Suppressed MEs for gestures from cancelled PEs

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 197 matching lines @@
     , m_eventHandlerWillResetCapturingMouseEventsNode(0)
     , m_clickCount(0)
     , m_shouldOnlyFireDragOverEvent(false)
     , m_mousePositionIsUnknown(true)
     , m_mouseDownTimestamp(0)
     , m_pointerEventManager(frame)
     , m_scrollManager(frame)
     , m_longTapShouldInvokeContextMenu(false)
     , m_activeIntervalTimer(this, &EventHandler::activeIntervalTimerFired)
     , m_lastShowPressTimestamp(0)
+    , m_suppressMouseEventsFromGestures(false)
 {
 }
 
 EventHandler::~EventHandler()
 {
     ASSERT(!m_fakeMouseMoveEventTimer.isActive());
 }
 
 DEFINE_TRACE(EventHandler)
 {
@@ skipping 46 matching lines @@
     m_lastShowPressTimestamp = 0;
     m_lastDeferredTapElement = nullptr;
     m_eventHandlerWillResetCapturingMouseEventsNode = false;
     m_mouseDownMayStartAutoscroll = false;
     m_svgPan = false;
     m_mouseDownPos = IntPoint();
     m_mouseDownTimestamp = 0;
     m_longTapShouldInvokeContextMenu = false;
     m_dragStartPos = LayoutPoint();
     m_mouseDown = PlatformMouseEvent();
+    m_suppressMouseEventsFromGestures = false;
 }
 
 WebInputEventResult EventHandler::mergeEventResult(
     WebInputEventResult resultA, WebInputEventResult resultB)
 {
     // The ordering of the enumeration is specific. There are times that
     // multiple events fire and we need to combine them into a single
     // result code. The enumeration is based on the level of consumption that
     // is most significant. The enumeration is ordered with smaller specified
     // numbers first. Examples of merged results are:
@@ skipping 1508 matching lines @@
         if (gestureDomEvent) {
             DispatchEventResult gestureDomEventResult = eventTarget->dispatchEvent(gestureDomEvent);
             if (gestureDomEventResult != DispatchEventResult::NotCanceled) {
                 ASSERT(gestureDomEventResult != DispatchEventResult::CanceledByEventHandler);
                 return toWebInputEventResult(gestureDomEventResult);
             }
         }
     }
 
     switch (gestureEvent.type()) {
+    case PlatformEvent::GestureTapDown:
+        return handleGestureTapDown(targetedEvent);
     case PlatformEvent::GestureTap:
         return handleGestureTap(targetedEvent);
     case PlatformEvent::GestureShowPress:
         return handleGestureShowPress();
     case PlatformEvent::GestureLongPress:
         return handleGestureLongPress(targetedEvent);
     case PlatformEvent::GestureLongTap:
         return handleGestureLongTap(targetedEvent);
     case PlatformEvent::GestureTwoFingerTap:
         return sendContextMenuEventForGesture(targetedEvent);
-    case PlatformEvent::GestureTapDown:
     case PlatformEvent::GesturePinchBegin:
     case PlatformEvent::GesturePinchEnd:
     case PlatformEvent::GesturePinchUpdate:
     case PlatformEvent::GestureTapDownCancel:
     case PlatformEvent::GestureTapUnconfirmed:
         break;
     default:
         ASSERT_NOT_REACHED();
     }
 
     return WebInputEventResult::NotHandled;
 }
 
 WebInputEventResult EventHandler::handleGestureScrollEvent(const PlatformGestureEvent& gestureEvent)
 {
     TRACE_EVENT0("input", "EventHandler::handleGestureScrollEvent");
 
     return m_scrollManager.handleGestureScrollEvent(gestureEvent);
 }
 
+WebInputEventResult EventHandler::handleGestureTapDown(const GestureEventWithHitTestResults& targetedEvent)
+{
+    m_suppressMouseEventsFromGestures =
+        m_pointerEventManager.primaryPointerdownCanceled(targetedEvent.event().uniqueTouchEventId());
+    return WebInputEventResult::NotHandled;
+}
+
 WebInputEventResult EventHandler::handleGestureTap(const GestureEventWithHitTestResults& targetedEvent)
 {
     FrameView* frameView(m_frame->view());
     const PlatformGestureEvent& gestureEvent = targetedEvent.event();
     HitTestRequest::HitTestRequestType hitType = getHitTypeForGestureType(gestureEvent.type());
     uint64_t preDispatchDomTreeVersion = m_frame->document()->domTreeVersion();
     uint64_t preDispatchStyleVersion = m_frame->document()->styleVersion();
 
