Add EventHandlerRegistry

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.

[abarth-chromium, 2014/04/10 21:25:58]

blank line after this line pls

[Sami, 2014/04/11 16:46:53]

Done.

+#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::WindowObserver::WindowObserver(EventHandlerRegistry& registry, DOMWindow& window)
+    : DOMWindowLifecycleObserver(&window)
+    , m_registry(registry)
+{
+}
+
+EventHandlerRegistry::WindowObserver::~WindowObserver()
+{
+}
+
+void EventHandlerRegistry::WindowObserver::didAddEventListener(DOMWindow* window, const AtomicString& eventType)
+{
+    m_registry.didAddEventHandler(*window, eventType);
+}
+
+void EventHandlerRegistry::WindowObserver::didRemoveEventListener(DOMWindow* window, const AtomicString& eventType)
+{
+    m_registry.didRemoveEventHandler(*window, eventType);
+}
+
+void EventHandlerRegistry::WindowObserver::didRemoveAllEventListeners(DOMWindow* window)
+{
+    m_registry.didRemoveAllEventHandlers(*window);
+}
+
+EventHandlerRegistry::DocumentObserver::DocumentObserver(Document& document)
+    : DocumentLifecycleObserver(&document) { }
+
+EventHandlerRegistry::DocumentObserver::~DocumentObserver()
+{
+}
+
+void EventHandlerRegistry::DocumentObserver::documentWasAttached()
+{
+    Document* document = lifecycleContext();
+    if (document->parentDocument())
+        return;
+    EventHandlerRegistry* registry = EventHandlerRegistry::from(*document);
+
+    // Make sure we are tracking handlers on the window.
+    if (!registry->m_windowObserver && document->domWindow()) {
+        ASSERT(!document->domWindow()->hasEventListeners());

[abarth-chromium, 2014/04/10 21:25:58]

I don't think this ASSERT is valid.  I think it's possible for a Document to
re-use a DOMWindow that existed previously and might have event listeners..

[Sami, 2014/04/11 16:46:53]

Ok, I wasn't sure if that was the case so I added the ASSERT as a precaution.
I'll add code to register any existing handlers on the window.

+        registry->m_windowObserver = adoptPtr(new WindowObserver(*registry, *document->domWindow()));
+    }
+
+    // When the root document is attached, notify clients of any handlers it has.
+    for (size_t i = 0; i < EventHandlerClassCount; ++i) {
+        EventHandlerClass handlerClass = static_cast<EventHandlerClass>(i);
+        if (registry->hasEventHandlers(handlerClass)) {
+            registry->notifyHasHandlersChanged(handlerClass, true);
+            registry->notifyDidAddOrRemoveEventHandlerTarget(handlerClass);
+        }
+    }

[abarth-chromium, 2014/04/10 21:25:58]

Why are we delaying this processing until attachment?  There's nothing special
about that time period for events...

[Sami, 2014/04/11 16:46:53]

This is something I cargo culted from DOMWindow::installNewDocument[1], but
wasn't entirely convinced we needed it either. I did some spelunking and looks
like the code originally came from
https://bugs.webkit.org/show_bug.cgi?id=60779. Its purpose was to ensure
ChromeClient was told the number of wheel handlers when a Frame's Document
changed.

Nowadays, if I understand correctly, Document::attach() will only called very
soon after the document is created in DOMWindow::installNewDocument. This
doesn't change the document's relationship to the frame, so it doesn't make
sense to (re)send these notifications. In other words, the document is prepared
to send the notifications as soon as it is constructed since it already knows
about the frame. Therefore, we can just remove this code.

Did I miss something?

