content/browser/renderer_host/browser_compositor_view_mac.h

// Copyright 2014 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 CONTENT_BROWSER_RENDERER_HOST_BROWSER_COMPOSITOR_VIEW_MAC_H_
#define CONTENT_BROWSER_RENDERER_HOST_BROWSER_COMPOSITOR_VIEW_MAC_H_

#include <memory>

#include "base/macros.h"
#include "ui/accelerated_widget_mac/accelerated_widget_mac.h"
#include "ui/compositor/compositor.h"
#include "ui/compositor/compositor_observer.h"

namespace content {

// A ui::Compositor and a gfx::AcceleratedWidget (and helper) that it draws
// into. This structure is used to efficiently recycle these structures across
// tabs (because creating a new ui::Compositor for each tab would be expensive
// in terms of time and resources).
class BrowserCompositorMac : public ui::CompositorObserver {
 public:
  virtual ~BrowserCompositorMac();

  // Create a compositor, or recycle a preexisting one.
  static std::unique_ptr<BrowserCompositorMac> Create();

  // Delete a compositor, or allow it to be recycled.
  static void Recycle(std::unique_ptr<BrowserCompositorMac> compositor);

  // Indicate that the recyclable compositor should be destroyed, and no future
  // compositors should be recycled.
  static void DisableRecyclingForShutdown();

  ui::Compositor* compositor() { return &compositor_; }
  ui::AcceleratedWidgetMac* accelerated_widget_mac() {
    return accelerated_widget_mac_.get();
  }

  // Suspend will prevent the compositor from producing new frames. This should
  // be called to avoid creating spurious frames while changing state.
  // Compositors are created as suspended.
  void Suspend();
  void Unsuspend();

 private:
  BrowserCompositorMac();

  // ui::CompositorObserver implementation:
  void OnCompositingDidCommit(ui::Compositor* compositor) override;
  void OnCompositingStarted(ui::Compositor* compositor,
                            base::TimeTicks start_time) override {}
  void OnCompositingEnded(ui::Compositor* compositor) override {}
  void OnCompositingAborted(ui::Compositor* compositor) override {}
  void OnCompositingLockStateChanged(ui::Compositor* compositor) override {}
  void OnCompositingShuttingDown(ui::Compositor* compositor) override {}

  std::unique_ptr<ui::AcceleratedWidgetMac> accelerated_widget_mac_;
  ui::Compositor compositor_;
  scoped_refptr<ui::CompositorLock> compositor_suspended_lock_;

  DISALLOW_COPY_AND_ASSIGN(BrowserCompositorMac);
};

// A class to keep around whenever a BrowserCompositorMac may be created.
// While at least one instance of this class exists, a spare
// BrowserCompositorViewCocoa will be kept around to be recycled so that the
// next BrowserCompositorMac to be created will be be created quickly.
class BrowserCompositorMacPlaceholder {
 public:
  BrowserCompositorMacPlaceholder();
  ~BrowserCompositorMacPlaceholder();

 private:
  DISALLOW_COPY_AND_ASSIGN(BrowserCompositorMacPlaceholder);
};

}  // namespace content

#endif  // CONTENT_BROWSER_RENDERER_HOST_BROWSER_COMPOSITOR_VIEW_MAC_H_