IntersectionObserver: second cut.

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

Index: third_party/WebKit/Source/core/dom/IntersectionObservationRegistry.cpp
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObservationRegistry.cpp b/third_party/WebKit/Source/core/dom/IntersectionObservationRegistry.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..fc52d6ce81368e37295223016f1cd0b3e8d4dbd9
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/IntersectionObservationRegistry.cpp
@@ -0,0 +1,82 @@
+// 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/IntersectionObservationRegistry.h"
+
+#include "core/dom/Document.h"
+
+namespace blink {
+
+typedef HeapVector<Member<IntersectionObserver>> IntersectionObserverVector;
+
+IntersectionObservationRegistry::IntersectionObservationRegistry(Timer<Document>& timer)
+    : m_timer(timer)
+{
+}
+
+void IntersectionObservationRegistry::activateIntersectionObserver(IntersectionObserver& observer)
+{
+    if (m_activeIntersectionObservers->isEmpty())
+        m_timer.startOneShot(0, BLINK_FROM_HERE);
+    m_activeIntersectionObservers->add(&observer);
+}
+
+void IntersectionObservationRegistry::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]);
+            activateIntersectionObserver(*suspended[i]);
+        }
+    }
+}
+
+void IntersectionObservationRegistry::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 IntersectionObservationRegistry::computeIntersectionObservations()
+{
+    // TODO: Need to define timestamp.
+    double timestamp = currentTime();
+    for (auto& observation: *m_intersectionObservations) {
+        ASSERT(observation->target()->isInTreeScope());
+        observation->computeIntersectionObservations(timestamp);
+    }
+}
+
+void IntersectionObservationRegistry::addObservation(IntersectionObservation& observation)
+{
+    m_intersectionObservations->add(&observation);
+}
+
+void IntersectionObservationRegistry::removeObservation(IntersectionObservation& observation)
+{
+    m_intersectionObservations->remove(&observation);
+}
+
+DEFINE_TRACE(IntersectionObservationRegistry)
+{
+    visitor->trace(m_activeIntersectionObservers);
+    visitor->trace(m_suspendedIntersectionObservers);
+    visitor->trace(m_intersectionObservations);
+}
+
+} // namespace blink {