--- rxvt-unicode/src/rxvtimg.C	2012/06/08 21:41:45	1.65
+++ rxvt-unicode/src/rxvtimg.C	2012/06/09 14:18:53	1.71
@@ -331,28 +331,61 @@
   return mask;
 }
 
+static void
+extract (int32_t cl0, int32_t cl1, int32_t &c, unsigned short &xc)
+{
+  int32_t x = clamp (c, cl0, cl1);
+  c -= x;
+  xc = x;
+}
+
+static bool
+extract (int32_t cl0, int32_t cl1, int32_t &r, int32_t &g, int32_t &b, int32_t &a, unsigned short &xr, unsigned short &xg, unsigned short &xb, unsigned short &xa)
+{
+  extract (cl0, cl1, r, xr);
+  extract (cl0, cl1, g, xg);
+  extract (cl0, cl1, b, xb);
+  extract (cl0, cl1, a, xa);
+
+  return xr | xg | xb | xa;
+}
+
 void
-rxvt_img::brightness (uint16_t r, uint16_t g, uint16_t b, uint16_t a)
+rxvt_img::brightness (int32_t r, int32_t g, int32_t b, int32_t a)
 {
+  unshare ();
+
   Display *dpy = s->display->dpy;
-  Picture src = create_xrender_mask (dpy, pm, True);
   Picture dst = XRenderCreatePicture (dpy, pm, format, 0, 0);
 
-  XRenderColor mask_c;
-  mask_c.red   = r;
-  mask_c.green = g;
-  mask_c.blue  = b;
-  mask_c.alpha = a;
-  XRenderFillRectangle (dpy, PictOpSrc, src, &mask_c, 0, 0, 1, 1);
+  // loop should not be needed for brightness, as only -1..1 makes sense
+  //while (r | g | b | a)
+    {
+      unsigned short xr, xg, xb, xa;
+      XRenderColor mask_c;
+
+      if (extract (0, 65535, r, g, b, a, mask_c.red, mask_c.green, mask_c.blue, mask_c.alpha))
+        XRenderFillRectangle (dpy, PictOpAdd, dst, &mask_c, 0, 0, w, h);
+
+      if (extract (-65535, 0, r, g, b, a, mask_c.red, mask_c.green, mask_c.blue, mask_c.alpha))
+        {
+          XRenderColor mask_w = { 65535, 65535, 65535, 65535 };
+          XRenderFillRectangle (dpy, PictOpDifference, dst, &mask_w, 0, 0, w, h);
+          mask_c.red   = -mask_c.red; //TODO: verify that doing clamp, assign, and negation does the right thing
+          mask_c.green = -mask_c.green;
+          mask_c.blue  = -mask_c.blue;
+          mask_c.alpha = -mask_c.alpha;
+          XRenderFillRectangle (dpy, PictOpAdd, dst, &mask_c, 0, 0, w, h);
+          XRenderFillRectangle (dpy, PictOpDifference, dst, &mask_w, 0, 0, w, h);
+        }
+    }
 
-  XRenderComposite (dpy, PictOpAdd, src, None, dst, 0, 0, 0, 0, 0, 0, w, h);
 
-  XRenderFreePicture (dpy, src);
   XRenderFreePicture (dpy, dst);
 }
 
 void
-rxvt_img::contrast (uint16_t r, uint16_t g, uint16_t b, uint16_t a)
+rxvt_img::contrast (int32_t r, int32_t g, int32_t b, int32_t a)
 {
   if (!(s->display->flags & DISPLAY_HAS_RENDER_MUL))
     {
@@ -360,8 +393,9 @@
       return;
     }
 
+  unshare ();
+
   Display *dpy = s->display->dpy;
-  Picture src = create_xrender_mask (dpy, pm, True);
   Picture dst = XRenderCreatePicture (dpy, pm, format, 0, 0);
 
   XRenderColor mask_c;
@@ -369,11 +403,8 @@
   mask_c.green = g;
   mask_c.blue  = b;
   mask_c.alpha = a;
-  XRenderFillRectangle (dpy, PictOpSrc, src, &mask_c, 0, 0, 1, 1);
+  XRenderFillRectangle (dpy, PictOpMultiply, dst, &mask_c, 0, 0, w, h);
 
-  XRenderComposite (dpy, PictOpMultiply, src, None, dst, 0, 0, 0, 0, 0, 0, w, h);
-
-  XRenderFreePicture (dpy, src);
   XRenderFreePicture (dpy, dst);
 }
 
@@ -474,10 +505,8 @@
     for (int j = 0; j < 3; ++j)
       xfrm.matrix [i][j] = XDoubleToFixed (matrix [i * 3 + j]);
 
-#if 0
   xfrm.matrix [0][2] -= XDoubleToFixed (x);//TODO
   xfrm.matrix [1][2] -= XDoubleToFixed (y);
-#endif
 
   XRenderSetPictureFilter (dpy, src, "good", 0, 0);
   XRenderSetPictureTransform (dpy, src, &xfrm);