Bug 1042104. Part 1: Cache prerender flag in nsDisplayTransform. r=tn

--HG--
extra : rebase_source : 79f39bb1b0d29cc28b4d492fbf6a497f99ec9dac

layout/base/FrameLayerBuilder.cpp

@@ -2861,9 +2861,7 @@ ContainerState::ProcessDisplayItems(nsDisplayList* aList,
         // that the transform item can potentially move under into a layer
         // above this item.
         if (itemType == nsDisplayItem::TYPE_TRANSFORM &&
-            nsDisplayTransform::ShouldPrerenderTransformedContent(mBuilder,
+            static_cast<nsDisplayTransform*>(item)->ShouldPrerender()) {
-                                                                  item->Frame(),
-                                                                  false)) {
           if (!itemClip.HasClip()) {
             // The transform item can move anywhere, treat all other content
             // as being above this item.

layout/base/nsDisplayList.cpp

@@ -4326,7 +4326,7 @@ nsDisplayTransform::nsDisplayTransform(nsDisplayListBuilder* aBuilder,
   MOZ_COUNT_CTOR(nsDisplayTransform);
   NS_ABORT_IF_FALSE(aFrame, "Must have a frame!");
   NS_ABORT_IF_FALSE(!aFrame->IsTransformed(), "Can't specify a transform getter for a transformed frame!");
-  mStoredList.SetClip(aBuilder, DisplayItemClip::NoClip());
+  Init(aBuilder);
 }
 
 void
@@ -4338,6 +4338,13 @@ nsDisplayTransform::SetReferenceFrameToAncestor(nsDisplayListBuilder* aBuilder)
   mVisibleRect = aBuilder->GetDirtyRect() + mToReferenceFrame;
 }
 
+void
+nsDisplayTransform::Init(nsDisplayListBuilder* aBuilder)
+{
+  mStoredList.SetClip(aBuilder, DisplayItemClip::NoClip());
+  mPrerender = ShouldPrerenderTransformedContent(aBuilder, mFrame);
+}
+
 nsDisplayTransform::nsDisplayTransform(nsDisplayListBuilder* aBuilder,
                                        nsIFrame *aFrame, nsDisplayList *aList,
                                        const nsRect& aChildrenVisibleRect,
@@ -4351,7 +4358,7 @@ nsDisplayTransform::nsDisplayTransform(nsDisplayListBuilder* aBuilder,
   MOZ_COUNT_CTOR(nsDisplayTransform);
   NS_ABORT_IF_FALSE(aFrame, "Must have a frame!");
   SetReferenceFrameToAncestor(aBuilder);
-  mStoredList.SetClip(aBuilder, DisplayItemClip::NoClip());
+  Init(aBuilder);
 }
 
 nsDisplayTransform::nsDisplayTransform(nsDisplayListBuilder* aBuilder,
@@ -4367,7 +4374,7 @@ nsDisplayTransform::nsDisplayTransform(nsDisplayListBuilder* aBuilder,
   MOZ_COUNT_CTOR(nsDisplayTransform);
   NS_ABORT_IF_FALSE(aFrame, "Must have a frame!");
   SetReferenceFrameToAncestor(aBuilder);
-  mStoredList.SetClip(aBuilder, DisplayItemClip::NoClip());
+  Init(aBuilder);
 }
 
 /* Returns the delta specified by the -moz-transform-origin property.
@@ -4690,9 +4697,12 @@ nsDisplayOpacity::CanUseAsyncAnimations(nsDisplayListBuilder* aBuilder)
 bool
 nsDisplayTransform::CanUseAsyncAnimations(nsDisplayListBuilder* aBuilder)
 {
-  return ShouldPrerenderTransformedContent(aBuilder,
+  if (mPrerender) {
-                                           Frame(),
+    return true;
-                                           nsLayoutUtils::IsAnimationLoggingEnabled());
+  }
+  DebugOnly<bool> prerender = ShouldPrerenderTransformedContent(aBuilder, mFrame, true);
+  NS_ASSERTION(!prerender, "Something changed under us!");
+  return false;
 }
 
