ash/accelerators/exit_warning_handler.h

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