     UserGestureIndicator gestureIndicator(DefinitelyProcessingUserGesture);
 
     HitTestResult currentHitTest = targetedEvent.hitTestResult();
 
     // 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());
 
-    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);
+    const unsigned modifiers = gestureEvent.getModifiers();
+
+    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
     // don't want to re-hit-test because it may be in the wrong frame (and there's no way the page
     // could have seen the event anyway).
     // Also note that the position of the frame may have changed, so we need to recompute the content
     // co-ordinates (updating layout/style as hitTestResultAtPoint normally would).
     // FIXME: Use a hit-test cache to avoid unnecessary hit tests. http://crbug.com/398920
     if (currentHitTest.innerNode()) {
         LocalFrame* mainFrame = m_frame->localFrameRoot();
         if (mainFrame && mainFrame->view())
             mainFrame->view()->updateLifecycleToCompositingCleanPlusScrolling();
         adjustedPoint = frameView->rootFrameToContents(gestureEvent.position());
         currentHitTest = hitTestResultInFrame(m_frame, adjustedPoint, hitType);
     }
     m_clickNode = currentHitTest.innerNode();
 
     // Capture data for showUnhandledTapUIIfNeeded.
     Node* tappedNode = m_clickNode;
     IntPoint tappedPosition = gestureEvent.position();
 
     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));
+        PlatformMouseEvent::FromTouch, gestureEvent.timestamp(), WebPointerProperties::PointerType::Mouse);
+
+    // TODO(mustaq): We suppress MEs plus all it's side effects. What would that
+    // mean for for TEs?  What's the right balance here? crbug.com/617255
+    WebInputEventResult mouseDownEventResult = WebInputEventResult::NotHandled;

[Rick Byers, 2016/06/09 16:07:33]

nit: this local isn't used outside the below scope - move the declaration into
the scope of the if.

[mustaq, 2016/06/09 16:41:03]

The mergeEventResult calls at the end combine all the individual results,
including this one, to get the "highest" result. If you think we can skip the
mousedown there, I will add a TODO to avoid changing any behavior in this CL).

[Rick Byers, 2016/06/09 17:01:33]

Oh sorry, my search missed it (due to wrapping in rietveld) - I was surprised
not to find that.  It's probably only contextual search that relies on the
return value from this function, and in that case cancelling the pointerDown
should definitely prevent CS UI from appearing (so you really don't want to
return NotHandled in that case).

[mustaq, 2016/06/09 17:17:27]

Acknowledged.

+    if (!m_suppressMouseEventsFromGestures) {
+        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));
+    }
 
     if (currentHitTest.innerNode()) {
         ASSERT(gestureEvent.type() == PlatformEvent::GestureTap);
         HitTestResult result = currentHitTest;
         result.setToShadowHostIfInUserAgentShadowRoot();
         m_frame->chromeClient().onMouseDown(result.innerNode());
     }
 
     // FIXME: Use a hit-test cache to avoid unnecessary hit tests. http://crbug.com/398920
     if (currentHitTest.innerNode()) {
         LocalFrame* mainFrame = m_frame->localFrameRoot();
         if (mainFrame && mainFrame->view())
             mainFrame->view()->updateAllLifecyclePhases();
         adjustedPoint = frameView->rootFrameToContents(gestureEvent.position());
         currentHitTest = hitTestResultInFrame(m_frame, adjustedPoint, hitType);
     }
+
     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);
+    WebInputEventResult mouseUpEventResult = WebInputEventResult::NotHandled;
+    if (!m_suppressMouseEventsFromGestures)
+        mouseUpEventResult = dispatchMouseEvent(EventTypeNames::mouseup, currentHitTest.innerNode(), gestureEvent.tapCount(), fakeMouseUp);
 
     WebInputEventResult clickEventResult = WebInputEventResult::NotHandled;
     if (m_clickNode) {
         if (currentHitTest.innerNode()) {
             // Updates distribution because a mouseup (or mousedown) event listener can make the
             // tree dirty at dispatchMouseEvent() invocation above.
             // Unless distribution is updated, commonAncestor would hit ASSERT.
             // Both m_clickNode and currentHitTest.innerNode()) don't need to be updated
             // because commonAncestor() will exit early if their documents are different.
             m_clickNode->updateDistribution();
             Node* clickTargetNode = currentHitTest.innerNode()->commonAncestor(*m_clickNode, parentForClickEvent);
             clickEventResult = dispatchMouseEvent(EventTypeNames::click, clickTargetNode, gestureEvent.tapCount(), fakeMouseUp);
         }
         m_clickNode = nullptr;
     }
 
