Create MouseEventManager and EventHandlingUtil

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

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/input/EventHandlingUtil.h"
+
+#include "core/frame/FrameView.h"
+
+namespace blink {
+namespace EventHandlingUtil {
+
+namespace {
+
+bool isInDocument(EventTarget* n)
+{
+    return n && n->toNode() && n->toNode()->isConnected();
+}
+
+void buildAncestorChain(
+    EventTarget* target,
+    HeapVector<Member<Node>, 20>* ancestors)
+{
+    if (!isInDocument(target))
+        return;
+    Node* targetNode = target->toNode();
+    DCHECK(targetNode);
+    targetNode->updateDistribution();
+    // Index 0 element in the ancestors arrays will be the corresponding
+    // target. So the root of their document will be their last element.
+    for (Node* node = targetNode; node; node = FlatTreeTraversal::parent(*node))
+        ancestors->append(node);
+}
+
+void buildAncestorChainsAndFindCommonAncestors(
+    EventTarget* exitedTarget, EventTarget* enteredTarget,
+    HeapVector<Member<Node>, 20>* exitedAncestorsOut,
+    HeapVector<Member<Node>, 20>* enteredAncestorsOut,
+    size_t* exitedAncestorsCommonParentIndexOut,
+    size_t* enteredAncestorsCommonParentIndexOut)
+{
+    DCHECK(exitedAncestorsOut);
+    DCHECK(enteredAncestorsOut);
+    DCHECK(exitedAncestorsCommonParentIndexOut);
+    DCHECK(enteredAncestorsCommonParentIndexOut);
+
+    buildAncestorChain(exitedTarget, exitedAncestorsOut);
+    buildAncestorChain(enteredTarget, enteredAncestorsOut);
+
+    *exitedAncestorsCommonParentIndexOut = exitedAncestorsOut->size();
+    *enteredAncestorsCommonParentIndexOut = enteredAncestorsOut->size();
+    while (*exitedAncestorsCommonParentIndexOut > 0
+        && *enteredAncestorsCommonParentIndexOut > 0) {
+        if ((*exitedAncestorsOut)[(*exitedAncestorsCommonParentIndexOut) - 1]
+            != (*enteredAncestorsOut)[(*enteredAncestorsCommonParentIndexOut) - 1])
+            break;
+        (*exitedAncestorsCommonParentIndexOut)--;
+        (*enteredAncestorsCommonParentIndexOut)--;
+    }
+}
+
+} // namespace
+
+HitTestResult hitTestResultInFrame(LocalFrame* frame, const LayoutPoint& point, HitTestRequest::HitTestRequestType hitType)
+{
+    HitTestResult result(HitTestRequest(hitType), point);
+
+    if (!frame || frame->contentLayoutItem().isNull())
+        return result;
+    if (frame->view()) {
+        IntRect rect = frame->view()->visibleContentRect(IncludeScrollbars);
+        if (!rect.contains(roundedIntPoint(point)))
+            return result;
+    }
+    frame->contentLayoutItem().hitTest(result);
+    return result;
+}
+
+WebInputEventResult 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:
+    // (HandledApplication, HandledSystem) -> HandledSystem
+    // (NotHandled, HandledApplication) -> HandledApplication
+    static_assert(static_cast<int>(WebInputEventResult::NotHandled) == 0, "WebInputEventResult not ordered");
+    static_assert(static_cast<int>(WebInputEventResult::HandledSuppressed) < static_cast<int>(WebInputEventResult::HandledApplication), "WebInputEventResult not ordered");
+    static_assert(static_cast<int>(WebInputEventResult::HandledApplication) < static_cast<int>(WebInputEventResult::HandledSystem), "WebInputEventResult not ordered");
+    return static_cast<WebInputEventResult>(max(static_cast<int>(resultA), static_cast<int>(resultB)));
+}
+
+WebInputEventResult toWebInputEventResult(
+    DispatchEventResult result)
+{
+    switch (result) {
+    case DispatchEventResult::NotCanceled:
+        return WebInputEventResult::NotHandled;
+    case DispatchEventResult::CanceledByEventHandler:
+        return WebInputEventResult::HandledApplication;
+    case DispatchEventResult::CanceledByDefaultEventHandler:
+        return WebInputEventResult::HandledSystem;
+    case DispatchEventResult::CanceledBeforeDispatch:
+        return WebInputEventResult::HandledSuppressed;
+    default:
+        NOTREACHED();
+        return WebInputEventResult::HandledSystem;
+    }
+}
+
+void sendBoundaryEvents(

[mustaq, 2016/08/23 15:20:48]

Make it a member function in BoundaryEventDispatcher class?

Consider the same for all the util methods in the anonymous namespace.

[Navid Zolghadr, 2016/08/24 16:07:28]

You mean the methods in anonymous name space in this file? Why would we expose
those in a header file while we don't need them to be? Having them in an
anonymous name space only in this file is less exposed. Isn't it?

