/*

* Copyright (c) 2005 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:  

*

*/

#ifndef MUSUICALLBACKSERVICE_H

#define MUSUICALLBACKSERVICE_H

#include "musuidefinitions.h"

#include <e32base.h>

class MMusUiCallbackObserver;

/**

 * Callback Service used to pass asynchronous events

 */

class CMusUiCallbackService : public CActive

    {

public: // Constructors and destructor

    /**

    * Two-phased constructor.

    * @param aCallbackObserver the observer that will receive the callbacks.

    * @return new instance of CMusUiCallbackService.

    */

    static CMusUiCallbackService* NewL( 

                            MMusUiCallbackObserver& aCallbackObserver );

    /**

    * Destructor.

    */

    ~CMusUiCallbackService();

private: // Constructors

    /**

    * C++ default constructor.

    * @param aCallbackObserver the observer that will receive the callbacks.

    */

    CMusUiCallbackService( MMusUiCallbackObserver& aCallbackObserver );

    /**

    * By default Symbian 2nd phase constructor is private.

    */

    void ConstructL();

public: // New functions

    /**

    * Buffer a request to trigger an event.

    * @param aEventId    Id of the event

    */

    void AsyncEventL( TMusUiAsyncEvent aEventId );

    /**

    * Called when the notifier has been deactivated so resources can be 

    * freed and outstanding messages completed.

    */

    void Cancel();

    /**

    * Check what event is currently pending

    * @return EMusUiAsyncUninitialized is no events are pending

    */

    TMusUiAsyncEvent CurrentEvent() const;

public: // Functions from CActive base class

    /**

    * From CActive.  Called when a request completes.

    */

    void RunL();

    /**

    * From CActive.  Called when a leave occurres in RunL.

    * @param aError Symbian OS errorcode.

    * @return Error Code.

    */

    TInt RunError(TInt aError);

    /**

    * From CActive.  Called when a request is cancelled.

    */

    void DoCancel();  

private: // New functions

    /**

    * Activate the object.

    */

    void Activate();

private:    // Data

    /**  Handle to callback observer. */

    MMusUiCallbackObserver& iCallbackObserver;

    /**  Event ID to pass through. */

    TMusUiAsyncEvent iEventId;

    };

#endif // MUSUICALLBACKSERVICE_H