From ae1f55d9ad84e6e86b13cbac8433f4cf838e59af Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Mon, 22 Apr 2013 14:40:52 +1200
Subject: [PATCH] Bug 809273 - Make mUseIntermediateSurface and
 mSupportsComponentAlpha on BasicShadowableContainerLayers match the
 compositor. r=roc

---
 gfx/layers/basic/BasicContainerLayer.cpp |  9 +++++++
 gfx/layers/basic/BasicContainerLayer.h   |  2 ++
 gfx/layers/basic/BasicLayerManager.cpp   | 32 ++++++++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/gfx/layers/basic/BasicContainerLayer.cpp b/gfx/layers/basic/BasicContainerLayer.cpp
index ce4a187e6c6..ef609149b4e 100644
--- a/gfx/layers/basic/BasicContainerLayer.cpp
+++ b/gfx/layers/basic/BasicContainerLayer.cpp
@@ -87,6 +87,15 @@ public:
     BasicShadowableLayer::Disconnect();
   }
 
+  virtual void ComputeEffectiveTransforms(const gfx3DMatrix& aTransformToSurface) MOZ_OVERRIDE
+  {
+    if (HasShadow()) {
+      DefaultComputeEffectiveTransforms(aTransformToSurface);
+    } else {
+      BasicContainerLayer::ComputeEffectiveTransforms(aTransformToSurface);
+    }
+  }
+
 private:
   BasicShadowLayerManager* ShadowManager()
   {
diff --git a/gfx/layers/basic/BasicContainerLayer.h b/gfx/layers/basic/BasicContainerLayer.h
index e7e9a30e32d..de52a5846ab 100644
--- a/gfx/layers/basic/BasicContainerLayer.h
+++ b/gfx/layers/basic/BasicContainerLayer.h
@@ -234,6 +234,8 @@ public:
 
   void ForceIntermediateSurface() { mUseIntermediateSurface = true; }
 
+  void SetSupportsComponentAlphaChildren(bool aSupports) { mSupportsComponentAlphaChildren = aSupports; }
+
 protected:
   BasicLayerManager* BasicManager()
   {
diff --git a/gfx/layers/basic/BasicLayerManager.cpp b/gfx/layers/basic/BasicLayerManager.cpp
index 23f38111f3a..c4ada48eb5a 100644
--- a/gfx/layers/basic/BasicLayerManager.cpp
+++ b/gfx/layers/basic/BasicLayerManager.cpp
@@ -873,6 +873,16 @@ BasicLayerManager::FlushGroup(PaintLayerContext& aPaintContext, bool aNeedsClipT
   }
 }
 
+static bool
+HasOpaqueAncestorLayer(Layer* aLayer)
+{
+  for (Layer* l = aLayer->GetParent(); l; l = l->GetParent()) {
+    if (l->GetContentFlags() & Layer::CONTENT_OPAQUE)
+      return true;
+    }
+ return false;
+}
+
 void
 BasicLayerManager::PaintLayer(gfxContext* aTarget,
                               Layer* aLayer,
@@ -907,6 +917,28 @@ BasicLayerManager::PaintLayer(gfxContext* aTarget,
                container->UseIntermediateSurface(),
                "ContainerLayer with mask layer should force UseIntermediateSurface");
 
+  // If we're a shadowable ContainerLayer, then setup mSupportsComponentAlphaChildren
+  // in the same way that ContainerLayerComposite will do. Otherwise leave it set to
+  // true.
+  ShadowableLayer* shadow = aLayer->AsShadowableLayer();
+  if (aLayer->GetFirstChild() && shadow && shadow->HasShadow()) {
+    if (needsGroup) {
+      if (container->GetEffectiveVisibleRegion().GetNumRects() != 1 ||
+          !(container->GetContentFlags() & Layer::CONTENT_OPAQUE))
+      {
+        const gfx3DMatrix& transform3D = container->GetEffectiveTransform();
+        gfxMatrix transform;
+        if (HasOpaqueAncestorLayer(container) &&
+            transform3D.Is2D(&transform) && !transform.HasNonIntegerTranslation()) {
+          container->SetSupportsComponentAlphaChildren(gfxPlatform::GetPlatform()->UsesSubpixelAATextRendering());
+        }
+      }
+    } else {
+      container->SetSupportsComponentAlphaChildren((container->GetContentFlags() & Layer::CONTENT_OPAQUE) ||
+        (container->GetParent() && container->GetParent()->SupportsComponentAlphaChildren()));
+    }
+  }
+
   gfxContextAutoSaveRestore contextSR;
   gfxMatrix transform;
   // Will return an identity matrix for 3d transforms, and is handled separately below.