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 2772 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 2036 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 67 matching lines @@
                 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());
     }
 
+    // mouseenter and mouseleave events do not bubble, so they are dispatched iff 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. We'll check the previously
+    // hovered node's ancestor tree for 'mouseleave' handlers here, then check the newly hovered node's
+    // ancestor tree for 'mouseenter' handlers after dispatching the 'mouseleave' events (as the handler
+    // for 'mouseleave' might set a capturing 'mouseenter' handler, odd as that might be).
+    bool ancestorHasCapturingMouseleaveListener = false;
+    if (event && newHoverNode != oldHoverNode.get()) {
+        for (Node* node = oldHoverNode.get(); node; node = node->parentOrShadowHostNode()) {
+            if (node->hasCapturingEventListeners(eventNames().mouseleaveEvent)) {
+                ancestorHasCapturingMouseleaveListener = true;
+                break;
+            }
+        }
+    }
+
     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 && (ancestorHasCapturingMouseleaveListener || nodesToRemoveFromChain[i]->hasEventListeners(eventNames().mouseleaveEvent)))
+            nodesToRemoveFromChain[i]->dispatchMouseEvent(*event, eventNames().mouseleaveEvent, 0, newHoverNode);
+    }
+
+    bool ancestorHasCapturingMouseenterListener = false;
+    if (event && newHoverNode != oldHoverNode.get()) {
+        for (Node* node = newHoverNode; node; node = node->parentOrShadowHostNode()) {
+            if (node->hasCapturingEventListeners(eventNames().mouseenterEvent)) {
+                ancestorHasCapturingMouseenterListener = true;
+                break;
+            }
+        }
+    }
 
     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 && (ancestorHasCapturingMouseenterListener || nodesToAddToChain[i]->hasEventListeners(eventNames().mouseenterEvent)))
+                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 136 matching lines @@
 {
     return DocumentLifecycleNotifier::create(this);
 }
 
 DocumentLifecycleNotifier* Document::lifecycleNotifier()
 {
     return static_cast<DocumentLifecycleNotifier*>(ScriptExecutionContext::lifecycleNotifier());
 }
 
 } // namespace WebCore