📄 pngrtran.c
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num_new_palette--;
palette[index_to_palette[j]] = palette[num_new_palette];
if (!full_dither)
{
int k;
for (k = 0; k < num_palette; k++)
{
if (png_ptr->dither_index[k] ==
index_to_palette[j])
png_ptr->dither_index[k] =
index_to_palette[next_j];
if ((int)png_ptr->dither_index[k] ==
num_new_palette)
png_ptr->dither_index[k] =
index_to_palette[j];
}
}
index_to_palette[palette_to_index[num_new_palette]] =
index_to_palette[j];
palette_to_index[index_to_palette[j]] =
palette_to_index[num_new_palette];
index_to_palette[j] = (png_byte)num_new_palette;
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)
{
png_dsortp t;
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, palette_to_index);
png_free(png_ptr, index_to_palette);
}
num_palette = maximum_colors;
}
if (png_ptr->palette == NULL)
{
png_ptr->palette = palette;
}
png_ptr->num_palette = (png_uint_16)num_palette;
if (full_dither)
{
int i;
png_bytep distance;
int total_bits = PNG_DITHER_RED_BITS + PNG_DITHER_GREEN_BITS +
PNG_DITHER_BLUE_BITS;
int num_red = (1 << PNG_DITHER_RED_BITS);
int num_green = (1 << PNG_DITHER_GREEN_BITS);
int num_blue = (1 << PNG_DITHER_BLUE_BITS);
png_size_t num_entries = ((png_size_t)1 << total_bits);
png_ptr->palette_lookup = (png_bytep )png_malloc(png_ptr,
(png_uint_32)(num_entries * sizeof (png_byte)));
png_memset(png_ptr->palette_lookup, 0, num_entries * sizeof (png_byte));
distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
sizeof(png_byte)));
png_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_DITHER_RED_BITS));
int g = (palette[i].green >> (8 - PNG_DITHER_GREEN_BITS));
int b = (palette[i].blue >> (8 - PNG_DITHER_BLUE_BITS));
for (ir = 0; ir < num_red; ir++)
{
int dr = abs(ir - r);
int index_r = (ir << (PNG_DITHER_BLUE_BITS + PNG_DITHER_GREEN_BITS));
for (ig = 0; ig < num_green; ig++)
{
int dg = abs(ig - g);
int dt = dr + dg;
int dm = ((dr > dg) ? dr : dg);
int index_g = index_r | (ig << PNG_DITHER_BLUE_BITS);
for (ib = 0; ib < num_blue; ib++)
{
int d_index = index_g | ib;
int db = abs(ib - b);
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
#if defined(PNG_READ_GAMMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
/* Transform the image from the file_gamma to the screen_gamma. We
* 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.
*/
void PNGAPI
png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
{
png_debug(1, "in png_set_gamma\n");
if (fabs(scrn_gamma * file_gamma - 1.0) > PNG_GAMMA_THRESHOLD)
png_ptr->transformations |= PNG_GAMMA;
png_ptr->gamma = (float)file_gamma;
png_ptr->screen_gamma = (float)scrn_gamma;
}
#endif
#if defined(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_structp png_ptr)
{
png_debug(1, "in png_set_expand\n");
png_ptr->transformations |= PNG_EXPAND;
}
/* 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.
