Implement 'mouseenter' and 'mouseleave' from DOM Level 3 Events.

Source/core/dom/Document.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 2877 matching lines @@
     // mousemove events before the first layout should not lead to a premature layout()
     // happening, which could show a flash of white.
     // See also the similar code in EventHandler::hitTestResultAtPoint.
     if (!renderer() || !view() || !view()->didFirstLayout())
         return MouseEventWithHitTestResults(event, HitTestResult(LayoutPoint()));
 
     HitTestResult result(documentPoint);
     renderView()->hitTest(request, result);
 
     if (!request.readOnly())
-        updateHoverActiveState(request, result.innerElement());
+        updateHoverActiveState(request, result.innerElement(), &event);
 
     return MouseEventWithHitTestResults(event, result);
 }
 
 // DOM Section 1.1.1
 bool Document::childTypeAllowed(NodeType type) const
 {
     switch (type) {
     case ATTRIBUTE_NODE:
     case CDATA_SECTION_NODE:
@@ skipping 2074 matching lines @@
     for (RenderObject* currObj1 = obj1; currObj1; currObj1 = currObj1->hoverAncestor()) {
         for (RenderObject* currObj2 = obj2; currObj2; currObj2 = currObj2->hoverAncestor()) {
             if (currObj1 == currObj2)
                 return currObj1;
         }
     }
 
     return 0;
 }
 
-void Document::updateHoverActiveState(const HitTestRequest& request, Element* innerElement)
+void Document::updateHoverActiveState(const HitTestRequest& request, Element* innerElement, const PlatformMouseEvent* event)
 {
     ASSERT(!request.readOnly());
 
     Element* innerElementInDocument = innerElement;
     while (innerElementInDocument && innerElementInDocument->document() != this) {
-        innerElementInDocument->document()->updateHoverActiveState(request, innerElementInDocument);
+        innerElementInDocument->document()->updateHoverActiveState(request, innerElementInDocument, event);
         innerElementInDocument = innerElementInDocument->document()->ownerElement();
     }
 
     Element* oldActiveElement = activeElement();
     if (oldActiveElement && !request.active()) {
         // We are clearing the :active chain because the mouse has been released.
         for (RenderObject* curr = oldActiveElement->renderer(); curr; curr = curr->parent()) {
             if (curr->node()) {
                 ASSERT(!curr->node()->isTextNode());
                 curr->node()->setActive(false);
@@ skipping 42 matching lines @@
     // We have two different objects. Fetch their renderers.
     RenderObject* oldHoverObj = oldHoverNode ? oldHoverNode->renderer() : 0;
     RenderObject* newHoverObj = newHoverNode ? newHoverNode->renderer() : 0;
 
     // Locate the common ancestor render object for the two renderers.
     RenderObject* ancestor = nearestCommonHoverAncestor(oldHoverObj, newHoverObj);
 
     Vector<RefPtr<Node>, 32> nodesToRemoveFromChain;
     Vector<RefPtr<Node>, 32> nodesToAddToChain;
 
+    // mouseenter and mouseleave events do not bubble, so they are dispatched iff there is a capturing

[PhistucK, 2013/07/08 17:57:26]

s/iff/if

[Mike West, 2013/07/09 09:37:00]

"iff" is short for "if and only if" (e.g. "necessary and sufficient"). I guess
that's not a well-known abbreviation. I'll change the text.

