_TO_RGB; | |
} | |
#endif | |
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED | |
void PNGFAPI | |
png_set_rgb_to_gray_fixed(png_structrp png_ptr, int error_action, | |
png_fixed_point red, png_fixed_point green) | |
{ | |
png_debug(1, "in png_set_rgb_to_gray"); | |
/* Need the IHDR here because of the check on color_type below. */ | |
/* TODO: fix this */ | |
if (!png_rtran_ok(png_ptr, 1)) | |
return; | |
switch(error_action) | |
{ | |
case PNG_ERROR_ACTION_NONE: | |
png_ptr->transformations |= PNG_RGB_TO_GRAY; | |
break; | |
case PNG_ERROR_ACTION_WARN: | |
png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN; | |
break; | |
case PNG_ERROR_ACTION_ERROR: | |
png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR; | |
break; | |
default: | |
png_error(png_ptr, "invalid error action to rgb_to_gray"); | |
break; | |
} | |
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) | |
#ifdef PNG_READ_EXPAND_SUPPORTED | |
png_ptr->transformations |= PNG_EXPAND; | |
#else | |
{ | |
/* Make this an error in 1.6 because otherwise the application may assume | |
* that it just worked and get a memory overwrite. | |
*/ | |
png_error(png_ptr, | |
"Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED"); | |
/* png_ptr->transformations &= ~PNG_RGB_TO_GRAY; */ | |
} | |
#endif | |
{ | |
if (red >= 0 && green >= 0 && red + green <= PNG_FP_1) | |
{ | |
png_uint_16 red_int, green_int; | |
/* NOTE: this calculation does not round, but this behavior is retained | |
* for consistency, the inaccuracy is very small. The code here always | |
* overwrites the coefficients, regardless of whether they have been | |
* defaulted or set already. | |
*/ | |
red_int = (png_uint_16)(((png_uint_32)red*32768)/100000); | |
green_int = (png_uint_16)(((png_uint_32)green*32768)/100000); | |
png_ptr->rgb_to_gray_red_coeff = red_int; | |
png_ptr->rgb_to_gray_green_coeff = green_int; | |
png_ptr->rgb_to_gray_coefficients_set = 1; | |
} | |
else | |
{ | |
if (red >= 0 && green >= 0) | |
png_app_warning(png_ptr, | |
"ignoring out of range rgb_to_gray coefficients"); | |
/* Use the defaults, from the cHRM chunk if set, else the historical | |
* values which are close to the sRGB/HDTV/ITU-Rec 709 values. See | |
* png_do_rgb_to_gray for more discussion of the values. In this case | |
* the coefficients are not marked as 'set' and are not overwritten if | |
* something has already provided a default. | |
*/ | |
if (png_ptr->rgb_to_gray_red_coeff == 0 && | |
png_ptr->rgb_to_gray_green_coeff == 0) | |
{ | |
png_ptr->rgb_to_gray_red_coeff = 6968; | |
png_ptr->rgb_to_gray_green_coeff = 23434; | |
/* png_ptr->rgb_to_gray_blue_coeff = 2366; */ | |
} | |
} | |
} | |
} | |
#ifdef PNG_FLOATING_POINT_SUPPORTED | |
/* Convert a RGB image to a grayscale of the same width. This allows us, | |
* for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image. | |
*/ | |
void PNGAPI | |
png_set_rgb_to_gray(png_structrp png_ptr, int error_action, double red, | |
double green) | |
{ | |
png_set_rgb_to_gray_fixed(png_ptr, error_action, | |
png_fixed(png_ptr, red, "rgb to gray red coefficient"), | |
png_fixed(png_ptr, green, "rgb to gray green coefficient")); | |
} | |
#endif /* FLOATING POINT */ | |
#endif /* RGB_TO_GRAY */ | |
#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \ | |
defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) | |
void PNGAPI | |
png_set_read_user_transform_fn(png_structrp png_ptr, png_user_transform_ptr | |
read_user_transform_fn) | |
{ | |
png_debug(1, "in png_set_read_user_transform_fn"); | |
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED | |
png_ptr->transformations |= PNG_USER_TRANSFORM; | |
png_ptr->read_user_transform_fn = read_user_transform_fn; | |
#endif | |
} | |
#endif | |
#ifdef PNG_READ_TRANSFORMS_SUPPORTED | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
/* In the case of gamma transformations only do transformations on images where | |
* the [file] gamma and screen_gamma are not close reciprocals, otherwise it | |
* slows things down slightly, and also needlessly introduces small errors. | |
*/ | |
static int /* PRIVATE */ | |
png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma) | |
{ | |
/* PNG_GAMMA_THRESHOLD is the threshold for performing gamma | |
* correction as a difference of the overall transform from 1.0 | |
* | |
* We want to compare the threshold with s*f - 1, if we get | |
* overflow here it is because of wacky gamma values so we | |
* turn on processing anyway. | |
*/ | |
png_fixed_point gtest; | |
return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) || | |
png_gamma_significant(gtest); | |
} | |
#endif | |
/* Initialize everything needed for the read. This includes modifying | |
* the palette. | |
*/ | |
/*For the moment 'png_init_palette_transformations' and | |
* 'png_init_rgb_transformations' only do some flag canceling optimizations. | |
* The intent is that these two routines should have palette or rgb operations | |
* extracted from 'png_init_read_transformations'. | |
*/ | |
static void /* PRIVATE */ | |
png_init_palette_transformations(png_structrp png_ptr) | |
{ | |
/* Called to handle the (input) palette case. In png_do_read_transformations | |
* the first step is to expand the palette if requested, so this code must | |
* take care to only make changes that are invariant with respect to the | |
* palette expansion, or only do them if there is no expansion. | |
* | |
* STRIP_ALPHA has already been handled in the caller (by setting num_trans | |
* to 0.) | |
*/ | |
int input_has_alpha = 0; | |
int input_has_transparency = 0; | |
if (png_ptr->num_trans > 0) | |
{ | |
int i; | |
/* Ignore if all the entries are opaque (unlikely!) */ | |
for (i=0; i<png_ptr->num_trans; ++i) | |
if (png_ptr->trans_alpha[i] == 255) | |
continue; | |
else if (png_ptr->trans_alpha[i] == 0) | |
input_has_transparency = 1; | |
else | |
input_has_alpha = 1; | |
} | |
/* If no alpha we can optimize. */ | |
if (!input_has_alpha) | |
{ | |
/* Any alpha means background and associative alpha processing is | |
* required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA | |
* and ENCODE_ALPHA are irrelevant. | |
*/ | |
png_ptr->transformations &= ~PNG_ENCODE_ALPHA; | |
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; | |
if (!input_has_transparency) | |
png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND); | |
} | |
#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED) | |
/* png_set_background handling - deals with the complexity of whether the | |
* background color is in the file format or the screen format in the case | |
* where an 'expand' will happen. | |
*/ | |
/* The following code cannot be entered in the alpha pre-multiplication case | |
* because PNG_BACKGROUND_EXPAND is cancelled below. | |
*/ | |
if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) && | |
(png_ptr->transformations & PNG_EXPAND)) | |
{ | |
{ | |
png_ptr->background.red = | |
png_ptr->palette[png_ptr->background.index].red; | |
png_ptr->background.green = | |
png_ptr->palette[png_ptr->background.index].green; | |
png_ptr->background.blue = | |
png_ptr->palette[png_ptr->background.index].blue; | |
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED | |
if (png_ptr->transformations & PNG_INVERT_ALPHA) | |
{ | |
if (!(png_ptr->transformations & PNG_EXPAND_tRNS)) | |
{ | |
/* Invert the alpha channel (in tRNS) unless the pixels are | |
* going to be expanded, in which case leave it for later | |
*/ | |
int i, istop = png_ptr->num_trans; | |
for (i=0; i<istop; i++) | |
png_ptr->trans_alpha[i] = (png_byte)(255 - | |
png_ptr->trans_alpha[i]); | |
} | |
} | |
#endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */ | |
} | |
} /* background expand and (therefore) no alpha association. */ | |
#endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */ | |
} | |
static void /* PRIVATE */ | |
png_init_rgb_transformations(png_structrp png_ptr) | |
{ | |
/* Added to libpng-1.5.4: check the color type to determine whether there | |
* is any alpha or transparency in the image and simply cancel the | |
* background and alpha mode stuff if there isn't. | |
*/ | |
int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0; | |
int input_has_transparency = png_ptr->num_trans > 0; | |
/* If no alpha we can optimize. */ | |
if (!input_has_alpha) | |
{ | |
/* Any alpha means background and associative alpha processing is | |
* required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA | |
* and ENCODE_ALPHA are irrelevant. | |
*/ | |
# ifdef PNG_READ_ALPHA_MODE_SUPPORTED | |
png_ptr->transformations &= ~PNG_ENCODE_ALPHA; | |
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; | |
# endif | |
if (!input_has_transparency) | |
png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND); | |
} | |
#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED) | |
/* png_set_background handling - deals with the complexity of whether the | |
* background color is in the file format or the screen format in the case | |
* where an 'expand' will happen. | |
*/ | |
/* The following code cannot be entered in the alpha pre-multiplication case | |
* because PNG_BACKGROUND_EXPAND is cancelled below. | |
*/ | |
if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) && | |
(png_ptr->transformations & PNG_EXPAND) && | |
!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) | |
/* i.e., GRAY or GRAY_ALPHA */ | |
{ | |
{ | |
/* Expand background and tRNS chunks */ | |
int gray = png_ptr->background.gray; | |
int trans_gray = png_ptr->trans_color.gray; | |
switch (png_ptr->bit_depth) | |
{ | |
case 1: | |
gray *= 0xff; | |
trans_gray *= 0xff; | |
break; | |
case 2: | |
gray *= 0x55; | |
trans_gray *= 0x55; | |
break; | |
case 4: | |
gray *= 0x11; | |
trans_gray *= 0x11; | |
break; | |
default: | |
case 8: | |
/* FALL THROUGH (Already 8 bits) */ | |
case 16: | |
/* Already a full 16 bits */ | |
break; | |
} | |
png_ptr->background.red = png_ptr->background.green = | |
png_ptr->background.blue = (png_uint_16)gray; | |
if (!(png_ptr->transformations & PNG_EXPAND_tRNS)) | |
{ | |
png_ptr->trans_color.red = png_ptr->trans_color.green = | |
png_ptr->trans_color.blue = (png_uint_16)trans_gray; | |
} | |
} | |
} /* background expand and (therefore) no alpha association. */ | |
#endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */ | |
} | |
void /* PRIVATE */ | |
png_init_read_transformations(png_structrp png_ptr) | |
{ | |
png_debug(1, "in png_init_read_transformations"); | |
/* This internal function is called from png_read_start_row in pngrutil.c | |
* and it is called before the 'rowbytes' calculation is done, so the code | |
* in here can change or update the transformations flags. | |
* | |
* First do updates that do not depend on the details of the PNG image data | |
* being processed. | |
*/ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
/* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds | |
* png_set_alpha_mode and this is another source for a default file gamma so | |
* the test needs to be performed later - here. In addition prior to 1.5.4 | |
* the tests were repeated for the PALETTE color type here - this is no | |
* longer necessary (and doesn't seem to have been necessary before.) | |
*/ | |
{ | |
/* The following temporary indicates if overall gamma correction is | |
* required. | |
*/ | |
int gamma_correction = 0; | |
if (png_ptr->colorspace.gamma != 0) /* has been set */ | |
{ | |
if (png_ptr->screen_gamma != 0) /* screen set too */ | |
gamma_correction = png_gamma_threshold(png_ptr->colorspace.gamma, | |
png_ptr->screen_gamma); | |
else | |
/* Assume the output matches the input; a long time default behavior | |
* of libpng, although the standard has nothing to say about this. | |
*/ | |
png_ptr->screen_gamma = png_reciprocal(png_ptr->colorspace.gamma); | |
} | |
else if (png_ptr->screen_gamma != 0) | |
/* The converse - assume the file matches the screen, note that this | |
* perhaps undesireable default can (from 1.5.4) be changed by calling | |
* png_set_alpha_mode (even if the alpha handling mode isn't required | |
* or isn't changed from the default.) | |
*/ | |
png_ptr->colorspace.gamma = png_reciprocal(png_ptr->screen_gamma); | |
else /* neither are set */ | |
/* Just in case the following prevents any processing - file and screen | |
* are both assumed to be linear and there is no way to introduce a | |
* third gamma value other than png_set_background with 'UNIQUE', and, | |
* prior to 1.5.4 | |
*/ | |
png_ptr->screen_gamma = png_ptr->colorspace.gamma = PNG_FP_1; | |
/* We have a gamma value now. */ | |
png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA; | |
/* Now turn the gamma transformation on or off as appropriate. Notice | |
* that PNG_GAMMA just refers to the file->screen correction. Alpha | |
* composition may independently cause gamma correction because it needs | |
* linear data (e.g. if the file has a gAMA chunk but the screen gamma | |
* hasn't been specified.) In any case this flag may get turned off in | |
* the code immediately below if the transform can be handled outside the | |
* row loop. | |
*/ | |
if (gamma_correction) | |
png_ptr->transformations |= PNG_GAMMA; | |
else | |
png_ptr->transformations &= ~PNG_GAMMA; | |
} | |
#endif | |
/* Certain transformations have the effect of preventing other | |
