Bug 1372912 - Extract a PushLayerClip helper method. r=jrmuizel

No functional changes. We'll want to reuse this code in a future patch.

MozReview-Commit-ID: LEuP38yXBHI

--HG--
extra : rebase_source : 11faa0123e987c255dd7495e4b704346ab2b714d

gfx/layers/wr/ScrollingLayersHelper.cpp

@@ -59,19 +59,8 @@ ScrollingLayersHelper::ScrollingLayersHelper(WebRenderLayer* aLayer,
   // on that layer. That is, the clip scrolls along with the content in
   // child layers. So we need to apply this after pushing all the scroll layers,
   // which we do above.
-  if (Maybe<LayerClip> scrolledClip = layer->GetScrolledClip()) {
-    LayerRect clipRect = IntRectToRect(ViewAs<LayerPixel>(
-        scrolledClip->GetClipRect(),
-        PixelCastJustification::MovingDownToChildren));
-    Maybe<WrImageMask> mask;
-    if (Maybe<size_t> maskLayerIndex = scrolledClip->GetMaskLayerIndex()) {
-      Layer* maskLayer = layer->GetAncestorMaskLayerAt(maskLayerIndex.value());
-      WebRenderLayer* maskWrLayer = WebRenderLayer::ToWebRenderLayer(maskLayer);
-      // TODO: check this transform is correct in all cases
-      mask = maskWrLayer->RenderMaskLayer(aStackingContext, maskLayer->GetTransform());
-    }
-    mBuilder->PushClip(aStackingContext.ToRelativeWrRect(clipRect),
-        mask.ptrOr(nullptr));
+  if (const Maybe<LayerClip>& scrolledClip = layer->GetScrolledClip()) {
+    PushLayerClip(scrolledClip.ref(), aStackingContext);
   }
 
   // If the layer is marked as fixed-position, it is fixed relative to something
@@ -114,6 +103,22 @@ ScrollingLayersHelper::PushLayerLocalClip(const StackingContextHelper& aStacking
   }
 }
 
+void
+ScrollingLayersHelper::PushLayerClip(const LayerClip& aClip,
+                                     const StackingContextHelper& aSc)
+{
+  LayerRect clipRect = IntRectToRect(ViewAs<LayerPixel>(aClip.GetClipRect(),
+        PixelCastJustification::MovingDownToChildren));
+  Maybe<WrImageMask> mask;
+  if (Maybe<size_t> maskLayerIndex = aClip.GetMaskLayerIndex()) {
+    Layer* maskLayer = mLayer->GetLayer()->GetAncestorMaskLayerAt(maskLayerIndex.value());
+    WebRenderLayer* maskWrLayer = WebRenderLayer::ToWebRenderLayer(maskLayer);
+    // TODO: check this transform is correct in all cases
+    mask = maskWrLayer->RenderMaskLayer(aSc, maskLayer->GetTransform());
+  }
+  mBuilder->PushClip(aSc.ToRelativeWrRect(clipRect), mask.ptrOr(nullptr));
+}
+
 ScrollingLayersHelper::~ScrollingLayersHelper()
 {
   Layer* layer = mLayer->GetLayer();

gfx/layers/wr/ScrollingLayersHelper.h

@@ -16,6 +16,7 @@ class DisplayListBuilder;
 
 namespace layers {
 
+struct LayerClip;
 class StackingContextHelper;
 class WebRenderLayer;
 
@@ -29,6 +30,8 @@ public:
 
 private:
   void PushLayerLocalClip(const StackingContextHelper& aStackingContext);
+  void PushLayerClip(const LayerClip& aClip,
+                     const StackingContextHelper& aSc);
 
   WebRenderLayer* mLayer;
   wr::DisplayListBuilder* mBuilder;