chrome/browser/background_application_list_model.h

// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_BACKGROUND_APPLICATION_LIST_MODEL_H_
#define CHROME_BROWSER_BACKGROUND_APPLICATION_LIST_MODEL_H_
#pragma once

#include <map>
#include <string>

#include "base/basictypes.h"
#include "base/observer_list.h"
#include "chrome/common/extensions/extension.h"
#include "content/common/notification_observer.h"
#include "content/common/notification_registrar.h"

class ExtensionService;
class PrefService;
class Profile;

// Model for list of Background Applications, that is, Extensions with
// kBackgroundPermission set, associated with a Profile.
class BackgroundApplicationListModel : public NotificationObserver {
 public:
  // Observer is informed of changes to the model.  Users of the
  // BackgroundApplicationListModel should anticipate that associated data,
  // e. g. the Icon, may exist and yet not be immediately available.  When the
  // data becomes available, OnApplicationDataChanged will be invoked for all
  // Observers of the model.
  class Observer {
   public:
    // Invoked when data that the model associates with the extension, such as
    // the Icon, has changed.
    virtual void OnApplicationDataChanged(const Extension* extension);

    // Invoked when the model detects a previously unknown extension and/or when
    // it no longer detects a previously known extension.
    virtual void OnApplicationListChanged();

   protected:
    virtual ~Observer();
  };

  // Create a new model associated with profile.
  explicit BackgroundApplicationListModel(Profile* profile);

  ~BackgroundApplicationListModel();

  // Associate observer with this model.
  void AddObserver(Observer* observer);

  // Return the icon associated with |extension| or NULL.  NULL indicates either
  // that there is no icon associated with the extension, or that a pending
  // task to retrieve the icon has not completed.  See the Observer class above.
  //
  // NOTE: The model manages the SkBitmap result, that is it "owns" the memory,
  //       releasing it if the associated background application is unloaded.
  // NOTE: All icons are currently sized as Extension::EXTENSION_ICON_BITTY.
  const SkBitmap* GetIcon(const Extension* extension);

  // Return the position of |extension| within this list model.
  int GetPosition(const Extension* extension) const;

  // Return the extension at the specified |position| in this list model.
  const Extension* GetExtension(int position) const;

  // Returns true if the passed extension is a background app.
  static bool IsBackgroundApp(const Extension& extension);

  // Dissociate observer from this model.
  void RemoveObserver(Observer* observer);

  ExtensionList::const_iterator begin() const {
    return extensions_.begin();
  }

  ExtensionList::const_iterator end() const {
    return extensions_.end();
  }

  size_t size() const {
    return extensions_.size();
  }

 private:
  // Contains data associated with a background application that is not
  // represented by the Extension class.
  class Application;

  // Associates extension id strings with Application objects.
  typedef std::map<std::string, Application*> ApplicationMap;

  // Identifies and caches data related to the extension.
  void AssociateApplicationData(const Extension* extension);

  // Clears cached data related to |extension|.
  void DissociateApplicationData(const Extension* extension);

  // Returns the Application associated with |extension| or NULL.
  const Application* FindApplication(const Extension* extension) const;

  // Returns the Application associated with |extension| or NULL.
  Application* FindApplication(const Extension* extension);

  // NotificationObserver implementation.
  virtual void Observe(NotificationType type,
                       const NotificationSource& source,
                       const NotificationDetails& details);

  // Notifies observers that some of the data associated with this background
  // application, e. g. the Icon, has changed.
  void OnApplicationDataChanged(const Extension* extension);

  // Notifies observers that at least one background application has been added
  // or removed.
  void OnApplicationListChanged();

  // Invoked by Observe for EXTENSION_LOADED notifications.
  void OnExtensionLoaded(Extension* extension);

  // Invoked by Observe for EXTENSION_UNLOADED notifications.
  void OnExtensionUnloaded(const Extension* extension);

  // Refresh the list of background applications and generate notifications.
  void Update();

  ApplicationMap applications_;
  ExtensionList extensions_;
  ObserverList<Observer> observers_;
  Profile* profile_;
  NotificationRegistrar registrar_;

  DISALLOW_COPY_AND_ASSIGN(BackgroundApplicationListModel);
};

#endif  // CHROME_BROWSER_BACKGROUND_APPLICATION_LIST_MODEL_H_