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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_OVERLAY_EVENT_FILTER_H_
#define ASH_WM_OVERLAY_EVENT_FILTER_H_
#include "ash/shell_observer.h"
#include "base/compiler_specific.h"
#include "ui/aura/window.h"
#include "ui/events/event_handler.h"
namespace ash {
namespace internal {
// EventFilter for the "overlay window", which intercepts events before they are
// processed by the usual path (e.g. the partial screenshot UI, the keyboard
// overlay). It does nothing the first time, but works when |Activate()| is
// called. The main task of this event filter is just to stop propagation
// of any key events during activation, and also signal cancellation when keys
// for canceling are pressed.
class OverlayEventFilter : public ui::EventHandler,
public ShellObserver {
public:
// Windows that need to receive events from OverlayEventFilter implement this.
class Delegate {
public:
// Invoked when OverlayEventFilter needs to stop handling events.
virtual void Cancel() = 0;
// Returns true if the overlay should be canceled in response to |event|.
virtual bool IsCancelingKeyEvent(ui::KeyEvent* event) = 0;
// Returns the window that needs to receive events. NULL if no window needs
// to receive key events from OverlayEventFilter.
virtual aura::Window* GetWindow() = 0;
};
OverlayEventFilter();
virtual ~OverlayEventFilter();
// Starts the filtering of events. It also notifies the specified
// |delegate| when a key event means cancel (like Esc). It holds the
// pointer to the specified |delegate| until Deactivate() is called, but
// does not take ownership.
void Activate(Delegate* delegate);
// Ends the filtering of events.
void Deactivate();
// Cancels the partial screenshot UI. Do nothing if it's not activated.
void Cancel();
// ui::EventHandler overrides:
virtual void OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
// ShellObserver overrides:
virtual void OnLoginStateChanged(user::LoginStatus status) OVERRIDE;
virtual void OnAppTerminating() OVERRIDE;
virtual void OnLockStateChanged(bool locked) OVERRIDE;
private:
Delegate* delegate_;
DISALLOW_COPY_AND_ASSIGN(OverlayEventFilter);
};
} // namespace internal
} // namespace ash
#endif // ASH_WM_OVERLAY_EVENT_FILTER_H_
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