*/
/* Expand paletted images to RGB. */
void PNGAPI
png_set_palette_to_rgb(png_structp png_ptr)
{
png_debug(1, "in png_set_expand\n");
png_ptr->transformations |= PNG_EXPAND;
}
/* Expand grayscale images of less than 8-bit depth to 8 bits. */
void PNGAPI
png_set_gray_1_2_4_to_8(png_structp png_ptr)
{
png_debug(1, "in png_set_expand\n");
png_ptr->transformations |= PNG_EXPAND;
}
/* Expand tRNS chunks to alpha channels. */
void PNGAPI
png_set_tRNS_to_alpha(png_structp png_ptr)
{
png_debug(1, "in png_set_expand\n");
png_ptr->transformations |= PNG_EXPAND;
}
#endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
#if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
void PNGAPI
png_set_gray_to_rgb(png_structp png_ptr)
{
png_debug(1, "in png_set_gray_to_rgb\n");
png_ptr->transformations |= PNG_GRAY_TO_RGB;
}
#endif
#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
#if defined(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_structp png_ptr, int error_action, double red,
double green)
{
int red_fixed = (int)((float)red*100000.0 + 0.5);
int green_fixed = (int)((float)green*100000.0 + 0.5);
png_set_rgb_to_gray_fixed(png_ptr, error_action, red_fixed, green_fixed);
}
#endif
void PNGAPI
png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
png_fixed_point red, png_fixed_point green)
{
png_debug(1, "in png_set_rgb_to_gray\n");
switch(error_action)
{
case 1: png_ptr->transformations |= PNG_RGB_TO_GRAY;
break;
case 2: png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
break;
case 3: png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
}
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
#if defined(PNG_READ_EXPAND_SUPPORTED)
png_ptr->transformations |= PNG_EXPAND;
#else
{
png_warning(png_ptr, "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED.");
png_ptr->transformations &= ~PNG_RGB_TO_GRAY;
}
#endif
{
png_uint_16 red_int, green_int;
if(red < 0 || green < 0)
{
red_int = 6968; /* .212671 * 32768 + .5 */
green_int = 23434; /* .715160 * 32768 + .5 */
}
else if(red + green < 100000L)
{
red_int = (png_uint_16)(((png_uint_32)red*32768L)/100000L);
green_int = (png_uint_16)(((png_uint_32)green*32768L)/100000L);
}
else
{
png_warning(png_ptr, "ignoring out of range rgb_to_gray coefficients");
red_int = 6968;
green_int = 23434;
}
png_ptr->rgb_to_gray_red_coeff = red_int;
png_ptr->rgb_to_gray_green_coeff = green_int;
png_ptr->rgb_to_gray_blue_coeff = (png_uint_16)(32768-red_int-green_int);
}
}
#endif
#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
defined(PNG_LEGACY_SUPPORTED)
void PNGAPI
png_set_read_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
read_user_transform_fn)
{
png_debug(1, "in png_set_read_user_transform_fn\n");
#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
png_ptr->transformations |= PNG_USER_TRANSFORM;
png_ptr->read_user_transform_fn = read_user_transform_fn;
#endif
#ifdef PNG_LEGACY_SUPPORTED
if(read_user_transform_fn)
png_warning(png_ptr,
"This version of libpng does not support user transforms");
#endif
}
#endif
/* Initialize everything needed for the read. This includes modifying
* the palette.
*/
void /* PRIVATE */
png_init_read_transformations(png_structp png_ptr)
{
png_debug(1, "in png_init_read_transformations\n");
#if defined(PNG_USELESS_TESTS_SUPPORTED)
if(png_ptr != NULL)
#endif
{
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || defined(PNG_READ_SHIFT_SUPPORTED) \
|| defined(PNG_READ_GAMMA_SUPPORTED)
int color_type = png_ptr->color_type;
#endif
#if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
(png_ptr->transformations & PNG_EXPAND))
{
if (!(color_type & PNG_COLOR_MASK_COLOR)) /* i.e., GRAY or GRAY_ALPHA */
{
/* expand background chunk. */
switch (png_ptr->bit_depth)
{
case 1:
png_ptr->background.gray *= (png_uint_16)0xff;
png_ptr->background.red = png_ptr->background.green =
png_ptr->background.blue = png_ptr->background.gray;
break;
case 2:
png_ptr->background.gray *= (png_uint_16)0x55;
png_ptr->background.red = png_ptr->background.green =
png_ptr->background.blue = png_ptr->background.gray;
break;
case 4:
png_ptr->background.gray *= (png_uint_16)0x11;
png_ptr->background.red = png_ptr->background.green =
png_ptr->background.blue = png_ptr->background.gray;
break;
case 8:
case 16:
png_ptr->background.red = png_ptr->background.green =
png_ptr->background.blue = png_ptr->background.gray;
break;
}
}
else if (color_type == PNG_COLOR_TYPE_PALETTE)
{
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;
#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
if (png_ptr->transformations & PNG_INVERT_ALPHA)
{
#if defined(PNG_READ_EXPAND_SUPPORTED)
if (!(png_ptr->transformations & PNG_EXPAND))
#endif
{
/* invert the alpha channel (in tRNS) unless the pixels are
going to be expanded, in which case leave it for later */
int i,istop;
istop=(int)png_ptr->num_trans;
for (i=0; i<istop; i++)
png_ptr->trans[i] = (png_byte)(255 - png_ptr->trans[i]);
}
}
#endif
}
}
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
png_ptr->background_1 = png_ptr->background;
#endif
#if defined(PNG_READ_GAMMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
if (png_ptr->transformations & (PNG_GAMMA | PNG_RGB_TO_GRAY))
{
png_build_gamma_table(png_ptr);
#if defined(PNG_READ_BACKGROUND_SUPPORTED)
if (png_ptr->transformations & PNG_BACKGROUND)
{
if (color_type == PNG_COLOR_TYPE_PALETTE)
{
png_color back, back_1;
png_colorp palette = png_ptr->palette;
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