Suppressed MEs for gestures from cancelled PEs

third_party/WebKit/Source/core/input/EventHandler.cpp

Index: third_party/WebKit/Source/core/input/EventHandler.cpp
diff --git a/third_party/WebKit/Source/core/input/EventHandler.cpp b/third_party/WebKit/Source/core/input/EventHandler.cpp
index 0ae26ba3d1e0713165e07821db931a4ca6935347..b7fe894272120c6b61ab4b9f475e272b3c85c81d 100644
--- a/third_party/WebKit/Source/core/input/EventHandler.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandler.cpp
@@ -261,6 +261,7 @@ EventHandler::EventHandler(LocalFrame* frame)
     , m_activeIntervalTimer(this, &EventHandler::activeIntervalTimerFired)
     , m_lastShowPressTimestamp(0)
     , m_deltaConsumedForScrollSequence(false)
+    , m_suppressMouseEventsFromGestures(false)
 {
 }
 
@@ -334,6 +335,7 @@ void EventHandler::clear()
     m_dragStartPos = LayoutPoint();
     m_offsetFromResizeCorner = LayoutSize();
     m_mouseDown = PlatformMouseEvent();
+    m_suppressMouseEventsFromGestures = false;
 }
 
 WebInputEventResult EventHandler::mergeEventResult(
@@ -2063,6 +2065,8 @@ WebInputEventResult EventHandler::handleGestureEventInFrame(const GestureEventWi
     }
 
     switch (gestureEvent.type()) {
+    case PlatformEvent::GestureTapDown:
+        return handleGestureTapDown(targetedEvent);
     case PlatformEvent::GestureTap:
         return handleGestureTap(targetedEvent);
     case PlatformEvent::GestureShowPress:
@@ -2073,7 +2077,6 @@ WebInputEventResult EventHandler::handleGestureEventInFrame(const GestureEventWi
         return handleGestureLongTap(targetedEvent);
     case PlatformEvent::GestureTwoFingerTap:
         return sendContextMenuEventForGesture(targetedEvent);
-    case PlatformEvent::GestureTapDown:
     case PlatformEvent::GesturePinchBegin:
     case PlatformEvent::GesturePinchEnd:
     case PlatformEvent::GesturePinchUpdate:
@@ -2161,6 +2164,13 @@ WebInputEventResult EventHandler::handleGestureScrollEvent(const PlatformGesture
     }
 }
 
+WebInputEventResult EventHandler::handleGestureTapDown(const GestureEventWithHitTestResults& targetedEvent)
+{
+    m_suppressMouseEventsFromGestures =

[dtapuska, 2016/05/27 20:54:07]

I see there is an ASSERT in debug mode for the Deque having enough elements. But
what happens in release? Is it ever a scenario when we might not have things in
the deque?

+        m_pointerEventManager.firstPrimaryPointerdownResult() != WebInputEventResult::NotHandled;
+    return WebInputEventResult::NotHandled;
+}
+
 WebInputEventResult EventHandler::handleGestureTap(const GestureEventWithHitTestResults& targetedEvent)
 {
     FrameView* frameView(m_frame->view());
@@ -2176,13 +2186,15 @@ WebInputEventResult EventHandler::handleGestureTap(const GestureEventWithHitTest
     // We use the adjusted position so the application isn't surprised to see a event with
     // co-ordinates outside the target's bounds.
     IntPoint adjustedPoint = frameView->rootFrameToContents(gestureEvent.position());
+    const unsigned modifiers = gestureEvent.getModifiers();
 
