Backed out changeset b049e0ae4d1d (bug 1039145)

gfx/layers/Layers.cpp

@@ -155,12 +155,6 @@ LayerManager::CreateAsynchronousImageContainer()
   return container.forget();
 }
 
-bool
-LayerManager::AreComponentAlphaLayersEnabled()
-{
-  return gfxPrefs::ComponentAlphaEnabled();
-}
-
 //--------------------------------------------------
 // Layer
 
@@ -1029,8 +1023,7 @@ ContainerLayer::DefaultComputeEffectiveTransforms(const Matrix4x4& aTransformToS
 void
 ContainerLayer::DefaultComputeSupportsComponentAlphaChildren(bool* aNeedsSurfaceCopy)
 {
-  if (!(GetContentFlags() & Layer::CONTENT_COMPONENT_ALPHA_DESCENDANT) ||
-      !Manager()->AreComponentAlphaLayersEnabled()) {
+  if (!(GetContentFlags() & Layer::CONTENT_COMPONENT_ALPHA_DESCENDANT)) {
     mSupportsComponentAlphaChildren = false;
     if (aNeedsSurfaceCopy) {
       *aNeedsSurfaceCopy = false;
@@ -1038,30 +1031,32 @@ ContainerLayer::DefaultComputeSupportsComponentAlphaChildren(bool* aNeedsSurface
     return;
   }
 
-  mSupportsComponentAlphaChildren = false;
+  bool supportsComponentAlphaChildren = false;
   bool needsSurfaceCopy = false;
   CompositionOp blendMode = GetEffectiveMixBlendMode();
   if (UseIntermediateSurface()) {
     if (GetEffectiveVisibleRegion().GetNumRects() == 1 &&
         (GetContentFlags() & Layer::CONTENT_OPAQUE))
     {
-      mSupportsComponentAlphaChildren = true;
+      supportsComponentAlphaChildren = true;
     } else {
       gfx::Matrix transform;
       if (HasOpaqueAncestorLayer(this) &&
           GetEffectiveTransform().Is2D(&transform) &&
           !gfx::ThebesMatrix(transform).HasNonIntegerTranslation() &&
           blendMode == gfx::CompositionOp::OP_OVER) {
-        mSupportsComponentAlphaChildren = true;
+        supportsComponentAlphaChildren = true;
         needsSurfaceCopy = true;
       }
     }
   } else if (blendMode == gfx::CompositionOp::OP_OVER) {
-    mSupportsComponentAlphaChildren =
+    supportsComponentAlphaChildren =
       (GetContentFlags() & Layer::CONTENT_OPAQUE) ||
       (GetParent() && GetParent()->SupportsComponentAlphaChildren());
   }
 
+  mSupportsComponentAlphaChildren = supportsComponentAlphaChildren &&
+                                    gfxPrefs::ComponentAlphaEnabled();
   if (aNeedsSurfaceCopy) {
     *aNeedsSurfaceCopy = mSupportsComponentAlphaChildren && needsSurfaceCopy;
   }

gfx/layers/Layers.h

@@ -308,20 +308,12 @@ public:
 
   bool IsSnappingEffectiveTransforms() { return mSnapEffectiveTransforms; }
 
-
-  /**
-   * Returns true if the layer manager can't render component alpha
-   * layers, and layer building should do it's best to avoid
-   * creating them.
-   */
-  virtual bool ShouldAvoidComponentAlphaLayers() { return false; }
-
   /**
    * Returns true if this LayerManager can properly support layers with
-   * SurfaceMode::SURFACE_COMPONENT_ALPHA. LayerManagers that can't will use
-   * transparent surfaces (and lose subpixel-AA for text).
+   * SurfaceMode::SURFACE_COMPONENT_ALPHA. This can include disabling component
+   * alpha if required.
    */
-  virtual bool AreComponentAlphaLayersEnabled();
+  virtual bool AreComponentAlphaLayersEnabled() { return true; }
 
   /**
    * CONSTRUCTION PHASE ONLY

gfx/layers/basic/BasicLayers.h

@@ -105,7 +105,7 @@ public:
   virtual void EndTransaction(DrawThebesLayerCallback aCallback,
                               void* aCallbackData,
                               EndTransactionFlags aFlags = END_DEFAULT);
-  virtual bool ShouldAvoidComponentAlphaLayers() { return IsWidgetLayerManager(); }
+  virtual bool AreComponentAlphaLayersEnabled() { return !IsWidgetLayerManager(); }
 
   void AbortTransaction();
 

gfx/layers/client/ClientLayerManager.h

@@ -146,7 +146,7 @@ public:
   CompositorChild* GetCompositorChild();
 
   // Disable component alpha layers with the software compositor.
-  virtual bool ShouldAvoidComponentAlphaLayers() { return !IsCompositingCheap(); }
+  virtual bool AreComponentAlphaLayersEnabled() MOZ_OVERRIDE { return IsCompositingCheap(); }
 
   /**
    * Called for each iteration of a progressive tile update. Updates

layout/base/FrameLayerBuilder.cpp

@@ -3419,7 +3419,7 @@ FrameLayerBuilder::BuildContainerLayerFor(nsDisplayListBuilder* aBuilder,
   int32_t appUnitsPerDevPixel;
   uint32_t stateFlags = 0;
   if ((aContainerFrame->GetStateBits() & NS_FRAME_NO_COMPONENT_ALPHA) &&
-      mRetainingManager && mRetainingManager->ShouldAvoidComponentAlphaLayers()) {
+      mRetainingManager && !mRetainingManager->AreComponentAlphaLayersEnabled()) {
     stateFlags = ContainerState::NO_COMPONENT_ALPHA;
   }
   uint32_t flags;
@@ -3441,7 +3441,7 @@ FrameLayerBuilder::BuildContainerLayerFor(nsDisplayListBuilder* aBuilder,
 
     if (hasComponentAlphaChildren &&
         mRetainingManager &&
-        mRetainingManager->ShouldAvoidComponentAlphaLayers() &&
+        !mRetainingManager->AreComponentAlphaLayersEnabled() &&
         containerLayer->HasMultipleChildren() &&
         !stateFlags) {
       // Since we don't want any component alpha layers on BasicLayers, we repeat