diff -r 000000000000 -r 6474c204b198 gfx/layers/ImageLayers.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/layers/ImageLayers.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,56 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ImageLayers.h"
+#include "ImageContainer.h"             // for ImageContainer
+#include "gfxRect.h"                    // for gfxRect
+#include "nsDebug.h"                    // for NS_ASSERTION
+#include "nsISupportsImpl.h"            // for ImageContainer::Release, etc
+#include "gfx2DGlue.h"
+
+namespace mozilla {
+namespace layers {
+
+ImageLayer::ImageLayer(LayerManager* aManager, void* aImplData)
+: Layer(aManager, aImplData), mFilter(GraphicsFilter::FILTER_GOOD)
+, mScaleMode(ScaleMode::SCALE_NONE), mDisallowBigImage(false)
+{}
+
+ImageLayer::~ImageLayer()
+{}
+
+void ImageLayer::SetContainer(ImageContainer* aContainer) 
+{
+  mContainer = aContainer;
+}
+
+void ImageLayer::ComputeEffectiveTransforms(const gfx::Matrix4x4& aTransformToSurface)
+{
+  gfx::Matrix4x4 local = GetLocalTransform();
+
+  // Snap image edges to pixel boundaries
+  gfxRect sourceRect(0, 0, 0, 0);
+  if (mContainer) {
+    sourceRect.SizeTo(gfx::ThebesIntSize(mContainer->GetCurrentSize()));
+    if (mScaleMode != ScaleMode::SCALE_NONE &&
+        sourceRect.width != 0.0 && sourceRect.height != 0.0) {
+      NS_ASSERTION(mScaleMode == ScaleMode::STRETCH,
+                   "No other scalemodes than stretch and none supported yet.");
+      local.Scale(mScaleToSize.width / sourceRect.width,
+                  mScaleToSize.height / sourceRect.height, 1.0);
+    }
+  }
+  // Snap our local transform first, and snap the inherited transform as well.
+  // This makes our snapping equivalent to what would happen if our content
+  // was drawn into a ThebesLayer (gfxContext would snap using the local
+  // transform, then we'd snap again when compositing the ThebesLayer).
+  mEffectiveTransform =
+      SnapTransform(local, sourceRect, nullptr) *
+      SnapTransformTranslation(aTransformToSurface, nullptr);
+  ComputeEffectiveTransformForMaskLayer(aTransformToSurface);
+}
+
+}
+}