ui/views/mouse_watcher_aura.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 "ui/views/mouse_watcher.h"
   6
   7 #include "base/bind.h"
   8 #include "base/compiler_specific.h"
   9 #include "base/event_types.h"
  10 #include "base/memory/weak_ptr.h"
  11 #include "base/message_loop/message_loop.h"
  12 #include "ui/aura/env.h"
  13 #include "ui/aura/window.h"
  14 #include "ui/events/event.h"
  15 #include "ui/events/event_constants.h"
  16 #include "ui/events/event_handler.h"
  17 #include "ui/events/event_utils.h"
  18 #include "ui/gfx/screen.h"
  19
  20 namespace views {
  21
  22 // Amount of time between when the mouse moves outside the Host's zone and when
  23 // the listener is notified.
  24 const int kNotifyListenerTimeMs = 300;
  25
  26 class MouseWatcher::Observer : public ui::EventHandler {
  27  public:
  28   explicit Observer(MouseWatcher* mouse_watcher)
  29       : mouse_watcher_(mouse_watcher),
  30         notify_listener_factory_(this) {
  31     aura::Env::GetInstance()->AddPreTargetHandler(this);
  32   }
  33
  34   virtual ~Observer() {
  35     aura::Env::GetInstance()->RemovePreTargetHandler(this);
  36   }
  37
  38   // ui::EventHandler implementation:
  39   virtual void OnMouseEvent(ui::MouseEvent* event) OVERRIDE {
  40     switch (event->type()) {
  41       case ui::ET_MOUSE_MOVED:
  42       case ui::ET_MOUSE_DRAGGED:
  43         HandleMouseEvent(MouseWatcherHost::MOUSE_MOVE);
  44         break;
  45       case ui::ET_MOUSE_EXITED:
  46         HandleMouseEvent(MouseWatcherHost::MOUSE_EXIT);
  47         break;
  48       default:
  49         break;
  50     }
  51   }
  52
  53  private:
  54   MouseWatcherHost* host() const { return mouse_watcher_->host_.get(); }
  55
  56   // Called when a mouse event we're interested is seen.
  57   void HandleMouseEvent(MouseWatcherHost::MouseEventType event_type) {
  58     // It's safe to use last_mouse_location() here as this function is invoked
  59     // during event dispatching.
  60     if (!host()->Contains(aura::Env::GetInstance()->last_mouse_location(),
  61                           event_type)) {
  62       // Mouse moved outside the host's zone, start a timer to notify the
  63       // listener.
  64       if (!notify_listener_factory_.HasWeakPtrs()) {
  65         base::MessageLoop::current()->PostDelayedTask(
  66             FROM_HERE,
  67             base::Bind(&Observer::NotifyListener,
  68                        notify_listener_factory_.GetWeakPtr()),
  69             event_type == MouseWatcherHost::MOUSE_MOVE
  70                 ? base::TimeDelta::FromMilliseconds(kNotifyListenerTimeMs)
  71                 : mouse_watcher_->notify_on_exit_time_);
  72       }
  73     } else {
  74       // Mouse moved quickly out of the host and then into it again, so cancel
  75       // the timer.
  76       notify_listener_factory_.InvalidateWeakPtrs();
  77     }
  78   }
  79
  80   void NotifyListener() {
  81     mouse_watcher_->NotifyListener();
  82     // WARNING: we've been deleted.
  83   }
  84
  85  private:
  86   MouseWatcher* mouse_watcher_;
  87
  88   // A factory that is used to construct a delayed callback to the listener.
  89   base::WeakPtrFactory<Observer> notify_listener_factory_;
  90
  91   DISALLOW_COPY_AND_ASSIGN(Observer);
  92 };
  93
  94 MouseWatcherListener::~MouseWatcherListener() {
  95 }
  96
  97 MouseWatcherHost::~MouseWatcherHost() {
  98 }
  99
 100 MouseWatcher::MouseWatcher(MouseWatcherHost* host,
 101                            MouseWatcherListener* listener)
 102     : host_(host),
 103       listener_(listener),
 104       notify_on_exit_time_(base::TimeDelta::FromMilliseconds(
 105           kNotifyListenerTimeMs)) {
 106 }
 107
 108 MouseWatcher::~MouseWatcher() {
 109 }
 110
 111 void MouseWatcher::Start() {
 112   if (!is_observing())
 113     observer_.reset(new Observer(this));
 114 }
 115
 116 void MouseWatcher::Stop() {
 117   observer_.reset(NULL);
 118 }
 119
 120 void MouseWatcher::NotifyListener() {
 121   observer_.reset(NULL);
 122   listener_->MouseMovedOutOfHost();
 123 }
 124
 125 }  // namespace views