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

+}
+
+void EventHandlerRegistry::DocumentObserver::willDetachDocument()
+{
+    Document* document = lifecycleContext();
+
+    // The detached document should no longer track handlers on its window.
+    EventHandlerRegistry* registry = EventHandlerRegistry::from(*document);
+    if (document->domWindow())
+        registry->didRemoveAllEventHandlers(*document->domWindow());
+    registry->m_windowObserver.clear();
+
+    // Unregister our Document node from the parent for all event classes that
+    // have handlers.
+    Document* parentDocument = document->parentDocument();
+    if (!parentDocument)
+        return;
+    EventHandlerRegistry* parentRegistry = EventHandlerRegistry::from(*parentDocument);
+    parentRegistry->didRemoveAllEventHandlers(*document);
+}
+
+EventHandlerRegistry::HandlerState::HandlerState()
+    : externalHandlerCount(0)
+{
+}
+
+EventHandlerRegistry::HandlerState::~HandlerState()
+{
+}
+
+EventHandlerRegistry::EventHandlerRegistry(Document& document)
+    : m_document(document)
+    , m_documentObserver(DocumentObserver(document))
+    , m_windowObserver(adoptPtr(new WindowObserver(*this, *document.domWindow())))
+{
+}
+
+EventHandlerRegistry::~EventHandlerRegistry()
+{
+}
+
+const char* EventHandlerRegistry::supplementName()
+{
+    return "EventHandlerRegistry";
+}
+
+EventHandlerRegistry* EventHandlerRegistry::from(Document& document)
+{
+    EventHandlerRegistry* registry = static_cast<EventHandlerRegistry*>(DocumentSupplement::from(document, supplementName()));
+    if (!registry) {
+        registry = new EventHandlerRegistry(document);
+        DocumentSupplement::provideTo(document, supplementName(), adoptPtr(registry));
+    }
+    return registry;
+}
+
+bool EventHandlerRegistry::eventTypeToClass(const AtomicString& eventType, EventHandlerClass* result)
+{
+    if (eventType == EventTypeNames::wheel || eventType == EventTypeNames::mousewheel) {
+        *result = WheelEvent;
+    } else if (eventType == EventTypeNames::scroll) {
+        *result = ScrollEvent;
+    } else if (isTouchEventType(eventType)) {
+        *result = TouchEvent;
+    } else {
+        return false;
+    }
+    return true;
+}
+
+const EventTargetSet* EventHandlerRegistry::eventHandlerTargets(EventHandlerClass handlerClass) const
+{
+    return m_eventHandlers[handlerClass].targets.get();
+}
+
+bool EventHandlerRegistry::hasEventHandlers(EventHandlerClass handlerClass) const
+{
+    EventTargetSet* targets = m_eventHandlers[handlerClass].targets.get();
+    return m_eventHandlers[handlerClass].externalHandlerCount || (targets && targets->size());
+}
+
+unsigned EventHandlerRegistry::externalEventHandlerCount(EventHandlerClass handlerClass) const
+{
+    return m_eventHandlers[handlerClass].externalHandlerCount;
+}
+
+void EventHandlerRegistry::updateExternalHandlerCount(ChangeOperation op, EventHandlerClass handlerClass)
+{
+    if (op == Add) {
+        m_eventHandlers[handlerClass].externalHandlerCount++;
+    } else {
+        ASSERT(op == Remove);
+        ASSERT(m_eventHandlers[handlerClass].externalHandlerCount > 0);
+        m_eventHandlers[handlerClass].externalHandlerCount--;
+    }
+}
+
+bool EventHandlerRegistry::updateEventHandlerTargets(ChangeOperation op, EventHandlerClass handlerClass, EventTarget* target)
+{
+    EventTargetSet* targets = m_eventHandlers[handlerClass].targets.get();
+    if (op == Add) {
+#ifndef NDEBUG
+        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() == &m_document
+                || (node->isDocumentNode() && toDocument(node)->parentDocument() == &m_document));
+        } else if (DOMWindow* window = target->toDOMWindow()) {
+            // The window should belong to this document.
+            ASSERT(window->document() == &m_document);
+        }
+#endif // NDEBUG
+
+        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 this is a child document node, then the count should never go above 1.
+#ifndef NDEBUG
