#961: fix transparency with pixbuf backing:

* partial revert of r9977: use pixbuf to honour alpha, draw_rgb_32_image otherwise
* skip unpremultiply step if there is no alpha

git-svn-id: https://xpra.org/svn/Xpra/trunk@10419 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/client/gtk2/pixmap_backing.py

@@ -100,9 +100,22 @@ def _do_paint_rgb24(self, img_data, x, y, width, height, rowstride, options):
         return True
 
     def _do_paint_rgb32(self, img_data, x, y, width, height, rowstride, options):
-        img_data = memoryview_to_bytes(self.unpremultiply(img_data))
+        has_alpha = options.boolget("has_alpha", False) or options.get("rgb_format", "").find("A")>=0
+        if has_alpha:
+            img_data = self.unpremultiply(img_data)
+        img_data = memoryview_to_bytes(img_data)
         if INDIRECT_BGR:
             img_data, rowstride = self.bgr_to_rgb(img_data, width, height, rowstride, options.strget("rgb_format", ""), "RGBA")
-        gc = self._backing.new_gc()
-        self._backing.draw_rgb_32_image(gc, x, y, width, height, gdk.RGB_DITHER_NONE, img_data, rowstride)
+        if has_alpha:
+            #draw_rgb_32_image does not honour alpha, we have to use pixbuf:
+            pixbuf = gdk.pixbuf_new_from_data(img_data, gdk.COLORSPACE_RGB, True, 8, width, height, rowstride)
+            cr = self._backing.cairo_create()
+            cr.rectangle(x, y, width, height)
+            cr.set_source_pixbuf(pixbuf, x, y)
+            cr.set_operator(cairo.OPERATOR_SOURCE)
+            cr.paint()
+        else:
+            #no alpha is easier:
+            gc = self._backing.new_gc()
+            self._backing.draw_rgb_32_image(gc, x, y, width, height, gdk.RGB_DITHER_NONE, img_data, rowstride)
         return True