1 // Copyright 2014 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_WINDOW_CYCLE_CONTROLLER_H_ 6 #define ASH_WM_WINDOW_CYCLE_CONTROLLER_H_ 7 8 #include "ash/ash_export.h" 9 #include "base/basictypes.h" 10 #include "base/memory/scoped_ptr.h" 11 #include "base/time/time.h" 12 13 namespace ui { 14 class EventHandler; 15 } 16 17 namespace ash { 18 19 class WindowCycleList; 20 21 // Controls cycling through windows with the keyboard via alt-tab. 22 // Windows are sorted primarily by most recently used, and then by screen order. 23 // We activate windows as you cycle through them, so the order on the screen 24 // may change during the gesture, but the most recently used list isn't updated 25 // until the cycling ends. Thus we maintain the state of the windows 26 // at the beginning of the gesture so you can cycle through in a consistent 27 // order. 28 class ASH_EXPORT WindowCycleController { 29 public: 30 enum Direction { 31 FORWARD, 32 BACKWARD 33 }; 34 35 WindowCycleController(); 36 virtual ~WindowCycleController(); 37 38 // Returns true if cycling through windows is enabled. This is false at 39 // certain times, such as when the lock screen is visible. 40 static bool CanCycle(); 41 42 // Cycles between windows in the given |direction|. 43 void HandleCycleWindow(Direction direction); 44 45 // Returns true if we are in the middle of a window cycling gesture. IsCycling()46 bool IsCycling() const { return window_cycle_list_.get() != NULL; } 47 48 // Call to start cycling windows. This funtion adds a pre-target handler to 49 // listen to the alt key release. 50 void StartCycling(); 51 52 // Stops the current window cycle and removes the event filter. 53 void StopCycling(); 54 55 // Returns the WindowCycleList. Really only useful for testing. window_cycle_list()56 const WindowCycleList* window_cycle_list() const { 57 return window_cycle_list_.get(); 58 } 59 60 private: 61 // Cycles to the next or previous window based on |direction|. 62 void Step(Direction direction); 63 64 scoped_ptr<WindowCycleList> window_cycle_list_; 65 66 // Event handler to watch for release of alt key. 67 scoped_ptr<ui::EventHandler> event_handler_; 68 69 base::Time cycle_start_time_; 70 71 DISALLOW_COPY_AND_ASSIGN(WindowCycleController); 72 }; 73 74 } // namespace ash 75 76 #endif // ASH_WM_WINDOW_CYCLE_CONTROLLER_H_ 77