Bug 950312 - Part 4: Create active layers for nsDisplayMixBlendMode and nsDisplayBlendContainer if the layer manager supports all contained blend mode. r=roc

layout/base/nsDisplayList.cpp

@@ -518,7 +518,6 @@ nsDisplayListBuilder::nsDisplayListBuilder(nsIFrame* aReferenceFrame,
       mIsPaintingToWindow(false),
       mIsCompositingCheap(false),
       mContainsPluginItem(false),
-      mContainsBlendMode(false),
       mAncestorHasTouchEventHandler(false),
       mHaveScrollableDisplayPort(false)
 {
@@ -553,6 +552,13 @@ static void MarkFrameForDisplay(nsIFrame* aFrame, nsIFrame* aStopAtFrame) {
   }
 }
 
+void nsDisplayListBuilder::SetContainsBlendMode(uint8_t aBlendMode)
+{
+  MOZ_ASSERT(aBlendMode != NS_STYLE_BLEND_NORMAL);
+  gfxContext::GraphicsOperator op = nsCSSRendering::GetGFXBlendMode(aBlendMode);
+  mContainedBlendModes += gfx::CompositionOpForOp(op);
+}
+
 void nsDisplayListBuilder::MarkOutOfFlowFrameForDisplay(nsIFrame* aDirtyFrame,
                                                         nsIFrame* aFrame,
                                                         const nsRect& aDirtyRect)
@@ -3384,6 +3390,18 @@ nsRegion nsDisplayMixBlendMode::GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
   return nsRegion();
 }
 
+LayerState
+nsDisplayMixBlendMode::GetLayerState(nsDisplayListBuilder* aBuilder,
+                                     LayerManager* aManager,
+                                     const ContainerLayerParameters& aParameters)
+{
+  gfxContext::GraphicsOperator op = nsCSSRendering::GetGFXBlendMode(mFrame->StyleDisplay()->mMixBlendMode);
+  if (aManager->SupportsMixBlendMode(gfx::CompositionOpForOp(op))) {
+    return LAYER_ACTIVE;
+  }
+  return LAYER_INACTIVE;
+}
+
 // nsDisplayMixBlendMode uses layers for rendering
 already_AddRefed<Layer>
 nsDisplayMixBlendMode::BuildLayer(nsDisplayListBuilder* aBuilder,
@@ -3437,8 +3455,19 @@ bool nsDisplayMixBlendMode::TryMerge(nsDisplayListBuilder* aBuilder, nsDisplayIt
 
 nsDisplayBlendContainer::nsDisplayBlendContainer(nsDisplayListBuilder* aBuilder,
                                                  nsIFrame* aFrame, nsDisplayList* aList,
-                                                 uint32_t aFlags)
+                                                 BlendModeSet& aContainedBlendModes)
-    : nsDisplayWrapList(aBuilder, aFrame, aList) {
+    : nsDisplayWrapList(aBuilder, aFrame, aList)
+    , mContainedBlendModes(aContainedBlendModes)
+    , mCanBeActive(true)
+{
+  MOZ_COUNT_CTOR(nsDisplayBlendContainer);
+}
+
+nsDisplayBlendContainer::nsDisplayBlendContainer(nsDisplayListBuilder* aBuilder,
+                                                 nsIFrame* aFrame, nsDisplayList* aList)
+    : nsDisplayWrapList(aBuilder, aFrame, aList)
+    , mCanBeActive(false)
+{
   MOZ_COUNT_CTOR(nsDisplayBlendContainer);
 }
 

layout/base/nsDisplayList.h

@@ -45,6 +45,10 @@ class ImageContainer;
 } //namepsace
 } //namepsace
 
+// A set of blend modes, that never includes OP_OVER (since it's
+// considered the default, rather than a specific blend mode).
+typedef mozilla::EnumSet<mozilla::gfx::CompositionOp> BlendModeSet;
+
 /*
  * An nsIFrame can have many different visual parts. For example an image frame
  * can have a background, border, and outline, the image itself, and a
@@ -688,8 +692,14 @@ public:
    * has a blend mode attached. We do this so we can insert a 
    * nsDisplayBlendContainer in the parent stacking context.
    */
-  void SetContainsBlendMode(bool aContainsBlendMode) { mContainsBlendMode = aContainsBlendMode; }
+  void SetContainsBlendMode(uint8_t aBlendMode);
-  bool ContainsBlendMode() const { return mContainsBlendMode; }
+  void SetContainsBlendModes(const BlendModeSet& aModes) {
+    mContainedBlendModes = aModes;
+  }
+  bool ContainsBlendMode() const { return !mContainedBlendModes.isEmpty(); }
+  BlendModeSet& ContainedBlendModes() {
+    return mContainedBlendModes;
+  }
 