* transformations that happen afterward in png_do_read_transformations, | |
* resolve the interdependencies here. From the code of | |
* png_do_read_transformations the order is: | |
* | |
* 1) PNG_EXPAND (including PNG_EXPAND_tRNS) | |
* 2) PNG_STRIP_ALPHA (if no compose) | |
* 3) PNG_RGB_TO_GRAY | |
* 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY | |
* 5) PNG_COMPOSE | |
* 6) PNG_GAMMA | |
* 7) PNG_STRIP_ALPHA (if compose) | |
* 8) PNG_ENCODE_ALPHA | |
* 9) PNG_SCALE_16_TO_8 | |
* 10) PNG_16_TO_8 | |
* 11) PNG_QUANTIZE (converts to palette) | |
* 12) PNG_EXPAND_16 | |
* 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY | |
* 14) PNG_INVERT_MONO | |
* 15) PNG_SHIFT | |
* 16) PNG_PACK | |
* 17) PNG_BGR | |
* 18) PNG_PACKSWAP | |
* 19) PNG_FILLER (includes PNG_ADD_ALPHA) | |
* 20) PNG_INVERT_ALPHA | |
* 21) PNG_SWAP_ALPHA | |
* 22) PNG_SWAP_BYTES | |
* 23) PNG_USER_TRANSFORM [must be last] | |
*/ | |
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED | |
if ((png_ptr->transformations & PNG_STRIP_ALPHA) && | |
!(png_ptr->transformations & PNG_COMPOSE)) | |
{ | |
/* Stripping the alpha channel happens immediately after the 'expand' | |
* transformations, before all other transformation, so it cancels out | |
* the alpha handling. It has the side effect negating the effect of | |
* PNG_EXPAND_tRNS too: | |
*/ | |
png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA | | |
PNG_EXPAND_tRNS); | |
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; | |
/* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen | |
* so transparency information would remain just so long as it wasn't | |
* expanded. This produces unexpected API changes if the set of things | |
* that do PNG_EXPAND_tRNS changes (perfectly possible given the | |
* documentation - which says ask for what you want, accept what you | |
* get.) This makes the behavior consistent from 1.5.4: | |
*/ | |
png_ptr->num_trans = 0; | |
} | |
#endif /* STRIP_ALPHA supported, no COMPOSE */ | |
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED | |
/* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA | |
* settings will have no effect. | |
*/ | |
if (!png_gamma_significant(png_ptr->screen_gamma)) | |
{ | |
png_ptr->transformations &= ~PNG_ENCODE_ALPHA; | |
png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA; | |
} | |
#endif | |
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED | |
/* Make sure the coefficients for the rgb to gray conversion are set | |
* appropriately. | |
*/ | |
if (png_ptr->transformations & PNG_RGB_TO_GRAY) | |
png_colorspace_set_rgb_coefficients(png_ptr); | |
#endif | |
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED | |
#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED) | |
/* Detect gray background and attempt to enable optimization for | |
* gray --> RGB case. | |
* | |
* Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or | |
* RGB_ALPHA (in which case need_expand is superfluous anyway), the | |
* background color might actually be gray yet not be flagged as such. | |
* This is not a problem for the current code, which uses | |
* PNG_BACKGROUND_IS_GRAY only to decide when to do the | |
* png_do_gray_to_rgb() transformation. | |
* | |
* TODO: this code needs to be revised to avoid the complexity and | |
* interdependencies. The color type of the background should be recorded in | |
* png_set_background, along with the bit depth, then the code has a record | |
* of exactly what color space the background is currently in. | |
*/ | |
if (png_ptr->transformations & PNG_BACKGROUND_EXPAND) | |
{ | |
/* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if | |
* the file was grayscale the background value is gray. | |
*/ | |
if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR)) | |
png_ptr->mode |= PNG_BACKGROUND_IS_GRAY; | |
} | |
else if (png_ptr->transformations & PNG_COMPOSE) | |
{ | |
/* PNG_COMPOSE: png_set_background was called with need_expand false, | |
* so the color is in the color space of the output or png_set_alpha_mode | |
* was called and the color is black. Ignore RGB_TO_GRAY because that | |
* happens before GRAY_TO_RGB. | |
*/ | |
if (png_ptr->transformations & PNG_GRAY_TO_RGB) | |
{ | |
if (png_ptr->background.red == png_ptr->background.green && | |
png_ptr->background.red == png_ptr->background.blue) | |
{ | |
png_ptr->mode |= PNG_BACKGROUND_IS_GRAY; | |
png_ptr->background.gray = png_ptr->background.red; | |
} | |
} | |
} | |
#endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */ | |
#endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED */ | |
/* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations | |
* can be performed directly on the palette, and some (such as rgb to gray) | |
* can be optimized inside the palette. This is particularly true of the | |
* composite (background and alpha) stuff, which can be pretty much all done | |
* in the palette even if the result is expanded to RGB or gray afterward. | |
* | |
* NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and | |
* earlier and the palette stuff is actually handled on the first row. This | |
* leads to the reported bug that the palette returned by png_get_PLTE is not | |
* updated. | |
*/ | |
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) | |
png_init_palette_transformations(png_ptr); | |
else | |
png_init_rgb_transformations(png_ptr); | |
#if defined(PNG_READ_BACKGROUND_SUPPORTED) && \ | |
defined(PNG_READ_EXPAND_16_SUPPORTED) | |
if ((png_ptr->transformations & PNG_EXPAND_16) && | |
(png_ptr->transformations & PNG_COMPOSE) && | |
!(png_ptr->transformations & PNG_BACKGROUND_EXPAND) && | |
png_ptr->bit_depth != 16) | |
{ | |
/* TODO: fix this. Because the expand_16 operation is after the compose | |
* handling the background color must be 8, not 16, bits deep, but the | |
* application will supply a 16-bit value so reduce it here. | |
* | |
* The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at | |
* present, so that case is ok (until do_expand_16 is moved.) | |
* | |
* NOTE: this discards the low 16 bits of the user supplied background | |
* color, but until expand_16 works properly there is no choice! | |
*/ | |
# define CHOP(x) (x)=((png_uint_16)PNG_DIV257(x)) | |
CHOP(png_ptr->background.red); | |
CHOP(png_ptr->background.green); | |
CHOP(png_ptr->background.blue); | |
CHOP(png_ptr->background.gray); | |
# undef CHOP | |
} | |
#endif /* PNG_READ_BACKGROUND_SUPPORTED && PNG_READ_EXPAND_16_SUPPORTED */ | |
#if defined(PNG_READ_BACKGROUND_SUPPORTED) && \ | |
(defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \ | |
defined(PNG_READ_STRIP_16_TO_8_SUPPORTED)) | |
if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) && | |
(png_ptr->transformations & PNG_COMPOSE) && | |
!(png_ptr->transformations & PNG_BACKGROUND_EXPAND) && | |
png_ptr->bit_depth == 16) | |
{ | |
/* On the other hand, if a 16-bit file is to be reduced to 8-bits per | |
* component this will also happen after PNG_COMPOSE and so the background | |
* color must be pre-expanded here. | |
* | |
* TODO: fix this too. | |
*/ | |
png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257); | |
png_ptr->background.green = | |
(png_uint_16)(png_ptr->background.green * 257); | |
png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257); | |
png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257); | |
} | |
#endif | |
/* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the | |
* background support (see the comments in scripts/pnglibconf.dfa), this | |
* allows pre-multiplication of the alpha channel to be implemented as | |
* compositing on black. This is probably sub-optimal and has been done in | |
* 1.5.4 betas simply to enable external critique and testing (i.e. to | |
* implement the new API quickly, without lots of internal changes.) | |
*/ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
# ifdef PNG_READ_BACKGROUND_SUPPORTED | |
/* Includes ALPHA_MODE */ | |
png_ptr->background_1 = png_ptr->background; | |
# endif | |
/* This needs to change - in the palette image case a whole set of tables are | |
* built when it would be quicker to just calculate the correct value for | |
* each palette entry directly. Also, the test is too tricky - why check | |
* PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that | |
* PNG_GAMMA is cancelled even if the gamma is known? The test excludes the | |
* PNG_COMPOSE case, so apparently if there is no *overall* gamma correction | |
* the gamma tables will not be built even if composition is required on a | |
* gamma encoded value. | |
* | |
* In 1.5.4 this is addressed below by an additional check on the individual | |
* file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the | |
* tables. | |
*/ | |
if ((png_ptr->transformations & PNG_GAMMA) | |
|| ((png_ptr->transformations & PNG_RGB_TO_GRAY) | |
&& (png_gamma_significant(png_ptr->colorspace.gamma) || | |
png_gamma_significant(png_ptr->screen_gamma))) | |
|| ((png_ptr->transformations & PNG_COMPOSE) | |
&& (png_gamma_significant(png_ptr->colorspace.gamma) | |
|| png_gamma_significant(png_ptr->screen_gamma) | |
# ifdef PNG_READ_BACKGROUND_SUPPORTED | |
|| (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE | |
&& png_gamma_significant(png_ptr->background_gamma)) | |
# endif | |
)) || ((png_ptr->transformations & PNG_ENCODE_ALPHA) | |
&& png_gamma_significant(png_ptr->screen_gamma)) | |
) | |
{ | |
png_build_gamma_table(png_ptr, png_ptr->bit_depth); | |
#ifdef PNG_READ_BACKGROUND_SUPPORTED | |
if (png_ptr->transformations & PNG_COMPOSE) | |
{ | |
/* Issue a warning about this combination: because RGB_TO_GRAY is | |
* optimized to do the gamma transform if present yet do_background has | |
* to do the same thing if both options are set a | |
* double-gamma-correction happens. This is true in all versions of | |
* libpng to date. | |
*/ | |
if (png_ptr->transformations & PNG_RGB_TO_GRAY) | |
png_warning(png_ptr, | |
"libpng does not support gamma+background+rgb_to_gray"); | |
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) | |
{ | |
/* We don't get to here unless there is a tRNS chunk with non-opaque | |
* entries - see the checking code at the start of this function. | |
*/ | |
png_color back, back_1; | |
png_colorp palette = png_ptr->palette; | |
int num_palette = png_ptr->num_palette; | |
int i; | |
if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE) | |
{ | |
back.red = png_ptr->gamma_table[png_ptr->background.red]; | |
back.green = png_ptr->gamma_table[png_ptr->background.green]; | |
back.blue = png_ptr->gamma_table[png_ptr->background.blue]; | |
back_1.red = png_ptr->gamma_to_1[png_ptr->background.red]; | |
back_1.green = png_ptr->gamma_to_1[png_ptr->background.green]; | |
back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue]; | |
} | |
else | |
{ | |
png_fixed_point g, gs; | |
switch (png_ptr->background_gamma_type) | |
{ | |
case PNG_BACKGROUND_GAMMA_SCREEN: | |
g = (png_ptr->screen_gamma); | |
gs = PNG_FP_1; | |
break; | |
case PNG_BACKGROUND_GAMMA_FILE: | |
g = png_reciprocal(png_ptr->colorspace.gamma); | |
gs = png_reciprocal2(png_ptr->colorspace.gamma, | |
png_ptr->screen_gamma); | |
break; | |
case PNG_BACKGROUND_GAMMA_UNIQUE: | |
g = png_reciprocal(png_ptr->background_gamma); | |
gs = png_reciprocal2(png_ptr->background_gamma, | |
png_ptr->screen_gamma); | |
break; | |
default: | |
g = PNG_FP_1; /* back_1 */ | |
gs = PNG_FP_1; /* back */ | |
break; | |
} | |
if (png_gamma_significant(gs)) | |
{ | |
back.red = png_gamma_8bit_correct(png_ptr->background.red, | |
gs); | |
back.green = png_gamma_8bit_correct(png_ptr->background.green, | |
gs); | |
back.blue = png_gamma_8bit_correct(png_ptr->background.blue, | |
gs); | |
} | |
else | |
{ | |
back.red = (png_byte)png_ptr->background.red; | |
back.green = (png_byte)png_ptr->background.green; | |
back.blue = (png_byte)png_ptr->background.blue; | |
} | |
if (png_gamma_significant(g)) | |
{ | |
back_1.red = png_gamma_8bit_correct(png_ptr->background.red, | |
g); | |
back_1.green = png_gamma_8bit_correct( | |
png_ptr->background.green, g); | |
back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue, | |
g); | |
} | |
else | |
{ | |
back_1.red = (png_byte)png_ptr->background.red; | |
back_1.green = (png_byte)png_ptr->background.green; | |
back_1.blue = (png_byte)png_ptr->background.blue; | |
} | |
} | |
for (i = 0; i < num_palette; i++) | |
{ | |
if (i < (int)png_ptr->num_trans && | |
png_ptr->trans_alpha[i] != 0xff) | |
{ | |
if (png_ptr->trans_alpha[i] == 0) | |
{ | |
palette[i] = back; | |
} | |
else /* if (png_ptr->trans_alpha[i] != 0xff) */ | |
{ | |
png_byte v, w; | |
v = png_ptr->gamma_to_1[palette[i].red]; | |
png_composite(w, v, png_ptr->trans_alpha[i], back_1.red); | |
palette[i].red = png_ptr->gamma_from_1[w]; | |
v = png_ptr->gamma_to_1[palette[i].green]; | |
png_composite(w, v, png_ptr->trans_alpha[i], back_1.green); | |
palette[i].green = png_ptr->gamma_from_1[w]; | |
v = png_ptr->gamma_to_1[palette[i].blue]; | |
png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue); | |
palette[i].blue = png_ptr->gamma_from_1[w]; | |
} | |
} | |
else | |
{ | |
palette[i].red = png_ptr->gamma_table[palette[i].red]; | |
palette[i].green = png_ptr->gamma_table[palette[i].green]; | |
palette[i].blue = png_ptr->gamma_table[palette[i].blue]; | |
} | |
} | |
/* Prevent the transformations being done again. | |
* | |
