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                 Rect *surarea)
   7 {
   8     gulong *draw = rgba->data;
   9     guint c, i, e, t, sfw, sfh;
  10     sfw = position->width;
  11     sfh = position->height;
  12
  13     /* it would be nice if this worked, but this function is well broken in
  14        these circumstances. */
  15     g_assert(position->width == surarea->width &&
  16              position->height == surarea->height);
  17
  18     g_assert(rgba->data != NULL);
  19
  20     if ((rgba->width != sfw || rgba->height != sfh) &&
  21         (rgba->width != rgba->cwidth || rgba->height != rgba->cheight)) {
  22         double dx = rgba->width / (double)sfw;
  23         double dy = rgba->height / (double)sfh;
  24         double px = 0.0;
  25         double py = 0.0;
  26         int iy = 0;
  27
  28         /* scale it and cache it */
  29         if (rgba->cache != NULL)
  30             g_free(rgba->cache);
  31         rgba->cache = g_new(unsigned long, sfw * sfh);
  32         rgba->cwidth = sfw;
  33         rgba->cheight = sfh;
  34         for (i = 0, c = 0, e = sfw*sfh; i < e; ++i) {
  35             rgba->cache[i] = rgba->data[(int)px + iy];
  36             if (++c >= sfw) {
  37                 c = 0;
  38                 px = 0;
  39                 py += dy;
  40                 iy = (int)py * rgba->width;
  41             } else
  42                 px += dx;
  43         }
  44
  45         /* do we use the cache we may have just created, or the original? */
  46         if (rgba->width != sfw || rgba->height != sfh)
  47             draw = rgba->cache;
  48
  49         /* apply the alpha channel */
  50         for (i = 0, c = 0, t = position->x, e = sfw*sfh; i < e; ++i, ++t) {
  51             guchar alpha, r, g, b, bgr, bgg, bgb;
  52
  53             alpha = draw[i] >> 24;
  54             r = draw[i] >> 16;
  55             g = draw[i] >> 8;
  56             b = draw[i];
  57
  58             if (c >= sfw) {
  59                 c = 0;
  60                 t += surarea->width - sfw;
  61             }
  62
  63             /* background color */
  64             bgr = target[t] >> default_red_shift;
  65             bgg = target[t] >> default_green_shift;
  66             bgb = target[t] >> default_blue_shift;
  67
  68             r = bgr + (((r - bgr) * alpha) >> 8);
  69             g = bgg + (((g - bgg) * alpha) >> 8);
  70             b = bgb + (((b - bgb) * alpha) >> 8);
  71
  72             target[t] = (r << default_red_shift) | (g << default_green_shift) |
  73                 (b << default_blue_shift);
  74         }
  75     }
  76 }