1// Copyright (c) 2011 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_VIEWS_FOCUS_EXTERNAL_FOCUS_TRACKER_H_
6#define UI_VIEWS_FOCUS_EXTERNAL_FOCUS_TRACKER_H_
7
8#include "base/compiler_specific.h"
9#include "ui/views/focus/focus_manager.h"
10
11namespace views {
12
13class View;
14class ViewStorage;
15
16// ExternalFocusTracker tracks the last focused view which belongs to the
17// provided focus manager and is not either the provided parent view or one of
18// its descendants. This is generally used if the parent view want to return
19// focus to some other view once it is dismissed. The parent view and the focus
20// manager must exist for the duration of the tracking. If the focus manager
21// must be deleted before this object is deleted, make sure to call
22// SetFocusManager(NULL) first.
23//
24// Typical use: When a view is added to the view hierarchy, it instantiates an
25// ExternalFocusTracker and passes in itself and its focus manager. Then,
26// when that view wants to return focus to the last focused view which is not
27// itself and not a descandant of itself, (usually when it is being closed)
28// it calls FocusLastFocusedExternalView.
29class VIEWS_EXPORT ExternalFocusTracker : public FocusChangeListener {
30 public:
31  ExternalFocusTracker(View* parent_view, FocusManager* focus_manager);
32  virtual ~ExternalFocusTracker();
33
34  // FocusChangeListener:
35  virtual void OnWillChangeFocus(View* focused_before,
36                                 View* focused_now) OVERRIDE;
37  virtual void OnDidChangeFocus(View* focused_before,
38                                View* focused_now) OVERRIDE;
39
40  // Focuses last focused view which is not a child of parent view and is not
41  // parent view itself. Returns true if focus for a view was requested, false
42  // otherwise.
43  void FocusLastFocusedExternalView();
44
45  // Sets the focus manager whose focus we are tracking. |focus_manager| can
46  // be NULL, but no focus changes will be tracked. This is useful if the focus
47  // manager went away, but you might later want to start tracking with a new
48  // manager later, or call FocusLastFocusedExternalView to focus the previous
49  // view.
50  void SetFocusManager(FocusManager* focus_manager);
51
52 private:
53  // Store the provided view. This view will be focused when
54  // FocusLastFocusedExternalView is called.
55  void StoreLastFocusedView(View* view);
56
57  // Store the currently focused view for our view manager and register as a
58  // listener for future focus changes.
59  void StartTracking();
60
61  // Focus manager which we are a listener for.
62  FocusManager* focus_manager_;
63
64  // ID of the last focused view, which we store in view_storage_.
65  int last_focused_view_storage_id_;
66
67  // Used to store the last focused view which is not a child of
68  // ExternalFocusTracker.
69  ViewStorage* view_storage_;
70
71  // The parent view of views which we should not track focus changes to. We
72  // also do not track changes to parent_view_ itself.
73  View* parent_view_;
74
75  DISALLOW_COPY_AND_ASSIGN(ExternalFocusTracker);
76};
77
78}  // namespace views
79
80#endif  // UI_VIEWS_FOCUS_EXTERNAL_FOCUS_TRACKER_H_
81