   DisplayListClipState& ClipState() { return mClipState; }
 
@@ -731,6 +741,7 @@ private:
   nsTArray<DisplayItemClip*>     mDisplayItemClipsToDestroy;
   Mode                           mMode;
   ViewID                         mCurrentScrollParentId;
+  BlendModeSet                   mContainedBlendModes;
   bool                           mBuildCaret;
   bool                           mIgnoreSuppression;
   bool                           mHadToIgnoreSuppression;
@@ -749,7 +760,6 @@ private:
   bool                           mIsPaintingToWindow;
   bool                           mIsCompositingCheap;
   bool                           mContainsPluginItem;
-  bool                           mContainsBlendMode;
   bool                           mAncestorHasTouchEventHandler;
   // True when the first async-scrollable scroll frame for which we build a
   // display list has a display port. An async-scrollable scroll frame is one
@@ -2730,10 +2740,7 @@ public:
   }
   virtual LayerState GetLayerState(nsDisplayListBuilder* aBuilder,
                                    LayerManager* aManager,
-                                   const ContainerLayerParameters& aParameters) MOZ_OVERRIDE
+                                   const ContainerLayerParameters& aParameters) MOZ_OVERRIDE;
-  {
-    return mozilla::LAYER_INACTIVE;
-  }
   virtual bool ComputeVisibility(nsDisplayListBuilder* aBuilder,
                                  nsRegion* aVisibleRegion,
                                  const nsRect& aAllowVisibleRegionExpansion) MOZ_OVERRIDE;
@@ -2744,7 +2751,10 @@ public:
 class nsDisplayBlendContainer : public nsDisplayWrapList {
 public:
     nsDisplayBlendContainer(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
-                          nsDisplayList* aList, uint32_t aFlags = 0);
+                            nsDisplayList* aList,
+                            BlendModeSet& aContainedBlendModes);
+    nsDisplayBlendContainer(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
+                            nsDisplayList* aList);
 #ifdef NS_BUILD_REFCNT_LOGGING
     virtual ~nsDisplayBlendContainer();
 #endif
@@ -2756,10 +2766,20 @@ public:
                                      LayerManager* aManager,
                                      const ContainerLayerParameters& aParameters) MOZ_OVERRIDE
     {
+      if (mCanBeActive && aManager->SupportsMixBlendModes(mContainedBlendModes)) {
+        return mozilla::LAYER_ACTIVE;
+      }
       return mozilla::LAYER_INACTIVE;
     }
     virtual bool TryMerge(nsDisplayListBuilder* aBuilder, nsDisplayItem* aItem) MOZ_OVERRIDE;
     NS_DISPLAY_DECL_NAME("BlendContainer", TYPE_BLEND_CONTAINER)
+
+private:
+    // The set of all blend modes used by nsDisplayMixBlendMode descendents of this container.
+    BlendModeSet mContainedBlendModes;
+    // If this is true, then we should make the layer active if all contained blend
+    // modes can be supported by the current layer manager.
+    bool mCanBeActive;
 };
 
 /**

layout/generic/nsFrame.cpp

@@ -1868,15 +1868,15 @@ WrapPreserve3DList(nsIFrame* aFrame, nsDisplayListBuilder* aBuilder, nsDisplayLi
 class AutoSaveRestoreBlendMode
 {
   nsDisplayListBuilder& mBuilder;
-  bool                  AutoResetContainsBlendMode;
+  EnumSet<gfx::CompositionOp> mSavedBlendModes;
 public:
   AutoSaveRestoreBlendMode(nsDisplayListBuilder& aBuilder)
-    : mBuilder(aBuilder),
+    : mBuilder(aBuilder)
-      AutoResetContainsBlendMode(aBuilder.ContainsBlendMode()) {
+    , mSavedBlendModes(aBuilder.ContainedBlendModes())
-  }
+  { }
 
   ~AutoSaveRestoreBlendMode() {
-    mBuilder.SetContainsBlendMode(AutoResetContainsBlendMode);
+    mBuilder.SetContainsBlendModes(mSavedBlendModes);
   }
 };
 
@@ -1929,7 +1929,7 @@ nsIFrame::BuildDisplayListForStackingContext(nsDisplayListBuilder* aBuilder,
   // a nsDisplayBlendContainer. Set the blend mode back when the routine exits
   // so we keep track if the parent stacking context needs a container too.
   AutoSaveRestoreBlendMode autoRestoreBlendMode(*aBuilder);
-  aBuilder->SetContainsBlendMode(false);
+  aBuilder->SetContainsBlendModes(BlendModeSet());
  
   if (isTransformed) {
     const nsRect overflow = GetVisualOverflowRectRelativeToSelf();
@@ -2129,7 +2129,7 @@ nsIFrame::BuildDisplayListForStackingContext(nsDisplayListBuilder* aBuilder,
 
   if (aBuilder->ContainsBlendMode()) {
       resultList.AppendNewToTop(
-        new (aBuilder) nsDisplayBlendContainer(aBuilder, this, &resultList));
+        new (aBuilder) nsDisplayBlendContainer(aBuilder, this, &resultList, aBuilder->ContainedBlendModes()));
   }
 
   /* If there's blending, wrap up the list in a blend-mode item. Note
@@ -2343,7 +2343,7 @@ nsIFrame::BuildDisplayListForChild(nsDisplayListBuilder*   aBuilder,
   nsDisplayList extraPositionedDescendants;
   if (isStackingContext) {
     if (disp->mMixBlendMode != NS_STYLE_BLEND_NORMAL) {
-      aBuilder->SetContainsBlendMode(true);
+      aBuilder->SetContainsBlendMode(disp->mMixBlendMode);
     }
     // True stacking context.
     // For stacking contexts, BuildDisplayListForStackingContext handles

mfbt/EnumSet.h

@@ -162,6 +162,10 @@ class EnumSet
       return count;
     }
 
+    bool isEmpty() const {
+      return mBitField == 0;
+    }
+
     uint32_t serialize() const {
       return mBitField;
     }