 /* static */ bool
@@ -4789,7 +4799,7 @@ nsDisplayTransform::GetTransform()
 bool
 nsDisplayTransform::ShouldBuildLayerEvenIfInvisible(nsDisplayListBuilder* aBuilder)
 {
-  return ShouldPrerenderTransformedContent(aBuilder, mFrame, false);
+  return ShouldPrerender();
 }
 
 already_AddRefed<Layer> nsDisplayTransform::BuildLayer(nsDisplayListBuilder *aBuilder,
@@ -4803,8 +4813,7 @@ already_AddRefed<Layer> nsDisplayTransform::BuildLayer(nsDisplayListBuilder *aBu
     return nullptr;
   }
 
-  bool prerender = ShouldPrerenderTransformedContent(aBuilder, mFrame, false);
+  uint32_t flags = ShouldPrerender() ?
-  uint32_t flags = prerender ?
     FrameLayerBuilder::CONTAINER_NOT_CLIPPED_BY_ANCESTORS : 0;
   nsRefPtr<ContainerLayer> container = aManager->GetLayerBuilder()->
     BuildContainerLayerFor(aBuilder, aManager, mFrame, this, mStoredList.GetChildren(),
@@ -4825,7 +4834,7 @@ already_AddRefed<Layer> nsDisplayTransform::BuildLayer(nsDisplayListBuilder *aBu
   nsDisplayListBuilder::AddAnimationsAndTransitionsToLayer(container, aBuilder,
                                                            this, mFrame,
                                                            eCSSProperty_transform);
-  if (prerender) {
+  if (ShouldPrerender()) {
     container->SetUserData(nsIFrame::LayerIsPrerenderedDataKey(),
                            /*the value is irrelevant*/nullptr);
     container->SetContentFlags(container->GetContentFlags() | Layer::CONTENT_MAY_CHANGE_TRANSFORM);
@@ -4878,7 +4887,7 @@ bool nsDisplayTransform::ComputeVisibility(nsDisplayListBuilder *aBuilder,
    * think that it's painting in its original rectangular coordinate space.
    * If we can't untransform, take the entire overflow rect */
   nsRect untransformedVisibleRect;
-  if (ShouldPrerenderTransformedContent(aBuilder, mFrame) ||
+  if (ShouldPrerender() ||
       !UntransformVisibleRect(aBuilder, &untransformedVisibleRect))
   {
     untransformedVisibleRect = mFrame->GetVisualOverflowRectRelativeToSelf();
@@ -5005,8 +5014,7 @@ nsDisplayTransform::GetHitDepthAtPoint(nsDisplayListBuilder* aBuilder, const nsP
  */
 nsRect nsDisplayTransform::GetBounds(nsDisplayListBuilder *aBuilder, bool* aSnap)
 {
-  nsRect untransformedBounds =
+  nsRect untransformedBounds = ShouldPrerender() ?
-    ShouldPrerenderTransformedContent(aBuilder, mFrame) ?
     mFrame->GetVisualOverflowRectRelativeToSelf() :
     mStoredList.GetBounds(aBuilder, aSnap);
   *aSnap = false;
@@ -5044,7 +5052,7 @@ nsRegion nsDisplayTransform::GetOpaqueRegion(nsDisplayListBuilder *aBuilder,
   // covers the entire window, but it allows our transform to be
   // updated extremely cheaply, without invalidating any other
   // content.
-  if (ShouldPrerenderTransformedContent(aBuilder, mFrame) ||
+  if (ShouldPrerender() ||
       !UntransformVisibleRect(aBuilder, &untransformedVisible)) {
       return nsRegion();
   }

layout/base/nsDisplayList.h

@@ -3369,11 +3369,15 @@ public:
                                                 bool aLogAnimations = false);
   bool CanUseAsyncAnimations(nsDisplayListBuilder* aBuilder) MOZ_OVERRIDE;
 
+  bool ShouldPrerender() const { return mPrerender; }
+
 #ifdef MOZ_DUMP_PAINTING
   virtual void WriteDebugInfo(nsACString& aTo) MOZ_OVERRIDE;
 #endif
+
 private:
   void SetReferenceFrameToAncestor(nsDisplayListBuilder* aBuilder);
+  void Init(nsDisplayListBuilder* aBuilder);
 
   static gfx3DMatrix GetResultingTransformMatrixInternal(const FrameTransformProperties& aProperties,
                                                          const nsPoint& aOrigin,
@@ -3387,6 +3391,7 @@ private:
   ComputeTransformFunction mTransformGetter;
   nsRect mChildrenVisibleRect;
   uint32_t mIndex;
+  bool mPrerender;
 };
 
 /**