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_(EventMonitor::CreateApplicationMonitor(this)),
  29         notify_listener_factory_(this) {
  30   }
  31
  32   // ui::EventHandler implementation:
  33   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       case ui::ET_MOUSE_PRESSED:
  43         HandleMouseEvent(MouseWatcherHost::MOUSE_PRESS);
  44         break;
  45       default:
  46         break;
  47     }
  48   }
  49
  50  private:
  51   MouseWatcherHost* host() const { return mouse_watcher_->host_.get(); }
  52
  53   // Called when a mouse event we're interested is seen.
  54   void HandleMouseEvent(MouseWatcherHost::MouseEventType event_type) {
  55     // It's safe to use last_mouse_location() here as this function is invoked
  56     // during event dispatching.
  57     if (!host()->Contains(EventMonitor::GetLastMouseLocation(), event_type)) {
  58       if (event_type == MouseWatcherHost::MOUSE_PRESS) {
  59         NotifyListener();
  60       } else if (!notify_listener_factory_.HasWeakPtrs()) {
  61         // Mouse moved outside the host's zone, start a timer to notify the
  62         // listener.
  63         base::MessageLoop::current()->PostDelayedTask(
  64             FROM_HERE,
  65             base::Bind(&Observer::NotifyListener,
  66                        notify_listener_factory_.GetWeakPtr()),
  67             event_type == MouseWatcherHost::MOUSE_MOVE
  68                 ? base::TimeDelta::FromMilliseconds(kNotifyListenerTimeMs)
  69                 : mouse_watcher_->notify_on_exit_time_);
  70       }
  71     } else {
  72       // Mouse moved quickly out of the host and then into it again, so cancel
  73       // the timer.
  74       notify_listener_factory_.InvalidateWeakPtrs();
  75     }
  76   }
  77
  78   void NotifyListener() {
  79     mouse_watcher_->NotifyListener();
  80     // WARNING: we've been deleted.
  81   }
  82
  83  private:
  84   MouseWatcher* mouse_watcher_;
  85   scoped_ptr<views::EventMonitor> event_monitor_;
  86
  87   // A factory that is used to construct a delayed callback to the listener.
  88   base::WeakPtrFactory<Observer> notify_listener_factory_;
  89
  90   DISALLOW_COPY_AND_ASSIGN(Observer);
  91 };
  92
  93 MouseWatcherListener::~MouseWatcherListener() {
  94 }
  95
  96 MouseWatcherHost::~MouseWatcherHost() {
  97 }
  98
  99 MouseWatcher::MouseWatcher(MouseWatcherHost* host,
 100                            MouseWatcherListener* listener)
 101     : host_(host),
 102       listener_(listener),
 103       notify_on_exit_time_(base::TimeDelta::FromMilliseconds(
 104           kNotifyListenerTimeMs)) {
 105 }
 106
 107 MouseWatcher::~MouseWatcher() {
 108 }
 109
 110 void MouseWatcher::Start() {
 111   if (!is_observing())
 112     observer_.reset(new Observer(this));
 113 }
 114
 115 void MouseWatcher::Stop() {
 116   observer_.reset(NULL);
 117 }
 118
 119 void MouseWatcher::NotifyListener() {
 120   observer_.reset(NULL);
 121   listener_->MouseMovedOutOfHost();
 122 }
 123
 124 }  // namespace views