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