ui/views/focus/external_focus_tracker.h

   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
  11 namespace views {
  12
  13 class View;
  14 class 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.
  29 class 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_