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/notification.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(NotificationBlocker* blocker) = 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 appear in the
  35   // message center. Default returns true always.
  36   virtual bool ShouldShowNotification(const NotifierId& notifier_id) const;
  37
  38   // Returns true when notifications from |notifier_id| should be shown as
  39   // popups on screen.  If it's false, those notifications should be queued.
  40   // When a blocker starts returning false for a notification which is already
  41   // shown as a popup, the notification should be closed as a popup immediately.
  42   virtual bool ShouldShowNotificationAsPopup(
  43       const NotifierId& notifier_id) const = 0;
  44
  45  protected:
  46   MessageCenter* message_center() { return message_center_; }
  47   void NotifyBlockingStateChanged();
  48
  49  private:
  50   base::ObserverList<Observer> observers_;
  51   MessageCenter* message_center_;  // weak
  52 };
  53
  54 typedef std::vector<NotificationBlocker*> NotificationBlockers;
  55
  56 }  // namespace message_center
  57
  58 #endif  // UI_MESSAGE_CENTER_NOTIFICATION_BLOCKER_H_