// Copyright (c) 2012 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 UI_COMPOSITOR_COMPOSITOR_OBSERVER_H_
#define UI_COMPOSITOR_COMPOSITOR_OBSERVER_H_

#include "base/time/time.h"
#include "ui/compositor/compositor_export.h"

namespace ui {

class Compositor;

// A compositor observer is notified when compositing completes.
class COMPOSITOR_EXPORT CompositorObserver {
 public:
  CompositorObserver();

  // A commit proxies information from the main thread to the compositor
  // thread. It typically happens when some state changes that will require a
  // composite. In the multi-threaded case, many commits may happen between
  // two successive composites. In the single-threaded, a single commit
  // between two composites (just before the composite as part of the
  // composite cycle). If the compositor is locked, it will not send this
  // this signal.
  virtual void OnCompositingDidCommit(Compositor* compositor) = 0;

  // Called when compositing started: it has taken all the layer changes into
  // account and has issued the graphics commands.
  virtual void OnCompositingStarted(Compositor* compositor,
                                    base::TimeTicks start_time) = 0;

  // Called when compositing completes: the present to screen has completed.
  virtual void OnCompositingEnded(Compositor* compositor) = 0;

  // Called when compositing is aborted (e.g. lost graphics context).
  virtual void OnCompositingAborted(Compositor* compositor) = 0;

  // Called when the compositor lock state changes.
  virtual void OnCompositingLockStateChanged(Compositor* compositor) = 0;

 protected:
#if defined(OS_MACOSX)
  // Debugging instrumentation for crbug.com/401630.
  // TODO(ccameron): remove this.
  friend class Compositor;
  int32 observing_count_;
#endif

  virtual ~CompositorObserver();
};

}  // namespace ui

#endif  // UI_COMPOSITOR_COMPOSITOR_OBSERVER_H_