Dogcows Code - chaz/openbox/blob - render/image.c

   1 #include <glib.h>
   2 #include "../kernel/geom.h"
   3 #include "image.h"
   4
   5 void image_draw(pixel32 *target, TextureRGBA *rgba, Rect *position)
   6 {
   7   unsigned long *draw = rgba->data;
   8   int c, sfw, sfh;
   9   unsigned int i, e, bgi;
  10   sfw = position->width;
  11   sfh = position->height;
  12
  13   g_assert(rgba->data != NULL);
  14
  15   if ((rgba->width != sfw || rgba->height != sfh) &&
  16       (rgba->width != rgba->cwidth || rgba->height != rgba->cheight)) {
  17     double dx = rgba->width / (double)sfw;
  18     double dy = rgba->height / (double)sfh;
  19     double px = 0.0;
  20     double py = 0.0;
  21     int iy = 0;
  22
  23     /* scale it and cache it */
  24     if (rgba->cache != NULL)
  25         g_free(rgba->cache);
  26     rgba->cache = g_new(unsigned long, sfw * sfh);
  27     rgba->cwidth = sfw;
  28     rgba->cheight = sfh;
  29     for (i = 0, c = 0, e = sfw*sfh; i < e; ++i) {
  30       rgba->cache[i] = rgba->data[(int)px + iy];
  31       if (++c >= sfw) {
  32         c = 0;
  33         px = 0;
  34         py += dy;
  35         iy = (int)py * rgba->width;
  36       } else
  37         px += dx;
  38     }
  39
  40 /* do we use the cache we may have just created, or the original? */
  41     if (rgba->width != sfw || rgba->height != sfh)
  42         draw = rgba->cache;
  43
  44     /* apply the alpha channel */
  45     for (i = 0, c = 0, e = sfw*sfh; i < e; ++i, ++bgi) {
  46       unsigned char alpha = draw[i] >> 24;
  47       unsigned char r = draw[i] >> 16;
  48       unsigned char g = draw[i] >> 8;
  49       unsigned char b = draw[i];
  50
  51       /* background color */
  52       unsigned char bgr = target[i] >> default_red_shift;
  53       unsigned char bgg = target[i] >> default_green_shift;
  54       unsigned char bgb = target[i] >> default_blue_shift;
  55
  56       r = bgr + (((r - bgr) * alpha) >> 8);
  57       g = bgg + (((g - bgg) * alpha) >> 8);
  58       b = bgb + (((b - bgb) * alpha) >> 8);
  59
  60       target[i] = (r << default_red_shift) | (g << default_green_shift) |
  61         (b << default_blue_shift);
  62     }
  63   }
  64 }