-    unsigned modifiers = gestureEvent.getModifiers();
-    PlatformMouseEvent fakeMouseMove(gestureEvent.position(), gestureEvent.globalPosition(),
-        NoButton, PlatformEvent::MouseMoved, /* clickCount */ 0,
-        static_cast<PlatformEvent::Modifiers>(modifiers),
-        PlatformMouseEvent::FromTouch, gestureEvent.timestamp(), WebPointerProperties::PointerType::Mouse);
-    dispatchMouseEvent(EventTypeNames::mousemove, currentHitTest.innerNode(), 0, fakeMouseMove);
+    if (!m_suppressMouseEventsFromGestures) {
+        PlatformMouseEvent fakeMouseMove(gestureEvent.position(), gestureEvent.globalPosition(),
+            NoButton, PlatformEvent::MouseMoved, /* clickCount */ 0,
+            static_cast<PlatformEvent::Modifiers>(modifiers),
+            PlatformMouseEvent::FromTouch, gestureEvent.timestamp(), WebPointerProperties::PointerType::Mouse);
+        dispatchMouseEvent(EventTypeNames::mousemove, currentHitTest.innerNode(), 0, fakeMouseMove);
+    }
 
     // Do a new hit-test in case the mousemove event changed the DOM.
     // Note that if the original hit test wasn't over an element (eg. was over a scrollbar) we
@@ -2207,16 +2219,19 @@ WebInputEventResult EventHandler::handleGestureTap(const GestureEventWithHitTest
     if (m_clickNode && m_clickNode->isTextNode())
         m_clickNode = FlatTreeTraversal::parent(*m_clickNode);
 
-    PlatformMouseEvent fakeMouseDown(gestureEvent.position(), gestureEvent.globalPosition(),
-        LeftButton, PlatformEvent::MousePressed, gestureEvent.tapCount(),
-        static_cast<PlatformEvent::Modifiers>(modifiers | PlatformEvent::LeftButtonDown),
-        PlatformMouseEvent::FromTouch,  gestureEvent.timestamp(), WebPointerProperties::PointerType::Mouse);
-    WebInputEventResult mouseDownEventResult = dispatchMouseEvent(EventTypeNames::mousedown, currentHitTest.innerNode(), gestureEvent.tapCount(), fakeMouseDown);
-    selectionController().initializeSelectionState();
-    if (mouseDownEventResult == WebInputEventResult::NotHandled)
-        mouseDownEventResult = handleMouseFocus(MouseEventWithHitTestResults(fakeMouseDown, currentHitTest), InputDeviceCapabilities::firesTouchEventsSourceCapabilities());
-    if (mouseDownEventResult == WebInputEventResult::NotHandled)
-        mouseDownEventResult = handleMousePressEvent(MouseEventWithHitTestResults(fakeMouseDown, currentHitTest));
+    WebInputEventResult mouseDownEventResult = WebInputEventResult::NotHandled;
+    if (!m_suppressMouseEventsFromGestures) {
+        PlatformMouseEvent fakeMouseDown(gestureEvent.position(), gestureEvent.globalPosition(),
+            LeftButton, PlatformEvent::MousePressed, gestureEvent.tapCount(),
+            static_cast<PlatformEvent::Modifiers>(modifiers | PlatformEvent::LeftButtonDown),
+            PlatformMouseEvent::FromTouch, gestureEvent.timestamp(), WebPointerProperties::PointerType::Mouse);
+        mouseDownEventResult = dispatchMouseEvent(EventTypeNames::mousedown, currentHitTest.innerNode(), gestureEvent.tapCount(), fakeMouseDown);
+        selectionController().initializeSelectionState();
+        if (mouseDownEventResult == WebInputEventResult::NotHandled)
+            mouseDownEventResult = handleMouseFocus(MouseEventWithHitTestResults(fakeMouseDown, currentHitTest), InputDeviceCapabilities::firesTouchEventsSourceCapabilities());
+        if (mouseDownEventResult == WebInputEventResult::NotHandled)
+            mouseDownEventResult = handleMousePressEvent(MouseEventWithHitTestResults(fakeMouseDown, currentHitTest));

[Rick Byers, 2016/05/27 20:39:27]

In addition to suppressing the generation of mouse events, I believe this change
also suppresses some/all of the default behavior associated with a tap (eg.
focusing an input field).  I'm pretty sure this is what you want (since
cancelling the pointerdown for a mouse would do the same), but there may be some
subtle cases here.  Anyway maybe just expand the CL description to describe this
broader impact, ideally also add at least a little test coverage (we really
should have interop tests for that sort of thing).

