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