Track scroll event handlers in nested documents

Source/core/page/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/page/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::EventHandlerRegistry(Page& page)
+    : m_page(page)
 {
 }
 
-EventHandlerRegistry::HandlerState::~HandlerState()
-{
-}
-
-EventHandlerRegistry::EventHandlerRegistry(Document& document)
-    : m_document(document)
-{
-}
-
 EventHandlerRegistry::~EventHandlerRegistry()
 {
 }
 
 const char* EventHandlerRegistry::supplementName()
 {
     return "EventHandlerRegistry";
 }
 
-EventHandlerRegistry* EventHandlerRegistry::from(Document& document)
+EventHandlerRegistry* EventHandlerRegistry::from(Page& page)
 {
-    EventHandlerRegistry* registry = static_cast<EventHandlerRegistry*>(DocumentSupplement::from(document, supplementName()));
+    EventHandlerRegistry* registry = static_cast<EventHandlerRegistry*>(Supplement<Page>::from(page, supplementName()));
     if (!registry) {
-        registry = new EventHandlerRegistry(document);
-        DocumentSupplement::provideTo(document, supplementName(), adoptPtr(registry));
+        registry = new EventHandlerRegistry(page);
+        Supplement<Page>::provideTo(page, supplementName(), adoptPtr(registry));
     }
     return registry;
 }
 
 bool EventHandlerRegistry::eventTypeToClass(const AtomicString& eventType, EventHandlerClass* result)
 {
     if (eventType == EventTypeNames::scroll) {
         *result = ScrollEvent;
     } else {
         return false;
     }
     return true;
 }
 
 const EventTargetSet* EventHandlerRegistry::eventHandlerTargets(EventHandlerClass handlerClass) const
 {
-    return m_eventHandlers[handlerClass].targets.get();
+    return &m_targets[handlerClass];
 }
 
 bool EventHandlerRegistry::hasEventHandlers(EventHandlerClass handlerClass) const
 {
-    EventTargetSet* targets = m_eventHandlers[handlerClass].targets.get();
-    return targets && targets->size();
+    return m_targets[handlerClass].size();
 }
 
 bool EventHandlerRegistry::updateEventHandlerTargets(ChangeOperation op, EventHandlerClass handlerClass, EventTarget* target)
 {
-    EventTargetSet* targets = m_eventHandlers[handlerClass].targets.get();
+    EventTargetSet* targets = &m_targets[handlerClass];
     if (op == Add) {
-#if ASSERT_ENABLED
-        if (Node* node = target->toNode())
-            ASSERT(&node->document() == &m_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.
             return false;
         }
     } else {
         // Note that we can't assert that |target| is in this document because

[Rick Byers, 2014/04/24 21:30:12]

nit: remove/update comment (no "this document" anymore)

[Sami, 2014/04/25 19:51:15]

Good find, done.

         // 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()) {
-        return;
-    }
-
     bool hadHandlers = hasEventHandlers(handlerClass);
     updateEventHandlerTargets(op, handlerClass, target);
     bool hasHandlers = hasEventHandlers(handlerClass);
 
-    // 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.
+    if (hadHandlers != hasHandlers) {
         notifyHasHandlersChanged(handlerClass, hasHandlers);
     }
 }
 
 void EventHandlerRegistry::updateEventHandlerOfType(ChangeOperation op, const AtomicString& eventType, EventTarget* target)
 {
     EventHandlerClass handlerClass;
     if (!eventTypeToClass(eventType, &handlerClass))
         return;
     updateEventHandlerInternal(op, handlerClass, target);
@@ skipping 14 matching lines @@
     updateEventHandlerInternal(Add, handlerClass, &target);
 }
 
 void EventHandlerRegistry::didRemoveEventHandler(EventTarget& target, EventHandlerClass handlerClass)
 {
     updateEventHandlerInternal(Remove, handlerClass, &target);
 }
 
 void EventHandlerRegistry::didMoveFromOtherDocument(EventTarget& target, Document& oldDocument)
 {
-    EventHandlerRegistry* oldRegistry = EventHandlerRegistry::from(oldDocument);
+    if (!oldDocument.page())
+        return;
+    EventHandlerRegistry* oldRegistry = EventHandlerRegistry::from(*oldDocument.page());
+    if (oldRegistry == this)

[Rick Byers, 2014/04/24 21:30:12]

Do you know in what scenarios this won't be true?  It seems surprising to me
that there would be scenarios where event handlers can move across Pages.

[Sami, 2014/04/25 19:51:15]

No, I don't have evidence whether this can actually happen. I'm mainly being
defensive here because I didn't see anything preventing a node from getting
detached from a document in one page and getting attached to a document in
another page. If that can't happen for a fact I'll just replace this with an
assert.

+        return;
     for (size_t i = 0; i < EventHandlerClassCount; ++i) {
         EventHandlerClass handlerClass = static_cast<EventHandlerClass>(i);
         const EventTargetSet* targets = oldRegistry->eventHandlerTargets(handlerClass);
         if (!targets)
             continue;
         for (unsigned count = targets->count(&target); count > 0; --count) {
             oldRegistry->updateEventHandlerInternal(Remove, handlerClass, &target);
             updateEventHandlerInternal(Add, handlerClass, &target);
         }
     }
 }
 
 void EventHandlerRegistry::didRemoveAllEventHandlers(EventTarget& target)
 {
     for (size_t i = 0; i < EventHandlerClassCount; ++i) {
         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();
-    ScrollingCoordinator* scrollingCoordinator = page ? page->scrollingCoordinator() : 0;
+    ScrollingCoordinator* scrollingCoordinator = m_page.scrollingCoordinator();
 
     switch (handlerClass) {
     case ScrollEvent:
         if (scrollingCoordinator)
             scrollingCoordinator->updateHaveScrollEventHandlers();
         break;
     default:
         ASSERT_NOT_REACHED();
         break;
     }
 }
 
 } // namespace WebCore