ash/wm/screen_dimmer.h

   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
  14 namespace aura {
  15 class RootWindow;
  16 }
  17
  18 namespace ui {
  19 class Layer;
  20 }
  21
  22 namespace ash {
  23 namespace internal {
  24
  25 // ScreenDimmer displays a partially-opaque layer above everything
  26 // else in the root window to darken the display.  It shouldn't be used
  27 // for long-term brightness adjustments due to performance
  28 // considerations -- it's only intended for cases where we want to
  29 // briefly dim the screen (e.g. to indicate to the user that we're
  30 // about to suspend a machine that lacks an internal backlight that
  31 // can be adjusted).
  32 class ASH_EXPORT ScreenDimmer : public aura::WindowObserver {
  33  public:
  34   class TestApi {
  35    public:
  36     explicit TestApi(ScreenDimmer* dimmer) : dimmer_(dimmer) {}
  37
  38     ui::Layer* layer() { return dimmer_->dimming_layer_.get(); }
  39
  40    private:
  41     ScreenDimmer* dimmer_;  // not owned
  42
  43     DISALLOW_COPY_AND_ASSIGN(TestApi);
  44   };
  45
  46   explicit ScreenDimmer(aura::RootWindow* root_window);
  47   virtual ~ScreenDimmer();
  48
  49   // Dim or undim the root window.
  50   void SetDimming(bool should_dim);
  51
  52   // aura::WindowObserver overrides:
  53   virtual void OnWindowBoundsChanged(aura::Window* root_window,
  54                                      const gfx::Rect& old_bounds,
  55                                      const gfx::Rect& new_bounds) OVERRIDE;
  56
  57  private:
  58   friend class TestApi;
  59
  60   aura::RootWindow* root_window_;
  61
  62   // Partially-opaque layer that's stacked above all of the root window's
  63   // children and used to dim the screen.  NULL until the first time we dim.
  64   scoped_ptr<ui::Layer> dimming_layer_;
  65
  66   // Are we currently dimming the screen?
  67   bool currently_dimming_;
  68
  69   DISALLOW_COPY_AND_ASSIGN(ScreenDimmer);
  70 };
  71
  72 }  // namespace internal
  73 }  // namespace ash
  74
  75 #endif  // ASH_WM_SCREEN_DIMMER_H_