* NOTE: this is highly dubious; it removes the transformations in | |
* place. This seems inconsistent with the general treatment of the | |
* transformations elsewhere. | |
*/ | |
png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA); | |
} /* color_type == PNG_COLOR_TYPE_PALETTE */ | |
/* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */ | |
else /* color_type != PNG_COLOR_TYPE_PALETTE */ | |
{ | |
int gs_sig, g_sig; | |
png_fixed_point g = PNG_FP_1; /* Correction to linear */ | |
png_fixed_point gs = PNG_FP_1; /* Correction to screen */ | |
switch (png_ptr->background_gamma_type) | |
{ | |
case PNG_BACKGROUND_GAMMA_SCREEN: | |
g = png_ptr->screen_gamma; | |
/* gs = PNG_FP_1; */ | |
break; | |
case PNG_BACKGROUND_GAMMA_FILE: | |
g = png_reciprocal(png_ptr->colorspace.gamma); | |
gs = png_reciprocal2(png_ptr->colorspace.gamma, | |
png_ptr->screen_gamma); | |
break; | |
case PNG_BACKGROUND_GAMMA_UNIQUE: | |
g = png_reciprocal(png_ptr->background_gamma); | |
gs = png_reciprocal2(png_ptr->background_gamma, | |
png_ptr->screen_gamma); | |
break; | |
default: | |
png_error(png_ptr, "invalid background gamma type"); | |
} | |
g_sig = png_gamma_significant(g); | |
gs_sig = png_gamma_significant(gs); | |
if (g_sig) | |
png_ptr->background_1.gray = png_gamma_correct(png_ptr, | |
png_ptr->background.gray, g); | |
if (gs_sig) | |
png_ptr->background.gray = png_gamma_correct(png_ptr, | |
png_ptr->background.gray, gs); | |
if ((png_ptr->background.red != png_ptr->background.green) || | |
(png_ptr->background.red != png_ptr->background.blue) || | |
(png_ptr->background.red != png_ptr->background.gray)) | |
{ | |
/* RGB or RGBA with color background */ | |
if (g_sig) | |
{ | |
png_ptr->background_1.red = png_gamma_correct(png_ptr, | |
png_ptr->background.red, g); | |
png_ptr->background_1.green = png_gamma_correct(png_ptr, | |
png_ptr->background.green, g); | |
png_ptr->background_1.blue = png_gamma_correct(png_ptr, | |
png_ptr->background.blue, g); | |
} | |
if (gs_sig) | |
{ | |
png_ptr->background.red = png_gamma_correct(png_ptr, | |
png_ptr->background.red, gs); | |
png_ptr->background.green = png_gamma_correct(png_ptr, | |
png_ptr->background.green, gs); | |
png_ptr->background.blue = png_gamma_correct(png_ptr, | |
png_ptr->background.blue, gs); | |
} | |
} | |
else | |
{ | |
/* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */ | |
png_ptr->background_1.red = png_ptr->background_1.green | |
= png_ptr->background_1.blue = png_ptr->background_1.gray; | |
png_ptr->background.red = png_ptr->background.green | |
= png_ptr->background.blue = png_ptr->background.gray; | |
} | |
/* The background is now in screen gamma: */ | |
png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN; | |
} /* color_type != PNG_COLOR_TYPE_PALETTE */ | |
}/* png_ptr->transformations & PNG_BACKGROUND */ | |
else | |
/* Transformation does not include PNG_BACKGROUND */ | |
#endif /* PNG_READ_BACKGROUND_SUPPORTED */ | |
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE | |
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED | |
/* RGB_TO_GRAY needs to have non-gamma-corrected values! */ | |
&& ((png_ptr->transformations & PNG_EXPAND) == 0 || | |
(png_ptr->transformations & PNG_RGB_TO_GRAY) == 0) | |
#endif | |
) | |
{ | |
png_colorp palette = png_ptr->palette; | |
int num_palette = png_ptr->num_palette; | |
int i; | |
/* NOTE: there are other transformations that should probably be in | |
* here too. | |
*/ | |
for (i = 0; i < num_palette; i++) | |
{ | |
palette[i].red = png_ptr->gamma_table[palette[i].red]; | |
palette[i].green = png_ptr->gamma_table[palette[i].green]; | |
palette[i].blue = png_ptr->gamma_table[palette[i].blue]; | |
} | |
/* Done the gamma correction. */ | |
png_ptr->transformations &= ~PNG_GAMMA; | |
} /* color_type == PALETTE && !PNG_BACKGROUND transformation */ | |
} | |
#ifdef PNG_READ_BACKGROUND_SUPPORTED | |
else | |
#endif | |
#endif /* PNG_READ_GAMMA_SUPPORTED */ | |
#ifdef PNG_READ_BACKGROUND_SUPPORTED | |
/* No GAMMA transformation (see the hanging else 4 lines above) */ | |
if ((png_ptr->transformations & PNG_COMPOSE) && | |
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)) | |
{ | |
int i; | |
int istop = (int)png_ptr->num_trans; | |
png_color back; | |
png_colorp palette = png_ptr->palette; | |
back.red = (png_byte)png_ptr->background.red; | |
back.green = (png_byte)png_ptr->background.green; | |
back.blue = (png_byte)png_ptr->background.blue; | |
for (i = 0; i < istop; i++) | |
{ | |
if (png_ptr->trans_alpha[i] == 0) | |
{ | |
palette[i] = back; | |
} | |
else if (png_ptr->trans_alpha[i] != 0xff) | |
{ | |
/* The png_composite() macro is defined in png.h */ | |
png_composite(palette[i].red, palette[i].red, | |
png_ptr->trans_alpha[i], back.red); | |
png_composite(palette[i].green, palette[i].green, | |
png_ptr->trans_alpha[i], back.green); | |
png_composite(palette[i].blue, palette[i].blue, | |
png_ptr->trans_alpha[i], back.blue); | |
} | |
} | |
png_ptr->transformations &= ~PNG_COMPOSE; | |
//png_ptr->flags |= PNG_FLAG_STRIP_ALPHA; /* Add by Sunliang.Liu */ | |
} | |
#endif /* PNG_READ_BACKGROUND_SUPPORTED */ | |
#ifdef PNG_READ_SHIFT_SUPPORTED | |
if ((png_ptr->transformations & PNG_SHIFT) && | |
!(png_ptr->transformations & PNG_EXPAND) && | |
(png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)) | |
{ | |
int i; | |
int istop = png_ptr->num_palette; | |
int shift = 8 - png_ptr->sig_bit.red; | |
png_ptr->transformations &= ~PNG_SHIFT; | |
/* significant bits can be in the range 1 to 7 for a meaninful result, if | |
* the number of significant bits is 0 then no shift is done (this is an | |
* error condition which is silently ignored.) | |
*/ | |
if (shift > 0 && shift < 8) for (i=0; i<istop; ++i) | |
{ | |
int component = png_ptr->palette[i].red; | |
component >>= shift; | |
png_ptr->palette[i].red = (png_byte)component; | |
} | |
shift = 8 - png_ptr->sig_bit.green; | |
if (shift > 0 && shift < 8) for (i=0; i<istop; ++i) | |
{ | |
int component = png_ptr->palette[i].green; | |
component >>= shift; | |
png_ptr->palette[i].green = (png_byte)component; | |
} | |
shift = 8 - png_ptr->sig_bit.blue; | |
if (shift > 0 && shift < 8) for (i=0; i<istop; ++i) | |
{ | |
int component = png_ptr->palette[i].blue; | |
component >>= shift; | |
png_ptr->palette[i].blue = (png_byte)component; | |
} | |
} | |
#endif /* PNG_READ_SHIFT_SUPPORTED */ | |
} | |
/* Modify the info structure to reflect the transformations. The | |
* info should be updated so a PNG file could be written with it, | |
* assuming the transformations result in valid PNG data. | |
*/ | |
void /* PRIVATE */ | |
png_read_transform_info(png_structrp png_ptr, png_inforp info_ptr) | |
{ | |
png_debug(1, "in png_read_transform_info"); | |
#ifdef PNG_READ_EXPAND_SUPPORTED | |
if (png_ptr->transformations & PNG_EXPAND) | |
{ | |
if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) | |
{ | |
/* This check must match what actually happens in | |
* png_do_expand_palette; if it ever checks the tRNS chunk to see if | |
* it is all opaque we must do the same (at present it does not.) | |
*/ | |
if (png_ptr->num_trans > 0) | |
info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA; | |
else | |
info_ptr->color_type = PNG_COLOR_TYPE_RGB; | |
info_ptr->bit_depth = 8; | |
info_ptr->num_trans = 0; | |
} | |
else | |
{ | |
if (png_ptr->num_trans) | |
{ | |
if (png_ptr->transformations & PNG_EXPAND_tRNS) | |
info_ptr->color_type |= PNG_COLOR_MASK_ALPHA; | |
} | |
if (info_ptr->bit_depth < 8) | |
info_ptr->bit_depth = 8; | |
info_ptr->num_trans = 0; | |
} | |
} | |
#endif | |
#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ | |
defined(PNG_READ_ALPHA_MODE_SUPPORTED) | |
/* The following is almost certainly wrong unless the background value is in | |
* the screen space! | |
*/ | |
if (png_ptr->transformations & PNG_COMPOSE) | |
info_ptr->background = png_ptr->background; | |
#endif | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
/* The following used to be conditional on PNG_GAMMA (prior to 1.5.4), | |
* however it seems that the code in png_init_read_transformations, which has | |
* been called before this from png_read_update_info->png_read_start_row | |
* sometimes does the gamma transform and cancels the flag. | |
* | |
* TODO: this looks wrong; the info_ptr should end up with a gamma equal to | |
* the screen_gamma value. The following probably results in weirdness if | |
* the info_ptr is used by the app after the rows have been read. | |
*/ | |
info_ptr->colorspace.gamma = png_ptr->colorspace.gamma; | |
#endif | |
if (info_ptr->bit_depth == 16) | |
{ | |
# ifdef PNG_READ_16BIT_SUPPORTED | |
# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED | |
if (png_ptr->transformations & PNG_SCALE_16_TO_8) | |
info_ptr->bit_depth = 8; | |
# endif | |
# ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED | |
if (png_ptr->transformations & PNG_16_TO_8) | |
info_ptr->bit_depth = 8; | |
# endif | |
# else | |
/* No 16 bit support: force chopping 16-bit input down to 8, in this case | |
* the app program can chose if both APIs are available by setting the | |
* correct scaling to use. | |
*/ | |
# ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED | |
/* For compatibility with previous versions use the strip method by | |
* default. This code works because if PNG_SCALE_16_TO_8 is already | |
* set the code below will do that in preference to the chop. | |
*/ | |
png_ptr->transformations |= PNG_16_TO_8; | |
info_ptr->bit_depth = 8; | |
# else | |
# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED | |
png_ptr->transformations |= PNG_SCALE_16_TO_8; | |
info_ptr->bit_depth = 8; | |
# else | |
CONFIGURATION ERROR: you must enable at least one 16 to 8 method | |
# endif | |
# endif | |
#endif /* !READ_16BIT_SUPPORTED */ | |
} | |
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED | |
if (png_ptr->transformations & PNG_GRAY_TO_RGB) | |
info_ptr->color_type = (png_byte)(info_ptr->color_type | | |
PNG_COLOR_MASK_COLOR); | |
#endif | |
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED | |
if (png_ptr->transformations & PNG_RGB_TO_GRAY) | |
info_ptr->color_type = (png_byte)(info_ptr->color_type & | |
~PNG_COLOR_MASK_COLOR); | |
#endif | |
#ifdef PNG_READ_QUANTIZE_SUPPORTED | |
if (png_ptr->transformations & PNG_QUANTIZE) | |
{ | |
if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) || | |
(info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) && | |
png_ptr->palette_lookup && info_ptr->bit_depth == 8) | |
{ | |
info_ptr->color_type = PNG_COLOR_TYPE_PALETTE; | |
} | |
} | |
#endif | |
#ifdef PNG_READ_EXPAND_16_SUPPORTED | |
if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 && | |
info_ptr->color_type != PNG_COLOR_TYPE_PALETTE) | |
{ | |
info_ptr->bit_depth = 16; | |
} | |
#endif | |
#ifdef PNG_READ_PACK_SUPPORTED | |
if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8)) | |
info_ptr->bit_depth = 8; | |
#endif | |
if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) | |
info_ptr->channels = 1; | |
else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR) | |
info_ptr->channels = 3; | |
else | |
info_ptr->channels = 1; | |
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED | |
if (png_ptr->transformations & PNG_STRIP_ALPHA) | |
{ | |
info_ptr->color_type = (png_byte)(info_ptr->color_type & | |
~PNG_COLOR_MASK_ALPHA); | |
info_ptr->num_trans = 0; | |
} | |
#endif | |
if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA) | |
info_ptr->channels++; | |
#ifdef PNG_READ_FILLER_SUPPORTED | |
/* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */ | |
if ((png_ptr->transformations & PNG_FILLER) && | |
((info_ptr->color_type == PNG_COLOR_TYPE_RGB) || | |
(info_ptr->color_type == PNG_COLOR_TYPE_GRAY))) | |
{ | |
info_ptr->channels++; | |
/* If adding a true alpha channel not just filler */ | |
if (png_ptr->transformations & PNG_ADD_ALPHA) | |
info_ptr->color_type |= PNG_COLOR_MASK_ALPHA; | |
} | |
#endif | |
#if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \ | |
defined(PNG_READ_USER_TRANSFORM_SUPPORTED) | |
if (png_ptr->transformations & PNG_USER_TRANSFORM) | |
{ | |
if (info_ptr->bit_depth < png_ptr->user_transform_depth) | |
info_ptr->bit_depth = png_ptr->user_transform_depth; | |
if (info_ptr->channels < png_ptr->user_transform_channels) | |
info_ptr->channels = png_ptr->user_transform_channels; | |
} | |
#endif | |
info_ptr->pixel_depth = (png_byte)(info_ptr->channels * | |
info_ptr->bit_depth); | |
info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width); | |
/* Adding in 1.5.4: cache the above value in png_struct so that we can later | |
* check in png_rowbytes that the user buffer won't get overwritten. Note | |
* that the field is not always set - if png_read_update_info isn't called | |
* the application has to either not do any transforms or get the calculation | |
* right itself. | |
*/ | |
png_ptr->info_rowbytes = info_ptr->rowbytes; | |
#ifndef PNG_READ_EXPAND_SUPPORTED | |
if (png_ptr) | |
return; | |
#endif | |
} | |
/* Transform the row. The order of transformations is significant, | |
* and is very touchy. If you add a transformation, take care to | |
* decide how it fits in with the other transformations here. | |
*/ | |
void /* PRIVATE */ | |
png_do_read_transformations(png_structrp png_ptr, png_row_infop row_info) | |
{ | |
