Create MouseEventManager and EventHandlingUtil

third_party/WebKit/Source/core/input/BoundaryEventDispatcher.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/BoundaryEventDispatcher.h"
+
+#include "core/dom/Node.h"
+#include "core/dom/shadow/FlatTreeTraversal.h"
+
+namespace blink {
+
+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
+
+void BoundaryEventDispatcher::sendBoundaryEvents(
+    EventTarget* exitedTarget,
+    EventTarget* enteredTarget)
+{
+    if (exitedTarget == enteredTarget)
+        return;
+
+    // Dispatch out event
+    if (isInDocument(exitedTarget))
+        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(getLeaveEvent()))

[dtapuska, 2016/09/02 03:26:27]

I don't think you need to call the getLeaveEvent() for every possible node in
the path do you?

Can't think loop exit early?

[Navid Zolghadr, 2016/09/02 16:36:45]

Yup. That is certainly possible. Didn't pay attention when I was copy pasting
here. Done.

+            exitedNodeHasCapturingAncestor = true;
+    }
+
+    // Dispatch leave events, in child-to-parent order.
+    for (size_t j = 0; j < exitedAncestorsCommonParentIndex; j++)
+        dispatchLeave(exitedAncestors[j], enteredTarget, !exitedNodeHasCapturingAncestor);
+
+    // Dispatch over event
+    if (isInDocument(enteredTarget))
+        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++) {

[dtapuska, 2016/09/02 03:26:27]

Same as above.

[Navid Zolghadr, 2016/09/02 16:36:45]

Done.

+        if (enteredAncestors[i]->hasCapturingEventListeners(getEnterEvent()))
+            enteredNodeHasCapturingAncestor = true;
+    }
+
+    // Dispatch enter events, in parent-to-child order.
+    for (size_t i = enteredAncestorsCommonParentIndex; i > 0; i--)
+        dispatchEnter(enteredAncestors[i - 1], exitedTarget, !enteredNodeHasCapturingAncestor);
+}
+
+} // namespace blink