-    if (mouseUpEventResult == WebInputEventResult::NotHandled)
+    if (!m_suppressMouseEventsFromGestures && mouseUpEventResult == WebInputEventResult::NotHandled)

[Rick Byers, 2016/06/09 16:07:33]

nit: you can simplify this slightly and have the exact same behavior by
initializing mouseUpEventResult to handledSuppressed, then you don't need to
re-check m_suppressMouseEventsFromGestures here (and logically it makes sense -
if m_suppressMouseEventsFromGestures is true, then the mouseUp event WASN'T "not
handled", it was never sent in the first place which is what "suppressed"
means).

[mustaq, 2016/06/09 16:41:03]

Done.

Dave, are you okay with this? This only affects the canceled pointerdown case,
so no regression from caller's perspective.

[dtapuska, 2016/06/09 16:55:02]

That is alright. Like I said we could interpret it either way. 

         mouseUpEventResult = handleMouseReleaseEvent(MouseEventWithHitTestResults(fakeMouseUp, currentHitTest));
 
     WebInputEventResult eventResult = mergeEventResult(mergeEventResult(mouseDownEventResult, mouseUpEventResult), clickEventResult);
     if (eventResult == WebInputEventResult::NotHandled && tappedNode && m_frame->page()) {
         bool domTreeChanged = preDispatchDomTreeVersion != m_frame->document()->domTreeVersion();
         bool styleChanged = preDispatchStyleVersion != m_frame->document()->styleVersion();
 
         IntPoint tappedPositionInViewport = frameHost()->visualViewport().rootFrameToViewport(tappedPosition);
         m_frame->chromeClient().showUnhandledTapUIIfNeeded(tappedPositionInViewport, tappedNode, domTreeChanged || styleChanged);
     }
     return eventResult;
 }
 
 WebInputEventResult EventHandler::handleGestureLongPress(const GestureEventWithHitTestResults& targetedEvent)
 {
     const PlatformGestureEvent& gestureEvent = targetedEvent.event();
     IntPoint adjustedPoint = gestureEvent.position();
 
     unsigned modifiers = gestureEvent.getModifiers();
 
     // FIXME: Ideally we should try to remove the extra mouse-specific hit-tests here (re-using the
     // supplied HitTestResult), but that will require some overhaul of the touch drag-and-drop code
     // and LongPress is such a special scenario that it's unlikely to matter much in practice.
 
     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);
         m_mouseDown = mouseDownEvent;
 
         PlatformMouseEvent mouseDragEvent(adjustedPoint, gestureEvent.globalPosition(), LeftButton, PlatformEvent::MouseMoved, 1,
             static_cast<PlatformEvent::Modifiers>(modifiers | PlatformEvent::LeftButtonDown),
             PlatformMouseEvent::FromTouch, WTF::monotonicallyIncreasingTime(), WebPointerProperties::PointerType::Mouse);
         HitTestRequest request(HitTestRequest::ReadOnly);
         MouseEventWithHitTestResults mev = prepareMouseEvent(request, mouseDragEvent);
@@ skipping 1109 matching lines @@
         if (!rect.contains(roundedIntPoint(point)))
             return result;
     }
     frame->contentLayoutItem().hitTest(result);
     return result;
 }
 
 WebInputEventResult EventHandler::handleTouchEvent(const PlatformTouchEvent& event)
 {
     TRACE_EVENT0("blink", "EventHandler::handleTouchEvent");
-
     return m_pointerEventManager.handleTouchEvents(event);
 }
 
 void EventHandler::setLastKnownMousePosition(const PlatformMouseEvent& event)
 {
     m_mousePositionIsUnknown = false;
     m_lastKnownMousePosition = event.position();
     m_lastKnownMouseGlobalPosition = event.globalPosition();
 }
 
@@ skipping 48 matching lines @@
 
 FrameHost* EventHandler::frameHost() const
 {
     if (!m_frame->page())
         return nullptr;
 
     return &m_frame->page()->frameHost();
 }
 
 } // namespace blink