openbox/render/image.c
2003-03-26 05:38:13 +00:00

64 lines
1.8 KiB
C

#include <glib.h>
#include "../kernel/geom.h"
#include "image.h"
void image_draw(pixel32 *target, TextureRGBA *rgba, Rect *position)
{
unsigned long *draw = rgba->data;
int c, sfw, sfh;
unsigned int i, e, bgi;
sfw = position->width;
sfh = position->height;
g_assert(rgba->data != NULL);
if ((rgba->width != sfw || rgba->height != sfh) &&
(rgba->width != rgba->cwidth || rgba->height != rgba->cheight)) {
double dx = rgba->width / (double)sfw;
double dy = rgba->height / (double)sfh;
double px = 0.0;
double py = 0.0;
int iy = 0;
/* scale it and cache it */
if (rgba->cache != NULL)
g_free(rgba->cache);
rgba->cache = g_new(unsigned long, sfw * sfh);
rgba->cwidth = sfw;
rgba->cheight = sfh;
for (i = 0, c = 0, e = sfw*sfh; i < e; ++i) {
rgba->cache[i] = rgba->data[(int)px + iy];
if (++c >= sfw) {
c = 0;
px = 0;
py += dy;
iy = (int)py * rgba->width;
} else
px += dx;
}
/* do we use the cache we may have just created, or the original? */
if (rgba->width != sfw || rgba->height != sfh)
draw = rgba->cache;
/* apply the alpha channel */
for (i = 0, c = 0, e = sfw*sfh; i < e; ++i, ++bgi) {
unsigned char alpha = draw[i] >> 24;
unsigned char r = draw[i] >> 16;
unsigned char g = draw[i] >> 8;
unsigned char b = draw[i];
/* background color */
unsigned char bgr = target[i] >> default_red_shift;
unsigned char bgg = target[i] >> default_green_shift;
unsigned char bgb = target[i] >> default_blue_shift;
r = bgr + (((r - bgr) * alpha) >> 8);
g = bgg + (((g - bgg) * alpha) >> 8);
b = bgb + (((b - bgb) * alpha) >> 8);
target[i] = (r << default_red_shift) | (g << default_green_shift) |
(b << default_blue_shift);
}
}
}