rgba icon rendering

render/image.c

@@ -0,0 +1,64 @@
+#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);
+    }
+  }
+}

render/image.h

@@ -0,0 +1,9 @@
+#ifndef __image_h
+#define __image_h
+
+#include "render.h"
+#include "../kernel/geom.h"
+
+void image_draw(pixel32 *target, TextureRGBA *rgba, Rect *position);
+
+#endif