png_debug(1, "in png_do_read_transformations"); | |
if (png_ptr->row_buf == NULL) | |
{ | |
/* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this | |
* error is incredibly rare and incredibly easy to debug without this | |
* information. | |
*/ | |
png_error(png_ptr, "NULL row buffer"); | |
} | |
/* The following is debugging; prior to 1.5.4 the code was never compiled in; | |
* in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro | |
* PNG_WARN_UNINITIALIZED_ROW removed. In 1.6 the new flag is set only for | |
* all transformations, however in practice the ROW_INIT always gets done on | |
* demand, if necessary. | |
*/ | |
if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 && | |
!(png_ptr->flags & PNG_FLAG_ROW_INIT)) | |
{ | |
/* Application has failed to call either png_read_start_image() or | |
* png_read_update_info() after setting transforms that expand pixels. | |
* This check added to libpng-1.2.19 (but not enabled until 1.5.4). | |
*/ | |
png_error(png_ptr, "Uninitialized row"); | |
} | |
#ifdef PNG_READ_EXPAND_SUPPORTED | |
if (png_ptr->transformations & PNG_EXPAND) | |
{ | |
if (row_info->color_type == PNG_COLOR_TYPE_PALETTE) | |
{ | |
png_do_expand_palette(row_info, png_ptr->row_buf + 1, | |
png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans); | |
} | |
else | |
{ | |
if (png_ptr->num_trans && | |
(png_ptr->transformations & PNG_EXPAND_tRNS)) | |
png_do_expand(row_info, png_ptr->row_buf + 1, | |
&(png_ptr->trans_color)); | |
else | |
png_do_expand(row_info, png_ptr->row_buf + 1, | |
NULL); | |
} | |
} | |
#endif | |
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED | |
if ((png_ptr->transformations & PNG_STRIP_ALPHA) && | |
!(png_ptr->transformations & PNG_COMPOSE) && | |
(row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)) | |
png_do_strip_channel(row_info, png_ptr->row_buf + 1, | |
0 /* at_start == false, because SWAP_ALPHA happens later */); | |
#endif | |
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED | |
if (png_ptr->transformations & PNG_RGB_TO_GRAY) | |
{ | |
int rgb_error = | |
png_do_rgb_to_gray(png_ptr, row_info, | |
png_ptr->row_buf + 1); | |
if (rgb_error) | |
{ | |
png_ptr->rgb_to_gray_status=1; | |
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == | |
PNG_RGB_TO_GRAY_WARN) | |
png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel"); | |
if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == | |
PNG_RGB_TO_GRAY_ERR) | |
png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel"); | |
} | |
} | |
#endif | |
/* From Andreas Dilger e-mail to png-implement, 26 March 1998: | |
* | |
* In most cases, the "simple transparency" should be done prior to doing | |
* gray-to-RGB, or you will have to test 3x as many bytes to check if a | |
* pixel is transparent. You would also need to make sure that the | |
* transparency information is upgraded to RGB. | |
* | |
* To summarize, the current flow is: | |
* - Gray + simple transparency -> compare 1 or 2 gray bytes and composite | |
* with background "in place" if transparent, | |
* convert to RGB if necessary | |
* - Gray + alpha -> composite with gray background and remove alpha bytes, | |
* convert to RGB if necessary | |
* | |
* To support RGB backgrounds for gray images we need: | |
* - Gray + simple transparency -> convert to RGB + simple transparency, | |
* compare 3 or 6 bytes and composite with | |
* background "in place" if transparent | |
* (3x compare/pixel compared to doing | |
* composite with gray bkgrnd) | |
* - Gray + alpha -> convert to RGB + alpha, composite with background and | |
* remove alpha bytes (3x float | |
* operations/pixel compared with composite | |
* on gray background) | |
* | |
* Greg's change will do this. The reason it wasn't done before is for | |
* performance, as this increases the per-pixel operations. If we would check | |
* in advance if the background was gray or RGB, and position the gray-to-RGB | |
* transform appropriately, then it would save a lot of work/time. | |
*/ | |
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED | |
/* If gray -> RGB, do so now only if background is non-gray; else do later | |
* for performance reasons | |
*/ | |
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) && | |
!(png_ptr->mode & PNG_BACKGROUND_IS_GRAY)) | |
png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1); | |
#endif | |
#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ | |
defined(PNG_READ_ALPHA_MODE_SUPPORTED) | |
if (png_ptr->transformations & PNG_COMPOSE) | |
png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr); | |
#endif | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if ((png_ptr->transformations & PNG_GAMMA) && | |
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED | |
/* Because RGB_TO_GRAY does the gamma transform. */ | |
!(png_ptr->transformations & PNG_RGB_TO_GRAY) && | |
#endif | |
#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ | |
defined(PNG_READ_ALPHA_MODE_SUPPORTED) | |
/* Because PNG_COMPOSE does the gamma transform if there is something to | |
* do (if there is an alpha channel or transparency.) | |
*/ | |
!((png_ptr->transformations & PNG_COMPOSE) && | |
((png_ptr->num_trans != 0) || | |
(png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) && | |
#endif | |
/* Because png_init_read_transformations transforms the palette, unless | |
* RGB_TO_GRAY will do the transform. | |
*/ | |
(png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)) | |
png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr); | |
#endif | |
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED | |
if ((png_ptr->transformations & PNG_STRIP_ALPHA) && | |
(png_ptr->transformations & PNG_COMPOSE) && | |
(row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA || | |
row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)) | |
png_do_strip_channel(row_info, png_ptr->row_buf + 1, | |
0 /* at_start == false, because SWAP_ALPHA happens later */); | |
#endif | |
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED | |
if ((png_ptr->transformations & PNG_ENCODE_ALPHA) && | |
(row_info->color_type & PNG_COLOR_MASK_ALPHA)) | |
png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr); | |
#endif | |
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED | |
if (png_ptr->transformations & PNG_SCALE_16_TO_8) | |
png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED | |
/* There is no harm in doing both of these because only one has any effect, | |
* by putting the 'scale' option first if the app asks for scale (either by | |
* calling the API or in a TRANSFORM flag) this is what happens. | |
*/ | |
if (png_ptr->transformations & PNG_16_TO_8) | |
png_do_chop(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_QUANTIZE_SUPPORTED | |
if (png_ptr->transformations & PNG_QUANTIZE) | |
{ | |
png_do_quantize(row_info, png_ptr->row_buf + 1, | |
png_ptr->palette_lookup, png_ptr->quantize_index); | |
if (row_info->rowbytes == 0) | |
png_error(png_ptr, "png_do_quantize returned rowbytes=0"); | |
} | |
#endif /* PNG_READ_QUANTIZE_SUPPORTED */ | |
#ifdef PNG_READ_EXPAND_16_SUPPORTED | |
/* Do the expansion now, after all the arithmetic has been done. Notice | |
* that previous transformations can handle the PNG_EXPAND_16 flag if this | |
* is efficient (particularly true in the case of gamma correction, where | |
* better accuracy results faster!) | |
*/ | |
if (png_ptr->transformations & PNG_EXPAND_16) | |
png_do_expand_16(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED | |
/* NOTE: moved here in 1.5.4 (from much later in this list.) */ | |
if ((png_ptr->transformations & PNG_GRAY_TO_RGB) && | |
(png_ptr->mode & PNG_BACKGROUND_IS_GRAY)) | |
png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_INVERT_SUPPORTED | |
if (png_ptr->transformations & PNG_INVERT_MONO) | |
png_do_invert(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_SHIFT_SUPPORTED | |
if (png_ptr->transformations & PNG_SHIFT) | |
png_do_unshift(row_info, png_ptr->row_buf + 1, | |
&(png_ptr->shift)); | |
#endif | |
#ifdef PNG_READ_PACK_SUPPORTED | |
if (png_ptr->transformations & PNG_PACK) | |
png_do_unpack(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED | |
/* Added at libpng-1.5.10 */ | |
if (row_info->color_type == PNG_COLOR_TYPE_PALETTE && | |
png_ptr->num_palette_max >= 0) | |
png_do_check_palette_indexes(png_ptr, row_info); | |
#endif | |
#ifdef PNG_READ_BGR_SUPPORTED | |
if (png_ptr->transformations & PNG_BGR) | |
png_do_bgr(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_PACKSWAP_SUPPORTED | |
if (png_ptr->transformations & PNG_PACKSWAP) | |
png_do_packswap(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_FILLER_SUPPORTED | |
if (png_ptr->transformations & PNG_FILLER) | |
png_do_read_filler(row_info, png_ptr->row_buf + 1, | |
(png_uint_32)png_ptr->filler, png_ptr->flags); | |
#endif | |
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED | |
if (png_ptr->transformations & PNG_INVERT_ALPHA) | |
png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED | |
if (png_ptr->transformations & PNG_SWAP_ALPHA) | |
png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1); | |
#endif | |
#ifdef PNG_READ_16BIT_SUPPORTED | |
#ifdef PNG_READ_SWAP_SUPPORTED | |
if (png_ptr->transformations & PNG_SWAP_BYTES) | |
png_do_swap(row_info, png_ptr->row_buf + 1); | |
#endif | |
#endif | |
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED | |
if (png_ptr->transformations & PNG_USER_TRANSFORM) | |
{ | |
if (png_ptr->read_user_transform_fn != NULL) | |
(*(png_ptr->read_user_transform_fn)) /* User read transform function */ | |
(png_ptr, /* png_ptr */ | |
row_info, /* row_info: */ | |
/* png_uint_32 width; width of row */ | |
/* png_size_t rowbytes; number of bytes in row */ | |
/* png_byte color_type; color type of pixels */ | |
/* png_byte bit_depth; bit depth of samples */ | |
/* png_byte channels; number of channels (1-4) */ | |
/* png_byte pixel_depth; bits per pixel (depth*channels) */ | |
png_ptr->row_buf + 1); /* start of pixel data for row */ | |
#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED | |
if (png_ptr->user_transform_depth) | |
row_info->bit_depth = png_ptr->user_transform_depth; | |
if (png_ptr->user_transform_channels) | |
row_info->channels = png_ptr->user_transform_channels; | |
#endif | |
row_info->pixel_depth = (png_byte)(row_info->bit_depth * | |
row_info->channels); | |
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width); | |
} | |
#endif | |
} | |
#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. | |
*/ | |
void /* PRIVATE */ | |
png_do_unpack(png_row_infop row_info, png_bytep row) | |
{ | |
png_debug(1, "in png_do_unpack"); | |
if (row_info->bit_depth < 8) | |
{ | |
png_uint_32 i; | |
png_uint_32 row_width=row_info->width; | |
switch (row_info->bit_depth) | |
{ | |
case 1: | |
{ | |
png_bytep sp = row + (png_size_t)((row_width - 1) >> 3); | |
png_bytep dp = row + (png_size_t)row_width - 1; | |
png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07); | |
for (i = 0; i < row_width; i++) | |
{ | |
*dp = (png_byte)((*sp >> shift) & 0x01); | |
if (shift == 7) | |
{ | |
shift = 0; | |
sp--; | |
} | |
else | |
shift++; | |
dp--; | |
} | |
break; | |
} | |
case 2: | |
{ | |
png_bytep sp = row + (png_size_t)((row_width - 1) >> 2); | |
png_bytep dp = row + (png_size_t)row_width - 1; | |
png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1); | |
for (i = 0; i < row_width; i++) | |
{ | |
*dp = (png_byte)((*sp >> shift) & 0x03); | |
if (shift == 6) | |
{ | |
shift = 0; | |
sp--; | |
} | |
else | |
shift += 2; | |
dp--; | |
} | |
break; | |
} | |
case 4: | |
{ | |
png_bytep sp = row + (png_size_t)((row_width - 1) >> 1); | |
png_bytep dp = row + (png_size_t)row_width - 1; | |
png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2); | |
for (i = 0; i < row_width; i++) | |
{ | |
*dp = (png_byte)((*sp >> shift) & 0x0f); | |
if (shift == 4) | |
{ | |
shift = 0; | |
sp--; | |
} | |
else | |
shift = 4; | |
dp--; | |
} | |
break; | |
} | |
default: | |
break; | |
} | |
row_info->bit_depth = 8; | |
row_info->pixel_depth = (png_byte)(8 * row_info->channels); | |
row_info->rowbytes = row_width * row_info->channels; | |
} | |
} | |
#endif | |
#ifdef PNG_READ_SHIFT_SUPPORTED | |
/* Reverse the effects of png_do_shift. This routine merely shifts the | |
* pixels back to their significant bits values. Thus, if you have | |
* a row of bit depth 8, but only 5 are significant, this will shift | |
* the values back to 0 through 31. | |
*/ | |
void /* PRIVATE */ | |
png_do_unshift(png_row_infop row_info, png_bytep row, | |
png_const_color_8p sig_bits) | |
{ | |
int color_type; | |
png_debug(1, "in png_do_unshift"); | |
/* The palette case has already been handled in the _init routine. */ | |
color_type = row_info->color_type; | |
if (color_type != PNG_COLOR_TYPE_PALETTE) | |
{ | |
int shift[4]; | |
int channels = 0; | |
int bit_depth = row_info->bit_depth; | |
if (color_type & PNG_COLOR_MASK_COLOR) | |
{ | |
shift[channels++] = bit_depth - sig_bits->red; | |
shift[channels++] = bit_depth - sig_bits->green; | |
shift[channels++] = bit_depth - sig_bits->blue; | |
} | |
else | |
{ | |
shift[channels++] = bit_depth - sig_bits->gray; | |
} | |
if (color_type & PNG_COLOR_MASK_ALPHA) | |
{ | |
shift[channels++] = bit_depth - sig_bits->alpha; | |
} | |
{ | |
int c, have_shift; | |
