Bug 990907 - Add a flag on nsIScrollableFrame to indicate if it is ac…

…tively being scrolled by APZ.
rmottola · Feb 15, 2019 · 3eb29e6 · 3eb29e6
1 parent 0f95f6f
commit 3eb29e6
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Showing 4 changed files with 35 additions and 0 deletions.
diff --git a/gfx/layers/apz/util/APZEventState.cpp b/gfx/layers/apz/util/APZEventState.cpp
@@ -249,6 +249,9 @@ APZEventState::ProcessAPZStateChange(const nsCOMPtr<nsIDocument>& aDocument,
   case APZStateChange::TransformBegin:
   {
     nsIScrollableFrame* sf = nsLayoutUtils::FindScrollableFrameFor(aViewId);
+    if (sf) {
+      sf->SetTransformingByAPZ(true);
+    }
     nsIScrollbarMediator* scrollbarMediator = do_QueryFrame(sf);
     if (scrollbarMediator) {
       scrollbarMediator->ScrollbarActivityStarted();
@@ -266,6 +269,9 @@ APZEventState::ProcessAPZStateChange(const nsCOMPtr<nsIDocument>& aDocument,
   case APZStateChange::TransformEnd:
   {
     nsIScrollableFrame* sf = nsLayoutUtils::FindScrollableFrameFor(aViewId);
+    if (sf) {
+      sf->SetTransformingByAPZ(false);
+    }
     nsIScrollbarMediator* scrollbarMediator = do_QueryFrame(sf);
     if (scrollbarMediator) {
       scrollbarMediator->ScrollbarActivityStopped();

diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
@@ -1912,6 +1912,7 @@ ScrollFrameHelper::ScrollFrameHelper(nsContainerFrame* aOuter,
   , mIsResolutionSet(false)
   , mIgnoreMomentumScroll(false)
   , mScaleToResolution(false)
+  , mTransformingByAPZ(false)
 {
   if (LookAndFeel::GetInt(LookAndFeel::eIntID_UseOverlayScrollbars) != 0) {
     mScrollbarActivity = new ScrollbarActivity(do_QueryFrame(aOuter));

diff --git a/layout/generic/nsGfxScrollFrame.h b/layout/generic/nsGfxScrollFrame.h
@@ -325,6 +325,13 @@ class ScrollFrameHelper : public nsIReflowCallback {
   void MarkNotRecentlyScrolled();
   nsExpirationState* GetExpirationState() { return &mActivityExpirationState; }
 
+  void SetTransformingByAPZ(bool aTransforming) {
+    mTransformingByAPZ = aTransforming;
+  }
+  bool IsTransformingByAPZ() const {
+    return mTransformingByAPZ;
+  }
+
   void ScheduleSyntheticMouseMove();
   static void ScrollActivityCallback(nsITimer *aTimer, void* anInstance);
 
@@ -471,6 +478,10 @@ class ScrollFrameHelper : public nsIReflowCallback {
   // Only meaningful for root scroll frames.
   bool mScaleToResolution:1;
 
+  // True if the APZ is in the process of async-transforming this scrollframe,
+  // (as best as we can tell on the main thread, anyway).
+  bool mTransformingByAPZ:1;
+
 protected:
   /**
    * @note This method might destroy the frame, pres shell and other objects.
@@ -817,6 +828,13 @@ class nsHTMLScrollFrame : public nsContainerFrame,
   }
   virtual void ScrollbarActivityStarted() const override;
   virtual void ScrollbarActivityStopped() const override;
+
+  virtual void SetTransformingByAPZ(bool aTransforming) MOZ_OVERRIDE {
+    mHelper.SetTransformingByAPZ(aTransforming);
+  }
+  bool IsTransformingByAPZ() const MOZ_OVERRIDE {
+    return mHelper.IsTransformingByAPZ();
+  }
 
 #ifdef DEBUG_FRAME_DUMP
   virtual nsresult GetFrameName(nsAString& aResult) const override;
@@ -1188,6 +1206,13 @@ class nsXULScrollFrame final : public nsBoxFrame,
   virtual void ScrollbarActivityStarted() const override;
   virtual void ScrollbarActivityStopped() const override;
 
+  virtual void SetTransformingByAPZ(bool aTransforming) MOZ_OVERRIDE {
+    mHelper.SetTransformingByAPZ(aTransforming);
+  }
+  bool IsTransformingByAPZ() const MOZ_OVERRIDE {
+    return mHelper.IsTransformingByAPZ();
+  }
+
 #ifdef DEBUG_FRAME_DUMP
   virtual nsresult GetFrameName(nsAString& aResult) const override;
 #endif

diff --git a/layout/generic/nsIScrollableFrame.h b/layout/generic/nsIScrollableFrame.h
@@ -406,6 +406,9 @@ class nsIScrollableFrame : public nsIScrollbarMediator {
    * Mark the scrollbar frames for reflow.
    */
   virtual void MarkScrollbarsDirtyForReflow() const = 0;
+
+  virtual void SetTransformingByAPZ(bool aTransforming) = 0;
+  virtual bool IsTransformingByAPZ() const = 0;
 };
 
 #endif