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Handle grayscale images as expected

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Signed-off-by: obskyr <powpowd@gmail.com>
This commit is contained in:
obskyr
2018-02-15 15:03:19 +01:00
parent 3075945367
commit b8af100c63
1 changed files with 85 additions and 19 deletions
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104
src/gfx/makepng.c
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@@ -18,7 +18,7 @@ static struct RawIndexedImage *indexed_png_to_raw(struct PNGImage *img);
static struct RawIndexedImage *grayscale_png_to_raw(struct PNGImage *img); static struct RawIndexedImage *grayscale_png_to_raw(struct PNGImage *img);
static struct RawIndexedImage *truecolor_png_to_raw(struct PNGImage *img); static struct RawIndexedImage *truecolor_png_to_raw(struct PNGImage *img);
static void get_text(const struct PNGImage *img, static void get_text(const struct PNGImage *img,
struct ImageOptions* png_options); struct ImageOptions *png_options);
static void set_text(const struct PNGImage *img, static void set_text(const struct PNGImage *img,
const struct ImageOptions *png_options); const struct ImageOptions *png_options);
static void free_png_data(const struct PNGImage *png); static void free_png_data(const struct PNGImage *png);
@@ -333,18 +333,8 @@ static void rgba_PLTE_palette(struct PNGImage *img,
PNG_USER_WILL_FREE_DATA, PNG_FREE_PLTE); PNG_USER_WILL_FREE_DATA, PNG_FREE_PLTE);
} }
/* A combined struct is needed to sort colors in order of luminance. */ static int fit_grayscale_palette(png_color *palette, int *num_colors);
struct ColorWithLuminance { static void order_color_palette(png_color *palette, int num_colors);
png_color color;
int luminance;
};
static int compare_luminance(const void *a,const void *b)
{
struct ColorWithLuminance *x = (struct ColorWithLuminance *) a;
struct ColorWithLuminance *y = (struct ColorWithLuminance *) b;
return y->luminance - x->luminance;
}
static void rgba_build_palette(struct PNGImage *img, static void rgba_build_palette(struct PNGImage *img,
png_color **palette_ptr_ptr, int *num_colors) png_color **palette_ptr_ptr, int *num_colors)
@@ -353,9 +343,9 @@ static void rgba_build_palette(struct PNGImage *img,
int y, value_index, i; int y, value_index, i;
png_color cur_pixel_color; png_color cur_pixel_color;
png_byte cur_alpha; png_byte cur_alpha;
bool only_grayscale = true;
bool color_exists; bool color_exists;
png_color cur_palette_color; png_color cur_palette_color;
struct ColorWithLuminance *palette_with_luminance;
/* /*
* By filling the palette up with black by default, if the image * By filling the palette up with black by default, if the image
@@ -381,6 +371,12 @@ static void rgba_build_palette(struct PNGImage *img,
continue; continue;
} }
if (only_grayscale &&
!(cur_pixel_color.red == cur_pixel_color.green &&
cur_pixel_color.red == cur_pixel_color.blue)) {
only_grayscale = false;
}
color_exists = false; color_exists = false;
for (i = 0; i < *num_colors; i++) { for (i = 0; i < *num_colors; i++) {
cur_palette_color = palette[i]; cur_palette_color = palette[i];
@@ -402,9 +398,79 @@ static void rgba_build_palette(struct PNGImage *img,
} }
} }
palette_with_luminance = /* In order not to count 100% transparent images as grayscale. */
malloc(sizeof(struct ColorWithLuminance) * colors); only_grayscale = *num_colors ? only_grayscale : false;
if (!only_grayscale || !fit_grayscale_palette(palette, num_colors)) {
order_color_palette(palette, *num_colors);
}
}
static int fit_grayscale_palette(png_color *palette, int *num_colors)
{
int i, shade_index;
int interval = 256 / colors;
png_color *fitted_palette = malloc(sizeof(png_color) * colors);
bool *set_indices = calloc(colors, sizeof(bool));
fitted_palette[0].red = 0xFF;
fitted_palette[0].green = 0xFF;
fitted_palette[0].blue = 0xFF;
fitted_palette[colors - 1].red = 0;
fitted_palette[colors - 1].green = 0;
fitted_palette[colors - 1].blue = 0;
if (colors == 4) {
fitted_palette[1].red = 0xA9;
fitted_palette[1].green = 0xA9;
fitted_palette[1].blue = 0xA9;
fitted_palette[2].red = 0x55;
fitted_palette[2].green = 0x55;
fitted_palette[2].blue = 0x55;
}
for (i = 0; i < *num_colors; i++) {
shade_index = colors - 1 - palette[i].red / interval;
if (set_indices[shade_index]) {
free(fitted_palette);
free(set_indices);
return false;
}
fitted_palette[shade_index] = palette[i];
set_indices[shade_index] = true;
}
for (i = 0; i < colors; i++) { for (i = 0; i < colors; i++) {
palette[i] = fitted_palette[i];
}
*num_colors = colors;
free(fitted_palette);
free(set_indices);
return true;
}
/* A combined struct is needed to sort csolors in order of luminance. */
struct ColorWithLuminance {
png_color color;
int luminance;
};
static int compare_luminance(const void *a, const void *b)
{
struct ColorWithLuminance *x = (struct ColorWithLuminance *) a;
struct ColorWithLuminance *y = (struct ColorWithLuminance *) b;
return y->luminance - x->luminance;
}
static void order_color_palette(png_color *palette, int num_colors)
{
int i;
struct ColorWithLuminance *palette_with_luminance;
palette_with_luminance =
malloc(sizeof(struct ColorWithLuminance) * num_colors);
for (i = 0; i < num_colors; i++) {
/* /*
* Normally this would be done with floats, but since it's only * Normally this would be done with floats, but since it's only
* used for comparison, we might as well use integer math. * used for comparison, we might as well use integer math.
@@ -414,9 +480,9 @@ static void rgba_build_palette(struct PNGImage *img,
7152 * palette[i].green + 7152 * palette[i].green +
722 * palette[i].blue; 722 * palette[i].blue;
} }
qsort(palette_with_luminance, colors, qsort(palette_with_luminance, num_colors,
sizeof(struct ColorWithLuminance), compare_luminance); sizeof(struct ColorWithLuminance), compare_luminance);
for (i = 0; i < colors; i++) { for (i = 0; i < num_colors; i++) {
palette[i] = palette_with_luminance[i].color; palette[i] = palette_with_luminance[i].color;
} }
free(palette_with_luminance); free(palette_with_luminance);
@@ -538,7 +604,7 @@ static void set_raw_image_palette(struct RawIndexedImage *raw_image,
} }
static void get_text(const struct PNGImage *img, static void get_text(const struct PNGImage *img,
struct ImageOptions* png_options) struct ImageOptions *png_options)
{ {
png_text *text; png_text *text;
int i, numtxts, numremoved; int i, numtxts, numremoved;