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

   1 #include "geom.h"
   2 #include "image.h"
   3 #include "color.h"
   4
   5 #include <glib.h>
   6
   7 void RrImageDraw(RrPixel32 *target, RrTextureRGBA *rgba, RrRect *area)
   8 {
   9     RrPixel32 *draw = rgba->data;
  10     gint c, i, e, t, sfw, sfh;
  11     sfw = area->width;
  12     sfh = area->height;
  13
  14     g_assert(rgba->data != NULL);
  15
  16     if ((rgba->width != sfw || rgba->height != sfh) &&
  17         (rgba->width != rgba->cwidth || rgba->height != rgba->cheight)) {
  18         double dx = rgba->width / (double)sfw;
  19         double dy = rgba->height / (double)sfh;
  20         double px = 0.0;
  21         double py = 0.0;
  22         int iy = 0;
  23
  24         /* scale it and cache it */
  25         if (rgba->cache != NULL)
  26             g_free(rgba->cache);
  27         rgba->cache = g_new(RrPixel32, sfw * sfh);
  28         rgba->cwidth = sfw;
  29         rgba->cheight = sfh;
  30         for (i = 0, c = 0, e = sfw*sfh; i < e; ++i) {
  31             rgba->cache[i] = rgba->data[(int)px + iy];
  32             if (++c >= sfw) {
  33                 c = 0;
  34                 px = 0;
  35                 py += dy;
  36                 iy = (int)py * rgba->width;
  37             } else
  38                 px += dx;
  39         }
  40
  41         /* do we use the cache we may have just created, or the original? */
  42         if (rgba->width != sfw || rgba->height != sfh)
  43             draw = rgba->cache;
  44
  45         /* apply the alpha channel */
  46         for (i = 0, c = 0, t = area->x, e = sfw*sfh; i < e; ++i, ++t) {
  47             guchar alpha, r, g, b, bgr, bgg, bgb;
  48
  49             alpha = draw[i] >> RrDefaultAlphaOffset;
  50             r = draw[i] >> RrDefaultRedOffset;
  51             g = draw[i] >> RrDefaultGreenOffset;
  52             b = draw[i] >> RrDefaultBlueOffset;
  53
  54             if (c >= sfw) {
  55                 c = 0;
  56                 t += area->width - sfw;
  57             }
  58
  59             /* background color */
  60             bgr = target[t] >> RrDefaultRedOffset;
  61             bgg = target[t] >> RrDefaultGreenOffset;
  62             bgb = target[t] >> RrDefaultBlueOffset;
  63
  64             r = bgr + (((r - bgr) * alpha) >> 8);
  65             g = bgg + (((g - bgg) * alpha) >> 8);
  66             b = bgb + (((b - bgb) * alpha) >> 8);
  67
  68             target[t] = (r << RrDefaultRedOffset)
  69                       | (g << RrDefaultGreenOffset)
  70                       | (b << RrDefaultBlueOffset);
  71         }
  72     }
  73 }