PointerEvents for long-press: fix double firing & canceling MEs

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 756 matching lines @@
 }
 
 static LayoutPoint contentPointFromRootFrame(LocalFrame* frame, const IntPoint& pointInRootFrame)
 {
     FrameView* view = frame->view();
     // FIXME: Is it really OK to use the wrong coordinates here when view is 0?
     // Historically the code would just crash; this is clearly no worse than that.
     return view ? view->rootFrameToContents(pointInRootFrame) : pointInRootFrame;
 }
 
-WebInputEventResult EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent)
+WebInputEventResult EventHandler::handleMousePressEvent(const PlatformMouseEvent& mouseEvent, const bool synthesizedFromTouch)
 {
     TRACE_EVENT0("blink", "EventHandler::handleMousePressEvent");
 
     // For 4th/5th button in the mouse since Chrome does not yet send
     // button value to Blink but in some cases it does send the event.
     // This check is needed to suppress such an event (crbug.com/574959)
     if (mouseEvent.button() == NoButton)
         return WebInputEventResult::HandledSuppressed;
 
     UserGestureIndicator gestureIndicator(DefinitelyProcessingUserGesture);
@@ skipping 58 matching lines @@
         return WebInputEventResult::HandledSuppressed;
     }
 #endif
 
     m_clickCount = mouseEvent.clickCount();
     m_clickNode = mev.innerNode()->isTextNode() ?  FlatTreeTraversal::parent(*mev.innerNode()) : mev.innerNode();
 
     if (!mouseEvent.fromTouch())
         m_frame->selection().setCaretBlinkingSuspended(true);
 
-    WebInputEventResult eventResult = updatePointerTargetAndDispatchEvents(EventTypeNames::mousedown, mev.innerNode(), m_clickCount, mev.event());
+    WebInputEventResult eventResult = updatePointerTargetAndDispatchEvents(
+        EventTypeNames::mousedown, mev.innerNode(), m_clickCount, mev.event(), synthesizedFromTouch);
 
     if (eventResult == WebInputEventResult::NotHandled && m_frame->view()) {
         FrameView* view = m_frame->view();
         PaintLayer* layer = mev.innerNode()->layoutObject() ? mev.innerNode()->layoutObject()->enclosingLayer() : nullptr;
         IntPoint p = view->rootFrameToContents(mouseEvent.position());
         if (layer && layer->getScrollableArea() && layer->getScrollableArea()->isPointInResizeControl(p, ResizerForPointer)) {
             m_scrollManager.setResizeScrollableArea(layer, p);
             return WebInputEventResult::HandledSystem;
         }
     }
 
     // m_selectionInitiationState is initialized after dispatching mousedown
     // event in order not to keep the selection by DOM APIs Because we can't
     // give the user the chance to handle the selection by user action like
     // dragging if we keep the selection in case of mousedown. FireFox also has
     // the same behavior and it's more compatible with other browsers.
     selectionController().initializeSelectionState();
     HitTestResult hitTestResult = hitTestResultInFrame(m_frame, documentPoint, HitTestRequest::ReadOnly);
-    InputDeviceCapabilities* sourceCapabilities = mouseEvent.getSyntheticEventType() == PlatformMouseEvent::FromTouch ? InputDeviceCapabilities::firesTouchEventsSourceCapabilities() :
-        InputDeviceCapabilities::doesntFireTouchEventsSourceCapabilities();
+    InputDeviceCapabilities* sourceCapabilities = mouseEvent.getSyntheticEventType() == PlatformMouseEvent::FromTouch
+        ? InputDeviceCapabilities::firesTouchEventsSourceCapabilities()
+        : InputDeviceCapabilities::doesntFireTouchEventsSourceCapabilities();
     if (eventResult == WebInputEventResult::NotHandled)
         eventResult = handleMouseFocus(MouseEventWithHitTestResults(mev.event(), hitTestResult), sourceCapabilities);
     m_capturesDragging = eventResult == WebInputEventResult::NotHandled || mev.scrollbar();
 
     // If the hit testing originally determined the event was in a scrollbar, refetch the MouseEventWithHitTestResults
     // in case the scrollbar widget was destroyed when the mouse event was handled.
     if (mev.scrollbar()) {
         const bool wasLastScrollBar = mev.scrollbar() == m_lastScrollbarUnderMouse.get();
         HitTestRequest request(HitTestRequest::ReadOnly | HitTestRequest::Active);
         mev = m_frame->document()->prepareMouseEvent(request, documentPoint, mouseEvent);
@@ skipping 603 matching lines @@
 {
     m_pointerEventManager.releasePointerCapture(pointerId, target);
 }
 
 void EventHandler::elementRemoved(EventTarget* target)
 {
     m_pointerEventManager.elementRemoved(target);
 }
 
