Track scroll event handlers in nested documents

Source/core/dom/EventHandlerRegistry.cpp

 // Copyright 2014 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 "config.h"
 #include "core/dom/EventHandlerRegistry.h"
 
 #include "core/dom/Document.h"
 #include "core/events/ThreadLocalEventNames.h"
 #include "core/events/WheelEvent.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/LocalFrame.h"
 #include "core/page/Chrome.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/Page.h"
 #include "core/page/scrolling/ScrollingCoordinator.h"
 
 namespace WebCore {
 
 EventHandlerRegistry::HandlerState::HandlerState()
 {
 }
 
 EventHandlerRegistry::HandlerState::~HandlerState()
 {
 }
 
+EventHandlerRegistry* EventHandlerRegistry::create(Document& document)
+{
+    EventHandlerRegistry* registry = new EventHandlerRegistry(document);
+    registry->suspendIfNeeded();
+    return registry;
+}
+
 EventHandlerRegistry::EventHandlerRegistry(Document& document)
-    : m_document(document)
+    : ActiveDOMObject(&document)
 {
 }
 
 EventHandlerRegistry::~EventHandlerRegistry()
 {
 }
 
 const char* EventHandlerRegistry::supplementName()
 {
     return "EventHandlerRegistry";
 }
 
+Document* EventHandlerRegistry::document() const
+{
+    return static_cast<Document*>(executionContext());
+}
+
 EventHandlerRegistry* EventHandlerRegistry::from(Document& document)
 {
     EventHandlerRegistry* registry = static_cast<EventHandlerRegistry*>(DocumentSupplement::from(document, supplementName()));
     if (!registry) {
-        registry = new EventHandlerRegistry(document);
+        registry = create(document);
         DocumentSupplement::provideTo(document, supplementName(), adoptPtr(registry));
     }
     return registry;
 }
 
 bool EventHandlerRegistry::eventTypeToClass(const AtomicString& eventType, EventHandlerClass* result)
 {
     if (eventType == EventTypeNames::scroll) {
         *result = ScrollEvent;
     } else {
@@ skipping 11 matching lines @@
 {
     EventTargetSet* targets = m_eventHandlers[handlerClass].targets.get();
     return targets && targets->size();
 }
 
 bool EventHandlerRegistry::updateEventHandlerTargets(ChangeOperation op, EventHandlerClass handlerClass, EventTarget* target)
 {
     EventTargetSet* targets = m_eventHandlers[handlerClass].targets.get();
     if (op == Add) {
 #if ASSERT_ENABLED
-        if (Node* node = target->toNode())
-            ASSERT(&node->document() == &m_document);
+        if (Node* node = target->toNode()) {
+            // The node should either be in the document, or be the Document node of a child
+            // of the document.
+            ASSERT(&node->document() == document()
+                || (node->isDocumentNode() && toDocument(node)->parentDocument() == document()));
+        }
 #endif // ASSERT_ENABLED
 
         if (!targets) {
             m_eventHandlers[handlerClass].targets = adoptPtr(new EventTargetSet);
             targets = m_eventHandlers[handlerClass].targets.get();
         }
 
         if (!targets->add(target).isNewEntry) {
             // Just incremented refcount, no real change.
+#if ASSERT_ENABLED
+            // If this is a child document node, then the count should never go above 1.
+            if (Node* node = target->toNode())
+                ASSERT(!node->isDocumentNode() || &node->document() == document());
+#endif // ASSERT_ENABLED
             return false;
         }
     } else {
         // Note that we can't assert that |target| is in this document because
         // it might be in the process of moving out of it.
         ASSERT(op == Remove || op == RemoveAll);
         ASSERT(op == RemoveAll || targets->contains(target));
         if (!targets)
             return false;
 
         if (op == RemoveAll) {
             if (!targets->contains(target))
                 return false;
             targets->removeAll(target);
         } else {
             if (!targets->remove(target)) {
                 // Just decremented refcount, no real update.
                 return false;
             }
         }
     }
     return true;
 }
 
 void EventHandlerRegistry::updateEventHandlerInternal(ChangeOperation op, EventHandlerClass handlerClass, EventTarget* target)
 {
     // After the document has stopped, all updates become no-ops.
-    if (!m_document.isActive()) {
+    if (!document()->isActive())
         return;
-    }
 
-    bool hadHandlers = hasEventHandlers(handlerClass);
-    updateEventHandlerTargets(op, handlerClass, target);
-    bool hasHandlers = hasEventHandlers(handlerClass);
+    // Notify our parent registry if we added the first or removed the last handler.
+    for (Document* document = this->document(); document; document = document->parentDocument()) {
+        EventHandlerRegistry* registry = EventHandlerRegistry::from(*document);
 
-    // Notify the parent document's registry if we added the first or removed
-    // the last handler.
-    if (hadHandlers != hasHandlers && !m_document.parentDocument()) {
-        // This is the root registry; notify clients accordingly.
-        notifyHasHandlersChanged(handlerClass, hasHandlers);
+        bool hadHandlers = registry->hasEventHandlers(handlerClass);
+        registry->updateEventHandlerTargets(op, handlerClass, target);
+        bool hasHandlers = registry->hasEventHandlers(handlerClass);
+
+        if (hadHandlers == hasHandlers) {
+            break;
+        }
+        if (!document->parentDocument()) {
+            // This is the root registry; notify clients accordingly.
+            registry->notifyHasHandlersChanged(handlerClass, hasHandlers);
+        } else {
+            // Report change to parent with our Document as the target.
+            target = document;

[abarth-chromium, 2014/04/23 17:25:54]

I see, I missed this line.

+        }
     }
 }
 
 void EventHandlerRegistry::updateEventHandlerOfType(ChangeOperation op, const AtomicString& eventType, EventTarget* target)
 {
     EventHandlerClass handlerClass;
     if (!eventTypeToClass(eventType, &handlerClass))
         return;
     updateEventHandlerInternal(op, handlerClass, target);
 }
@@ skipping 39 matching lines @@
         EventHandlerClass handlerClass = static_cast<EventHandlerClass>(i);
         const EventTargetSet* targets = eventHandlerTargets(handlerClass);
         if (!targets)
             continue;
         updateEventHandlerInternal(RemoveAll, handlerClass, &target);
     }
 }
 
 void EventHandlerRegistry::notifyHasHandlersChanged(EventHandlerClass handlerClass, bool hasActiveHandlers)
 {
-    Page* page = m_document.page();
+    Page* page = document()->page();
     ScrollingCoordinator* scrollingCoordinator = page ? page->scrollingCoordinator() : 0;
 
     switch (handlerClass) {
     case ScrollEvent:
         if (scrollingCoordinator)
             scrollingCoordinator->updateHaveScrollEventHandlers();
         break;
     default:
         ASSERT_NOT_REACHED();
         break;
     }
 }
 
+void EventHandlerRegistry::stop()
+{
+    Document* parentDocument = document()->parentDocument();
+    if (!parentDocument)
+        return;
+    EventHandlerRegistry* parentRegistry = EventHandlerRegistry::from(*parentDocument);
+    parentRegistry->didRemoveAllEventHandlers(*document());
+}
+
 } // namespace WebCore