for (c = have_shift = 0; c < channels; ++c) | |
{ | |
/* A shift of more than the bit depth is an error condition but it | |
* gets ignored here. | |
*/ | |
if (shift[c] <= 0 || shift[c] >= bit_depth) | |
shift[c] = 0; | |
else | |
have_shift = 1; | |
} | |
if (!have_shift) | |
return; | |
} | |
switch (bit_depth) | |
{ | |
default: | |
/* Must be 1bpp gray: should not be here! */ | |
/* NOTREACHED */ | |
break; | |
case 2: | |
/* Must be 2bpp gray */ | |
/* assert(channels == 1 && shift[0] == 1) */ | |
{ | |
png_bytep bp = row; | |
png_bytep bp_end = bp + row_info->rowbytes; | |
while (bp < bp_end) | |
{ | |
int b = (*bp >> 1) & 0x55; | |
*bp++ = (png_byte)b; | |
} | |
break; | |
} | |
case 4: | |
/* Must be 4bpp gray */ | |
/* assert(channels == 1) */ | |
{ | |
png_bytep bp = row; | |
png_bytep bp_end = bp + row_info->rowbytes; | |
int gray_shift = shift[0]; | |
int mask = 0xf >> gray_shift; | |
mask |= mask << 4; | |
while (bp < bp_end) | |
{ | |
int b = (*bp >> gray_shift) & mask; | |
*bp++ = (png_byte)b; | |
} | |
break; | |
} | |
case 8: | |
/* Single byte components, G, GA, RGB, RGBA */ | |
{ | |
png_bytep bp = row; | |
png_bytep bp_end = bp + row_info->rowbytes; | |
int channel = 0; | |
while (bp < bp_end) | |
{ | |
int b = *bp >> shift[channel]; | |
if (++channel >= channels) | |
channel = 0; | |
*bp++ = (png_byte)b; | |
} | |
break; | |
} | |
#ifdef PNG_READ_16BIT_SUPPORTED | |
case 16: | |
/* Double byte components, G, GA, RGB, RGBA */ | |
{ | |
png_bytep bp = row; | |
png_bytep bp_end = bp + row_info->rowbytes; | |
int channel = 0; | |
while (bp < bp_end) | |
{ | |
int value = (bp[0] << 8) + bp[1]; | |
value >>= shift[channel]; | |
if (++channel >= channels) | |
channel = 0; | |
*bp++ = (png_byte)(value >> 8); | |
*bp++ = (png_byte)(value & 0xff); | |
} | |
break; | |
} | |
#endif | |
} | |
} | |
} | |
#endif | |
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED | |
/* Scale rows of bit depth 16 down to 8 accurately */ | |
void /* PRIVATE */ | |
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 | |
void /* PRIVATE */ | |
/* 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 | |
void /* PRIVATE */ | |
png_do_read_swap_alpha(png_row_infop row_info, png_bytep row) | |
{ | |
png_debug(1, "in png_do_read_swap_alpha"); | |
{ | |
png_uint_32 row_width = row_info->width; | |
if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) | |
{ | |
/* This converts from RGBA to ARGB */ | |
if (row_info->bit_depth == 8) | |
{ | |
png_bytep sp = row + row_info->rowbytes; | |
png_bytep dp = sp; | |
png_byte save; | |
png_uint_32 i; | |
for (i = 0; i < row_width; i++) | |
{ | |
save = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = save; | |
} | |
} | |
#ifdef PNG_READ_16BIT_SUPPORTED | |
/* This converts from RRGGBBAA to AARRGGBB */ | |
else | |
{ | |
png_bytep sp = row + row_info->rowbytes; | |
png_bytep dp = sp; | |
png_byte save[2]; | |
png_uint_32 i; | |
for (i = 0; i < row_width; i++) | |
{ | |
save[0] = *(--sp); | |
save[1] = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = save[0]; | |
*(--dp) = save[1]; | |
} | |
} | |
#endif | |
} | |
else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) | |
{ | |
/* This converts from GA to AG */ | |
if (row_info->bit_depth == 8) | |
{ | |
png_bytep sp = row + row_info->rowbytes; | |
png_bytep dp = sp; | |
png_byte save; | |
png_uint_32 i; | |
for (i = 0; i < row_width; i++) | |
{ | |
save = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = save; | |
} | |
} | |
#ifdef PNG_READ_16BIT_SUPPORTED | |
/* This converts from GGAA to AAGG */ | |
else | |
{ | |
png_bytep sp = row + row_info->rowbytes; | |
png_bytep dp = sp; | |
png_byte save[2]; | |
png_uint_32 i; | |
for (i = 0; i < row_width; i++) | |
{ | |
save[0] = *(--sp); | |
save[1] = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = save[0]; | |
*(--dp) = save[1]; | |
} | |
} | |
#endif | |
} | |
} | |
} | |
#endif | |
#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED | |
void /* PRIVATE */ | |
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 */ | |
void /* PRIVATE */ | |
png_do_read_filler(png_row_infop row_info, png_bytep row, | |
png_uint_32 filler, png_uint_32 flags) | |
{ | |
png_uint_32 i; | |
png_uint_32 row_width = row_info->width; | |
#ifdef PNG_READ_16BIT_SUPPORTED | |
png_byte hi_filler = (png_byte)((filler>>8) & 0xff); | |
#endif | |
png_byte lo_filler = (png_byte)(filler & 0xff); | |
png_debug(1, "in png_do_read_filler"); | |
if ( | |
row_info->color_type == PNG_COLOR_TYPE_GRAY) | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
if (flags & PNG_FLAG_FILLER_AFTER) | |
{ | |
/* This changes the data from G to GX */ | |
png_bytep sp = row + (png_size_t)row_width; | |
png_bytep dp = sp + (png_size_t)row_width; | |
for (i = 1; i < row_width; i++) | |
{ | |
*(--dp) = lo_filler; | |
*(--dp) = *(--sp); | |
} | |
*(--dp) = lo_filler; | |
row_info->channels = 2; | |
row_info->pixel_depth = 16; | |
row_info->rowbytes = row_width * 2; | |
} | |
else | |
{ | |
/* This changes the data from G to XG */ | |
png_bytep sp = row + (png_size_t)row_width; | |
png_bytep dp = sp + (png_size_t)row_width; | |
for (i = 0; i < row_width; i++) | |
{ | |
*(--dp) = *(--sp); | |
*(--dp) = lo_filler; | |
} | |
row_info->channels = 2; | |
row_info->pixel_depth = 16; | |
row_info->rowbytes = row_width * 2; | |
} | |
} | |
#ifdef PNG_READ_16BIT_SUPPORTED | |
else if (row_info->bit_depth == 16) | |
{ | |
if (flags & PNG_FLAG_FILLER_AFTER) | |
{ | |
/* This changes the data from GG to GGXX */ | |
png_bytep sp = row + (png_size_t)row_width * 2; | |
png_bytep dp = sp + (png_size_t)row_width * 2; | |
for (i = 1; i < row_width; i++) | |
{ | |
*(--dp) = hi_filler; | |
*(--dp) = lo_filler; | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
} | |
*(--dp) = hi_filler; | |
*(--dp) = lo_filler; | |
row_info->channels = 2; | |
row_info->pixel_depth = 32; | |
row_info->rowbytes = row_width * 4; | |
} | |
else | |
{ | |
/* This changes the data from GG to XXGG */ | |
png_bytep sp = row + (png_size_t)row_width * 2; | |
png_bytep dp = sp + (png_size_t)row_width * 2; | |
for (i = 0; i < row_width; i++) | |
{ | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = hi_filler; | |
*(--dp) = lo_filler; | |
} | |
row_info->channels = 2; | |
row_info->pixel_depth = 32; | |
row_info->rowbytes = row_width * 4; | |
} | |
} | |
#endif | |
} /* COLOR_TYPE == GRAY */ | |
else if (row_info->color_type == PNG_COLOR_TYPE_RGB) | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
if (flags & PNG_FLAG_FILLER_AFTER) | |
{ | |
/* This changes the data from RGB to RGBX */ | |
png_bytep sp = row + (png_size_t)row_width * 3; | |
png_bytep dp = sp + (png_size_t)row_width; | |
for (i = 1; i < row_width; i++) | |
{ | |
*(--dp) = lo_filler; | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
} | |
*(--dp) = lo_filler; | |
row_info->channels = 4; | |
row_info->pixel_depth = 32; | |
row_info->rowbytes = row_width * 4; | |
} | |
else | |
{ | |
/* This changes the data from RGB to XRGB */ | |
png_bytep sp = row + (png_size_t)row_width * 3; | |
png_bytep dp = sp + (png_size_t)row_width; | |
for (i = 0; i < row_width; i++) | |
{ | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = lo_filler; | |
} | |
row_info->channels = 4; | |
row_info->pixel_depth = 32; | |
row_info->rowbytes = row_width * 4; | |
} | |
} | |
#ifdef PNG_READ_16BIT_SUPPORTED | |
else if (row_info->bit_depth == 16) | |
{ | |
if (flags & PNG_FLAG_FILLER_AFTER) | |
{ | |
/* This changes the data from RRGGBB to RRGGBBXX */ | |
png_bytep sp = row + (png_size_t)row_width * 6; | |
png_bytep dp = sp + (png_size_t)row_width * 2; | |
for (i = 1; i < row_width; i++) | |
{ | |
*(--dp) = hi_filler; | |
*(--dp) = lo_filler; | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
} | |
*(--dp) = hi_filler; | |
*(--dp) = lo_filler; | |
row_info->channels = 4; | |
row_info->pixel_depth = 64; | |
row_info->rowbytes = row_width * 8; | |
} | |
else | |
{ | |
/* This changes the data from RRGGBB to XXRRGGBB */ | |
png_bytep sp = row + (png_size_t)row_width * 6; | |
png_bytep dp = sp + (png_size_t)row_width * 2; | |
for (i = 0; i < row_width; i++) | |
{ | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = *(--sp); | |
*(--dp) = hi_filler; | |
*(--dp) = lo_filler; | |
} | |
row_info->channels = 4; | |
row_info->pixel_depth = 64; | |
row_info->rowbytes = row_width * 8; | |
} | |
} | |
#endif | |
} /* COLOR_TYPE == RGB */ | |
} | |
#endif | |
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED | |
/* Expand grayscale files to RGB, with or without alpha */ | |
void /* PRIVATE */ | |
png_do_gray_to_rgb(png_row_infop row_info, png_bytep row) | |
{ | |
png_uint_32 i; | |
png_uint_32 row_width = row_info->width; | |
png_debug(1, "in png_do_gray_to_rgb"); | |
if (row_info->bit_depth >= 8 && | |
!(row_info->color_type & PNG_COLOR_MASK_COLOR)) | |
{ | |
if (row_info->color_type == PNG_COLOR_TYPE_GRAY) | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
/* This changes G to RGB */ | |
png_bytep sp = row + (png_size_t)row_width - 1; | |
png_bytep dp = sp + (png_size_t)row_width * 2; | |
for (i = 0; i < row_width; i++) | |
{ | |
*(dp--) = *sp; | |
*(dp--) = *sp; | |
*(dp--) = *(sp--); | |
} | |
} | |
else | |
{ | |
/* This changes GG to RRGGBB */ | |
png_bytep sp = row + (png_size_t)row_width * 2 - 1; | |
png_bytep dp = sp + (png_size_t)row_width * 4; | |
for (i = 0; i < row_width; i++) | |
{ | |
*(dp--) = *sp; | |
*(dp--) = *(sp - 1); | |
*(dp--) = *sp; | |
*(dp--) = *(sp - 1); | |
*(dp--) = *(sp--); | |
*(dp--) = *(sp--); | |
} | |
} | |
} | |
else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
/* This changes GA to RGBA */ | |
png_bytep sp = row + (png_size_t)row_width * 2 - 1; | |
png_bytep dp = sp + (png_size_t)row_width * 2; | |
for (i = 0; i < row_width; i++) | |
{ | |
*(dp--) = *(sp--); | |
*(dp--) = *sp; | |
*(dp--) = *sp; | |
*(dp--) = *(sp--); | |
} | |
} | |
else | |
{ | |
/* This changes GGAA to RRGGBBAA */ | |
png_bytep sp = row + (png_size_t)row_width * 4 - 1; | |
png_bytep dp = sp + (png_size_t)row_width * 4; | |
for (i = 0; i < row_width; i++) | |
{ | |
*(dp--) = *(sp--); | |
*(dp--) = *(sp--); | |
*(dp--) = *sp; | |
*(dp--) = *(sp - 1); | |
*(dp--) = *sp; | |
*(dp--) = *(sp - 1); | |
*(dp--) = *(sp--); | |
*(dp--) = *(sp--); | |
} | |
} | |
} | |
row_info->channels = (png_byte)(row_info->channels + 2); | |
row_info->color_type |= PNG_COLOR_MASK_COLOR; | |
row_info->pixel_depth = (png_byte)(row_info->channels * | |
row_info->bit_depth); | |
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); | |
} | |
} | |
#endif | |
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED | |
/* Reduce RGB files to grayscale, with or without alpha | |
* using the equation given in Poynton's ColorFAQ of 1998-01-04 at | |
* <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but | |
* versions dated 1998 through November 2002 have been archived at | |
* http://web.archive.org/web/20000816232553/http://www.inforamp.net/ | |
* ~poynton/notes/colour_and_gamma/ColorFAQ.txt ) | |
* Charles Poynton poynton at poynton.com | |
* | |
* Y = 0.212671 * R + 0.715160 * G + 0.072169 * B | |
* | |
* which can be expressed with integers as | |
* | |
* Y = (6969 * R + 23434 * G + 2365 * B)/32768 | |
* | |
* Poynton's current link (as of January 2003 through July 2011): | |
* <http://www.poynton.com/notes/colour_and_gamma/> | |
* has changed the numbers slightly: | |
* | |
* Y = 0.2126*R + 0.7152*G + 0.0722*B | |
* | |
* which can be expressed with integers as | |
* | |
* Y = (6966 * R + 23436 * G + 2366 * B)/32768 | |
* | |
* Historically, however, libpng uses numbers derived from the ITU-R Rec 709 | |
* end point chromaticities and the D65 white point. Depending on the | |
* precision used for the D65 white point this produces a variety of different | |
* numbers, however if the four decimal place value used in ITU-R Rec 709 is | |
* used (0.3127,0.3290) the Y calculation would be: | |
* | |
* Y = (6968 * R + 23435 * G + 2366 * B)/32768 | |
* | |
* While this is correct the rounding results in an overflow for white, because | |
* the sum of the rounded coefficients is 32769, not 32768. Consequently | |
* libpng uses, instead, the closest non-overflowing approximation: | |
* | |
* Y = (6968 * R + 23434 * G + 2366 * B)/32768 | |
* | |
* Starting with libpng-1.5.5, if the image being converted has a cHRM chunk | |
* (including an sRGB chunk) then the chromaticities are used to calculate the | |
* coefficients. See the chunk handling in pngrutil.c for more information. | |
* | |
* In all cases the calculation is to be done in a linear colorspace. If no | |
* gamma information is available to correct the encoding of the original RGB | |
* values this results in an implicit assumption that the original PNG RGB | |
* values were linear. | |
* | |
* Other integer coefficents can be used via png_set_rgb_to_gray(). Because | |
* the API takes just red and green coefficients the blue coefficient is | |
* calculated to make the sum 32768. This will result in different rounding | |
* to that used above. | |
*/ | |
int /* PRIVATE */ | |
png_do_rgb_to_gray(png_structrp png_ptr, png_row_infop row_info, png_bytep row) | |
{ | |
int rgb_error = 0; | |
png_debug(1, "in png_do_rgb_to_gray"); | |
if (!(row_info->color_type & PNG_COLOR_MASK_PALETTE) && | |
(row_info->color_type & PNG_COLOR_MASK_COLOR)) | |
