IntersectionObserver: second cut.

third_party/WebKit/Source/core/dom/IntersectionObserverRegistry.cpp

+// Copyright 2015 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/IntersectionObserverRegistry.h"
+
+#include "core/dom/Document.h"
+
+namespace blink {
+
+typedef HeapVector<Member<IntersectionObserver>> IntersectionObserverVector;
+
+IntersectionObserverRegistry::IntersectionObserverRegistry(Timer<Document>& timer)
+    : m_timer(timer)
+    , m_trackedIntersectionObservers(new IntersectionObserver::WeakHashSet())
+    , m_activeIntersectionObservers(new IntersectionObserver::HashSet())
+    , m_suspendedIntersectionObservers(new IntersectionObserver::HashSet())
+{
+}
+
+void IntersectionObserverRegistry::scheduleIntersectionObserverForDelivery(IntersectionObserver& observer)
+{
+    if (m_activeIntersectionObservers->isEmpty())
+        m_timer.startOneShot(0, BLINK_FROM_HERE);
+    m_activeIntersectionObservers->add(&observer);
+}
+
+void IntersectionObserverRegistry::resumeSuspendedIntersectionObservers()
+{
+    ASSERT(isMainThread());
+    if (m_suspendedIntersectionObservers->isEmpty())
+        return;
+
+    IntersectionObserverVector suspended;
+    copyToVector(*m_suspendedIntersectionObservers, suspended);
+    for (size_t i = 0; i < suspended.size(); ++i) {
+        if (!suspended[i]->shouldBeSuspended()) {
+            m_suspendedIntersectionObservers->remove(suspended[i]);
+            scheduleIntersectionObserverForDelivery(*suspended[i]);
+        }
+    }
+}
+
+void IntersectionObserverRegistry::deliverIntersectionObservations()
+{
+    IntersectionObserverVector observers;
+    copyToVector(*m_activeIntersectionObservers, observers);
+    m_activeIntersectionObservers->clear();
+    for (size_t i = 0; i < observers.size(); ++i) {
+        if (observers[i]->shouldBeSuspended())
+            m_suspendedIntersectionObservers->add(observers[i]);
+        else
+            observers[i]->deliver();
+    }
+}
+
+void IntersectionObserverRegistry::computeTrackedIntersectionObservations()
+{
+    // TODO: Need to define timestamp.
+    double timestamp = currentTime();
+    for (auto& observer: *m_trackedIntersectionObservers)
+        observer->computeIntersectionObservations(timestamp);
+}
+
+void IntersectionObserverRegistry::addTrackedObserver(IntersectionObserver& observer)
+{
+    m_trackedIntersectionObservers->add(&observer);
+}
+
+void IntersectionObserverRegistry::removeTrackedObserversForRoot(Element* root)
+{
+    HeapVector<Member<IntersectionObserver>> toRemove;
+    for (auto& observer: *m_trackedIntersectionObservers) {
+        if (observer->root() == root)
+            toRemove.append(observer);
+    }
+    for (auto& observer: toRemove)
+        m_trackedIntersectionObservers->remove(observer);
+}
+
+DEFINE_TRACE(IntersectionObserverRegistry)
+{
+    visitor->trace(m_trackedIntersectionObservers);
+    visitor->trace(m_activeIntersectionObservers);
+    visitor->trace(m_suspendedIntersectionObservers);
+}
+
+} // namespace blink {