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 ui {
  15 class Layer;
  16 }
  17
  18 namespace 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).
  27 class 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_