ui/message_center/notification_blocker.h

   1 // Copyright 2013 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 #ifndef UI_MESSAGE_CENTER_NOTIFICATION_BLOCKER_H_
   6 #define UI_MESSAGE_CENTER_NOTIFICATION_BLOCKER_H_
   7
   8 #include "base/observer_list.h"
   9 #include "ui/message_center/message_center_export.h"
  10 #include "ui/message_center/notifier_settings.h"
  11
  12 namespace message_center {
  13 class MessageCenter;
  14
  15 // NotificationBlocker manages the availability of notifications based on the
  16 // current system status. Each NotificationBlocker implementation covers a
  17 // single state such as screen lock or fullscreen.
  18 class MESSAGE_CENTER_EXPORT NotificationBlocker {
  19  public:
  20   class Observer {
  21    public:
  22     virtual void OnBlockingStateChanged() = 0;
  23   };
  24
  25   explicit NotificationBlocker(MessageCenter* message_center);
  26   virtual ~NotificationBlocker();
  27
  28   void AddObserver(Observer* observer);
  29   void RemoveObserver(Observer* observer);
  30
  31   // Checks the current state and updates the availability.
  32   virtual void CheckState() {}
  33
  34   // Returns true when notifications from |notifier_id| should be shown as
  35   // popups on screen.  If it's false, those notifications should be queued.
  36   // When a blocker starts returning false for a notification which is already
  37   // shown as a popup, the notification should be closed as a popup immediately.
  38   virtual bool ShouldShowNotificationAsPopup(
  39       const NotifierId& notifier_id) const = 0;
  40
  41  protected:
  42   ObserverList<Observer>& observers() { return observers_; }
  43
  44  private:
  45   ObserverList<Observer> observers_;
  46   MessageCenter* message_center_;  // weak
  47 };
  48
  49 }  // namespace message_center
  50
  51 #endif  // UI_MESSAGE_CENTER_NOTIFICATION_BLOCKER_H_