Bug 1678771. Set mIsNoLineOrPageDelta on WidgetWheelEvents we create from PanGestureInput when we don't know the line scroll amount so EventStateManager will fill those in for us. r=botond

Differential Revision: https://phabricator.services.mozilla.com/D114358

widget/InputData.cpp

@@ -430,7 +430,8 @@ PanGestureInput::PanGestureInput()
       mFollowedByMomentum(false),
       mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection(false),
       mOverscrollBehaviorAllowsSwipe(false),
-      mSimulateMomentum(false) {}
+      mSimulateMomentum(false),
+      mIsNoLineOrPageDelta(true) {}
 
 PanGestureInput::PanGestureInput(PanGestureType aType, uint32_t aTime,
                                  TimeStamp aTimeStamp,
@@ -449,7 +450,15 @@ PanGestureInput::PanGestureInput(PanGestureType aType, uint32_t aTime,
       mFollowedByMomentum(false),
       mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection(false),
       mOverscrollBehaviorAllowsSwipe(false),
-      mSimulateMomentum(false) {}
+      mSimulateMomentum(false),
+      mIsNoLineOrPageDelta(true) {}
+
+void PanGestureInput::SetLineOrPageDeltas(int32_t aLineOrPageDeltaX,
+                                          int32_t aLineOrPageDeltaY) {
+  mLineOrPageDeltaX = aLineOrPageDeltaX;
+  mLineOrPageDeltaY = aLineOrPageDeltaY;
+  mIsNoLineOrPageDelta = false;
+}
 
 bool PanGestureInput::IsMomentum() const {
   switch (mType) {
@@ -480,10 +489,12 @@ WidgetWheelEvent PanGestureInput::ToWidgetEvent(nsIWidget* aWidget) const {
   wheelEvent.mDeltaY = mPanDisplacement.y;
   wheelEvent.mFlags.mHandledByAPZ = mHandledByAPZ;
   wheelEvent.mFocusSequenceNumber = mFocusSequenceNumber;
+  wheelEvent.mIsNoLineOrPageDelta = mIsNoLineOrPageDelta;
   if (mDeltaType == PanGestureInput::PANDELTA_PAGE) {
+    // widget/gtk is currently the only consumer that uses delta type
+    // PANDELTA_PAGE
     // Emulate legacy widget/gtk behavior
     wheelEvent.mDeltaMode = WheelEvent_Binding::DOM_DELTA_LINE;
-    wheelEvent.mIsNoLineOrPageDelta = true;
     wheelEvent.mScrollType = WidgetWheelEvent::SCROLL_ASYNCHRONOUSELY;
     wheelEvent.mDeltaX *= 3;
     wheelEvent.mDeltaY *= 3;

widget/InputData.h

@@ -397,6 +397,9 @@ class PanGestureInput : public InputData {
                   const ScreenPoint& aPanStartPoint,
                   const ScreenPoint& aPanDisplacement, Modifiers aModifiers);
 
+  void SetLineOrPageDeltas(int32_t aLineOrPageDeltaX,
+                           int32_t aLineOrPageDeltaY);
+
   bool IsMomentum() const;
 
   WidgetWheelEvent ToWidgetEvent(nsIWidget* aWidget) const;
@@ -456,6 +459,13 @@ class PanGestureInput : public InputData {
   // events.)
   bool mSimulateMomentum : 1;
 
+  // true if the creator of this object does not set the mLineOrPageDeltaX/Y
+  // fields and when/if WidgetWheelEvent's are generated from this object wants
+  // the corresponding mLineOrPageDeltaX/Y fields in the WidgetWheelEvent to be
+  // automatically calculated (upon event dispatch by the EventStateManager
+  // code).
+  bool mIsNoLineOrPageDelta : 1;
+
   void SetHandledByAPZ(bool aHandled) { mHandledByAPZ = aHandled; }
   void SetFollowedByMomentum(bool aFollowed) {
     mFollowedByMomentum = aFollowed;
@@ -469,6 +479,9 @@ class PanGestureInput : public InputData {
     mOverscrollBehaviorAllowsSwipe = aAllows;
   }
   void SetSimulateMomentum(bool aSimulate) { mSimulateMomentum = aSimulate; }
+  void SetIsNoLineOrPageDelta(bool aIsNoLineOrPageDelta) {
+    mIsNoLineOrPageDelta = aIsNoLineOrPageDelta;
+  }
 };
 
 /**

widget/cocoa/nsChildView.mm

@@ -3393,8 +3393,7 @@ static gfx::IntPoint GetIntegerDeltaForEvent(NSEvent* aEvent) {
   if (usePreciseDeltas && hasPhaseInformation) {
     PanGestureInput panEvent(PanGestureTypeForEvent(theEvent), eventIntervalTime, eventTimeStamp,
                              position, preciseDelta, modifiers);
-    panEvent.mLineOrPageDeltaX = lineOrPageDelta.x;
-    panEvent.mLineOrPageDeltaY = lineOrPageDelta.y;
+    panEvent.SetLineOrPageDeltas(lineOrPageDelta.x, lineOrPageDelta.y);
 
     if (panEvent.mType == PanGestureInput::PANGESTURE_END) {
       // Check if there's a momentum start event in the event queue, so that we

widget/nsGUIEventIPC.h

@@ -1237,6 +1237,7 @@ struct ParamTraits<mozilla::PanGestureInput>
             .mRequiresContentResponseIfCannotScrollHorizontallyInStartDirection);
     WriteParam(aMsg, aParam.mOverscrollBehaviorAllowsSwipe);
     WriteParam(aMsg, aParam.mSimulateMomentum);
+    WriteParam(aMsg, aParam.mIsNoLineOrPageDelta);
   }
 
   static bool Read(const Message* aMsg, PickleIterator* aIter,
@@ -1263,7 +1264,9 @@ struct ParamTraits<mozilla::PanGestureInput>
            ReadBoolForBitfield(aMsg, aIter, aResult,
                                &paramType::SetOverscrollBehaviorAllowsSwipe) &&
            ReadBoolForBitfield(aMsg, aIter, aResult,
-                               &paramType::SetSimulateMomentum);
+                               &paramType::SetSimulateMomentum) &&
+           ReadBoolForBitfield(aMsg, aIter, aResult,
+                               &paramType::SetIsNoLineOrPageDelta);
   }
 };
 

widget/windows/DirectManipulationOwner.cpp

@@ -506,11 +506,6 @@ void DManipEventHandler::SendPan(Phase aPhase, float x, float y,
   PanGestureInput event{panGestureType, eventIntervalTime, eventTimeStamp,
                         position,       ScreenPoint(x, y), mods};
 
-  gfx::IntPoint lineOrPageDelta =
-      PanGestureInput::GetIntegerDeltaForEvent((aPhase == Phase::eStart), x, y);
-  event.mLineOrPageDeltaX = lineOrPageDelta.x;
-  event.mLineOrPageDeltaY = lineOrPageDelta.y;
-
   mWindow->SendAnAPZEvent(event);
 }