[mustaq, 2016/08/26 19:31:44]

- The methods in the anonymous namespace have no use outside the
BoundaryEventDispatcher class, so |private| in the class seems better to me.

- All calls to this sendBoundaryEvents() are made right after the dispatcher
object is created. It suggests that these two steps should appear atomic from
the caller's side. Another possibility is to make the dispatcher class private
here, and have two exposed sendBoundaryEvents for ME & PE. Just a food for
thought, I will leave it on your judgement.

[Navid Zolghadr, 2016/08/30 18:46:26]

I moved the BoundaryEventDispatcher class to another file so that these methods
are only visible to that file.
The two functions that send Boundary event for ME and PE are essentially
PointerEventManager::sendBoundaryEvents and
MouseEventManager::sendBoundaryEvents and I use these everywhere else in these
files.

+    EventTarget* exitedTarget,
+    EventTarget* enteredTarget,
+    BoundaryEventDispatcher* dispatcher)
+{
+    if (exitedTarget == enteredTarget)
+        return;
+
+    // Dispatch out/out events
+    if (isInDocument(exitedTarget))
+        dispatcher->dispatchOut(exitedTarget, enteredTarget);
+
+    // Create lists of all exited/entered ancestors, locate the common ancestor
+    // Based on httparchive, in more than 97% cases the depth of DOM is less
+    // than 20.
+    HeapVector<Member<Node>, 20> exitedAncestors;
+    HeapVector<Member<Node>, 20> enteredAncestors;
+    size_t exitedAncestorsCommonParentIndex = 0;
+    size_t enteredAncestorsCommonParentIndex = 0;
+
+    // A note on mouseenter and mouseleave: These are non-bubbling events, and they are dispatched if there
+    // is a capturing event handler on an ancestor or a normal event handler on the element itself. This special
+    // handling is necessary to avoid O(n^2) capturing event handler checks.
+    //
+    //   Note, however, that this optimization can possibly cause some unanswered/missing/redundant mouseenter or
+    // mouseleave events in certain contrived eventhandling scenarios, e.g., when:
+    // - the mouseleave handler for a node sets the only capturing-mouseleave-listener in its ancestor, or
+    // - DOM mods in any mouseenter/mouseleave handler changes the common ancestor of exited & entered nodes, etc.
+    // We think the spec specifies a "frozen" state to avoid such corner cases (check the discussion on "candidate event
+    // listeners" at http://www.w3.org/TR/uievents), but our code below preserves one such behavior from past only to
+    // match Firefox and IE behavior.
+    //
+    // TODO(mustaq): Confirm spec conformance, double-check with other browsers.
+
+    buildAncestorChainsAndFindCommonAncestors(
+        exitedTarget, enteredTarget,
+        &exitedAncestors, &enteredAncestors,
+        &exitedAncestorsCommonParentIndex, &enteredAncestorsCommonParentIndex);
+
+    bool exitedNodeHasCapturingAncestor = false;
+    for (size_t j = 0; j < exitedAncestors.size(); j++) {
+        if (exitedAncestors[j]->hasCapturingEventListeners(EventTypeNames::mouseleave)
+            || (RuntimeEnabledFeatures::pointerEventEnabled()
+                && exitedAncestors[j]->hasCapturingEventListeners(EventTypeNames::pointerleave)))
+            exitedNodeHasCapturingAncestor = true;
+    }
+
+    // Dispatch leave events, in child-to-parent order.
+    for (size_t j = 0; j < exitedAncestorsCommonParentIndex; j++)
+        dispatcher->dispatchLeave(exitedTarget, enteredTarget, !exitedNodeHasCapturingAncestor);
+
+    // Dispatch over
+    if (isInDocument(enteredTarget))
+        dispatcher->dispatchOver(enteredTarget, exitedTarget);
+
+    // Defer locating capturing enter listener until /after/ dispatching the leave events because
+    // the leave handlers might set a capturing enter handler.
+    bool enteredNodeHasCapturingAncestor = false;
+    for (size_t i = 0; i < enteredAncestors.size(); i++) {
+        if (enteredAncestors[i]->hasCapturingEventListeners(EventTypeNames::mouseenter)
+            || (RuntimeEnabledFeatures::pointerEventEnabled()
+                && enteredAncestors[i]->hasCapturingEventListeners(EventTypeNames::pointerenter)))
+            enteredNodeHasCapturingAncestor = true;
+    }
+
+    // Dispatch enter events, in parent-to-child order.
+    for (size_t i = enteredAncestorsCommonParentIndex; i > 0; i--)
+        dispatcher->dispatchEnter(enteredTarget, exitedTarget, !enteredNodeHasCapturingAncestor);
+}
+
+} // namespace EventHandlingUtil
+} // namespace blink