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      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_WIDGET_FOCUS_MANAGER_H_
      6 #define UI_VIEWS_FOCUS_WIDGET_FOCUS_MANAGER_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "base/observer_list.h"
     10 #include "ui/gfx/native_widget_types.h"
     11 #include "ui/views/views_export.h"
     12 
     13 template <typename T> struct DefaultSingletonTraits;
     14 
     15 namespace views {
     16 
     17 // This interface should be implemented by classes that want to be notified when
     18 // the native focus is about to change.  Listeners implementing this interface
     19 // will be invoked for all native focus changes across the entire Chrome
     20 // application.  FocusChangeListeners are only called for changes within the
     21 // children of a single top-level native-view.
     22 class WidgetFocusChangeListener {
     23  public:
     24   virtual void OnNativeFocusChange(gfx::NativeView focused_before,
     25                                    gfx::NativeView focused_now) = 0;
     26 
     27  protected:
     28   virtual ~WidgetFocusChangeListener() {}
     29 };
     30 
     31 class VIEWS_EXPORT WidgetFocusManager {
     32  public:
     33   // Returns the singleton instance.
     34   static WidgetFocusManager* GetInstance();
     35 
     36   // Adds/removes a WidgetFocusChangeListener |listener| to the set of
     37   // active listeners.
     38   void AddFocusChangeListener(WidgetFocusChangeListener* listener);
     39   void RemoveFocusChangeListener(WidgetFocusChangeListener* listener);
     40 
     41   // To be called when native-focus shifts from |focused_before| to
     42   // |focused_now|.
     43   // TODO(port) : Invocations to this routine are only implemented for
     44   // the Win32 platform.  Calls need to be placed appropriately for
     45   // non-Windows environments.
     46   void OnWidgetFocusEvent(gfx::NativeView focused_before,
     47                           gfx::NativeView focused_now);
     48 
     49   // Enable/Disable notification of registered listeners during calls
     50   // to OnWidgetFocusEvent.  Used to prevent unwanted focus changes from
     51   // propagating notifications.
     52   void EnableNotifications() { enabled_ = true; }
     53   void DisableNotifications() { enabled_ = false; }
     54 
     55  private:
     56   friend struct DefaultSingletonTraits<WidgetFocusManager>;
     57 
     58   WidgetFocusManager();
     59   ~WidgetFocusManager();
     60 
     61   ObserverList<WidgetFocusChangeListener> focus_change_listeners_;
     62 
     63   bool enabled_;
     64 
     65   DISALLOW_COPY_AND_ASSIGN(WidgetFocusManager);
     66 };
     67 
     68 // A basic helper class that is used to disable native focus change
     69 // notifications within a scope.
     70 class VIEWS_EXPORT AutoNativeNotificationDisabler {
     71  public:
     72   AutoNativeNotificationDisabler();
     73   ~AutoNativeNotificationDisabler();
     74 
     75  private:
     76   DISALLOW_COPY_AND_ASSIGN(AutoNativeNotificationDisabler);
     77 };
     78 
     79 }  // namespace views
     80 
     81 #endif  // UI_VIEWS_FOCUS_WIDGET_FOCUS_MANAGER_H_
     82