 // TODO(mustaq): Make PE drive ME dispatch & bookkeeping in EventHandler.
-WebInputEventResult EventHandler::updatePointerTargetAndDispatchEvents(const AtomicString& mouseEventType, Node* targetNode, int clickCount, const PlatformMouseEvent& mouseEvent)
+WebInputEventResult EventHandler::updatePointerTargetAndDispatchEvents(const AtomicString& mouseEventType, Node* targetNode, int clickCount, const PlatformMouseEvent& mouseEvent, const bool synthesizedFromTouch)
 {
     ASSERT(mouseEventType == EventTypeNames::mousedown
         || mouseEventType == EventTypeNames::mousemove
         || mouseEventType == EventTypeNames::mouseup);
 
     Node* lastNodeUnderMouse = updateMouseEventTargetNode(targetNode, mouseEvent);
 
+    if (synthesizedFromTouch)
+        return dispatchMouseEvent(mouseEventType, m_nodeUnderMouse, clickCount, mouseEvent);
+
     return m_pointerEventManager.sendMousePointerEvent(
         m_nodeUnderMouse, mouseEventType, clickCount, mouseEvent, nullptr,
         lastNodeUnderMouse);
 }
 
 WebInputEventResult EventHandler::handleMouseFocus(const MouseEventWithHitTestResults& targetedEvent, InputDeviceCapabilities* sourceCapabilities)
 {
     // If clicking on a frame scrollbar, do not mess up with content focus.
     if (targetedEvent.hitTestResult().scrollbar() && !m_frame->contentLayoutItem().isNull()) {
         if (targetedEvent.hitTestResult().scrollbar()->getScrollableArea() == m_frame->contentLayoutItem().getScrollableArea())
@@ skipping 864 matching lines @@
     // Always set right button down as we are sending mousedown event regardless
     modifiers |= PlatformEvent::RightButtonDown;
 
     // TODO(crbug.com/579564): Maybe we should not send mouse down at all
     PlatformMouseEvent mouseEvent(targetedEvent.event().position(), targetedEvent.event().globalPosition(), RightButton, eventType, 1,
         static_cast<PlatformEvent::Modifiers>(modifiers),
         PlatformMouseEvent::FromTouch, WTF::monotonicallyIncreasingTime(), WebPointerProperties::PointerType::Mouse);
     // To simulate right-click behavior, we send a right mouse down and then
     // context menu event.
     // FIXME: Send HitTestResults to avoid redundant hit tests.
-    handleMousePressEvent(mouseEvent);
+
+    handleMousePressEvent(mouseEvent, true);

[Rick Byers, 2016/07/14 14:27:10]

I think the real bug here related to the above FIXME and TODO comments.  

HandleGestureTap is careful to be explicit about what additional hit-tests need
to happen and call only in to the DOM mouse-event generation logic.  But here
we're calling the raw PlatformMouseEvent entrypoint.  That seems inconsistent
and wrong.  Couldn't we just follow the same pattern as HandleGestureTap (and
for the mousemove above) and invoke just the DOM event-generation logic rather
than re-using the entire low-level handleMousePressEvent code path?

That would then also open up the possibility of not firing the mousedown (I
think we probably shouldn't) and potentially avoiding the hit-test (though it
might be required for web compat).

Is that easy to do without a ton of code duplication / refactoring?  At a
minimum you shouldn't have to add any new "from touch" tracking, you've already
marked the PlatformMouseEvent as "FromTouch" above.

[mustaq, 2016/07/14 15:05:14]

I tried to address the TODO but Edge sends mousedown/up before a contextmenu
event triggerred by a long-tap, so suppressing them looks breaking to me. I will
avoid doing it in this CL.

Also considered triggering only the DOM generation logic here but that would
bypass all the mouse-pressed related bookkeeping we are triggering here for
GestureLongPree, GestureLongTap & GestureTwoFingerTap. Do you it is safe to do
so?

I missed the FromTouch bit here, will use it if minimal DOM event generation
seems unsafe.

+
     return sendContextMenuEvent(mouseEvent);
     // We do not need to send a corresponding mouse release because in case of
     // right-click, the context menu takes capture and consumes all events.
 }
 
 void EventHandler::scheduleHoverStateUpdate()
 {
     if (!m_hoverTimer.isActive())
         m_hoverTimer.startOneShot(0, BLINK_FROM_HERE);
 }
@@ skipping 449 matching lines @@
 
 FrameHost* EventHandler::frameHost() const
 {
     if (!m_frame->page())
         return nullptr;
 
     return &m_frame->page()->frameHost();
 }
 
 } // namespace blink