Fix asynchronously scrolling containerful subframes. (bug 1148582 part 6.1, r=tn)

gfx/ipc/GfxMessageUtils.h

@@ -734,6 +734,7 @@ struct ParamTraits<mozilla::layers::FrameMetrics>
     WriteParam(aMsg, aParam.AllowVerticalScrollWithWheel());
     WriteParam(aMsg, aParam.mClipRect);
     WriteParam(aMsg, aParam.mIsLayersIdRoot);
+    WriteParam(aMsg, aParam.mUsesContainerScrolling);
     WriteParam(aMsg, aParam.GetContentDescription());
   }
 
@@ -778,6 +779,7 @@ struct ParamTraits<mozilla::layers::FrameMetrics>
             ReadParam(aMsg, aIter, &aResult->mAllowVerticalScrollWithWheel) &&
             ReadParam(aMsg, aIter, &aResult->mClipRect) &&
             ReadParam(aMsg, aIter, &aResult->mIsLayersIdRoot) &&
+            ReadParam(aMsg, aIter, &aResult->mUsesContainerScrolling) &&
             ReadContentDescription(aMsg, aIter, aResult));
   }
 };

gfx/layers/FrameMetrics.h

@@ -14,6 +14,7 @@
 #include "mozilla/gfx/ScaleFactor.h"    // for ScaleFactor
 #include "mozilla/gfx/Logging.h"        // for Log
 #include "gfxColor.h"
+#include "gfxPrefs.h"                   // for LayoutUseContainersForRootFrames
 #include "nsString.h"
 
 namespace IPC {
@@ -68,6 +69,7 @@ public:
     , mPageScrollAmount(0, 0)
     , mAllowVerticalScrollWithWheel(false)
     , mIsLayersIdRoot(false)
+    , mUsesContainerScrolling(false)
   {
   }
 
@@ -102,7 +104,8 @@ public:
            mPageScrollAmount == aOther.mPageScrollAmount &&
            mAllowVerticalScrollWithWheel == aOther.mAllowVerticalScrollWithWheel &&
            mClipRect == aOther.mClipRect &&
-           mIsLayersIdRoot == aOther.mIsLayersIdRoot;
+           mIsLayersIdRoot == aOther.mIsLayersIdRoot &&
+		   mUsesContainerScrolling == aOther.mUsesContainerScrolling;
   }
   bool operator!=(const FrameMetrics& aOther) const
   {
@@ -534,6 +537,14 @@ public:
     return mIsLayersIdRoot;
   }
 
+  void SetUsesContainerScrolling(bool aValue) {
+    MOZ_ASSERT_IF(aValue, gfxPrefs::LayoutUseContainersForRootFrames());
+    mUsesContainerScrolling = aValue;
+  }
+  bool UsesContainerScrolling() const {
+    return mUsesContainerScrolling;
+  }
+
 private:
 
   // The pres-shell resolution that has been induced on the document containing
@@ -712,6 +723,10 @@ private:
   // we don't have a root scroll frame) for its layers id.
   bool mIsLayersIdRoot;
 
+  // True if scrolling using containers, false otherwise. This can be removed
+  // when containerful scrolling is eliminated.
+  bool mUsesContainerScrolling;
+
   // WARNING!!!!
   //
   // When adding new fields to FrameMetrics, the following places should be

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -2903,6 +2903,7 @@ void AsyncPanZoomController::NotifyLayersUpdated(const FrameMetrics& aLayerMetri
     mFrameMetrics.SetPageScrollAmount(aLayerMetrics.GetPageScrollAmount());
     mFrameMetrics.SetClipRect(aLayerMetrics.GetClipRect());
     mFrameMetrics.SetIsLayersIdRoot(aLayerMetrics.IsLayersIdRoot());
+    mFrameMetrics.SetUsesContainerScrolling(aLayerMetrics.UsesContainerScrolling());
 
     if (scrollOffsetUpdated) {
       APZC_LOG("%p updating scroll offset from %s to %s\n", this,

gfx/layers/composite/AsyncCompositionManager.cpp

@@ -633,13 +633,9 @@ AsyncCompositionManager::ApplyAsyncContentTransformToTree(Layer *aLayer)
     mLayerManager->GetCompositor()->SetScreenRenderOffset(offset);
 
     // Transform the current local clip by this APZC's async transform. If we're
-    // using containerful scrolling, the layer's clip is pre-transform instead
-    // of post-transform, so we skip this to avoid transforming it twice.
-    if (asyncClip &&
-        !(gfxPrefs::LayoutUseContainersForRootFrames() &&
-          aLayer->AsContainerLayer() &&
-          i == 0))
-    {
+    // using containerful scrolling, then the clip is not part of the scrolled
+    // frame and should not be transformed.
+    if (asyncClip && !metrics.UsesContainerScrolling()) {
       asyncClip = Some(TransformTo<ParentLayerPixel>(asyncTransform, *asyncClip));
     }
 

layout/base/nsLayoutUtils.cpp

@@ -8219,6 +8219,8 @@ nsLayoutUtils::ComputeFrameMetrics(nsIFrame* aForFrame,
     {
       metrics.SetAllowVerticalScrollWithWheel();
     }
+
+    metrics.SetUsesContainerScrolling(scrollableFrame->UsesContainerScrolling());
   }
 
   // If we have the scrollparent being the same as the scroll id, the

layout/generic/nsGfxScrollFrame.cpp

@@ -5586,3 +5586,12 @@ ScrollFrameHelper::GetSnapPointForDestination(nsIScrollableFrame::ScrollUnit aUn
   }
   return snapped;
 }
+
+bool
+ScrollFrameHelper::UsesContainerScrolling() const
+{
+  if (gfxPrefs::LayoutUseContainersForRootFrames()) {
+    return mIsRoot;
+  }
+  return false;
+}

layout/generic/nsGfxScrollFrame.h

@@ -359,6 +359,7 @@ public:
   bool IsTransformingByAPZ() const {
     return mTransformingByAPZ;
   }
+  bool UsesContainerScrolling() const;
 
   void ScheduleSyntheticMouseMove();
   static void ScrollActivityCallback(nsITimer *aTimer, void* anInstance);
@@ -845,6 +846,9 @@ public:
   virtual void MarkScrollbarsDirtyForReflow() const override {
     mHelper.MarkScrollbarsDirtyForReflow();
   }
+  virtual bool UsesContainerScrolling() const override {
+    return mHelper.UsesContainerScrolling();
+  }
 
   // nsIStatefulFrame
   NS_IMETHOD SaveState(nsPresState** aState) override {
@@ -1306,6 +1310,9 @@ public:
   virtual void SetTransformingByAPZ(bool aTransforming) override {
     mHelper.SetTransformingByAPZ(aTransforming);
   }
+  virtual bool UsesContainerScrolling() const override {
+    return mHelper.UsesContainerScrolling();
+  }
   bool IsTransformingByAPZ() const override {
     return mHelper.IsTransformingByAPZ();
   }

layout/generic/nsIScrollableFrame.h

@@ -432,6 +432,11 @@ public:
 
   virtual void SetTransformingByAPZ(bool aTransforming) = 0;
   virtual bool IsTransformingByAPZ() const = 0;
+
+  /**
+   * Whether or not this frame uses containerful scrolling.
+   */
+  virtual bool UsesContainerScrolling() const = 0;
 };
 
 #endif