/*

* Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:    Class that stores the active media list pointer

*

*/

#ifndef __C_GLXACTIVEMEDIALISTREGISTRY_H__

#define __C_GLXACTIVEMEDIALISTREGISTRY_H__

#include <e32std.h>

#include <e32base.h>

#include "mglxactivemedialistresolver.h"

class MGlxMediaList;

class MGlxActiveMediaListChangeObserver;

/**

 * Class to store the active media list

 */

NONSHARABLE_CLASS( CGlxActiveMediaListRegistry ) : public CBase, public MGlxActiveMediaListResolver

    {

public:

    /**

     * Return a (singleton) instance of the interface

     * Close the instance by calling Close() when done with the instance

     * @param aObserver Observer to add

     */

    IMPORT_C static CGlxActiveMediaListRegistry* InstanceL(

        MGlxActiveMediaListChangeObserver* aObserver = NULL); 

    /**

     * Close the instance and remove observer if any

     * See @ref MGlxActiveMediaListResolver::Close

     * @param aObserver Observer to remove

     */

    void Close(MGlxActiveMediaListChangeObserver* aObserver = NULL);

    /**

     * Registers a media list as being active

     * Calls MGlxActiveMediaListChangeObserver::HandleActiveMediaListChanged

     * @param aMediaList list to register as active 

     */

    IMPORT_C void RegisterActiveMediaList(MGlxMediaList* aMediaList);

    /**

     * Deregisters a media list that has previously registerd as active

     * Takes a pointer to the media list, so that implementation can 

     * know if the deregistration refers to a list that has been registered 

     * before the currenlty active list has been registered.

     * The background is that the DoDeactivateL of the previous view

     * is called after the DoActivateL of the new view.

     * Note: This must be called while the media list is still alive,

     * i.e., not closed!

     * If no other media list has been registered, the currently active

     * media list will be set to NULL.

     * Calls MGlxActiveMediaListChangeObserver::HandleActiveMediaListChanged

     * @param aMediaList list to deregister as active

     */

    IMPORT_C void DeregisterActiveMediaList(MGlxMediaList* aMediaList);

    /** 

     * See @ref MGlxActiveMediaListResolver::ActiveMediaList

     * @return the active media list

     */

    MGlxMediaList* ActiveMediaList() const;

private:

    /**

     * Constructor 

     */

    CGlxActiveMediaListRegistry();

    /** 

     * Destructor 

     */

    ~CGlxActiveMediaListRegistry();

    /** 

     * Notify observers of change to the list pointer

     */

    void NotifyObservers();

    /**

     * 2-phase constructor

     */

    static CGlxActiveMediaListRegistry* NewL();

private:

    /** 

     * The list in the currently open view that the user is navigating, or 

     * NULL if that media list is not known 

     */    

    MGlxMediaList* iActiveMediaList;

    /** 

     * True if two views have registered the currently active list 

     * Allows the current and previous view to register the same list

     */

    TBool iRegisteredTwice;

    /** List of observers */

    RPointerArray<MGlxActiveMediaListChangeObserver> iObservers;

    };     

#endif // __C_GLXACTIVEMEDIALISTREGISTRY_H__