Bug 951793 - Obey overscroll-behavior for swipe navigation. r=mstange

MozReview-Commit-ID: i2BuiAfG71

gfx/layers/apz/src/APZCTreeManager.cpp

@@ -1198,6 +1198,9 @@ APZCTreeManager::ReceiveInputEvent(InputData& aEvent,
         apzc->GetGuid(aOutTargetGuid);
         panInput.mPanStartPoint = *untransformedStartPoint;
         panInput.mPanDisplacement = *untransformedDisplacement;
+
+        panInput.mOverscrollBehaviorAllowsSwipe =
+            apzc->OverscrollBehaviorAllowsSwipe();
       }
       break;
     } case PINCHGESTURE_INPUT: {  // note: no one currently sends these

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -2880,6 +2880,12 @@ ParentLayerPoint AsyncPanZoomController::AdjustHandoffVelocityForOverscrollBehav
   return residualVelocity;
 }
 
+bool AsyncPanZoomController::OverscrollBehaviorAllowsSwipe() const
+{
+  RecursiveMutexAutoLock lock(mRecursiveMutex);
+  // Swipe navigation is a "non-local" overscroll behavior like handoff.
+  return mX.OverscrollBehaviorAllowsHandoff();
+}
 
 void AsyncPanZoomController::HandleFlingOverscroll(const ParentLayerPoint& aVelocity,
                                                    const RefPtr<const OverscrollHandoffChain>& aOverscrollHandoffChain,

gfx/layers/apz/src/AsyncPanZoomController.h

@@ -442,6 +442,8 @@ public:
 
   void NotifyMozMouseScrollEvent(const nsString& aString) const;
 
+  bool OverscrollBehaviorAllowsSwipe() const;
+
 protected:
   // Protected destructor, to discourage deletion outside of Release():
   virtual ~AsyncPanZoomController();

widget/InputData.cpp

@@ -490,6 +490,7 @@ PanGestureInput::PanGestureInput()
   , mHandledByAPZ(false)
   , mFollowedByMomentum(false)
   , mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection(false)
+  , mOverscrollBehaviorAllowsSwipe(false)
 {
 }
 
@@ -509,6 +510,7 @@ PanGestureInput::PanGestureInput(PanGestureType aType, uint32_t aTime,
   , mHandledByAPZ(false)
   , mFollowedByMomentum(false)
   , mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection(false)
+  , mOverscrollBehaviorAllowsSwipe(false)
 {
 }
 

widget/InputData.h

@@ -385,6 +385,14 @@ public:
   // confirmed target.
   // This is used by events that can result in a swipe instead of a scroll.
   bool mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection;
+
+  // This is used by APZ to communicate to the macOS widget code whether
+  // the overscroll-behavior of the scroll frame handling this swipe allows
+  // non-local overscroll behaviors in the horizontal direction (such as
+  // swipe navigation).
+  bool mOverscrollBehaviorAllowsSwipe;
+
+  // XXX: If adding any more bools, switch to using bitfields instead.
 };
 
 /**

widget/cocoa/nsChildView.mm

@@ -2923,7 +2923,7 @@ nsChildView::DispatchAPZWheelInputEvent(InputData& aEvent, bool aCanTriggerSwipe
         PanGestureInput& panInput = aEvent.AsPanGestureInput();
 
         event = panInput.ToWidgetWheelEvent(this);
-        if (aCanTriggerSwipe) {
+        if (aCanTriggerSwipe && panInput.mOverscrollBehaviorAllowsSwipe) {
           SwipeInfo swipeInfo = SendMayStartSwipe(panInput);
           event.mCanTriggerSwipe = swipeInfo.wantsSwipe;
           if (swipeInfo.wantsSwipe) {

widget/nsGUIEventIPC.h

@@ -1225,6 +1225,7 @@ struct ParamTraits<mozilla::PanGestureInput>
     WriteParam(aMsg, aParam.mHandledByAPZ);
     WriteParam(aMsg, aParam.mFollowedByMomentum);
     WriteParam(aMsg, aParam.mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection);
+    WriteParam(aMsg, aParam.mOverscrollBehaviorAllowsSwipe);
   }
 
   static bool Read(const Message* aMsg, PickleIterator* aIter, paramType* aResult)
@@ -1241,7 +1242,8 @@ struct ParamTraits<mozilla::PanGestureInput>
            ReadParam(aMsg, aIter, &aResult->mUserDeltaMultiplierY) &&
            ReadParam(aMsg, aIter, &aResult->mHandledByAPZ) &&
            ReadParam(aMsg, aIter, &aResult->mFollowedByMomentum) &&
-           ReadParam(aMsg, aIter, &aResult->mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection);
+           ReadParam(aMsg, aIter, &aResult->mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection) &&
+           ReadParam(aMsg, aIter, &aResult->mOverscrollBehaviorAllowsSwipe);
   }
 };