--- rxvt-unicode/src/rxvtimg.C	2012/06/04 18:17:25	1.17
+++ rxvt-unicode/src/rxvtimg.C	2012/06/07 20:35:35	1.58
@@ -4,17 +4,160 @@
 
 #if HAVE_IMG
 
-#define float_to_component(d) ((d) * 65535.99)
+rxvt_img::rxvt_img (rxvt_screen *screen, XRenderPictFormat *format, int x, int y, int width, int height, int repeat)
+: s(screen), x(x), y(y), w(width), h(height), format(format), repeat(repeat),
+  pm(0), ref(0)
+{
+}
 
-rxvt_img::rxvt_img (rxvt_screen *screen, XRenderPictFormat *format, int width, int height)
-: s(screen), w(width), h(height), format(format), shared(false)
+rxvt_img::rxvt_img (const rxvt_img &img)
+: s(img.s), x(img.x), y(img.y), w(img.w), h(img.h), format(img.format), repeat(img.repeat), pm(img.pm), ref(img.ref)
 {
-  pm = XCreatePixmap (s->display->dpy, s->display->root, w, h, format->depth);
+  ++ref->cnt;
 }
 
+#if 0
 rxvt_img::rxvt_img (rxvt_screen *screen, XRenderPictFormat *format, int width, int height, Pixmap pixmap)
-: s(screen), pm(pixmap), w(width), h(height), format(format), shared(false)
+: s(screen), x(0), y(0), w(width), h(height), format(format), repeat(RepeatNormal), shared(false), pm(pixmap)
+{
+}
+#endif
+
+rxvt_img *
+rxvt_img::new_from_root (rxvt_screen *s)
+{
+  Display *dpy = s->display->dpy;
+  unsigned int root_pm_w, root_pm_h;
+  Pixmap root_pixmap = s->display->get_pixmap_property (s->display->xa[XA_XROOTPMAP_ID]);
+  if (root_pixmap == None)
+    root_pixmap = s->display->get_pixmap_property (s->display->xa[XA_ESETROOT_PMAP_ID]);
+
+  if (root_pixmap == None)
+    return 0;
+
+  Window wdummy;
+  int idummy;
+  unsigned int udummy;
+
+  if (!XGetGeometry (dpy, root_pixmap, &wdummy, &idummy, &idummy, &root_pm_w, &root_pm_h, &udummy, &udummy))
+    return 0;
+
+  rxvt_img *img = new rxvt_img (
+     s,
+     XRenderFindVisualFormat (dpy, DefaultVisual (dpy, s->display->screen)),
+     0,
+     0,
+     root_pm_w,
+     root_pm_h
+  );
+
+  img->pm = root_pixmap;
+  img->ref = new pixref (root_pm_w, root_pm_h);
+  img->ref->ours = false;
+
+  return img;
+}
+
+rxvt_img *
+rxvt_img::new_from_pixbuf (rxvt_screen *s, GdkPixbuf *pb)
 {
+  Display *dpy = s->display->dpy;
+
+  int width  = gdk_pixbuf_get_width  (pb);
+  int height = gdk_pixbuf_get_height (pb);
+
+  if (width > 32767 || height > 32767) // well, we *could* upload in chunks
+    rxvt_fatal ("rxvt_img::new_from_pixbuf: image too big (maximum size 32768x32768).\n");
+
+  // since we require rgb24/argb32 formats from xrender we assume
+  // that both 24 and 32 bpp MUST be supported by any screen that supports xrender
+  int depth = gdk_pixbuf_get_has_alpha (pb) ? 32 : 24;
+
+  int byte_order = ecb_big_endian () ? MSBFirst : LSBFirst;
+
+  XImage xi;
+
+  xi.width            = width;
+  xi.height           = height;
+  xi.xoffset          = 0;
+  xi.format           = ZPixmap;
+  xi.byte_order       = ImageByteOrder (dpy);
+  xi.bitmap_unit      = 0;         //XY only, unused
+  xi.bitmap_bit_order = 0;         //XY only, unused
+  xi.bitmap_pad       = BitmapPad (dpy);
+  xi.depth            = depth;
+  xi.bytes_per_line   = 0;
+  xi.bits_per_pixel   = 32;         //Z only
+  xi.red_mask         = 0x00000000; //Z only, unused
+  xi.green_mask       = 0x00000000; //Z only, unused
+  xi.blue_mask        = 0x00000000; //Z only, unused
+  xi.obdata           = 0;          // probably unused
+
+  bool byte_order_mismatch = byte_order != xi.byte_order;
+
+  if (!XInitImage (&xi))
+    rxvt_fatal ("unable to initialise ximage, please report.\n");
+
+  if (height > INT_MAX / xi.bytes_per_line)
+    rxvt_fatal ("rxvt_img::new_from_pixbuf: image too big for Xlib.\n");
+
+  xi.data = (char *)rxvt_malloc (height * xi.bytes_per_line);
+
+  int rowstride = gdk_pixbuf_get_rowstride (pb);
+
+  assert (3 + (depth == 32) == gdk_pixbuf_get_n_channels (pb));
+  unsigned char *row = gdk_pixbuf_get_pixels (pb);
+  char *line = xi.data;
+
+  for (int y = 0; y < height; y++)
+    {
+      unsigned char *src = row;
+      uint32_t      *dst = (uint32_t *)line;
+
+      if (depth == 24)
+        for (int x = 0; x < width; x++)
+          {
+            uint8_t r = *src++;
+            uint8_t g = *src++;
+            uint8_t b = *src++;
+
+            uint32_t v = (r << 16) | (g << 8) | b;
+            
+            if (ecb_big_endian () ? !byte_order_mismatch : byte_order_mismatch)
+              v = ecb_bswap32 (v);
+
+            *dst++ = v;
+          }
+      else
+        for (int x = 0; x < width; x++)
+          {
+            uint32_t v = *(uint32_t *)src; src += 4;
+
+            if (ecb_big_endian ())
+              v = ecb_bswap32 (v);
+
+            v = ecb_rotl32 (v, 8); // abgr to bgra
+
+            if (!byte_order_mismatch)
+              v = ecb_bswap32 (v);
+
+            *dst++ = v;
+          }
+
+      row += rowstride;
+      line += xi.bytes_per_line;
+    }
+
+  rxvt_img *img = new rxvt_img (s, XRenderFindStandardFormat (dpy, depth == 24 ? PictStandardRGB24 : PictStandardARGB32), 0, 0, width, height);
+  img->alloc ();
+
+  GC gc = XCreateGC (dpy, img->pm, 0, 0);
+  XPutImage (dpy, img->pm, gc, &xi, 0, 0, 0, 0, width, height);
+  XFreeGC (dpy, gc);
+
+  free (xi.data);
+
+  return img;
 }
 
