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
12namespace message_center {
13class 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.
18class 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  ObserverList<Observer> observers_;
51  MessageCenter* message_center_;  // weak
52};
53
54typedef std::vector<NotificationBlocker*> NotificationBlockers;
55
56}  // namespace message_center
57
58#endif  // UI_MESSAGE_CENTER_NOTIFICATION_BLOCKER_H_
59