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/IntersectionObservationRegistry.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:
+    static IntersectionObserver* create(Document* owningDocument, const IntersectionObserverInit&, IntersectionObserverCallback*, ExceptionState&);
+    static void resumeSuspendedObservers();
+
+    void observe(Element*, ExceptionState&);
+    void unobserve(Element*, ExceptionState&);
+    void disconnect(IntersectionObservation&);
+    void disconnect();
+    IntersectionObserverEntryVector takeRecords();
+
+    bool isDescendantOfRoot(Element*);
+    void enqueueIntersectionObserverEntry(IntersectionObserverEntry*);
+
+    bool hasRoot() const { return m_hasRoot; }
+    Element* root() { return m_root.get(); }
+    Document* owningDocument() { return m_owningDocument.get(); }
+    Document* trackingDocument() { return m_trackingDocument.get(); }
+    const Vector<float>& thresholds() const { return m_thresholds; }
+    size_t firstThresholdGreaterThan(float ratio) const;
+    bool shouldBeSuspended() const;
+    void deliver();
+
+    DECLARE_TRACE();
+
+private:
+    explicit IntersectionObserver(Document* owningDocument, IntersectionObserverCallback*, PassRefPtrWillBeRawPtr<Element>, int, const Vector<float>&);
+
+    Document& getTrackingDocumentForTarget(Element*);
+    IntersectionObservation* createObservation(Element*);
+
+    Member<IntersectionObserverCallback> m_callback;
+    WeakPtrWillBeWeakMember<Element> m_root;
+    WeakPtrWillBeWeakMember<Document> m_owningDocument;
+    WeakPtrWillBeWeakMember<Document> m_trackingDocument;
+    Member<IntersectionObservation::HashSet> m_observations;
+    Member<IntersectionObserverEntryVector> m_entries;
+    Vector<float> m_thresholds;
+    int m_rootMargin;
+    // m_root is a weak pointer, so may become null if the root Element is deallocated.
+    // Only m_hasRoot indicates for certain that there *should* be a root.
+    bool m_hasRoot;
+};
+
+} // namespace blink
+
+#endif // IntersectionObserver_h