 rxvt_img *
@@ -26,36 +169,65 @@
   if (!pb)
     rxvt_fatal ("rxvt_img::new_from_file: %s\n", err->message);
 
-  rxvt_img *img = new rxvt_img (
-     s,
-     XRenderFindStandardFormat (s->display->dpy, gdk_pixbuf_get_has_alpha (pb) ? PictStandardARGB32 : PictStandardRGB24),
-     gdk_pixbuf_get_width (pb),
-     gdk_pixbuf_get_height (pb)
-  );
+  rxvt_img *img = new_from_pixbuf (s, pb);
 
-  img->render_pixbuf (pb, 0, 0, img->w, img->h, 0, 0);
+  g_object_unref (pb);
 
   return img;
 }
 
-rxvt_img::~rxvt_img ()
+void
+rxvt_img::destroy ()
 {
-  if (!shared)
+  if (--ref->cnt)
+    return;
+
+  if (pm && ref->ours)
     XFreePixmap (s->display->dpy, pm);
+
+  delete ref;
+}
+
+rxvt_img::~rxvt_img ()
+{
+  destroy ();
+}
+
+void
+rxvt_img::alloc ()
+{
+  pm = XCreatePixmap (s->display->dpy, s->display->root, w, h, format->depth);
+  ref = new pixref (w, h);
+}
+
+Picture
+rxvt_img::src_picture ()
+{
+  Display *dpy = s->display->dpy;
+
+  XRenderPictureAttributes pa;
+  pa.repeat = repeat;
+  Picture pic = XRenderCreatePicture (dpy, pm, format, CPRepeat, &pa);
+
+  return pic;
 }
 
 void
 rxvt_img::unshare ()
 {
-  if (!shared)
+  if (ref->cnt == 1 && ref->ours)
     return;
 
