components/ui/zoom/zoom_event_manager.h

   1 // Copyright 2014 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 COMPONENTS_UI_ZOOM_ZOOM_EVENT_MANAGER_H_
   6 #define COMPONENTS_UI_ZOOM_ZOOM_EVENT_MANAGER_H_
   7
   8 #include "base/callback_list.h"
   9 #include "base/memory/weak_ptr.h"
  10 #include "base/observer_list.h"
  11 #include "base/supports_user_data.h"
  12 #include "content/public/browser/host_zoom_map.h"
  13
  14 namespace content {
  15 class BrowserContext;
  16 }  // namespace content
  17
  18 namespace ui_zoom {
  19
  20 class ZoomEventManagerObserver;
  21
  22 // This class serves as a target for event notifications from all ZoomController
  23 // objects. Classes that need to know about browser-specific zoom events (e.g.
  24 // manual-mode zoom) should subscribe here.
  25 class ZoomEventManager : public base::SupportsUserData::Data {
  26  public:
  27   ZoomEventManager();
  28   ~ZoomEventManager() override;
  29
  30   // Returns the ZoomEventManager for the specified BrowserContext. This
  31   // function creates the ZoomEventManager if it hasn't been created already.
  32   static ZoomEventManager* GetForBrowserContext(
  33       content::BrowserContext* context);
  34
  35   // Called by ZoomControllers when changes are made to zoom levels in manual
  36   // mode in order that browser listeners can be notified.
  37   void OnZoomLevelChanged(const content::HostZoomMap::ZoomLevelChange& change);
  38
  39   // Add and remove zoom level changed callbacks.
  40   // TODO(wjmaclean): Convert this callback mechanism to use
  41   // ZoomEventManagerObserver instead.
  42   scoped_ptr<content::HostZoomMap::Subscription> AddZoomLevelChangedCallback(
  43       const content::HostZoomMap::ZoomLevelChangedCallback& callback);
  44
  45   // Called by ZoomLevelDelegates when changes are made to the default zoom
  46   // level for their associated HostZoomMap.
  47   void OnDefaultZoomLevelChanged();
  48
  49   // Add and remove observers.
  50   void AddZoomEventManagerObserver(ZoomEventManagerObserver* observer);
  51   void RemoveZoomEventManagerObserver(ZoomEventManagerObserver* observer);
  52
  53   // Get a weak ptr to be used by clients who may themselves be UserData for
  54   // the context, since the order of destruction is undefined between the client
  55   // and this class.
  56   base::WeakPtr<ZoomEventManager> GetWeakPtr() {
  57     return weak_ptr_factory_.GetWeakPtr();
  58   }
  59
  60  private:
  61   base::CallbackList<void(const content::HostZoomMap::ZoomLevelChange&)>
  62       zoom_level_changed_callbacks_;
  63   ObserverList<ZoomEventManagerObserver> observers_;
  64   base::WeakPtrFactory<ZoomEventManager> weak_ptr_factory_;
  65
  66   DISALLOW_COPY_AND_ASSIGN(ZoomEventManager);
  67 };
  68
  69 }  // namespace ui_zoom
  70
  71 #endif  // COMPONENTS_UI_ZOOM_ZOOM_EVENT_MANAGER_H_