Bug 807408 - Cache the temporary surface used when drawing ThebesLayers with BasicLayers. r=jrmuizel

gfx/layers/basic/BasicLayerManager.cpp

@@ -537,9 +537,13 @@ BasicLayerManager::EndTransactionInternal(DrawThebesLayerCallback aCallback,
   mTransactionIncomplete = false;
 
   if (aFlags & END_NO_COMPOSITE) {
-    // TODO: We should really just set mTarget to null and make sure we can handle that further down the call chain
-    nsRefPtr<gfxASurface> surf = gfxPlatform::GetPlatform()->CreateOffscreenSurface(gfxIntSize(1, 1), gfxASurface::CONTENT_COLOR);
-    mTarget = new gfxContext(surf);
+    if (!mDummyTarget) {
+      // TODO: We should really just set mTarget to null and make sure we can handle that further down the call chain
+      // Creating this temporary surface can be expensive on some platforms (d2d in particular), so cache it between paints.
+      nsRefPtr<gfxASurface> surf = gfxPlatform::GetPlatform()->CreateOffscreenSurface(gfxIntSize(1, 1), gfxASurface::CONTENT_COLOR);
+      mDummyTarget = new gfxContext(surf);
+    }
+    mTarget = mDummyTarget;
   }
 
   if (mTarget && mRoot && !(aFlags & END_NO_IMMEDIATE_REDRAW)) {