Bug 1148350 - Have ConvertToGecko use a live screen-to-apzc transform to avoid transform mismatches. r=botond

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -1395,13 +1395,16 @@ nsEventStatus AsyncPanZoomController::OnScaleEnd(const PinchGestureInput& aEvent
 }
 
 bool
-AsyncPanZoomController::ConvertToGecko(const ParentLayerPoint& aPoint, CSSPoint* aOut)
+AsyncPanZoomController::ConvertToGecko(const ScreenIntPoint& aPoint, CSSPoint* aOut)
 {
   if (APZCTreeManager* treeManagerLocal = GetApzcTreeManager()) {
+    Matrix4x4 transformToApzc = treeManagerLocal->GetScreenToApzcTransform(this);
     Matrix4x4 transformToGecko = treeManagerLocal->GetApzcToGeckoTransform(this);
     // NOTE: This isn't *quite* LayoutDevicePoint, we just don't have a name
     // for this coordinate space and it maps the closest to LayoutDevicePoint.
-    LayoutDevicePoint layoutPoint = TransformTo<LayoutDevicePixel>(transformToGecko, aPoint);
+    LayoutDevicePoint layoutPoint = TransformTo<LayoutDevicePixel>(
+        transformToApzc * transformToGecko, aPoint);
+
     { // scoped lock to access mFrameMetrics
       ReentrantMonitorAutoEnter lock(mMonitor);
       *aOut = layoutPoint / mFrameMetrics.GetDevPixelsPerCSSPixel();
@@ -1732,7 +1735,7 @@ nsEventStatus AsyncPanZoomController::OnLongPress(const TapGestureInput& aEvent)
   nsRefPtr<GeckoContentController> controller = GetGeckoContentController();
   if (controller) {
     CSSPoint geckoScreenPoint;
-    if (ConvertToGecko(aEvent.mLocalPoint, &geckoScreenPoint)) {
+    if (ConvertToGecko(aEvent.mPoint, &geckoScreenPoint)) {
       if (CurrentTouchBlock()->IsDuringFastMotion()) {
         APZC_LOG("%p dropping long-press because of fast motion\n", this);
         return nsEventStatus_eIgnore;
@@ -1747,10 +1750,10 @@ nsEventStatus AsyncPanZoomController::OnLongPress(const TapGestureInput& aEvent)
 
 nsEventStatus AsyncPanZoomController::OnLongPressUp(const TapGestureInput& aEvent) {
   APZC_LOG("%p got a long-tap-up in state %d\n", this, mState);
-  return GenerateSingleTap(aEvent.mLocalPoint, aEvent.modifiers);
+  return GenerateSingleTap(aEvent.mPoint, aEvent.modifiers);
 }
 
-nsEventStatus AsyncPanZoomController::GenerateSingleTap(const ParentLayerPoint& aPoint, mozilla::Modifiers aModifiers) {
+nsEventStatus AsyncPanZoomController::GenerateSingleTap(const ScreenIntPoint& aPoint, mozilla::Modifiers aModifiers) {
   nsRefPtr<GeckoContentController> controller = GetGeckoContentController();
   if (controller) {
     CSSPoint geckoScreenPoint;
@@ -1786,14 +1789,14 @@ nsEventStatus AsyncPanZoomController::OnSingleTapUp(const TapGestureInput& aEven
   // If mZoomConstraints.mAllowDoubleTapZoom is true we wait for a call to OnSingleTapConfirmed before
   // sending event to content
   if (!(mZoomConstraints.mAllowDoubleTapZoom && CurrentTouchBlock()->TouchActionAllowsDoubleTapZoom())) {
-    return GenerateSingleTap(aEvent.mLocalPoint, aEvent.modifiers);
+    return GenerateSingleTap(aEvent.mPoint, aEvent.modifiers);
   }
   return nsEventStatus_eIgnore;
 }
 
 nsEventStatus AsyncPanZoomController::OnSingleTapConfirmed(const TapGestureInput& aEvent) {
   APZC_LOG("%p got a single-tap-confirmed in state %d\n", this, mState);
-  return GenerateSingleTap(aEvent.mLocalPoint, aEvent.modifiers);
+  return GenerateSingleTap(aEvent.mPoint, aEvent.modifiers);
 }
 
 nsEventStatus AsyncPanZoomController::OnDoubleTap(const TapGestureInput& aEvent) {
@@ -1802,7 +1805,7 @@ nsEventStatus AsyncPanZoomController::OnDoubleTap(const TapGestureInput& aEvent)
   if (controller) {
     if (mZoomConstraints.mAllowDoubleTapZoom && CurrentTouchBlock()->TouchActionAllowsDoubleTapZoom()) {
       CSSPoint geckoScreenPoint;
-      if (ConvertToGecko(aEvent.mLocalPoint, &geckoScreenPoint)) {
+      if (ConvertToGecko(aEvent.mPoint, &geckoScreenPoint)) {
         controller->HandleDoubleTap(geckoScreenPoint, aEvent.modifiers, GetGuid());
       }
     }

gfx/layers/apz/src/AsyncPanZoomController.h

@@ -607,12 +607,12 @@ protected:
   void FireAsyncScrollOnTimeout();
 
   /**
-   * Convert ScreenPoint relative to this APZC to CSSPoint relative
+   * Convert ScreenPoint relative to the screen to CSSPoint relative
    * to the parent document. This excludes the transient compositor transform.
    * NOTE: This must be converted to CSSPoint relative to the child
-   * document before sending over IPC.
+   * document before sending over IPC to a child process.
    */
-  bool ConvertToGecko(const ParentLayerPoint& aPoint, CSSPoint* aOut);
+  bool ConvertToGecko(const ScreenIntPoint& aPoint, CSSPoint* aOut);
 
   enum AxisLockMode {
     FREE,     /* No locking at all */
@@ -623,7 +623,7 @@ protected:
   static AxisLockMode GetAxisLockMode();
 
   // Helper function for OnSingleTapUp() and OnSingleTapConfirmed().
-  nsEventStatus GenerateSingleTap(const ParentLayerPoint& aPoint, mozilla::Modifiers aModifiers);
+  nsEventStatus GenerateSingleTap(const ScreenIntPoint& aPoint, mozilla::Modifiers aModifiers);
 
   // Common processing at the end of a touch block.
   void OnTouchEndOrCancel();

gfx/layers/apz/src/GestureEventListener.cpp

@@ -55,9 +55,7 @@ TapGestureInput CreateTapEvent(const MultiTouchInput& aTouch, TapGestureInput::T
   return TapGestureInput(aType,
                          aTouch.mTime,
                          aTouch.mTimeStamp,
-                         // Use mLocalScreenPoint as this goes directly to APZC
-                         // without being transformed in APZCTreeManager.
-                         aTouch.mTouches[0].mLocalScreenPoint,
+                         aTouch.mTouches[0].mScreenPoint,
                          aTouch.modifiers);
 }