Bug 1205087 - Cache AnimatedGeometryRoot on nsDisplayItem. r=roc

--HG--
extra : rebase_source : 75bf6cd82232dad91bfd35d2ef0f3bc5fcd3b26b

layout/base/FrameLayerBuilder.cpp

@@ -1029,7 +1029,7 @@ public:
     MOZ_ASSERT_IF(isAtRoot, mContainerReferenceFrame == mBuilder->RootReferenceFrame());
     mContainerAnimatedGeometryRoot = isAtRoot
       ? mContainerReferenceFrame
-      : nsLayoutUtils::GetAnimatedGeometryRootFor(aContainerItem, aBuilder);
+      : aContainerItem->AnimatedGeometryRoot();
     MOZ_ASSERT(nsLayoutUtils::IsAncestorFrameCrossDoc(mBuilder->RootReferenceFrame(),
                                                       mContainerAnimatedGeometryRoot));
     NS_ASSERTION(!aContainerItem || !aContainerItem->ShouldFixToViewport(mBuilder),
@@ -3636,8 +3636,7 @@ ContainerState::ChooseAnimatedGeometryRoot(const nsDisplayList& aList,
 
     // Try using the actual active scrolled root of the backmost item, as that
     // should result in the least invalidation when scrolling.
-    *aAnimatedGeometryRoot =
-      nsLayoutUtils::GetAnimatedGeometryRootFor(item, mBuilder);
+    *aAnimatedGeometryRoot = item->AnimatedGeometryRoot();
     return true;
   }
   return false;
@@ -3813,8 +3812,7 @@ ContainerState::ProcessDisplayItems(nsDisplayList* aList)
     bool forceInactive;
     const nsIFrame* animatedGeometryRoot;
     const nsIFrame* animatedGeometryRootForScrollMetadata = nullptr;
-    const nsIFrame* realAnimatedGeometryRootOfItem =
-      nsLayoutUtils::GetAnimatedGeometryRootFor(item, mBuilder);
+    const nsIFrame* realAnimatedGeometryRootOfItem = item->AnimatedGeometryRoot();
     if (mFlattenToSingleLayer) {
       forceInactive = true;
       animatedGeometryRoot = lastAnimatedGeometryRoot;

layout/base/nsDisplayList.cpp

@@ -1984,11 +1984,15 @@ void nsDisplayList::Sort(nsDisplayListBuilder* aBuilder,
 nsDisplayItem::nsDisplayItem(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame)
   : mFrame(aFrame)
   , mClip(aBuilder->ClipState().GetCurrentCombinedClip(aBuilder))
+  , mAnimatedGeometryRoot(nullptr)
 #ifdef MOZ_DUMP_PAINTING
   , mPainted(false)
 #endif
 {
   mReferenceFrame = aBuilder->FindReferenceFrameFor(aFrame, &mToReferenceFrame);
+  // This can return the wrong result if the item override ShouldFixToViewport(),
+  // the item needs to set it again in its constructor.
+  mAnimatedGeometryRoot = nsLayoutUtils::GetAnimatedGeometryRootFor(this, aBuilder);
   NS_ASSERTION(aBuilder->GetDirtyRect().width >= 0 ||
                !aBuilder->IsForPainting(), "dirty rect not set");
   // The dirty rect is for mCurrentFrame, so we have to use
@@ -2128,6 +2132,9 @@ nsDisplayBackgroundImage::nsDisplayBackgroundImage(nsDisplayListBuilder* aBuilde
   MOZ_COUNT_CTOR(nsDisplayBackgroundImage);
 
   mBounds = GetBoundsInternal(aBuilder);
+  if (ShouldFixToViewport(aBuilder)) {
+    mAnimatedGeometryRoot = nsLayoutUtils::GetAnimatedGeometryRootFor(this, aBuilder);
+  }
 }
 
 nsDisplayBackgroundImage::~nsDisplayBackgroundImage()
@@ -3713,8 +3720,7 @@ RequiredLayerStateForChildren(nsDisplayListBuilder* aBuilder,
   LayerState result = LAYER_INACTIVE;
   for (nsDisplayItem* i = aList.GetBottom(); i; i = i->GetAbove()) {
     if (result == LAYER_INACTIVE &&
-        nsLayoutUtils::GetAnimatedGeometryRootFor(i, aBuilder) !=
-          aExpectedAnimatedGeometryRootForChildren) {
+        i->AnimatedGeometryRoot() != aExpectedAnimatedGeometryRootForChildren) {
       result = LAYER_ACTIVE;
     }
 
@@ -3971,8 +3977,7 @@ nsDisplayOpacity::GetLayerState(nsDisplayListBuilder* aBuilder,
   if (NeedsActiveLayer(aBuilder))
     return LAYER_ACTIVE;
 
-  return RequiredLayerStateForChildren(aBuilder, aManager, aParameters, mList,
-    nsLayoutUtils::GetAnimatedGeometryRootFor(this, aBuilder));
+  return RequiredLayerStateForChildren(aBuilder, aManager, aParameters, mList, AnimatedGeometryRoot());
 }
 
 bool

layout/base/nsDisplayList.h

@@ -1067,6 +1067,7 @@ public:
     : mFrame(aFrame)
     , mClip(nullptr)
     , mReferenceFrame(nullptr)
+    , mAnimatedGeometryRoot(nullptr)
 #ifdef MOZ_DUMP_PAINTING
     , mPainted(false)
 #endif
@@ -1513,6 +1514,11 @@ public:
    */
   virtual const nsIFrame* ReferenceFrameForChildren() const { return mReferenceFrame; }
 
+  nsIFrame* AnimatedGeometryRoot() const {
+    MOZ_ASSERT(mAnimatedGeometryRoot, "Must have cached AGR before accessing it!");
+    return mAnimatedGeometryRoot;
+  }
+
   /**
    * Checks if this display item (or any children) contains content that might
    * be rendered with component alpha (e.g. subpixel antialiasing). Returns the
@@ -1568,6 +1574,7 @@ protected:
   const DisplayItemClip* mClip;
   // Result of FindReferenceFrameFor(mFrame), if mFrame is non-null
   const nsIFrame* mReferenceFrame;
+  nsIFrame* mAnimatedGeometryRoot;
   // Result of ToReferenceFrame(mFrame), if mFrame is non-null
   nsPoint   mToReferenceFrame;
   // This is the rectangle that needs to be painted.

layout/base/nsLayoutDebugger.cpp

@@ -162,9 +162,7 @@ PrintDisplayItemTo(nsDisplayListBuilder* aBuilder, nsDisplayItem* aItem,
   }
   bool snap;
   nsRect rect = aItem->GetBounds(aBuilder, &snap);
-  nsRect layerRect = rect -
-    nsLayoutUtils::GetAnimatedGeometryRootFor(aItem, aBuilder)->
-      GetOffsetToCrossDoc(aItem->ReferenceFrame());
+  nsRect layerRect = rect - aItem->AnimatedGeometryRoot()->GetOffsetToCrossDoc(aItem->ReferenceFrame());
   nscolor color;
   nsRect vis = aItem->GetVisibleRect();
   nsRect component = aItem->GetComponentAlphaBounds(aBuilder);