{ | |
PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff; | |
PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff; | |
PNG_CONST png_uint_32 bc = 32768 - rc - gc; | |
PNG_CONST png_uint_32 row_width = row_info->width; | |
PNG_CONST int have_alpha = | |
(row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0; | |
if (row_info->bit_depth == 8) | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
/* Notice that gamma to/from 1 are not necessarily inverses (if | |
* there is an overall gamma correction). Prior to 1.5.5 this code | |
* checked the linearized values for equality; this doesn't match | |
* the documentation, the original values must be checked. | |
*/ | |
if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL) | |
{ | |
png_bytep sp = row; | |
png_bytep dp = row; | |
png_uint_32 i; | |
for (i = 0; i < row_width; i++) | |
{ | |
png_byte red = *(sp++); | |
png_byte green = *(sp++); | |
png_byte blue = *(sp++); | |
if (red != green || red != blue) | |
{ | |
red = png_ptr->gamma_to_1[red]; | |
green = png_ptr->gamma_to_1[green]; | |
blue = png_ptr->gamma_to_1[blue]; | |
rgb_error |= 1; | |
*(dp++) = png_ptr->gamma_from_1[ | |
(rc*red + gc*green + bc*blue + 16384)>>15]; | |
} | |
else | |
{ | |
/* If there is no overall correction the table will not be | |
* set. | |
*/ | |
if (png_ptr->gamma_table != NULL) | |
red = png_ptr->gamma_table[red]; | |
*(dp++) = red; | |
} | |
if (have_alpha) | |
*(dp++) = *(sp++); | |
} | |
} | |
else | |
#endif | |
{ | |
png_bytep sp = row; | |
png_bytep dp = row; | |
png_uint_32 i; | |
for (i = 0; i < row_width; i++) | |
{ | |
png_byte red = *(sp++); | |
png_byte green = *(sp++); | |
png_byte blue = *(sp++); | |
if (red != green || red != blue) | |
{ | |
rgb_error |= 1; | |
/* NOTE: this is the historical approach which simply | |
* truncates the results. | |
*/ | |
*(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15); | |
} | |
else | |
*(dp++) = red; | |
if (have_alpha) | |
*(dp++) = *(sp++); | |
} | |
} | |
} | |
else /* RGB bit_depth == 16 */ | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL) | |
{ | |
png_bytep sp = row; | |
png_bytep dp = row; | |
png_uint_32 i; | |
for (i = 0; i < row_width; i++) | |
{ | |
png_uint_16 red, green, blue, w; | |
red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; | |
green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; | |
blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; | |
if (red == green && red == blue) | |
{ | |
if (png_ptr->gamma_16_table != NULL) | |
w = png_ptr->gamma_16_table[(red&0xff) | |
>> png_ptr->gamma_shift][red>>8]; | |
else | |
w = red; | |
} | |
else | |
{ | |
png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff) | |
>> png_ptr->gamma_shift][red>>8]; | |
png_uint_16 green_1 = | |
png_ptr->gamma_16_to_1[(green&0xff) >> | |
png_ptr->gamma_shift][green>>8]; | |
png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff) | |
>> png_ptr->gamma_shift][blue>>8]; | |
png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1 | |
+ bc*blue_1 + 16384)>>15); | |
w = png_ptr->gamma_16_from_1[(gray16&0xff) >> | |
png_ptr->gamma_shift][gray16 >> 8]; | |
rgb_error |= 1; | |
} | |
*(dp++) = (png_byte)((w>>8) & 0xff); | |
*(dp++) = (png_byte)(w & 0xff); | |
if (have_alpha) | |
{ | |
*(dp++) = *(sp++); | |
*(dp++) = *(sp++); | |
} | |
} | |
} | |
else | |
#endif | |
{ | |
png_bytep sp = row; | |
png_bytep dp = row; | |
png_uint_32 i; | |
for (i = 0; i < row_width; i++) | |
{ | |
png_uint_16 red, green, blue, gray16; | |
red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; | |
green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; | |
blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2; | |
if (red != green || red != blue) | |
rgb_error |= 1; | |
/* From 1.5.5 in the 16 bit case do the accurate conversion even | |
* in the 'fast' case - this is because this is where the code | |
* ends up when handling linear 16 bit data. | |
*/ | |
gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >> | |
15); | |
*(dp++) = (png_byte)((gray16>>8) & 0xff); | |
*(dp++) = (png_byte)(gray16 & 0xff); | |
if (have_alpha) | |
{ | |
*(dp++) = *(sp++); | |
*(dp++) = *(sp++); | |
} | |
} | |
} | |
} | |
row_info->channels = (png_byte)(row_info->channels - 2); | |
row_info->color_type = (png_byte)(row_info->color_type & | |
~PNG_COLOR_MASK_COLOR); | |
row_info->pixel_depth = (png_byte)(row_info->channels * | |
row_info->bit_depth); | |
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); | |
} | |
return rgb_error; | |
} | |
#endif | |
#endif /* PNG_READ_TRANSFORMS_SUPPORTED */ | |
#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED | |
/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth | |
* large of png_color. This lets grayscale images be treated as | |
* paletted. Most useful for gamma correction and simplification | |
* of code. This API is not used internally. | |
*/ | |
void PNGAPI | |
png_build_grayscale_palette(int bit_depth, png_colorp palette) | |
{ | |
int num_palette; | |
int color_inc; | |
int i; | |
int v; | |
png_debug(1, "in png_do_build_grayscale_palette"); | |
if (palette == NULL) | |
return; | |
switch (bit_depth) | |
{ | |
case 1: | |
num_palette = 2; | |
color_inc = 0xff; | |
break; | |
case 2: | |
num_palette = 4; | |
color_inc = 0x55; | |
break; | |
case 4: | |
num_palette = 16; | |
color_inc = 0x11; | |
break; | |
case 8: | |
num_palette = 256; | |
color_inc = 1; | |
break; | |
default: | |
num_palette = 0; | |
color_inc = 0; | |
break; | |
} | |
for (i = 0, v = 0; i < num_palette; i++, v += color_inc) | |
{ | |
palette[i].red = (png_byte)v; | |
palette[i].green = (png_byte)v; | |
palette[i].blue = (png_byte)v; | |
} | |
} | |
#endif | |
#ifdef PNG_READ_TRANSFORMS_SUPPORTED | |
#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\ | |
defined(PNG_READ_ALPHA_MODE_SUPPORTED) | |
/* Replace any alpha or transparency with the supplied background color. | |
* "background" is already in the screen gamma, while "background_1" is | |
* at a gamma of 1.0. Paletted files have already been taken care of. | |
*/ | |
void /* PRIVATE */ | |
png_do_compose(png_row_infop row_info, png_bytep row, png_structrp png_ptr) | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
png_const_bytep gamma_table = png_ptr->gamma_table; | |
png_const_bytep gamma_from_1 = png_ptr->gamma_from_1; | |
png_const_bytep gamma_to_1 = png_ptr->gamma_to_1; | |
png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table; | |
png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1; | |
png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1; | |
int gamma_shift = png_ptr->gamma_shift; | |
int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0; | |
#endif | |
png_bytep sp; | |
png_uint_32 i; | |
png_uint_32 row_width = row_info->width; | |
int shift; | |
png_debug(1, "in png_do_compose"); | |
{ | |
switch (row_info->color_type) | |
{ | |
case PNG_COLOR_TYPE_GRAY: | |
{ | |
switch (row_info->bit_depth) | |
{ | |
case 1: | |
{ | |
sp = row; | |
shift = 7; | |
for (i = 0; i < row_width; i++) | |
{ | |
if ((png_uint_16)((*sp >> shift) & 0x01) | |
== png_ptr->trans_color.gray) | |
{ | |
unsigned int tmp = *sp & (0x7f7f >> (7 - shift)); | |
tmp |= png_ptr->background.gray << shift; | |
*sp = (png_byte)(tmp & 0xff); | |
} | |
if (!shift) | |
{ | |
shift = 7; | |
sp++; | |
} | |
else | |
shift--; | |
} | |
break; | |
} | |
case 2: | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_table != NULL) | |
{ | |
sp = row; | |
shift = 6; | |
for (i = 0; i < row_width; i++) | |
{ | |
if ((png_uint_16)((*sp >> shift) & 0x03) | |
== png_ptr->trans_color.gray) | |
{ | |
unsigned int tmp = *sp & (0x3f3f >> (6 - shift)); | |
tmp |= png_ptr->background.gray << shift; | |
*sp = (png_byte)(tmp & 0xff); | |
} | |
else | |
{ | |
unsigned int p = (*sp >> shift) & 0x03; | |
unsigned int g = (gamma_table [p | (p << 2) | | |
(p << 4) | (p << 6)] >> 6) & 0x03; | |
unsigned int tmp = *sp & (0x3f3f >> (6 - shift)); | |
tmp |= g << shift; | |
*sp = (png_byte)(tmp & 0xff); | |
} | |
if (!shift) | |
{ | |
shift = 6; | |
sp++; | |
} | |
else | |
shift -= 2; | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
shift = 6; | |
for (i = 0; i < row_width; i++) | |
{ | |
if ((png_uint_16)((*sp >> shift) & 0x03) | |
== png_ptr->trans_color.gray) | |
{ | |
unsigned int tmp = *sp & (0x3f3f >> (6 - shift)); | |
tmp |= png_ptr->background.gray << shift; | |
*sp = (png_byte)(tmp & 0xff); | |
} | |
if (!shift) | |
{ | |
shift = 6; | |
sp++; | |
} | |
else | |
shift -= 2; | |
} | |
} | |
break; | |
} | |
case 4: | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_table != NULL) | |
{ | |
sp = row; | |
shift = 4; | |
for (i = 0; i < row_width; i++) | |
{ | |
if ((png_uint_16)((*sp >> shift) & 0x0f) | |
== png_ptr->trans_color.gray) | |
{ | |
unsigned int tmp = *sp & (0xf0f >> (4 - shift)); | |
tmp |= png_ptr->background.gray << shift; | |
*sp = (png_byte)(tmp & 0xff); | |
} | |
else | |
{ | |
unsigned int p = (*sp >> shift) & 0x0f; | |
unsigned int g = (gamma_table[p | (p << 4)] >> 4) & | |
0x0f; | |
unsigned int tmp = *sp & (0xf0f >> (4 - shift)); | |
tmp |= g << shift; | |
*sp = (png_byte)(tmp & 0xff); | |
} | |
if (!shift) | |
{ | |
shift = 4; | |
sp++; | |
} | |
else | |
shift -= 4; | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
shift = 4; | |
for (i = 0; i < row_width; i++) | |
{ | |
if ((png_uint_16)((*sp >> shift) & 0x0f) | |
== png_ptr->trans_color.gray) | |
{ | |
unsigned int tmp = *sp & (0xf0f >> (4 - shift)); | |
tmp |= png_ptr->background.gray << shift; | |
*sp = (png_byte)(tmp & 0xff); | |
} | |
if (!shift) | |
{ | |
shift = 4; | |
sp++; | |
} | |
else | |
shift -= 4; | |
} | |
} | |
break; | |
} | |
case 8: | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_table != NULL) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp++) | |
{ | |
if (*sp == png_ptr->trans_color.gray) | |
*sp = (png_byte)png_ptr->background.gray; | |
else | |
*sp = gamma_table[*sp]; | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp++) | |
{ | |
if (*sp == png_ptr->trans_color.gray) | |
*sp = (png_byte)png_ptr->background.gray; | |
} | |
} | |
break; | |
} | |
case 16: | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_16 != NULL) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 2) | |
{ | |
png_uint_16 v; | |
v = (png_uint_16)(((*sp) << 8) + *(sp + 1)); | |
if (v == png_ptr->trans_color.gray) | |
{ | |
/* Background is already in screen gamma */ | |
*sp = (png_byte)((png_ptr->background.gray >> 8) | |
& 0xff); | |
*(sp + 1) = (png_byte)(png_ptr->background.gray | |
& 0xff); | |
} | |
else | |
{ | |
v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
} | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 2) | |
{ | |
png_uint_16 v; | |
v = (png_uint_16)(((*sp) << 8) + *(sp + 1)); | |
if (v == png_ptr->trans_color.gray) | |
{ | |
*sp = (png_byte)((png_ptr->background.gray >> 8) | |
& 0xff); | |
*(sp + 1) = (png_byte)(png_ptr->background.gray | |
& 0xff); | |
} | |
} | |
} | |
break; | |
} | |
default: | |
break; | |
} | |
break; | |
} | |
case PNG_COLOR_TYPE_RGB: | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_table != NULL) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 3) | |
{ | |
if (*sp == png_ptr->trans_color.red && | |
*(sp + 1) == png_ptr->trans_color.green && | |
*(sp + 2) == png_ptr->trans_color.blue) | |
{ | |
*sp = (png_byte)png_ptr->background.red; | |
*(sp + 1) = (png_byte)png_ptr->background.green; | |
*(sp + 2) = (png_byte)png_ptr->background.blue; | |
} | |
else | |
{ | |
*sp = gamma_table[*sp]; | |
*(sp + 1) = gamma_table[*(sp + 1)]; | |
*(sp + 2) = gamma_table[*(sp + 2)]; | |
} | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 3) | |
{ | |
if (*sp == png_ptr->trans_color.red && | |
*(sp + 1) == png_ptr->trans_color.green && | |
*(sp + 2) == png_ptr->trans_color.blue) | |
{ | |
*sp = (png_byte)png_ptr->background.red; | |
*(sp + 1) = (png_byte)png_ptr->background.green; | |
*(sp + 2) = (png_byte)png_ptr->background.blue; | |
} | |
} | |
} | |
} | |
else /* if (row_info->bit_depth == 16) */ | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_16 != NULL) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 6) | |
{ | |
png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1)); | |
png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8) | |
+ *(sp + 3)); | |
png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8) | |
+ *(sp + 5)); | |
if (r == png_ptr->trans_color.red && | |
g == png_ptr->trans_color.green && | |
b == png_ptr->trans_color.blue) | |
{ | |
/* Background is already in screen gamma */ | |
*sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); | |
*(sp + 2) = (png_byte)((png_ptr->background.green >> 8) | |
& 0xff); | |
*(sp + 3) = (png_byte)(png_ptr->background.green | |
& 0xff); | |
*(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) | |
& 0xff); | |
*(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); | |
} | |
else | |
{ | |
png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)]; | |
*(sp + 2) = (png_byte)((v >> 8) & 0xff); | |
*(sp + 3) = (png_byte)(v & 0xff); | |
v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)]; | |
*(sp + 4) = (png_byte)((v >> 8) & 0xff); | |
*(sp + 5) = (png_byte)(v & 0xff); | |
} | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 6) | |
{ | |
