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Fix alpha blending for RGBA destinations.

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* Also enable PNG loading in `view`
* Also enable RGBA PNG loading in general
This commit is contained in:
Kevin Lange 2012-09-13 23:22:38 -07:00
parent 4c67b5da84
commit 66c2df40c1
3 changed files with 38 additions and 12 deletions
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37
userspace/lib/graphics.c
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@ -76,11 +76,12 @@ uint32_t alpha_blend(uint32_t bottom, uint32_t top, uint32_t mask) {
uint32_t alpha_blend_rgba(uint32_t bottom, uint32_t top) {
uint8_t a = _ALP(top);
uint8_t red = (_RED(bottom) * (255 - a) + _RED(top) * a) / 255;
uint8_t gre = (_GRE(bottom) * (255 - a) + _GRE(top) * a) / 255;
uint8_t blu = (_BLU(bottom) * (255 - a) + _BLU(top) * a) / 255;
uint8_t alp = a + _ALP(bottom) > 255 ? 255 : a + _ALP(bottom);
return rgba(red,gre,blu, alp);
uint8_t b = ((int)_ALP(bottom) * (255 - a)) / 255;
uint8_t alp = a + b;
uint8_t red = alp ? (int)(_RED(bottom) * (b) + _RED(top) * a) / (alp): 0;
uint8_t gre = alp ? (int)(_GRE(bottom) * (b) + _GRE(top) * a) / (alp): 0;
uint8_t blu = alp ? (int)(_BLU(bottom) * (b) + _BLU(top) * a) / (alp): 0;
return rgba(red,gre,blu,alp);
}
void load_sprite(sprite_t * sprite, char * filename) {
@ -182,13 +183,27 @@ int load_sprite_png(sprite_t * sprite, char * file) {
sprite->alpha = 0;
sprite->blank = 0;
printf(">> Notice, loaded with bit_depth = %d\n", bit_depth);
for (y = 0; y < height; ++y) {
png_byte* row = row_pointers[y];
for (x = 0; x < width; ++x) {
png_byte * ptr = &(row[x*3]);
sprite->bitmap[(y) * width + x] = rgb(ptr[0], ptr[1], ptr[2]);
if (color_type == 2) {
sprite->alpha = ALPHA_OPAQUE;
for (y = 0; y < height; ++y) {
png_byte* row = row_pointers[y];
for (x = 0; x < width; ++x) {
png_byte * ptr = &(row[x*3]);
sprite->bitmap[(y) * width + x] = rgb(ptr[0], ptr[1], ptr[2]);
}
}
} else if (color_type == 6) {
sprite->alpha = ALPHA_EMBEDDED;
for (y = 0; y < height; ++y) {
png_byte* row = row_pointers[y];
for (x = 0; x < width; ++x) {
png_byte * ptr = &(row[x*4]);
sprite->bitmap[(y) * width + x] = rgba(ptr[0], ptr[1], ptr[2], ptr[3]);
}
}
} else {
printf("XXX: UNKNOWN COLOR TYPE: %d!\n", color_type);
}
for (y = 0; y < height; ++y) {

1
userspace/lib/graphics.h
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@ -52,6 +52,7 @@ gfx_context_t * init_graphics_fullscreen_double_buffer();
#define ALPHA_INDEXED 3
uint32_t rgb(uint8_t r, uint8_t g, uint8_t b);
uint32_t rgba(uint8_t r, uint8_t g, uint8_t b, uint8_t a);
uint32_t alpha_blend(uint32_t bottom, uint32_t top, uint32_t mask);
uint32_t alpha_blend_rgba(uint32_t bottom, uint32_t top);

12
userspace/view.c
View File

@ -34,7 +34,12 @@ int main (int argc, char ** argv) {
int left = 30;
int top = 30;
init_sprite(0, argv[1], NULL);
if (strstr(argv[1], ".png")) {
sprites[0] = malloc(sizeof(sprite_t));
load_sprite_png(sprites[0], argv[1]);
} else {
init_sprite(0, argv[1], NULL);
}
int width = sprites[0]->width;
int height = sprites[0]->height;
@ -46,6 +51,11 @@ int main (int argc, char ** argv) {
ctx = init_graphics_window(wina);
draw_fill(ctx, rgb(0,0,0));
if (sprites[0]->alpha == ALPHA_EMBEDDED) {
draw_fill(ctx, rgba(0,0,0,0));
window_enable_alpha(wina);
}
draw_sprite(ctx, sprites[0], 0, 0);
while (1) {