-  rxvt_img *img = clone ();
+  //TODO: maybe should reify instead
+  Pixmap pm2 = XCreatePixmap (s->display->dpy, s->display->root, ref->w, ref->h, format->depth);
+  GC gc = XCreateGC (s->display->dpy, pm, 0, 0);
+  XCopyArea (s->display->dpy, pm, pm2, gc, 0, 0, ref->w, ref->h, 0, 0);
+  XFreeGC (s->display->dpy, gc);
 
-  ::swap (pm    , img->pm);
-  ::swap (shared, img->shared);
+  destroy ();
 
-  delete img;
+  pm = pm2;
+  ref = new pixref (ref->w, ref->h);
 }
 
 void
@@ -89,24 +261,28 @@
     params[i+2] = XDoubleToFixed (kernel[i] / sum);
 }
 
-void
+rxvt_img *
 rxvt_img::blur (int rh, int rv)
 {
   if (!(s->display->flags & DISPLAY_HAS_RENDER_CONV))
-    return;
+    return clone ();
 
   Display *dpy = s->display->dpy;
   int size = max (rh, rv) * 2 + 1;
   double *kernel = (double *)malloc (size * sizeof (double));
   XFixed *params = (XFixed *)malloc ((size + 2) * sizeof (XFixed));
+  rxvt_img *img = new rxvt_img (s, format, x, y, w, h, repeat);
+  img->alloc ();
 
-  XRenderPictureAttributes pa;
+  Picture src = src_picture ();
 
+  XRenderPictureAttributes pa;
   pa.repeat = RepeatPad;
-  Picture src = XRenderCreatePicture (dpy, pm , format, CPRepeat, &pa);
-  Pixmap tmp = XCreatePixmap (dpy, pm, w, h, format->depth);
-  Picture dst = XRenderCreatePicture (dpy, tmp, format, CPRepeat, &pa);
-  XFreePixmap (dpy, tmp);
+  Picture dst = XRenderCreatePicture (dpy, img->pm, format, CPRepeat, &pa);
+
+  Pixmap tmp_pm = XCreatePixmap (dpy, pm, w, h, format->depth);
+  Picture tmp = XRenderCreatePicture (dpy, tmp_pm , format, CPRepeat, &pa);
+  XFreePixmap (dpy, tmp_pm);
 
   if (kernel && params)
     {
@@ -118,14 +294,12 @@
                         PictOpSrc,
                         src,
                         None,
-                        dst,
+                        tmp,
                         0, 0,
                         0, 0,
                         0, 0,
                         w, h);
 
-      ::swap (src, dst);
-
       size = rv * 2 + 1;
       get_gaussian_kernel (rv, size, kernel, params);
       ::swap (params[0], params[1]);
@@ -133,7 +307,7 @@
       XRenderSetPictureFilter (dpy, src, FilterConvolution, params, size+2);
       XRenderComposite (dpy,
                         PictOpSrc,
-                        src,
+                        tmp,
                         None,
                         dst,
                         0, 0,
@@ -146,6 +320,9 @@
   free (params);
   XRenderFreePicture (dpy, src);
   XRenderFreePicture (dpy, dst);
+  XRenderFreePicture (dpy, tmp);
+
+  return img;
 }
 
 static Picture
@@ -164,24 +341,27 @@
 }
 
 void
-rxvt_img::brightness (double r, double g, double b, double a)
+rxvt_img::brightness (unsigned short r, unsigned short g, unsigned short b, unsigned short a)
 {
   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   = float_to_component (r);
-  mask_c.green = float_to_component (g);
-  mask_c.blue  = float_to_component (b);
-  mask_c.alpha = float_to_component (a);
+  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);
 
   XRenderComposite (dpy, PictOpAdd, src, None, dst, 0, 0, 0, 0, 0, 0, w, h);
+
+  XRenderFreePicture (dpy, src);
+  XRenderFreePicture (dpy, dst);
 }
 
 void
-rxvt_img::contrast (double r, double g, double b, double a)
+rxvt_img::contrast (unsigned short r, unsigned short g, unsigned short b, unsigned short a)
 {
   if (!(s->display->flags & DISPLAY_HAS_RENDER_MUL))
     return;
@@ -191,156 +371,107 @@
   Picture dst = XRenderCreatePicture (dpy, pm, format, 0, 0);
 