[mustaq, 2016/06/02 19:26:26]

A milder approach seems to make more sense to me now: minimize the effect of
canceled pointerdown on GEs. In this particular case focusing was originally
triggered by gestureTap, and we are not suppressing gestureTaps, so let's keep
the behavior unchanged. Wdyt?

[Rick Byers, 2016/06/03 15:31:39]

I think it's important that cancelling pointerdown prevents all behavior that
cancelling the associated mousedown originally would have in the GestureTap
scenario (otherwise switching from handling MEs to PEs may break some
scenarios).  So yes, keeping the behavior unchanged makes sense.

+    }
 
     if (currentHitTest.innerNode()) {
         ASSERT(gestureEvent.type() == PlatformEvent::GestureTap);
@@ -2233,11 +2248,15 @@ WebInputEventResult EventHandler::handleGestureTap(const GestureEventWithHitTest
         adjustedPoint = frameView->rootFrameToContents(gestureEvent.position());
         currentHitTest = hitTestResultInFrame(m_frame, adjustedPoint, hitType);
     }
+
+    WebInputEventResult mouseUpEventResult = WebInputEventResult::NotHandled;
     PlatformMouseEvent fakeMouseUp(gestureEvent.position(), gestureEvent.globalPosition(),
         LeftButton, PlatformEvent::MouseReleased, gestureEvent.tapCount(),
         static_cast<PlatformEvent::Modifiers>(modifiers),
-        PlatformMouseEvent::FromTouch,  gestureEvent.timestamp(), WebPointerProperties::PointerType::Mouse);
-    WebInputEventResult mouseUpEventResult = dispatchMouseEvent(EventTypeNames::mouseup, currentHitTest.innerNode(), gestureEvent.tapCount(), fakeMouseUp);
+        PlatformMouseEvent::FromTouch, gestureEvent.timestamp(), WebPointerProperties::PointerType::Mouse);
+    if (!m_suppressMouseEventsFromGestures) {
+        mouseUpEventResult = dispatchMouseEvent(EventTypeNames::mouseup, currentHitTest.innerNode(), gestureEvent.tapCount(), fakeMouseUp);
+    }
 
     WebInputEventResult clickEventResult = WebInputEventResult::NotHandled;
     if (m_clickNode) {
@@ -2254,7 +2273,7 @@ WebInputEventResult EventHandler::handleGestureTap(const GestureEventWithHitTest
         m_clickNode = nullptr;
     }
 
-    if (mouseUpEventResult == WebInputEventResult::NotHandled)
+    if (!m_suppressMouseEventsFromGestures && mouseUpEventResult == WebInputEventResult::NotHandled)
         mouseUpEventResult = handleMouseReleaseEvent(MouseEventWithHitTestResults(fakeMouseUp, currentHitTest));
 
     WebInputEventResult eventResult = mergeEventResult(mergeEventResult(mouseDownEventResult, mouseUpEventResult), clickEventResult);
@@ -2281,6 +2300,8 @@ WebInputEventResult EventHandler::handleGestureLongPress(const GestureEventWithH
 
     m_longTapShouldInvokeContextMenu = false;
     if (m_frame->settings() && m_frame->settings()->touchDragDropEnabled() && m_frame->view()) {
+        // TODO(mustaq): Suppressing long-tap MouseEvents could break
+        // drag-drop. Will do separately because of the risk. crbug.com/606938.
         PlatformMouseEvent mouseDownEvent(adjustedPoint, gestureEvent.globalPosition(), LeftButton, PlatformEvent::MousePressed, 1,
             static_cast<PlatformEvent::Modifiers>(modifiers | PlatformEvent::LeftButtonDown),
             PlatformMouseEvent::FromTouch, WTF::monotonicallyIncreasingTime(), WebPointerProperties::PointerType::Mouse);
@@ -3638,7 +3659,6 @@ HitTestResult EventHandler::hitTestResultInFrame(LocalFrame* frame, const Layout
 WebInputEventResult EventHandler::handleTouchEvent(const PlatformTouchEvent& event)
 {
     TRACE_EVENT0("blink", "EventHandler::handleTouchEvent");
-
     return m_pointerEventManager.handleTouchEvents(event);
 }