[gtk+/broadway: 243/246] broadway: Fix flicker when resizing windows

[Alexander Larsson <alexl src gnome org>]

commit 2635a27814410e8e0fe5c15f1171474e81430ec7
Author: Alexander Larsson <alexl redhat com>
Date:   Tue Mar 15 10:18:07 2011 +0100

    broadway: Fix flicker when resizing windows
    
    Resizing a canvas causes a clear, so we have to save the previous
    content and restore to avoid flickering.

 gdk/broadway/broadway.js |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)
---
diff --git a/gdk/broadway/broadway.js b/gdk/broadway/broadway.js
index 89242e3..286f0de 100644
--- a/gdk/broadway/broadway.js
+++ b/gdk/broadway/broadway.js
@@ -276,10 +276,26 @@ function handleCommands(cmd_obj)
         i = i + 3;
         var h = base64_16(cmd, i);
         i = i + 3;
-	flushSurface(surfaces[id]);
-	surfaces[id].canvas.width = w;
-	surfaces[id].canvas.height = h;
-        break;
+	var surface = surfaces[id];
+
+	/* Flush any outstanding draw ops before changing size */
+	flushSurface(surface);
+
+	/* Canvas resize clears the data, so we need to save it first */
+	var tmpCanvas = document.createElement("canvas");
+	tmpCanvas.width = surface.canvas.width;
+	tmpCanvas.height = surface.canvas.height;
+	var tmpContext = tmpCanvas.getContext("2d");
+	tmpContext.globalCompositeOperation = "copy";
+	tmpContext.drawImage(surface.canvas, 0, 0, tmpCanvas.width, tmpCanvas.height);
+
+	surface.canvas.width = w;
+	surface.canvas.height = h;
+
+	surface.globalCompositeOperation = "copy";
+	surface.drawImage(tmpCanvas, 0, 0, tmpCanvas.width, tmpCanvas.height);
+
+	break;
 
       /* put image data surface */
       case 'i':