   XRenderColor mask_c;
-  mask_c.red   = float_to_component (r);
-  mask_c.green = float_to_component (g);
-  mask_c.blue  = float_to_component (b);
-  mask_c.alpha = float_to_component (a);
+  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);
 
   XRenderComposite (dpy, PictOpMultiply, src, None, dst, 0, 0, 0, 0, 0, 0, w, h);
+
+  XRenderFreePicture (dpy, src);
+  XRenderFreePicture (dpy, dst);
 }
 
-bool
-rxvt_img::render_pixbuf (GdkPixbuf *pixbuf, int src_x, int src_y, int width, int height, int dst_x, int dst_y)
+rxvt_img *
+rxvt_img::clone ()
 {
-  bool argb = format->id == PictStandardARGB32;
+  return new rxvt_img (*this);
+}
 
-  Display *dpy = s->display->dpy;
+static XRenderPictFormat *
+find_alpha_format_for (Display *dpy, XRenderPictFormat *format)
+{
+  if (format->direct.alphaMask)
+    return format; // already has alpha
 
-  if (s->visual->c_class != TrueColor)
-    return false;
+  // try to find a suitable alpha format, one bit alpha is enough for our purposes
+  if (format->type == PictTypeDirect)
+    for (int n = 0; XRenderPictFormat *f = XRenderFindFormat (dpy, 0, 0, n); ++n)
+      if (f->direct.alphaMask
+          && f->type == PictTypeDirect
+          && ecb_popcount32 (f->direct.redMask  ) >= ecb_popcount32 (format->direct.redMask  )
+          && ecb_popcount32 (f->direct.greenMask) >= ecb_popcount32 (format->direct.greenMask)
+          && ecb_popcount32 (f->direct.blueMask ) >= ecb_popcount32 (format->direct.blueMask ))
+        return f;
 
-  uint32_t red_mask, green_mask, blue_mask, alpha_mask;
+  // should be a very good fallback
+  return XRenderFindStandardFormat (dpy, PictStandardARGB32);
+}
 
-  if (argb)
-    {
-      red_mask   = 0xff << 16;
-      green_mask = 0xff << 8;
-      blue_mask  = 0xff;
-      alpha_mask = 0xff << 24;
-    }
-  else
-    {
-      red_mask   = s->visual->red_mask;
-      green_mask = s->visual->green_mask;
-      blue_mask  = s->visual->blue_mask;
-      alpha_mask = (uint32_t)format->direct.alphaMask << format->direct.alpha;
-    }
+rxvt_img *
+rxvt_img::reify ()
+{
+  if (x == 0 && y == 0 && w == ref->w && h == ref->h)
+    return clone ();
 
-  int width_r = ecb_popcount32 (red_mask);
-  int width_g = ecb_popcount32 (green_mask);
-  int width_b = ecb_popcount32 (blue_mask);
-  int width_a = ecb_popcount32 (alpha_mask);
-
-  if (width_r > 8 || width_g > 8 || width_b > 8 || width_a > 8)
-    return false;
-
-  int sh_r = ecb_ctz32 (red_mask);
-  int sh_g = ecb_ctz32 (green_mask);
-  int sh_b = ecb_ctz32 (blue_mask);
-  int sh_a = ecb_ctz32 (alpha_mask);
-
-  if (width > 32767 || height > 32767)
-    return false;
-
-  XImage *ximage = XCreateImage (dpy, s->visual, argb ? 32 : format->depth, ZPixmap, 0, 0,
-                                 width, height, 32, 0);
-  if (!ximage)
-    return false;
+  Display *dpy = s->display->dpy;
 
-  if (height > INT_MAX / ximage->bytes_per_line
-      || !(ximage->data = (char *)malloc (height * ximage->bytes_per_line)))
+  bool alpha = !format->direct.alphaMask
+               && (x || y)
+               && repeat == RepeatNone;
+
+  rxvt_img *img = new rxvt_img (s, alpha ? find_alpha_format_for (dpy, format) : format, 0, 0, w, h, repeat);
+  img->alloc ();
+
+  Picture src = src_picture ();
+  Picture dst = XRenderCreatePicture (dpy, img->pm, img->format, 0, 0);
+  
+  if (alpha)
     {
-      XDestroyImage (ximage);
-      return false;
+      XRenderColor rc = { 0, 0, 0, 0 };
+      XRenderFillRectangle (dpy, PictOpSrc, dst, &rc, 0, 0, w, h);//TODO: split into four fillrectangles
+      XRenderComposite (dpy, PictOpSrc, src, None, dst, 0, 0, 0, 0, -x, -y, ref->w, ref->h);
     }
+  else
+    XRenderComposite (dpy, PictOpSrc, src, None, dst, x, y, 0, 0, 0, 0, w, h);
 