+            if (Node* node = target->toNode())
+                ASSERT(!node->isDocumentNode() || &node->document() == &m_document);
+#endif // NDEBUG
+            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)
+{
+    bool hadHandlers = hasEventHandlers(handlerClass);
+    bool targetSetChanged;
+    if (target) {
+        targetSetChanged = updateEventHandlerTargets(op, handlerClass, target);
+    } else {
+        updateExternalHandlerCount(op, handlerClass);
+        targetSetChanged = true;
+    }
+    bool hasHandlers = hasEventHandlers(handlerClass);
+
+    // Notify the parent document's registry if we added the first or removed
+    // the last handler.
+    if (hadHandlers != hasHandlers) {
+        if (Document* parent = m_document.parentDocument()) {
+            // Report change to parent with our Document as the target.
+            EventHandlerRegistry::from(*parent)->updateEventHandlerInternal(op, handlerClass, &m_document);
+        } else {
+            // This is the root registry; notify clients accordingly.
+            notifyHasHandlersChanged(handlerClass, hasHandlers);
+        }
+    }
+
+    // Only notify the client when something actually changed, and then only if
+    // this wasn't a notification that was sent by a sub-registry.
+    if (!targetSetChanged)
+        return;
+    Node* node = target ? target->toNode() : 0;
+    if (!node || !node->isDocumentNode() || node == &m_document)
+        notifyDidAddOrRemoveEventHandlerTarget(handlerClass);
+}
+
+void EventHandlerRegistry::updateEventHandlerOfType(ChangeOperation op, const AtomicString& eventType, EventTarget* target)
+{
+    EventHandlerClass handlerClass;
+    if (!eventTypeToClass(eventType, &handlerClass))
+        return;
+    updateEventHandlerInternal(op, handlerClass, target);
+}
+
+void EventHandlerRegistry::didAddExternalEventHandler(const AtomicString& eventType)
+{
+    updateEventHandlerOfType(Add, eventType, 0);
+}
+
+void EventHandlerRegistry::didRemoveExternalEventHandler(const AtomicString& eventType)
+{
+    updateEventHandlerOfType(Remove, eventType, 0);
+}
+
+void EventHandlerRegistry::didAddEventHandler(EventTarget& target, const AtomicString& eventType)
+{
+    updateEventHandlerOfType(Add, eventType, &target);
+}
+
+void EventHandlerRegistry::didRemoveEventHandler(EventTarget& target, const AtomicString& eventType)
+{
+    updateEventHandlerOfType(Remove, eventType, &target);
+}
+
+void EventHandlerRegistry::didAddEventHandler(EventTarget& target, EventHandlerClass handlerClass)
+{
+    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);
+    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();
+    LocalFrame* mainFrame = page ? page->mainFrame() : 0;
+    ScrollingCoordinator* scrollingCoordinator = page ? page->scrollingCoordinator() : 0;
+
+    switch (handlerClass) {
+    case WheelEvent:
+        if (mainFrame) {
+            // TODO(skyostil): This notification is wired up to a black hole, so remove it.
+            mainFrame->notifyChromeClientWheelEventHandlerCountChanged();
+        }
+        if (scrollingCoordinator)
+            scrollingCoordinator->haveWheelEventHandlersChangedForPage();
+        break;
+    case ScrollEvent:
+        if (scrollingCoordinator)
+            scrollingCoordinator->haveScrollEventHandlersChangedForPage();
+        break;
+    case TouchEvent:
+        if (FrameHost* frameHost = m_document.frameHost())
+            frameHost->chrome().client().needTouchEvents(hasActiveHandlers);
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+        break;
+    }
+}
+
+void EventHandlerRegistry::notifyDidAddOrRemoveEventHandlerTarget(EventHandlerClass handlerClass)
+{
+    Page* page = m_document.page();
+    if (!page)
+        return;
+
+    ScrollingCoordinator* scrollingCoordinator = page->scrollingCoordinator();
+    if (!scrollingCoordinator)
+        return;
+
+    if (handlerClass == TouchEvent)
+        scrollingCoordinator->touchEventTargetRectsDidChange();
+}
+
+} // namespace WebCore