1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef ASH_WM_SCREEN_DIMMER_H_
6#define ASH_WM_SCREEN_DIMMER_H_
7
8#include "ash/ash_export.h"
9#include "base/basictypes.h"
10#include "base/compiler_specific.h"
11#include "base/memory/scoped_ptr.h"
12#include "ui/aura/window_observer.h"
13
14namespace ui {
15class Layer;
16}
17
18namespace ash {
19
20// ScreenDimmer displays a partially-opaque layer above everything
21// else in the root window to darken the display.  It shouldn't be used
22// for long-term brightness adjustments due to performance
23// considerations -- it's only intended for cases where we want to
24// briefly dim the screen (e.g. to indicate to the user that we're
25// about to suspend a machine that lacks an internal backlight that
26// can be adjusted).
27class ASH_EXPORT ScreenDimmer : public aura::WindowObserver {
28 public:
29  class TestApi {
30   public:
31    explicit TestApi(ScreenDimmer* dimmer) : dimmer_(dimmer) {}
32
33    ui::Layer* layer() { return dimmer_->dimming_layer_.get(); }
34
35   private:
36    ScreenDimmer* dimmer_;  // not owned
37
38    DISALLOW_COPY_AND_ASSIGN(TestApi);
39  };
40
41  explicit ScreenDimmer(aura::Window* root_window);
42  virtual ~ScreenDimmer();
43
44  // Dim or undim the root window.
45  void SetDimming(bool should_dim);
46
47  // aura::WindowObserver overrides:
48  virtual void OnWindowBoundsChanged(aura::Window* root_window,
49                                     const gfx::Rect& old_bounds,
50                                     const gfx::Rect& new_bounds) OVERRIDE;
51
52 private:
53  friend class TestApi;
54
55  aura::Window* root_window_;
56
57  // Partially-opaque layer that's stacked above all of the root window's
58  // children and used to dim the screen.  NULL until the first time we dim.
59  scoped_ptr<ui::Layer> dimming_layer_;
60
61  // Are we currently dimming the screen?
62  bool currently_dimming_;
63
64  DISALLOW_COPY_AND_ASSIGN(ScreenDimmer);
65};
66
67}  // namespace ash
68
69#endif  // ASH_WM_SCREEN_DIMMER_H_
70