-  GC gc = XCreateGC (dpy, pm, 0, 0);
-
-  ximage->byte_order = ecb_big_endian () ? MSBFirst : LSBFirst;
+  XRenderFreePicture (dpy, src);
+  XRenderFreePicture (dpy, dst);
 
-  int rowstride = gdk_pixbuf_get_rowstride (pixbuf);
-  int channels = gdk_pixbuf_get_n_channels (pixbuf);
-  unsigned char *row = gdk_pixbuf_get_pixels (pixbuf) + src_y * rowstride + src_x * channels;
-  char *line = ximage->data;
+  return img;
+}
 
-  rgba c (0, 0, 0);
+rxvt_img *
+rxvt_img::sub_rect (int x, int y, int width, int height)
+{
+  rxvt_img *img = clone ();
 
-  if (channels == 4 && alpha_mask == 0)
-    {
-      //pix_colors[Color_bg].get (c);
-      //TODO
-      c.r = 0xffff; c.g = 0xc0c0; c.b = 0xcbcb;//D
-      c.r >>= 8;
-      c.g >>= 8;
-      c.b >>= 8;
-    }
+  img->x += x;
+  img->y += y;
 
-  for (int y = 0; y < height; y++)
+  if (w != width || h != height)
     {
-      for (int x = 0; x < width; x++)
-        {
-          unsigned char *pixel = row + x * channels;
-          uint32_t value;
-          unsigned char r, g, b, a;
-
-          if (channels == 4)
-            {
-              a = pixel[3];
-              r = (pixel[0] * a + c.r * (0xff - a)) / 0xff;
-              g = (pixel[1] * a + c.g * (0xff - a)) / 0xff;
-              b = (pixel[2] * a + c.b * (0xff - a)) / 0xff;
-            }
-          else
-            {
-              a = 0xff;
-              r = pixel[0];
-              g = pixel[1];
-              b = pixel[2];
-            }
-
-          value  = ((r >> (8 - width_r)) << sh_r)
-                 | ((g >> (8 - width_g)) << sh_g)
-                 | ((b >> (8 - width_b)) << sh_b)
-                 | ((a >> (8 - width_a)) << sh_a);
-
-          if (ximage->bits_per_pixel == 32)
-            ((uint32_t *)line)[x] = value;
-          else
-            XPutPixel (ximage, x, y, value);
-        }
+      img->w = width;
+      img->h = height;
 
-      row += rowstride;
-      line += ximage->bytes_per_line;
+      rxvt_img *img2 = img->reify ();
+      delete img;
+      img = img2;
     }
 
-  XPutImage (dpy, pm, gc, ximage, 0, 0, dst_x, dst_y, width, height);
-  XDestroyImage (ximage);
-  XFreeGC (dpy, gc);
-
-  return true;
-}
-
-rxvt_img *
-rxvt_img::clone ()
-{
-  GC gc = XCreateGC (s->display->dpy, pm, 0, 0);
-  Pixmap pm2 = XCreatePixmap (s->display->dpy, pm, w, h, format->depth);
-  XCopyArea (s->display->dpy, pm, pm2, gc, 0, 0, w, h, 0, 0);
-  XFreeGC (s->display->dpy, gc);
-  return new rxvt_img (s, format, w, h, pm2);
+  return img;
 }
 
 rxvt_img *
-rxvt_img::transform (int new_width, int new_height, int repeat, double matrix[9])
+rxvt_img::transform (int new_width, int new_height, double matrix[9])
 {
-  rxvt_img *img = new rxvt_img (s, format, new_width, new_height);
+  rxvt_img *img = new rxvt_img (s, format, 0, 0, new_width, new_height, repeat);
+  img->alloc ();
 
