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#ifndef COMPOSITOR_H
#define COMPOSITOR_H

#include <base/memory/weak_ptr.h>
#include <components/viz/common/frame_sinks/begin_frame_source.h>

#include <QtCore/qglobal.h>
#include <QtCore/qshareddata.h>

QT_BEGIN_NAMESPACE
class QSGNode;
QT_END_NAMESPACE

namespace viz {
class CompositorFrame;
struct ReturnedResource;
namespace mojom {
class CompositorFrameSinkClient;
} // namespace mojom
} // namespace viz

namespace QtWebEngineCore {

class RenderWidgetHostViewQtDelegate;
class ChromiumCompositorData;

// Receives viz::CompositorFrames from child compositors and provides QSGNodes
// to the Qt Quick renderer.
//
// The life cycle of a frame:
//
//   Step 1. A new CompositorFrame is received from child compositors and handed
//   off to submitFrame(). The new frame will start off in a pending state.
//
//   Step 2. Once the new frame is ready to be rendered, Compositor will call
//   update() on the delegate.
//
//   Step 3. Once the delegate is ready to render, updatePaintNode() should be
//   called to receive the scene graph for the new frame. This call will commit
//   the pending frame. Until the next frame is ready, all subsequent calls to
//   updatePaintNode() will keep using this same committed frame.
//
//   Step 4. The Compositor will return unneeded resources back to the child
//   compositors. Go to step 1.
class Compositor final : private viz::BeginFrameObserverBase
{
public:
    explicit Compositor();
    ~Compositor() override;

    void setViewDelegate(RenderWidgetHostViewQtDelegate *viewDelegate);
    void setFrameSinkClient(viz::mojom::CompositorFrameSinkClient *frameSinkClient);
    void setNeedsBeginFrames(bool needsBeginFrames);

    void submitFrame(viz::CompositorFrame frame);

    QSGNode *updatePaintNode(QSGNode *oldNode);

private:
    void notifyFrameCommitted();

    // viz::BeginFrameObserverBase
    bool OnBeginFrameDerivedImpl(const viz::BeginFrameArgs &args) override;
    void OnBeginFrameSourcePausedChanged(bool paused) override;

    std::vector<viz::ReturnedResource> m_resourcesToRelease;
    QExplicitlySharedDataPointer<ChromiumCompositorData> m_chromiumCompositorData;
    RenderWidgetHostViewQtDelegate *m_viewDelegate = nullptr;
    std::unique_ptr<viz::SyntheticBeginFrameSource> m_beginFrameSource;
    viz::mojom::CompositorFrameSinkClient *m_frameSinkClient = nullptr;
    bool m_havePendingFrame = false;
    bool m_needsBeginFrames = false;

    base::WeakPtrFactory<Compositor> m_weakPtrFactory{this};

    DISALLOW_COPY_AND_ASSIGN(Compositor);
};

} // namespace QtWebEngineCore

#endif // !COMPOSITOR_H