+
+void reduce_depth(pixel32 *data, XImage *im)
+{
+ // since pixel32 is the largest possible pixel size, we can share the array
+ int r, g, b;
+ int x,y;
+ pixel16 *p = (pixel16*) data;
+ switch (im->bits_per_pixel) {
+ case 32:
+ if ((render_red_offset != default_red_shift) ||
+ (render_blue_offset != default_blue_shift) ||
+ (render_green_offset != default_green_shift)) {
+ for (y = 0; y < im->height; y++) {
+ for (x = 0; x < im->width; x++) {
+ r = (data[x] >> default_red_shift) & 0xFF;
+ g = (data[x] >> default_green_shift) & 0xFF;
+ b = (data[x] >> default_blue_shift) & 0xFF;
+ data[x] = (r << render_red_offset) + (g << render_green_offset) +
+ (b << render_blue_offset);
+ }
+ data += im->width;
+ }
+ }
+ break;
+ case 16:
+ for (y = 0; y < im->height; y++) {
+ for (x = 0; x < im->width; x++) {
+ r = (data[x] >> default_red_shift) & 0xFF;
+ r = r >> render_red_shift;
+ g = (data[x] >> default_green_shift) & 0xFF;
+ g = g >> render_green_shift;
+ b = (data[x] >> default_blue_shift) & 0xFF;
+ b = b >> render_blue_shift;
+ p[x] = (r << render_red_offset)
+ + (g << render_green_offset)
+ + (b << render_blue_offset);
+ }
+ data += im->width;
+ p += im->bytes_per_line/2;
+ }
+ break;
+ default:
+ g_message("your bit depth is currently unhandled\n");
+ }
+}