+    // 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.
+    bool hasCapturingMouseEnterListener = false;
+    bool hasCapturingMouseLeaveListener = false;
+    if (event && newHoverNode != oldHoverNode.get()) {
+        // Walk up the newly hovered node's ancestor tree for 'mouseenter' events, and the previously
+        // hovered node's ancestor tree for 'mouseleave' events.
+        for (Node* node = newHoverNode; node; node = node->parentOrShadowHostNode()) {
+            if (node->hasCapturingEventListeners(eventNames().mouseenterEvent)) {
+                hasCapturingMouseEnterListener = true;
+                break;
+            }
+        }
+        for (Node* node = oldHoverNode.get(); node; node = node->parentOrShadowHostNode()) {
+            if (node->hasCapturingEventListeners(eventNames().mouseleaveEvent)) {
+                hasCapturingMouseLeaveListener = true;
+                break;
+            }
+        }
+    }
+
     if (oldHoverObj != newHoverObj) {
         // If the old hovered node is not nil but it's renderer is, it was probably detached as part of the :hover style
         // (for instance by setting display:none in the :hover pseudo-class). In this case, the old hovered element (and its ancestors)
         // must be updated, to ensure it's normal style is re-applied.
         if (oldHoverNode && !oldHoverObj) {
             for (Node* node = oldHoverNode.get(); node; node = node->parentNode()) {
                 if (!mustBeInActiveChain || (node->isElementNode() && toElement(node)->inActiveChain()))
                     nodesToRemoveFromChain.append(node);
             }
 
         }
 
         // The old hover path only needs to be cleared up to (and not including) the common ancestor;
         for (RenderObject* curr = oldHoverObj; curr && curr != ancestor; curr = curr->hoverAncestor()) {
             if (curr->node() && !curr->isText() && (!mustBeInActiveChain || curr->node()->inActiveChain()))
                 nodesToRemoveFromChain.append(curr->node());
         }
     }
 
     // Now set the hover state for our new object up to the root.
     for (RenderObject* curr = newHoverObj; curr; curr = curr->hoverAncestor()) {
         if (curr->node() && !curr->isText() && (!mustBeInActiveChain || curr->node()->inActiveChain()))
             nodesToAddToChain.append(curr->node());
     }
 
     size_t removeCount = nodesToRemoveFromChain.size();
-    for (size_t i = 0; i < removeCount; ++i)
+    for (size_t i = 0; i < removeCount; ++i) {
         nodesToRemoveFromChain[i]->setHovered(false);
+        if (event && (hasCapturingMouseLeaveListener || nodesToRemoveFromChain[i]->hasEventListeners(eventNames().mouseleaveEvent)))
+            nodesToRemoveFromChain[i]->dispatchMouseEvent(*event, eventNames().mouseleaveEvent, 0, newHoverNode);
+    }
 
     bool sawCommonAncestor = false;
     size_t addCount = nodesToAddToChain.size();
     for (size_t i = 0; i < addCount; ++i) {
         // Elements past the common ancestor do not change hover state, but might change active state.
         if (ancestor && nodesToAddToChain[i] == ancestor->node())
             sawCommonAncestor = true;
         if (allowActiveChanges)
             nodesToAddToChain[i]->setActive(true);
-        if (!sawCommonAncestor)
+        if (!sawCommonAncestor) {
             nodesToAddToChain[i]->setHovered(true);
+            if (event && (hasCapturingMouseEnterListener || nodesToAddToChain[i]->hasEventListeners(eventNames().mouseenterEvent)))

[esprehn, 2013/07/08 18:13:02]

This is not correct, I could add a listener inside the mouseleave handler and
you'd not fire the event because you checked too early.

[Mike West, 2013/07/09 09:37:00]

You're right; I didn't think of that case at all. I'll split up the checks, and
add a new test to cover that behavior.

+                nodesToAddToChain[i]->dispatchMouseEvent(*event, eventNames().mouseenterEvent, 0, oldHoverNode.get());
+        }
     }
 
     updateStyleIfNeeded();
 }
 
 void Document::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
 {
     MemoryClassInfo info(memoryObjectInfo, this, WebCoreMemoryTypes::DOM);
     ContainerNode::reportMemoryUsage(memoryObjectInfo);
     TreeScope::reportMemoryUsage(memoryObjectInfo);
@@ skipping 138 matching lines @@
 {
     return DocumentLifecycleNotifier::create(this);
 }
 
 DocumentLifecycleNotifier* Document::lifecycleNotifier()
 {
     return static_cast<DocumentLifecycleNotifier*>(ScriptExecutionContext::lifecycleNotifier());
 }
 
 } // namespace WebCore