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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 CHROME_BROWSER_UI_PANELS_DISPLAY_SETTINGS_PROVIDER_H_
      6 #define CHROME_BROWSER_UI_PANELS_DISPLAY_SETTINGS_PROVIDER_H_
      7 
      8 #include "base/observer_list.h"
      9 #include "base/timer/timer.h"
     10 #include "ui/gfx/rect.h"
     11 
     12 // Encapsulates the logic to provide display settings support, including the
     13 // information for:
     14 // 1) Work area
     15 // 2) Auto-hiding desktop bars, like Windows taskbar and MacOSX dock.
     16 class DisplaySettingsProvider {
     17  public:
     18   // Indicates which screen edge the desktop bar is aligned to.
     19   // We do not care about the desktop aligned to the top screen edge.
     20   enum DesktopBarAlignment {
     21     DESKTOP_BAR_ALIGNED_BOTTOM = 0,
     22     DESKTOP_BAR_ALIGNED_LEFT = 1,
     23     DESKTOP_BAR_ALIGNED_RIGHT = 2
     24   };
     25 
     26   // Indicates current visibility state of the desktop bar.
     27   enum DesktopBarVisibility {
     28     DESKTOP_BAR_VISIBLE,
     29     DESKTOP_BAR_ANIMATING,
     30     DESKTOP_BAR_HIDDEN
     31   };
     32 
     33   class DisplayObserver {
     34    public:
     35     virtual void OnDisplayChanged() = 0;
     36   };
     37 
     38   class DesktopBarObserver {
     39    public:
     40     virtual void OnAutoHidingDesktopBarVisibilityChanged(
     41         DesktopBarAlignment alignment, DesktopBarVisibility visibility) = 0;
     42     virtual void OnAutoHidingDesktopBarThicknessChanged(
     43         DesktopBarAlignment alignment, int thickness) = 0;
     44   };
     45 
     46   class FullScreenObserver {
     47    public:
     48     virtual void OnFullScreenModeChanged(bool is_full_screen) = 0;
     49   };
     50 
     51   static DisplaySettingsProvider* Create();
     52 
     53   virtual ~DisplaySettingsProvider();
     54 
     55   // Subscribes/unsubscribes from the display settings change notification.
     56   void AddDisplayObserver(DisplayObserver* observer);
     57   void RemoveDisplayObserver(DisplayObserver* observer);
     58 
     59   void AddDesktopBarObserver(DesktopBarObserver* observer);
     60   void RemoveDesktopBarObserver(DesktopBarObserver* observer);
     61 
     62   void AddFullScreenObserver(FullScreenObserver* observer);
     63   void RemoveFullScreenObserver(FullScreenObserver* observer);
     64 
     65   //
     66   // Display Area:
     67   //   This is the area of a display (monitor). There could be multiple display
     68   //   areas.
     69   // Work Area:
     70   //   This is the standard work area returned by the system. It is usually
     71   //   computed by the system as the part of display area that excludes
     72   //   top-most system menu or bars aligned to the screen edges.
     73   //
     74 
     75   // Returns the bounds of primary display.
     76   virtual gfx::Rect GetPrimaryDisplayArea() const;
     77 
     78   // Returns the bounds of the work area of primary display.
     79   virtual gfx::Rect GetPrimaryWorkArea() const;
     80 
     81   // Returns the bounds of the display area that most closely intersects the
     82   // provided bounds.
     83   virtual gfx::Rect GetDisplayAreaMatching(const gfx::Rect& bounds) const;
     84 
     85   // Returns the bounds of the work area that most closely intersects the
     86   // provided bounds.
     87   virtual gfx::Rect GetWorkAreaMatching(const gfx::Rect& bounds) const;
     88 
     89   // Invoked when the display settings has changed, due to any of the following:
     90   // 1) screen resolution changes
     91   // 2) the thickness of desktop bar changes
     92   // 3) desktop bar switches between auto-hiding and non-auto-hiding
     93   virtual void OnDisplaySettingsChanged();
     94 
     95   // Returns true if there is a desktop bar that is aligned to the specified
     96   // screen edge and set to auto-hide.
     97   virtual bool IsAutoHidingDesktopBarEnabled(DesktopBarAlignment alignment);
     98 
     99   // Returns the thickness of the desktop bar that is aligned to the specified
    100   // screen edge, when it is visible. When the desktop bar is aligned to bottom
    101   // edge, this is the height of the bar. If the desktop bar is aligned to
    102   // left or right edge, this is the width of the bar.
    103   virtual int GetDesktopBarThickness(DesktopBarAlignment alignment) const;
    104 
    105   // Returns the visibility state of the desktop bar that is aligned to the
    106   // specified screen edge.
    107   virtual DesktopBarVisibility GetDesktopBarVisibility(
    108       DesktopBarAlignment alignment) const;
    109 
    110   ObserverList<DisplayObserver>& display_observers() {
    111     return display_observers_;
    112   }
    113 
    114   ObserverList<DesktopBarObserver>& desktop_bar_observers() {
    115     return desktop_bar_observers_;
    116   }
    117 
    118   ObserverList<FullScreenObserver>& full_screen_observers() {
    119     return full_screen_observers_;
    120   }
    121 
    122   bool is_full_screen() const { return is_full_screen_; }
    123 
    124  protected:
    125   enum FullScreenCheckMode {
    126     ASSUME_FULLSCREEN_ON,
    127     ASSUME_FULLSCREEN_OFF,
    128     PERFORM_FULLSCREEN_CHECK
    129   };
    130 
    131   DisplaySettingsProvider();
    132 
    133   // Returns true if we need to perform fullscreen check periodically.
    134   virtual bool NeedsPeriodicFullScreenCheck() const;
    135 
    136   // Returns true if full screen or presentation mode in main screen is entered.
    137   virtual bool IsFullScreen();
    138 
    139   // Callback to perform periodic check for full screen mode changes.
    140   void CheckFullScreenMode(FullScreenCheckMode check_mode);
    141 
    142  private:
    143   // Observers that listen to various display settings changes.
    144   ObserverList<DisplayObserver> display_observers_;
    145   ObserverList<DesktopBarObserver> desktop_bar_observers_;
    146   ObserverList<FullScreenObserver> full_screen_observers_;
    147 
    148   // True if full screen mode or presentation mode is entered.
    149   bool is_full_screen_;
    150 
    151   // Timer used to detect full-screen mode change.
    152   base::RepeatingTimer<DisplaySettingsProvider> full_screen_mode_timer_;
    153 
    154   DISALLOW_COPY_AND_ASSIGN(DisplaySettingsProvider);
    155 };
    156 
    157 #endif  // CHROME_BROWSER_UI_PANELS_DISPLAY_SETTINGS_PROVIDER_H_
    158