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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef ASH_WM_WINDOW_CYCLE_CONTROLLER_H_
#define ASH_WM_WINDOW_CYCLE_CONTROLLER_H_
#include "ash/ash_export.h"
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
namespace ui {
class EventHandler;
}
namespace ash {
class WindowCycleList;
// Controls cycling through windows with the keyboard, for example, via alt-tab.
// Windows are sorted primarily by most recently used, and then by screen order.
// We activate windows as you cycle through them, so the order on the screen
// may change during the gesture, but the most recently used list isn't updated
// until the cycling ends. Thus we maintain the state of the windows
// at the beginning of the gesture so you can cycle through in a consistent
// order.
class ASH_EXPORT WindowCycleController {
public:
enum Direction {
FORWARD,
BACKWARD
};
WindowCycleController();
virtual ~WindowCycleController();
// Returns true if cycling through windows is enabled. This is false at
// certain times, such as when the lock screen is visible.
static bool CanCycle();
// Cycles between windows in the given |direction|. If |is_alt_down| then
// interprets this call as the start of a multi-step cycle sequence and
// installs a key filter to watch for alt being released.
void HandleCycleWindow(Direction direction, bool is_alt_down);
// Cycles between windows without maintaining a multi-step cycle sequence
// (see above).
void HandleLinearCycleWindow();
// Informs the controller that the Alt key has been released and it can
// terminate the existing multi-step cycle.
void AltKeyReleased();
// Returns true if we are in the middle of a window cycling gesture.
bool IsCycling() const { return windows_.get() != NULL; }
// Returns the WindowCycleList. Really only useful for testing.
const WindowCycleList* windows() const { return windows_.get(); }
private:
// Call to start cycling windows. You must call StopCycling() when done.
void StartCycling();
// Cycles to the next or previous window based on |direction|.
void Step(Direction direction);
// Installs an event filter to watch for release of the alt key.
void InstallEventFilter();
// Stops the current window cycle and cleans up the event filter.
void StopCycling();
scoped_ptr<WindowCycleList> windows_;
// Event handler to watch for release of alt key.
scoped_ptr<ui::EventHandler> event_handler_;
DISALLOW_COPY_AND_ASSIGN(WindowCycleController);
};
} // namespace ash
#endif // ASH_WM_WINDOW_CYCLE_CONTROLLER_H_
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