third_party/WebKit/Source/core/observer/ResizeObservation.h

// Copyright 2016 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 ResizeObservation_h
#define ResizeObservation_h

#include "core/observer/ResizeObserverEntry.h"
#include "platform/geometry/LayoutSize.h"
#include "platform/heap/Handle.h"

namespace blink {

class Element;
class ResizeObserver;

// ResizeObservation represents an element that is being observed.
class CORE_EXPORT ResizeObservation final : public GarbageCollected<ResizeObservation> {
public:
    ResizeObservation(Element* target, ResizeObserver*);

    Element* target() const { return m_target; }
    size_t targetDepth();
    void setObservationSize(const LayoutSize&);
    // True if observationSize differs from target's current size.
    bool observationSizeOutOfSync() const;
    void elementSizeChanged();

    static LayoutSize getTargetSize(Element* target);

    DECLARE_TRACE();

private:
    WeakMember<Element> m_target;
    Member<ResizeObserver> m_observer;
    // Target size sent in last observation notification.
    LayoutSize m_observationSize;
    bool m_elementSizeChanged;
};

} // namespace blink

#endif // ResizeObservation_h