IntersectionObserver: second cut.

third_party/WebKit/Source/core/dom/IntersectionObserver.h

+// 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.
+
+#ifndef IntersectionObserver_h
+#define IntersectionObserver_h
+
+#include "bindings/core/v8/ScriptWrappable.h"
+#include "core/dom/Element.h"
+#include "core/dom/IntersectionObservation.h"
+#include "core/dom/IntersectionObserverEntry.h"
+#include "platform/heap/Handle.h"
+#include "wtf/HashSet.h"
+#include "wtf/RefCounted.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+class ExceptionState;
+class IntersectionObserverCallback;
+class IntersectionObserverInit;
+
+typedef HeapVector<Member<IntersectionObserverEntry>> IntersectionObserverEntryVector;
+
+class IntersectionObserver final : public GarbageCollectedFinalized<IntersectionObserver>, public ScriptWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    typedef HeapHashSet<Member<IntersectionObserver>> HashSet;
+    typedef HeapHashSet<WeakMember<IntersectionObserver>> WeakHashSet;
+
+    static IntersectionObserver* create(const IntersectionObserverInit&, IntersectionObserverCallback*, ExceptionState&);
+    static void resumeSuspendedObservers();
+
+    // API methods
+    void observe(Element*, ExceptionState&);
+    void unobserve(Element*, ExceptionState&);
+    void disconnect();
+    IntersectionObserverEntryVector takeRecords();
+
+    Element* root() { return m_root.get(); }
+    void computeIntersectionObservations(int);
+    void disconnect(IntersectionObservation&);
+    bool isDescendantOfRoot(Element*);
+    void enqueueIntersectionObserverEntry(IntersectionObserverEntry*);
+    size_t firstThresholdGreaterThan(float ratio) const;
+    bool shouldBeSuspended() const;
+    void deliver();
+    void setActive(bool);
+
+    DECLARE_TRACE();
+
+private:
+    explicit IntersectionObserver(IntersectionObserverCallback*, Element*, int, const Vector<float>&);
+
+    void checkRootAndDetachIfNecessary();
+    IntersectionObservation* createObservation(Element*);
+
+    Member<IntersectionObserverCallback> m_callback;
+    WeakPtrWillBeWeakMember<Element> m_root;
+    Member<IntersectionObservation::WeakHashSet> m_observations;
+    Member<IntersectionObserverEntryVector> m_entries;
+    Vector<float> m_thresholds;
+    int m_rootMargin;
+};
+
+} // namespace blink
+
+#endif // IntersectionObserver_h