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 *area)
   6 {
   7     pixel32 *draw = rgba->data;
   8     guint c, i, e, t, sfw, sfh;
   9     sfw = area->width;
  10     sfh = area->height;
  11
  12     g_assert(rgba->data != NULL);
  13
  14     if ((rgba->width != sfw || rgba->height != sfh) &&
  15         (rgba->width != rgba->cwidth || rgba->height != rgba->cheight)) {
  16         double dx = rgba->width / (double)sfw;
  17         double dy = rgba->height / (double)sfh;
  18         double px = 0.0;
  19         double py = 0.0;
  20         int iy = 0;
  21
  22         /* scale it and cache it */
  23         if (rgba->cache != NULL)
  24             g_free(rgba->cache);
  25         rgba->cache = g_new(pixel32, sfw * sfh);
  26         rgba->cwidth = sfw;
  27         rgba->cheight = sfh;
  28         for (i = 0, c = 0, e = sfw*sfh; i < e; ++i) {
  29             rgba->cache[i] = rgba->data[(int)px + iy];
  30             if (++c >= sfw) {
  31                 c = 0;
  32                 px = 0;
  33                 py += dy;
  34                 iy = (int)py * rgba->width;
  35             } else
  36                 px += dx;
  37         }
  38
  39         /* do we use the cache we may have just created, or the original? */
  40         if (rgba->width != sfw || rgba->height != sfh)
  41             draw = rgba->cache;
  42
  43         /* apply the alpha channel */
  44         for (i = 0, c = 0, t = area->x, e = sfw*sfh; i < e; ++i, ++t) {
  45             guchar alpha, r, g, b, bgr, bgg, bgb;
  46
  47             alpha = draw[i] >> default_alpha_offset;
  48             r = draw[i] >> default_red_offset;
  49             g = draw[i] >> default_green_offset;
  50             b = draw[i] >> default_blue_offset;
  51
  52             if (c >= sfw) {
  53                 c = 0;
  54                 t += area->width - sfw;
  55             }
  56
  57             /* background color */
  58             bgr = target[t] >> default_red_offset;
  59             bgg = target[t] >> default_green_offset;
  60             bgb = target[t] >> default_blue_offset;
  61
  62             r = bgr + (((r - bgr) * alpha) >> 8);
  63             g = bgg + (((g - bgg) * alpha) >> 8);
  64             b = bgb + (((b - bgb) * alpha) >> 8);
  65
  66             target[t] = (r << default_red_offset)
  67                       | (g << default_green_offset)
  68                       | (b << default_blue_offset);
  69         }
  70     }
  71 }