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
20namespace views {
21
22// Amount of time between when the mouse moves outside the Host's zone and when
23// the listener is notified.
24const int kNotifyListenerTimeMs = 300;
25
26class 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
94MouseWatcherListener::~MouseWatcherListener() {
95}
96
97MouseWatcherHost::~MouseWatcherHost() {
98}
99
100MouseWatcher::MouseWatcher(MouseWatcherHost* host,
101                           MouseWatcherListener* listener)
102    : host_(host),
103      listener_(listener),
104      notify_on_exit_time_(base::TimeDelta::FromMilliseconds(
105          kNotifyListenerTimeMs)) {
106}
107
108MouseWatcher::~MouseWatcher() {
109}
110
111void MouseWatcher::Start() {
112  if (!is_observing())
113    observer_.reset(new Observer(this));
114}
115
116void MouseWatcher::Stop() {
117  observer_.reset(NULL);
118}
119
120void MouseWatcher::NotifyListener() {
121  observer_.reset(NULL);
122  listener_->MouseMovedOutOfHost();
123}
124
125}  // namespace views
126