ash/wm/window_cycle_controller.cc

   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 #include "ash/wm/window_cycle_controller.h"
   6
   7 #include "ash/session/session_state_delegate.h"
   8 #include "ash/shell.h"
   9 #include "ash/wm/mru_window_tracker.h"
  10 #include "ash/wm/window_cycle_list.h"
  11 #include "base/metrics/histogram.h"
  12 #include "ui/events/event.h"
  13 #include "ui/events/event_handler.h"
  14
  15 namespace ash {
  16
  17 namespace {
  18
  19 // Filter to watch for the termination of a keyboard gesture to cycle through
  20 // multiple windows.
  21 class WindowCycleEventFilter : public ui::EventHandler {
  22  public:
  23   WindowCycleEventFilter();
  24   virtual ~WindowCycleEventFilter();
  25
  26   // Overridden from ui::EventHandler:
  27   virtual void OnKeyEvent(ui::KeyEvent* event) OVERRIDE;
  28
  29  private:
  30   DISALLOW_COPY_AND_ASSIGN(WindowCycleEventFilter);
  31 };
  32
  33 WindowCycleEventFilter::WindowCycleEventFilter() {
  34   Shell::GetInstance()->AddPreTargetHandler(this);
  35 }
  36
  37 WindowCycleEventFilter::~WindowCycleEventFilter() {
  38   Shell::GetInstance()->RemovePreTargetHandler(this);
  39 }
  40
  41 void WindowCycleEventFilter::OnKeyEvent(ui::KeyEvent* event) {
  42   // Views uses VKEY_MENU for both left and right Alt keys.
  43   if (event->key_code() == ui::VKEY_MENU &&
  44       event->type() == ui::ET_KEY_RELEASED) {
  45     Shell::GetInstance()->window_cycle_controller()->StopCycling();
  46     // Warning: |this| will be deleted from here on.
  47   }
  48 }
  49
  50 }  // namespace
  51
  52 //////////////////////////////////////////////////////////////////////////////
  53 // WindowCycleController, public:
  54
  55 WindowCycleController::WindowCycleController() {
  56 }
  57
  58 WindowCycleController::~WindowCycleController() {
  59 }
  60
  61 // static
  62 bool WindowCycleController::CanCycle() {
  63   // Don't allow window cycling if the screen is locked or a modal dialog is
  64   // open.
  65   return !Shell::GetInstance()->session_state_delegate()->IsScreenLocked() &&
  66          !Shell::GetInstance()->IsSystemModalWindowOpen();
  67 }
  68
  69 void WindowCycleController::HandleCycleWindow(Direction direction) {
  70   if (!CanCycle())
  71     return;
  72
  73   if (!IsCycling())
  74     StartCycling();
  75
  76   Step(direction);
  77 }
  78
  79 void WindowCycleController::StartCycling() {
  80   window_cycle_list_.reset(new WindowCycleList(ash::Shell::GetInstance()->
  81       mru_window_tracker()->BuildMruWindowList()));
  82   event_handler_.reset(new WindowCycleEventFilter());
  83   cycle_start_time_ = base::Time::Now();
  84   Shell::GetInstance()->metrics()->RecordUserMetricsAction(UMA_WINDOW_CYCLE);
  85 }
  86
  87 //////////////////////////////////////////////////////////////////////////////
  88 // WindowCycleController, private:
  89
  90 void WindowCycleController::Step(Direction direction) {
  91   DCHECK(window_cycle_list_.get());
  92   window_cycle_list_->Step(direction);
  93 }
  94
  95 void WindowCycleController::StopCycling() {
  96   window_cycle_list_.reset();
  97   // Remove our key event filter.
  98   event_handler_.reset();
  99   UMA_HISTOGRAM_MEDIUM_TIMES("Ash.WindowCycleController.CycleTime",
 100                              base::Time::Now() - cycle_start_time_);
 101 }
 102
 103 }  // namespace ash