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GTK: make image component manipulation endian-safe.

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This commit is contained in:
John-Mark Bell 2014-02-16 00:00:21 +00:00
parent d9002dc71c
commit 5e0efcbd6c
1 changed files with 50 additions and 41 deletions
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91
gtk/bitmap.c
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@ -187,48 +187,54 @@ unsigned char *bitmap_get_buffer(void *vbitmap)
struct bitmap *gbitmap = (struct bitmap *)vbitmap;
int pixel_loop;
int pixel_count;
uint32_t *pixels;
uint32_t pixel;
uint8_t *pixels;
uint32_t t, r, g, b;
cairo_format_t fmt;
assert(gbitmap);
cairo_surface_flush(gbitmap->surface);
pixels = (uint32_t *)cairo_image_surface_get_data(gbitmap->surface);
pixels = cairo_image_surface_get_data(gbitmap->surface);
if (!gbitmap->converted)
return (unsigned char *) pixels;
return pixels;
fmt = cairo_image_surface_get_format(gbitmap->surface);
pixel_count = cairo_image_surface_get_width(gbitmap->surface) *
cairo_image_surface_get_height(gbitmap->surface);
if (fmt == CAIRO_FORMAT_RGB24) {
/* Opaque image: simply swap R & B channels */
for (pixel_loop=0; pixel_loop < pixel_count; pixel_loop++) {
pixel = pixels[pixel_loop];
pixels[pixel_loop] = (pixel & 0xff00ff00) |
((pixel & 0xff) << 16) |
((pixel & 0xff0000) >> 16);
b = pixels[4 * pixel_loop + 0];
r = pixels[4 * pixel_loop + 2];
pixels[4 * pixel_loop + 0] = r;
pixels[4 * pixel_loop + 2] = b;
}
} else {
uint32_t t, r, g, b;
/* Alpha image: swap R & B channels, and de-multiply alpha */
for (pixel_loop=0; pixel_loop < pixel_count; pixel_loop++) {
pixel = pixels[pixel_loop];
t = (pixel & 0xff000000) >> 24;
if (t == 0) {
pixels[pixel_loop] = 0;
} else {
r = ((pixel & 0xff0000) >> 8) / t;
g = ((pixel & 0xff00)) / t;
b = ((pixel & 0xff) << 8) / t;
b = pixels[4 * pixel_loop + 0];
g = pixels[4 * pixel_loop + 1];
r = pixels[4 * pixel_loop + 2];
t = pixels[4 * pixel_loop + 3];
if (t != 0) {
r = (r << 8) / t;
g = (g << 8) / t;
b = (b << 8) / t;
r = (r > 255) ? 255 : r;
g = (g > 255) ? 255 : g;
b = (b > 255) ? 255 : b;
pixels[pixel_loop] = (t << 24) |
(r) | (g << 8) | (b << 16);
} else {
r = g = b = 0;
}
pixels[4 * pixel_loop + 0] = r;
pixels[4 * pixel_loop + 1] = g;
pixels[4 * pixel_loop + 2] = b;
pixels[4 * pixel_loop + 3] = t;
}
}
@ -319,8 +325,8 @@ void bitmap_modified(void *vbitmap) {
struct bitmap *gbitmap = (struct bitmap *)vbitmap;
int pixel_loop;
int pixel_count;
uint32_t *pixels;
uint32_t pixel;
uint8_t *pixels;
uint32_t t, r, g, b;
cairo_format_t fmt;
assert(gbitmap);
@ -329,7 +335,7 @@ void bitmap_modified(void *vbitmap) {
pixel_count = cairo_image_surface_get_width(gbitmap->surface) *
cairo_image_surface_get_height(gbitmap->surface);
pixels = (uint32_t *)cairo_image_surface_get_data(gbitmap->surface);
pixels = cairo_image_surface_get_data(gbitmap->surface);
if (gbitmap->converted) {
cairo_surface_mark_dirty(gbitmap->surface);
@ -337,30 +343,33 @@ void bitmap_modified(void *vbitmap) {
}
if (fmt == CAIRO_FORMAT_RGB24) {
/* Opaque image: simply swap R & B channels */
for (pixel_loop=0; pixel_loop < pixel_count; pixel_loop++) {
pixel = pixels[pixel_loop];
pixels[pixel_loop] = (pixel & 0xff00ff00) |
((pixel & 0xff) << 16) |
((pixel & 0xff0000) >> 16);
r = pixels[4 * pixel_loop + 0];
b = pixels[4 * pixel_loop + 2];
pixels[4 * pixel_loop + 0] = b;
pixels[4 * pixel_loop + 2] = r;
}
} else {
uint8_t t, r, g, b;
/* Alpha image: swap R & B channels, and pre-multiply alpha */
for (pixel_loop=0; pixel_loop < pixel_count; pixel_loop++) {
pixel = pixels[pixel_loop];
t = (pixel & 0xff000000) >> 24;
if (t == 0) {
pixels[pixel_loop] = 0;
r = pixels[4 * pixel_loop + 0];
g = pixels[4 * pixel_loop + 1];
b = pixels[4 * pixel_loop + 2];
t = pixels[4 * pixel_loop + 3];
if (t != 0) {
r = ((r * t) >> 8) & 0xff;
g = ((g * t) >> 8) & 0xff;
b = ((b * t) >> 8) & 0xff;
} else {
r = (pixel & 0xff0000) >> 16;
g = (pixel & 0xff00) >> 8;
b = pixel & 0xff;
pixels[pixel_loop] = (t << 24) |
((r * t) >> 8) |
((g * t) >> 8) << 8 |
((b * t) >> 8) << 16;
r = g = b = 0;
}
pixels[4 * pixel_loop + 0] = b;
pixels[4 * pixel_loop + 1] = g;
pixels[4 * pixel_loop + 2] = r;
pixels[4 * pixel_loop + 3] = t;
}
}