/*

* Copyright (c) 2005-2008 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:   Active object that tracks changes on a PS property.

*

*/

#ifndef C_VCCPSPROPERTYLISTENER_H

#define C_VCCPSPROPERTYLISTENER_H

#include <e32base.h>

#include <e32property.h>

#include "mvccpspropertylistenerobserver.h"

/*

 *  CVccUiPsPropertyListener notes its observers when the value of the VCC

 *  property changes.

 *

 *  This class can get notifications about the VCC properties.

 *

 *  @code

 *  void CExampleClass::ConstructL()

 *  {

 *   CVccUiPsPropertyListener* iHoStatusListener =

 *              CVccUiPsPropertyListener::NewL( KVccPropKeyHoStatus );

 *   iHoStatusListener.AddObserver( this );

 *   iHoStatusListener.Start();

 *  }

 *

 *  void CExampleClass::VccPropertyChangedL( const TUint aKeyId,

            const TInt aValue )

 *  {

 *      if( aKeyId )

 *          {

 *          switch( aValue )

 *              {

 *              case EVccCsToPsHoStarted:

 *                  // show UI notification

 *                  break;

 *              default:

 *                  break;

 *              }

 *          }

 *  }

 *

 *  @endcode

 *

 *  @lib vccuipropertyhandler.lib

 *  @since S60 v3.2

 */

class CVccUiPsPropertyListener : public CActive

    {

public:

    /**

     * Symbian two-phased constructor.

     *

     * @param aKeyId Id of a key of the property.

     */

    IMPORT_C static CVccUiPsPropertyListener* NewL( const TUint aKeyId );

    /**

     * Destructor.

     */

    IMPORT_C virtual ~CVccUiPsPropertyListener();

    /**

     * Add an observer

     * @param aObserver Reference to observer object 

     */

    IMPORT_C void AddObserverL( MVccPsPropertyListenerObserver& aObserver );

    /**

     * Remove an observer.

     * @param aObserver Reference to observer object

     */

    IMPORT_C void RemoveObserver( MVccPsPropertyListenerObserver& aObserver );

    /**

     * Get the current value of the property.

     * @return Property value

     */

    IMPORT_C TInt CurrentValue();

    /**

     * Start the listener. The listener subscribes to the given property.

     */

    IMPORT_C void Start();

private:

    /**

     * Constructor.

     *

     * @param aKeyId Id of a key of the property.

     */

    CVccUiPsPropertyListener( const TUint aKeyId );

    /**

     * Symbian 2nd phase constructor

     */

    void ConstructL();

    /**

     * Notifies the observers about the Ho state change.

     */

    void NotifyObserversL();

// from base class CActive.

    /**

     * @see CActive::RunL()

     */

    void RunL();

    /**

     * @see CActive::DoCancel()

     */

    void DoCancel();

private: //data

    /**

     * The uid of the property category to be watched.

     */

    TUid iCategoryId;

    /**

     * The property key uid to be watched.

     */

    TUint iKeyId;

    /**

     * the property category.

     */

    RProperty iProperty;

    /**

     * Obsevers for callback from this.

     * Observers are not owned.

     */

    RPointerArray<MVccPsPropertyListenerObserver> iObservers;

    };

#endif // C_VCCPSPROPERTYLISTENER_H