ui/gfx/mac/scoped_cocoa_disable_screen_updates.h

// Copyright (c) 2011 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_GFX_MAC_SCOPED_COCOA_DISABLE_SCREEN_UPDATES_H_
#define UI_GFX_MAC_SCOPED_COCOA_DISABLE_SCREEN_UPDATES_H_

#import <Cocoa/Cocoa.h>

#include "base/mac/mac_util.h"
#include "base/macros.h"

namespace gfx {

// A stack-based class to disable Cocoa screen updates. When instantiated, it
// disables screen updates and enables them when destroyed. Update disabling
// can be nested, and there is a time-maximum (about 1 second) after which
// Cocoa will automatically re-enable updating. This class doesn't attempt to
// overrule that.
class ScopedCocoaDisableScreenUpdates {
 public:
  ScopedCocoaDisableScreenUpdates() {
    if (base::mac::IsAtLeastOS10_11()) {
      // Beginning with OS X 10.11, [NSAnimationContext beginGrouping] is the
      // preferred way of disabling screen updates. Use of
      // NSDisableScreenUpdates() is discouraged.
      [NSAnimationContext beginGrouping];
    } else {
      NSDisableScreenUpdates();
    }
  }
  ~ScopedCocoaDisableScreenUpdates() {
    if (base::mac::IsAtLeastOS10_11()) {
      [NSAnimationContext endGrouping];
    } else {
      NSEnableScreenUpdates();
    }
  }

 private:
  DISALLOW_COPY_AND_ASSIGN(ScopedCocoaDisableScreenUpdates);
};

}  // namespace gfx

#endif  // UI_GFX_MAC_SCOPED_COCOA_DISABLE_SCREEN_UPDATES_H_