fix for animations on linux r=saari sr=waterson bug 73342

gfx/src/gtk/nsImageGTK.cpp

@@ -1546,7 +1546,8 @@ nsImageGTK::SetDecodedRect(PRInt32 x1, PRInt32 y1, PRInt32 x2, PRInt32 y2 )
 }
 
 #ifdef USE_IMG2
-NS_IMETHODIMP nsImageGTK::DrawToImage(nsIImage* aDstImage, nscoord aDX, nscoord aDY,
+NS_IMETHODIMP nsImageGTK::DrawToImage(nsIImage* aDstImage,
+                                      nscoord aDX, nscoord aDY,
                                       nscoord aDWidth, nscoord aDHeight)
 {
   nsImageGTK *dest = NS_STATIC_CAST(nsImageGTK *, aDstImage);
@@ -1554,20 +1555,30 @@ NS_IMETHODIMP nsImageGTK::DrawToImage(nsIImage* aDstImage, nscoord aDX, nscoord
   if (!dest)
     return NS_ERROR_FAILURE;
   
-  if (!dest->mImagePixmap)
+  if (!dest->mImagePixmap) {
+    dest->CreateOffscreenPixmap(dest->mWidth, dest->mHeight);
+  }
+  
+  if (!dest->mImagePixmap) {
     return NS_ERROR_FAILURE;
+  }
 
   if (!mImagePixmap)
     return NS_ERROR_FAILURE;
 
-  // XXX copy the mask too :-)
-
   GdkGC *gc = gdk_gc_new(dest->mImagePixmap);
 
+  if (mAlphaDepth == 1)
+    CreateAlphaBitmap(mWidth, mHeight);
+  
+  if (mAlphaPixmap) {
+    SetupGCForAlpha(gc, 0, 0);
+  }
+
   gdk_window_copy_area(dest->mImagePixmap, gc,
                        aDX, aDY,
                        mImagePixmap,
-                       0, 0, aDWidth, aDHeight);
+                       0, 0, mWidth, mHeight);
 
   gdk_gc_unref(gc);