   Display *dpy = s->display->dpy;
-  XRenderPictureAttributes pa;
-  pa.repeat = repeat;
-  Picture src = XRenderCreatePicture (dpy,      pm,      format, CPRepeat, &pa);
-  Picture dst = XRenderCreatePicture (dpy, img->pm, img->format,        0,   0);
+  Picture src = src_picture ();
+  Picture dst = XRenderCreatePicture (dpy, img->pm, img->format, 0, 0);
 
   XTransform xfrm;
 
@@ -348,6 +479,11 @@
     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);
   XRenderComposite (dpy, PictOpSrc, src, None, dst, 0, 0, 0, 0, 0, 0, new_width, new_height);
@@ -361,17 +497,28 @@
 rxvt_img *
 rxvt_img::scale (int new_width, int new_height)
 {
+  if (w == new_width && h == new_height)
+    return clone ();
+
   double matrix[9] = {
     w  / (double)new_width, 0, 0,
     0, h / (double)new_height, 0,
     0,                      0, 1
   };
 
-  return transform (new_width, new_height, RepeatNormal, matrix);
+  int old_repeat_mode = repeat;
+  repeat = RepeatPad; // not right, but xrender can't proeprly scale it seems
+
+  rxvt_img *img = transform (new_width, new_height, matrix);
+
+  repeat = old_repeat_mode;
+  img->repeat = repeat;
+
+  return img;
 }
 
 rxvt_img *
-rxvt_img::rotate (int new_width, int new_height, int repeat, int x, int y, double phi)
+rxvt_img::rotate (int new_width, int new_height, int x, int y, double phi)
 {
   double s = sin (phi);
   double c = cos (phi);
@@ -382,19 +529,36 @@
     0,  0,                  1
   };
 
-  return transform (new_width, new_height, repeat, matrix);
+  return transform (new_width, new_height, matrix);
 }
 
 rxvt_img *
-rxvt_img::convert_to (XRenderPictFormat *new_format)
+rxvt_img::convert_format (XRenderPictFormat *new_format, const rxvt_color &bg)
 {
-  rxvt_img *img = new rxvt_img (s, new_format, w, h);
+  if (new_format == format)
+    return clone ();
+
+  rxvt_img *img = new rxvt_img (s, new_format, x, y, w, h, repeat);
+  img->alloc ();
 
   Display *dpy = s->display->dpy;
-  Picture src = XRenderCreatePicture (dpy,      pm,     format, 0, 0);
+  Picture src = src_picture ();
   Picture dst = XRenderCreatePicture (dpy, img->pm, new_format, 0, 0);
+  int op = PictOpSrc;
 
-  XRenderComposite (dpy, PictOpSrc, src, None, dst, 0, 0, 0, 0, 0, 0, w, h);
+  if (format->direct.alphaMask && !new_format->direct.alphaMask)
+    {
+      // does it have to be that complicated
+      rgba c;
+      bg.get (c);
+
+      XRenderColor rc = { c.r, c.g, c.b, 0xffff };
+      XRenderFillRectangle (dpy, PictOpSrc, dst, &rc, 0, 0, w, h);
+
+      op = PictOpOver;
+    }
+
+  XRenderComposite (dpy, op, src, None, dst, 0, 0, 0, 0, 0, 0, w, h);
 
   XRenderFreePicture (dpy, src);
   XRenderFreePicture (dpy, dst);
@@ -402,5 +566,31 @@
   return img;
 }
 
+rxvt_img *
+rxvt_img::blend (rxvt_img *img, double factor)
+{
+  rxvt_img *img2 = clone ();
+  Display *dpy = s->display->dpy;
+  Picture src = img->src_picture ();
+  Picture dst = XRenderCreatePicture (dpy, img2->pm, img2->format, 0, 0);
+  Picture mask = create_xrender_mask (dpy, img->pm, False);
+
+  XRenderColor mask_c;
+
+  mask_c.alpha = float_to_component (factor);
+  mask_c.red   =
+  mask_c.green =
+  mask_c.blue  = 0;
+  XRenderFillRectangle (dpy, PictOpSrc, mask, &mask_c, 0, 0, 1, 1);
+
+  XRenderComposite (dpy, PictOpOver, src, mask, dst, 0, 0, 0, 0, 0, 0, w, h);
+
+  XRenderFreePicture (dpy, src);
+  XRenderFreePicture (dpy, dst);
+  XRenderFreePicture (dpy, mask);
+
+  return img2;
+}
+
 #endif