Bug 1016035 - Delay the processing of a PanGestureInput block until we know whether it's a swipe. r=kats

--HG--
extra : commitid : 5utp02GzYAW
extra : rebase_source : 4415c7ac8fd3a8dbb718593bee63e89e8ba1625c

gfx/layers/apz/src/InputBlockState.cpp

@@ -426,6 +426,7 @@ PanGestureBlockState::PanGestureBlockState(const nsRefPtr<AsyncPanZoomController
                                            const PanGestureInput& aInitialEvent)
   : CancelableBlockState(aTargetApzc, aTargetConfirmed)
   , mInterrupted(false)
+  , mWaitingForContentResponse(aInitialEvent.mRequiresContentResponse)
 {
   if (aTargetConfirmed) {
     // Find the nearest APZC in the overscroll handoff chain that is scrollable.
@@ -509,7 +510,22 @@ PanGestureBlockState::SetContentResponse(bool aPreventDefault)
   if (aPreventDefault) {
     mInterrupted = true;
   }
-  return CancelableBlockState::SetContentResponse(aPreventDefault);
+  bool stateChanged = CancelableBlockState::SetContentResponse(aPreventDefault);
+  if (mWaitingForContentResponse) {
+    mWaitingForContentResponse = false;
+    stateChanged = true;
+  }
+  return stateChanged;
+}
+
+bool
+PanGestureBlockState::IsReadyForHandling() const
+{
+  if (!CancelableBlockState::IsReadyForHandling()) {
+    return false;
+  }
+  return !mWaitingForContentResponse ||
+         IsContentResponseTimerExpired();
 }
 
 bool

gfx/layers/apz/src/InputBlockState.h

@@ -262,6 +262,7 @@ public:
                        const PanGestureInput& aEvent);
 
   bool SetContentResponse(bool aPreventDefault) override;
+  bool IsReadyForHandling() const override;
   bool HasEvents() const override;
   void DropEvents() override;
   void HandleEvents() override;
@@ -285,6 +286,7 @@ public:
 private:
   nsTArray<PanGestureInput> mEvents;
   bool mInterrupted;
+  bool mWaitingForContentResponse;
 };
 
 /**

widget/InputData.h

@@ -310,7 +310,8 @@ public:
       mPanDisplacement(aPanDisplacement),
       mLineOrPageDeltaX(0),
       mLineOrPageDeltaY(0),
-      mHandledByAPZ(false)
+      mHandledByAPZ(false),
+      mRequiresContentResponse(false)
   {
   }
 
@@ -336,6 +337,12 @@ public:
   int32_t mLineOrPageDeltaY;
 
   bool mHandledByAPZ;
+
+  // If this is true, the input block started by this event needs to be put
+  // on hold until a content response has arrived, even if the block has a
+  // confirmed target. This is used by events that can result in a swipe
+  // instead of a scroll.
+  bool mRequiresContentResponse;
 };
 
 /**

widget/cocoa/nsChildView.mm

@@ -4872,6 +4872,7 @@ PanGestureTypeForEvent(NSEvent* aEvent)
     panEvent.mLineOrPageDeltaY = lineOrPageDeltaY;
 
     bool canTriggerSwipe = [self shouldConsiderStartingSwipeFromEvent:theEvent];
+    panEvent.mRequiresContentResponse = canTriggerSwipe;
     mGeckoChild->DispatchAPZWheelInputEvent(panEvent, canTriggerSwipe);
   } else if (usePreciseDeltas) {
     // This is on 10.6 or old touchpads that don't have any phase information.