png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1)); | |
png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8) | |
+ *(sp + 3)); | |
png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8) | |
+ *(sp + 5)); | |
if (r == png_ptr->trans_color.red && | |
g == png_ptr->trans_color.green && | |
b == png_ptr->trans_color.blue) | |
{ | |
*sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); | |
*(sp + 2) = (png_byte)((png_ptr->background.green >> 8) | |
& 0xff); | |
*(sp + 3) = (png_byte)(png_ptr->background.green | |
& 0xff); | |
*(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) | |
& 0xff); | |
*(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); | |
} | |
} | |
} | |
} | |
break; | |
} | |
case PNG_COLOR_TYPE_GRAY_ALPHA: | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_to_1 != NULL && gamma_from_1 != NULL && | |
gamma_table != NULL) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 2) | |
{ | |
png_uint_16 a = *(sp + 1); | |
if (a == 0xff) | |
*sp = gamma_table[*sp]; | |
else if (a == 0) | |
{ | |
/* Background is already in screen gamma */ | |
*sp = (png_byte)png_ptr->background.gray; | |
} | |
else | |
{ | |
png_byte v, w; | |
v = gamma_to_1[*sp]; | |
png_composite(w, v, a, png_ptr->background_1.gray); | |
if (!optimize) | |
w = gamma_from_1[w]; | |
*sp = w; | |
} | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 2) | |
{ | |
png_byte a = *(sp + 1); | |
if (a == 0) | |
*sp = (png_byte)png_ptr->background.gray; | |
else if (a < 0xff) | |
png_composite(*sp, *sp, a, png_ptr->background.gray); | |
} | |
} | |
} | |
else /* if (png_ptr->bit_depth == 16) */ | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_16 != NULL && gamma_16_from_1 != NULL && | |
gamma_16_to_1 != NULL) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 4) | |
{ | |
png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8) | |
+ *(sp + 3)); | |
if (a == (png_uint_16)0xffff) | |
{ | |
png_uint_16 v; | |
v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
} | |
else if (a == 0) | |
{ | |
/* Background is already in screen gamma */ | |
*sp = (png_byte)((png_ptr->background.gray >> 8) | |
& 0xff); | |
*(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff); | |
} | |
else | |
{ | |
png_uint_16 g, v, w; | |
g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp]; | |
png_composite_16(v, g, a, png_ptr->background_1.gray); | |
if (optimize) | |
w = v; | |
else | |
w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8]; | |
*sp = (png_byte)((w >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(w & 0xff); | |
} | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 4) | |
{ | |
png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8) | |
+ *(sp + 3)); | |
if (a == 0) | |
{ | |
*sp = (png_byte)((png_ptr->background.gray >> 8) | |
& 0xff); | |
*(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff); | |
} | |
else if (a < 0xffff) | |
{ | |
png_uint_16 g, v; | |
g = (png_uint_16)(((*sp) << 8) + *(sp + 1)); | |
png_composite_16(v, g, a, png_ptr->background.gray); | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
} | |
} | |
} | |
} | |
break; | |
} | |
case PNG_COLOR_TYPE_RGB_ALPHA: | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_to_1 != NULL && gamma_from_1 != NULL && | |
gamma_table != NULL) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 4) | |
{ | |
png_byte a = *(sp + 3); | |
if (a == 0xff) | |
{ | |
*sp = gamma_table[*sp]; | |
*(sp + 1) = gamma_table[*(sp + 1)]; | |
*(sp + 2) = gamma_table[*(sp + 2)]; | |
} | |
else if (a == 0) | |
{ | |
/* Background is already in screen gamma */ | |
*sp = (png_byte)png_ptr->background.red; | |
*(sp + 1) = (png_byte)png_ptr->background.green; | |
*(sp + 2) = (png_byte)png_ptr->background.blue; | |
} | |
else | |
{ | |
png_byte v, w; | |
v = gamma_to_1[*sp]; | |
png_composite(w, v, a, png_ptr->background_1.red); | |
if (!optimize) w = gamma_from_1[w]; | |
*sp = w; | |
v = gamma_to_1[*(sp + 1)]; | |
png_composite(w, v, a, png_ptr->background_1.green); | |
if (!optimize) w = gamma_from_1[w]; | |
*(sp + 1) = w; | |
v = gamma_to_1[*(sp + 2)]; | |
png_composite(w, v, a, png_ptr->background_1.blue); | |
if (!optimize) w = gamma_from_1[w]; | |
*(sp + 2) = w; | |
} | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 4) | |
{ | |
png_byte a = *(sp + 3); | |
if (a == 0) | |
{ | |
*sp = (png_byte)png_ptr->background.red; | |
*(sp + 1) = (png_byte)png_ptr->background.green; | |
*(sp + 2) = (png_byte)png_ptr->background.blue; | |
} | |
else if (a < 0xff) | |
{ | |
png_composite(*sp, *sp, a, png_ptr->background.red); | |
png_composite(*(sp + 1), *(sp + 1), a, | |
png_ptr->background.green); | |
png_composite(*(sp + 2), *(sp + 2), a, | |
png_ptr->background.blue); | |
} | |
} | |
} | |
} | |
else /* if (row_info->bit_depth == 16) */ | |
{ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
if (gamma_16 != NULL && gamma_16_from_1 != NULL && | |
gamma_16_to_1 != NULL) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 8) | |
{ | |
png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6)) | |
<< 8) + (png_uint_16)(*(sp + 7))); | |
if (a == (png_uint_16)0xffff) | |
{ | |
png_uint_16 v; | |
v = gamma_16[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)]; | |
*(sp + 2) = (png_byte)((v >> 8) & 0xff); | |
*(sp + 3) = (png_byte)(v & 0xff); | |
v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)]; | |
*(sp + 4) = (png_byte)((v >> 8) & 0xff); | |
*(sp + 5) = (png_byte)(v & 0xff); | |
} | |
else if (a == 0) | |
{ | |
/* Background is already in screen gamma */ | |
*sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); | |
*(sp + 2) = (png_byte)((png_ptr->background.green >> 8) | |
& 0xff); | |
*(sp + 3) = (png_byte)(png_ptr->background.green | |
& 0xff); | |
*(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) | |
& 0xff); | |
*(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); | |
} | |
else | |
{ | |
png_uint_16 v, w; | |
v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp]; | |
png_composite_16(w, v, a, png_ptr->background_1.red); | |
if (!optimize) | |
w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> | |
8]; | |
*sp = (png_byte)((w >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(w & 0xff); | |
v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)]; | |
png_composite_16(w, v, a, png_ptr->background_1.green); | |
if (!optimize) | |
w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> | |
8]; | |
*(sp + 2) = (png_byte)((w >> 8) & 0xff); | |
*(sp + 3) = (png_byte)(w & 0xff); | |
v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)]; | |
png_composite_16(w, v, a, png_ptr->background_1.blue); | |
if (!optimize) | |
w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> | |
8]; | |
*(sp + 4) = (png_byte)((w >> 8) & 0xff); | |
*(sp + 5) = (png_byte)(w & 0xff); | |
} | |
} | |
} | |
else | |
#endif | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp += 8) | |
{ | |
png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6)) | |
<< 8) + (png_uint_16)(*(sp + 7))); | |
if (a == 0) | |
{ | |
*sp = (png_byte)((png_ptr->background.red >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(png_ptr->background.red & 0xff); | |
*(sp + 2) = (png_byte)((png_ptr->background.green >> 8) | |
& 0xff); | |
*(sp + 3) = (png_byte)(png_ptr->background.green | |
& 0xff); | |
*(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) | |
& 0xff); | |
*(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff); | |
} | |
else if (a < 0xffff) | |
{ | |
png_uint_16 v; | |
png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1)); | |
png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8) | |
+ *(sp + 3)); | |
png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8) | |
+ *(sp + 5)); | |
png_composite_16(v, r, a, png_ptr->background.red); | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
png_composite_16(v, g, a, png_ptr->background.green); | |
*(sp + 2) = (png_byte)((v >> 8) & 0xff); | |
*(sp + 3) = (png_byte)(v & 0xff); | |
png_composite_16(v, b, a, png_ptr->background.blue); | |
*(sp + 4) = (png_byte)((v >> 8) & 0xff); | |
*(sp + 5) = (png_byte)(v & 0xff); | |
} | |
} | |
} | |
} | |
break; | |
} | |
default: | |
break; | |
} | |
} | |
} | |
#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_READ_ALPHA_MODE_SUPPORTED */ | |
#ifdef PNG_READ_GAMMA_SUPPORTED | |
/* Gamma correct the image, avoiding the alpha channel. Make sure | |
* you do this after you deal with the transparency issue on grayscale | |
* or RGB images. If your bit depth is 8, use gamma_table, if it | |
* is 16, use gamma_16_table and gamma_shift. Build these with | |
* build_gamma_table(). | |
*/ | |
void /* PRIVATE */ | |
png_do_gamma(png_row_infop row_info, png_bytep row, png_structrp png_ptr) | |
{ | |
png_const_bytep gamma_table = png_ptr->gamma_table; | |
png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table; | |
int gamma_shift = png_ptr->gamma_shift; | |
png_bytep sp; | |
png_uint_32 i; | |
png_uint_32 row_width=row_info->width; | |
png_debug(1, "in png_do_gamma"); | |
if (((row_info->bit_depth <= 8 && gamma_table != NULL) || | |
(row_info->bit_depth == 16 && gamma_16_table != NULL))) | |
{ | |
switch (row_info->color_type) | |
{ | |
case PNG_COLOR_TYPE_RGB: | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
*sp = gamma_table[*sp]; | |
sp++; | |
*sp = gamma_table[*sp]; | |
sp++; | |
*sp = gamma_table[*sp]; | |
sp++; | |
} | |
} | |
else /* if (row_info->bit_depth == 16) */ | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
png_uint_16 v; | |
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
sp += 2; | |
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
sp += 2; | |
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
sp += 2; | |
} | |
} | |
break; | |
} | |
case PNG_COLOR_TYPE_RGB_ALPHA: | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
*sp = gamma_table[*sp]; | |
sp++; | |
*sp = gamma_table[*sp]; | |
sp++; | |
*sp = gamma_table[*sp]; | |
sp++; | |
sp++; | |
} | |
} | |
else /* if (row_info->bit_depth == 16) */ | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
sp += 2; | |
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
sp += 2; | |
v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
sp += 4; | |
} | |
} | |
break; | |
} | |
case PNG_COLOR_TYPE_GRAY_ALPHA: | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
*sp = gamma_table[*sp]; | |
sp += 2; | |
} | |
} | |
else /* if (row_info->bit_depth == 16) */ | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
sp += 4; | |
} | |
} | |
break; | |
} | |
case PNG_COLOR_TYPE_GRAY: | |
{ | |
if (row_info->bit_depth == 2) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i += 4) | |
{ | |
int a = *sp & 0xc0; | |
int b = *sp & 0x30; | |
int c = *sp & 0x0c; | |
int d = *sp & 0x03; | |
*sp = (png_byte)( | |
((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)| | |
((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)| | |
((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)| | |
((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) )); | |
sp++; | |
} | |
} | |
if (row_info->bit_depth == 4) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i += 2) | |
{ | |
int msb = *sp & 0xf0; | |
int lsb = *sp & 0x0f; | |
*sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0) | |
| (((int)gamma_table[(lsb << 4) | lsb]) >> 4)); | |
sp++; | |
} | |
} | |
else if (row_info->bit_depth == 8) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
*sp = gamma_table[*sp]; | |
sp++; | |
} | |
} | |
else if (row_info->bit_depth == 16) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp]; | |
*sp = (png_byte)((v >> 8) & 0xff); | |
*(sp + 1) = (png_byte)(v & 0xff); | |
sp += 2; | |
} | |
} | |
break; | |
} | |
default: | |
break; | |
} | |
} | |
} | |
#endif | |
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED | |
/* Encode the alpha channel to the output gamma (the input channel is always | |
* linear.) Called only with color types that have an alpha channel. Needs the | |
* from_1 tables. | |
*/ | |
void /* PRIVATE */ | |
png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structrp png_ptr) | |
{ | |
png_uint_32 row_width = row_info->width; | |
png_debug(1, "in png_do_encode_alpha"); | |
if (row_info->color_type & PNG_COLOR_MASK_ALPHA) | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
PNG_CONST png_bytep table = png_ptr->gamma_from_1; | |
if (table != NULL) | |
{ | |
PNG_CONST int step = | |
(row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2; | |
/* The alpha channel is the last component: */ | |
row += step - 1; | |
for (; row_width > 0; --row_width, row += step) | |
*row = table[*row]; | |
return; | |
} | |
} | |
else if (row_info->bit_depth == 16) | |
{ | |
PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1; | |
PNG_CONST int gamma_shift = png_ptr->gamma_shift; | |
if (table != NULL) | |
{ | |
PNG_CONST int step = | |
(row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4; | |
/* The alpha channel is the last component: */ | |
row += step - 2; | |
for (; row_width > 0; --row_width, row += step) | |
{ | |
png_uint_16 v; | |
v = table[*(row + 1) >> gamma_shift][*row]; | |
*row = (png_byte)((v >> 8) & 0xff); | |
*(row + 1) = (png_byte)(v & 0xff); | |
} | |
return; | |
} | |
} | |
} | |
/* Only get to here if called with a weird row_info; no harm has been done, | |
* so just issue a warning. | |
*/ | |
