Home | History | Annotate | Download | only in accelerators 
      1 // Copyright 2013 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_ACCELERATORS_EXIT_WARNING_HANDLER_H_
      6 #define ASH_ACCELERATORS_EXIT_WARNING_HANDLER_H_
      7 
      8 #include "ash/ash_export.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "base/timer/timer.h"
     11 #include "ui/base/accelerators/accelerator.h"
     12 
     13 namespace views {
     14 class Widget;
     15 }
     16 
     17 namespace ash {
     18 
     19 // In order to avoid accidental exits when the user presses the exit
     20 // shortcut by mistake, we require the user press it twice within a
     21 // period of time. During that time we show a popup informing the
     22 // user of this.
     23 //
     24 // Notes:
     25 //
     26 // The corresponding accelerator must be non-repeatable (see
     27 // kNonrepeatableActions in accelerator_table.cc). Otherwise the "Double Press
     28 // Exit" will be activated just by holding it down, i.e. probably every time.
     29 //
     30 // State Transition Diagrams:
     31 //
     32 //  IDLE
     33 //   | Press
     34 //  WAIT_FOR_DOUBLE_PRESS action: show ui & start timers
     35 //   | Press (before time limit )
     36 //  EXITING action: hide ui, stop timer, exit
     37 //
     38 //  IDLE
     39 //   | Press
     40 //  WAIT_FOR_DOUBLE_PRESS action: show ui & start timers
     41 //   | T timer expires
     42 //  IDLE action: hide ui
     43 //
     44 
     45 class AcceleratorControllerTest;
     46 
     47 class ASH_EXPORT ExitWarningHandler {
     48  public:
     49   ExitWarningHandler();
     50 
     51   ~ExitWarningHandler();
     52 
     53   // Handles accelerator for exit (Ctrl-Shift-Q).
     54   void HandleAccelerator();
     55 
     56  private:
     57   friend class AcceleratorControllerTest;
     58 
     59   enum State {
     60     IDLE,
     61     WAIT_FOR_DOUBLE_PRESS,
     62     EXITING
     63   };
     64 
     65   // Performs actions when the time limit is exceeded.
     66   void TimerAction();
     67 
     68   void StartTimer();
     69   void CancelTimer();
     70 
     71   void Show();
     72   void Hide();
     73 
     74   State state_;
     75   scoped_ptr<views::Widget> widget_;
     76   base::OneShotTimer<ExitWarningHandler> timer_;
     77 
     78   // Flag to suppress starting the timer for testing. For test we call
     79   // TimerAction() directly to simulate the expiration of the timer.
     80   bool stub_timer_for_test_;
     81 
     82   DISALLOW_COPY_AND_ASSIGN(ExitWarningHandler);
     83 };
     84 
     85 }  // namespace ash
     86 
     87 #endif  // ASH_ACCELERATORS_EXIT_WARNING_HANDLER_H_
     88