png_warning(png_ptr, "png_do_encode_alpha: unexpected call"); | |
} | |
#endif | |
#ifdef PNG_READ_EXPAND_SUPPORTED | |
/* Expands a palette row to an RGB or RGBA row depending | |
* upon whether you supply trans and num_trans. | |
*/ | |
void /* PRIVATE */ | |
png_do_expand_palette(png_row_infop row_info, png_bytep row, | |
png_const_colorp palette, png_const_bytep trans_alpha, int num_trans) | |
{ | |
int shift, value; | |
png_bytep sp, dp; | |
png_uint_32 i; | |
png_uint_32 row_width=row_info->width; | |
png_debug(1, "in png_do_expand_palette"); | |
if (row_info->color_type == PNG_COLOR_TYPE_PALETTE) | |
{ | |
if (row_info->bit_depth < 8) | |
{ | |
switch (row_info->bit_depth) | |
{ | |
case 1: | |
{ | |
sp = row + (png_size_t)((row_width - 1) >> 3); | |
dp = row + (png_size_t)row_width - 1; | |
shift = 7 - (int)((row_width + 7) & 0x07); | |
for (i = 0; i < row_width; i++) | |
{ | |
if ((*sp >> shift) & 0x01) | |
*dp = 1; | |
else | |
*dp = 0; | |
if (shift == 7) | |
{ | |
shift = 0; | |
sp--; | |
} | |
else | |
shift++; | |
dp--; | |
} | |
break; | |
} | |
case 2: | |
{ | |
sp = row + (png_size_t)((row_width - 1) >> 2); | |
dp = row + (png_size_t)row_width - 1; | |
shift = (int)((3 - ((row_width + 3) & 0x03)) << 1); | |
for (i = 0; i < row_width; i++) | |
{ | |
value = (*sp >> shift) & 0x03; | |
*dp = (png_byte)value; | |
if (shift == 6) | |
{ | |
shift = 0; | |
sp--; | |
} | |
else | |
shift += 2; | |
dp--; | |
} | |
break; | |
} | |
case 4: | |
{ | |
sp = row + (png_size_t)((row_width - 1) >> 1); | |
dp = row + (png_size_t)row_width - 1; | |
shift = (int)((row_width & 0x01) << 2); | |
for (i = 0; i < row_width; i++) | |
{ | |
value = (*sp >> shift) & 0x0f; | |
*dp = (png_byte)value; | |
if (shift == 4) | |
{ | |
shift = 0; | |
sp--; | |
} | |
else | |
shift += 4; | |
dp--; | |
} | |
break; | |
} | |
default: | |
break; | |
} | |
row_info->bit_depth = 8; | |
row_info->pixel_depth = 8; | |
row_info->rowbytes = row_width; | |
} | |
if (row_info->bit_depth == 8) | |
{ | |
{ | |
if (num_trans > 0) | |
{ | |
sp = row + (png_size_t)row_width - 1; | |
dp = row + (png_size_t)(row_width << 2) - 1; | |
for (i = 0; i < row_width; i++) | |
{ | |
if ((int)(*sp) >= num_trans) | |
*dp-- = 0xff; | |
else | |
*dp-- = trans_alpha[*sp]; | |
*dp-- = palette[*sp].blue; | |
*dp-- = palette[*sp].green; | |
*dp-- = palette[*sp].red; | |
sp--; | |
} | |
row_info->bit_depth = 8; | |
row_info->pixel_depth = 32; | |
row_info->rowbytes = row_width * 4; | |
row_info->color_type = 6; | |
row_info->channels = 4; | |
} | |
else | |
{ | |
sp = row + (png_size_t)row_width - 1; | |
dp = row + (png_size_t)(row_width * 3) - 1; | |
for (i = 0; i < row_width; i++) | |
{ | |
*dp-- = palette[*sp].blue; | |
*dp-- = palette[*sp].green; | |
*dp-- = palette[*sp].red; | |
sp--; | |
} | |
row_info->bit_depth = 8; | |
row_info->pixel_depth = 24; | |
row_info->rowbytes = row_width * 3; | |
row_info->color_type = 2; | |
row_info->channels = 3; | |
} | |
} | |
} | |
} | |
} | |
/* If the bit depth < 8, it is expanded to 8. Also, if the already | |
* expanded transparency value is supplied, an alpha channel is built. | |
*/ | |
void /* PRIVATE */ | |
png_do_expand(png_row_infop row_info, png_bytep row, | |
png_const_color_16p trans_color) | |
{ | |
int shift, value; | |
png_bytep sp, dp; | |
png_uint_32 i; | |
png_uint_32 row_width=row_info->width; | |
png_debug(1, "in png_do_expand"); | |
{ | |
if (row_info->color_type == PNG_COLOR_TYPE_GRAY) | |
{ | |
unsigned int gray = trans_color ? trans_color->gray : 0; | |
if (row_info->bit_depth < 8) | |
{ | |
switch (row_info->bit_depth) | |
{ | |
case 1: | |
{ | |
gray = (gray & 0x01) * 0xff; | |
sp = row + (png_size_t)((row_width - 1) >> 3); | |
dp = row + (png_size_t)row_width - 1; | |
shift = 7 - (int)((row_width + 7) & 0x07); | |
for (i = 0; i < row_width; i++) | |
{ | |
if ((*sp >> shift) & 0x01) | |
*dp = 0xff; | |
else | |
*dp = 0; | |
if (shift == 7) | |
{ | |
shift = 0; | |
sp--; | |
} | |
else | |
shift++; | |
dp--; | |
} | |
break; | |
} | |
case 2: | |
{ | |
gray = (gray & 0x03) * 0x55; | |
sp = row + (png_size_t)((row_width - 1) >> 2); | |
dp = row + (png_size_t)row_width - 1; | |
shift = (int)((3 - ((row_width + 3) & 0x03)) << 1); | |
for (i = 0; i < row_width; i++) | |
{ | |
value = (*sp >> shift) & 0x03; | |
*dp = (png_byte)(value | (value << 2) | (value << 4) | | |
(value << 6)); | |
if (shift == 6) | |
{ | |
shift = 0; | |
sp--; | |
} | |
else | |
shift += 2; | |
dp--; | |
} | |
break; | |
} | |
case 4: | |
{ | |
gray = (gray & 0x0f) * 0x11; | |
sp = row + (png_size_t)((row_width - 1) >> 1); | |
dp = row + (png_size_t)row_width - 1; | |
shift = (int)((1 - ((row_width + 1) & 0x01)) << 2); | |
for (i = 0; i < row_width; i++) | |
{ | |
value = (*sp >> shift) & 0x0f; | |
*dp = (png_byte)(value | (value << 4)); | |
if (shift == 4) | |
{ | |
shift = 0; | |
sp--; | |
} | |
else | |
shift = 4; | |
dp--; | |
} | |
break; | |
} | |
default: | |
break; | |
} | |
row_info->bit_depth = 8; | |
row_info->pixel_depth = 8; | |
row_info->rowbytes = row_width; | |
} | |
if (trans_color != NULL) | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
gray = gray & 0xff; | |
sp = row + (png_size_t)row_width - 1; | |
dp = row + (png_size_t)(row_width << 1) - 1; | |
for (i = 0; i < row_width; i++) | |
{ | |
if (*sp == gray) | |
*dp-- = 0; | |
else | |
*dp-- = 0xff; | |
*dp-- = *sp--; | |
} | |
} | |
else if (row_info->bit_depth == 16) | |
{ | |
unsigned int gray_high = (gray >> 8) & 0xff; | |
unsigned int gray_low = gray & 0xff; | |
sp = row + row_info->rowbytes - 1; | |
dp = row + (row_info->rowbytes << 1) - 1; | |
for (i = 0; i < row_width; i++) | |
{ | |
if (*(sp - 1) == gray_high && *(sp) == gray_low) | |
{ | |
*dp-- = 0; | |
*dp-- = 0; | |
} | |
else | |
{ | |
*dp-- = 0xff; | |
*dp-- = 0xff; | |
} | |
*dp-- = *sp--; | |
*dp-- = *sp--; | |
} | |
} | |
row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA; | |
row_info->channels = 2; | |
row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1); | |
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, | |
row_width); | |
} | |
} | |
else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_color) | |
{ | |
if (row_info->bit_depth == 8) | |
{ | |
png_byte red = (png_byte)(trans_color->red & 0xff); | |
png_byte green = (png_byte)(trans_color->green & 0xff); | |
png_byte blue = (png_byte)(trans_color->blue & 0xff); | |
sp = row + (png_size_t)row_info->rowbytes - 1; | |
dp = row + (png_size_t)(row_width << 2) - 1; | |
for (i = 0; i < row_width; i++) | |
{ | |
if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue) | |
*dp-- = 0; | |
else | |
*dp-- = 0xff; | |
*dp-- = *sp--; | |
*dp-- = *sp--; | |
*dp-- = *sp--; | |
} | |
} | |
else if (row_info->bit_depth == 16) | |
{ | |
png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff); | |
png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff); | |
png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff); | |
png_byte red_low = (png_byte)(trans_color->red & 0xff); | |
png_byte green_low = (png_byte)(trans_color->green & 0xff); | |
png_byte blue_low = (png_byte)(trans_color->blue & 0xff); | |
sp = row + row_info->rowbytes - 1; | |
dp = row + (png_size_t)(row_width << 3) - 1; | |
for (i = 0; i < row_width; i++) | |
{ | |
if (*(sp - 5) == red_high && | |
*(sp - 4) == red_low && | |
*(sp - 3) == green_high && | |
*(sp - 2) == green_low && | |
*(sp - 1) == blue_high && | |
*(sp ) == blue_low) | |
{ | |
*dp-- = 0; | |
*dp-- = 0; | |
} | |
else | |
{ | |
*dp-- = 0xff; | |
*dp-- = 0xff; | |
} | |
*dp-- = *sp--; | |
*dp-- = *sp--; | |
*dp-- = *sp--; | |
*dp-- = *sp--; | |
*dp-- = *sp--; | |
*dp-- = *sp--; | |
} | |
} | |
row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA; | |
row_info->channels = 4; | |
row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2); | |
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); | |
} | |
} | |
} | |
#endif | |
#ifdef PNG_READ_EXPAND_16_SUPPORTED | |
/* If the bit depth is 8 and the color type is not a palette type expand the | |
* whole row to 16 bits. Has no effect otherwise. | |
*/ | |
void /* PRIVATE */ | |
png_do_expand_16(png_row_infop row_info, png_bytep row) | |
{ | |
if (row_info->bit_depth == 8 && | |
row_info->color_type != PNG_COLOR_TYPE_PALETTE) | |
{ | |
/* The row have a sequence of bytes containing [0..255] and we need | |
* to turn it into another row containing [0..65535], to do this we | |
* calculate: | |
* | |
* (input / 255) * 65535 | |
* | |
* Which happens to be exactly input * 257 and this can be achieved | |
* simply by byte replication in place (copying backwards). | |
*/ | |
png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */ | |
png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */ | |
while (dp > sp) | |
dp[-2] = dp[-1] = *--sp, dp -= 2; | |
row_info->rowbytes *= 2; | |
row_info->bit_depth = 16; | |
row_info->pixel_depth = (png_byte)(row_info->channels * 16); | |
} | |
} | |
#endif | |
#ifdef PNG_READ_QUANTIZE_SUPPORTED | |
void /* PRIVATE */ | |
png_do_quantize(png_row_infop row_info, png_bytep row, | |
png_const_bytep palette_lookup, png_const_bytep quantize_lookup) | |
{ | |
png_bytep sp, dp; | |
png_uint_32 i; | |
png_uint_32 row_width=row_info->width; | |
png_debug(1, "in png_do_quantize"); | |
if (row_info->bit_depth == 8) | |
{ | |
if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup) | |
{ | |
int r, g, b, p; | |
sp = row; | |
dp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
r = *sp++; | |
g = *sp++; | |
b = *sp++; | |
/* This looks real messy, but the compiler will reduce | |
* it down to a reasonable formula. For example, with | |
* 5 bits per color, we get: | |
* p = (((r >> 3) & 0x1f) << 10) | | |
* (((g >> 3) & 0x1f) << 5) | | |
* ((b >> 3) & 0x1f); | |
*/ | |
p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) & | |
((1 << PNG_QUANTIZE_RED_BITS) - 1)) << | |
(PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) | | |
(((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) & | |
((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) << | |
(PNG_QUANTIZE_BLUE_BITS)) | | |
((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) & | |
((1 << PNG_QUANTIZE_BLUE_BITS) - 1)); | |
*dp++ = palette_lookup[p]; | |
} | |
row_info->color_type = PNG_COLOR_TYPE_PALETTE; | |
row_info->channels = 1; | |
row_info->pixel_depth = row_info->bit_depth; | |
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); | |
} | |
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA && | |
palette_lookup != NULL) | |
{ | |
int r, g, b, p; | |
sp = row; | |
dp = row; | |
for (i = 0; i < row_width; i++) | |
{ | |
r = *sp++; | |
g = *sp++; | |
b = *sp++; | |
sp++; | |
p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) & | |
((1 << PNG_QUANTIZE_RED_BITS) - 1)) << | |
(PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) | | |
(((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) & | |
((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) << | |
(PNG_QUANTIZE_BLUE_BITS)) | | |
((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) & | |
((1 << PNG_QUANTIZE_BLUE_BITS) - 1)); | |
*dp++ = palette_lookup[p]; | |
} | |
row_info->color_type = PNG_COLOR_TYPE_PALETTE; | |
row_info->channels = 1; | |
row_info->pixel_depth = row_info->bit_depth; | |
row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width); | |
} | |
else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE && | |
quantize_lookup) | |
{ | |
sp = row; | |
for (i = 0; i < row_width; i++, sp++) | |
{ | |
*sp = quantize_lookup[*sp]; | |
} | |
} | |
} | |
} | |
#endif /* PNG_READ_QUANTIZE_SUPPORTED */ | |
#endif /* PNG_READ_TRANSFORMS_SUPPORTED */ | |
#ifdef PNG_MNG_FEATURES_SUPPORTED | |
/* Undoes intrapixel differencing */ | |
void /* PRIVATE */ | |
png_do_read_intrapixel(png_row_infop row_info, png_bytep row) | |
{ | |
png_debug(1, "in png_do_read_intrapixel"); | |
if ( | |
(row_info->color_type & PNG_COLOR_MASK_COLOR)) | |
{ | |
int bytes_per_pixel; | |
png_uint_32 row_width = row_info->width; | |
if (row_info->bit_depth == 8) | |
{ | |
png_bytep rp; | |
png_uint_32 i; | |
if (row_info->color_type == PNG_COLOR_TYPE_RGB) | |
bytes_per_pixel = 3; | |
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) | |
bytes_per_pixel = 4; | |
else | |
return; | |
for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) | |
{ | |
*(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff); | |
*(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff); | |
} | |
} | |
else if (row_info->bit_depth == 16) | |
{ | |
png_bytep rp; | |
png_uint_32 i; | |
if (row_info->color_type == PNG_COLOR_TYPE_RGB) | |
bytes_per_pixel = 6; | |
else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA) | |
bytes_per_pixel = 8; | |
else | |
return; | |
for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel) | |
{ | |
png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1); | |
png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3); | |
png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5); | |
png_uint_32 red = (s0 + s1 + 65536) & 0xffff; | |
png_uint_32 blue = (s2 + s1 + 65536) & 0xffff; | |
*(rp ) = (png_byte)((red >> 8) & 0xff); | |
*(rp + 1) = (png_byte)(red & 0xff); | |
*(rp + 4) = (png_byte)((blue >> 8) & 0xff); | |
*(rp + 5) = (png_byte)(blue & 0xff); | |
} | |
} | |
} | |
} | |
#endif /* PNG_MNG_FEATURES_SUPPORTED */ | |
#endif /* PNG_READ_SUPPORTED */ |