/*

* Copyright (c) 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:  Field event queue interface

*

*/

#ifndef MESMRFIELDEVENTQUEUE_H

#define MESMRFIELDEVENTQUEUE_H

class MESMRFieldEvent;

class MESMRFieldEventObserver;

/**

 *  MESMRFieldEventQueue defines an iterface for field event queue.

 *  It provides event queue for CESMRField to send events to its

 *  event observers. The interface provides both synchronous and

 *  asynchrounous event notification methods.

 */

class MESMRFieldEventQueue

    {

public:

    /**

     * Adds observer to the event queue.

     *

     * @param aObserver the observer.

     */

    virtual void AddObserverL( MESMRFieldEventObserver* aObserver ) = 0;

    /**

     * Removes observer from the event queue.

     *

     * @param aObserver the observer.

     */

    virtual void RemoveObserver( MESMRFieldEventObserver* aObserver ) = 0;

    /**

     * Notifies event to the event observers in the queue.

     * Event is notified synchronously.

     * 

     * @param aEvent the event.

     */

    virtual void NotifyEventL( const MESMRFieldEvent& aEvent ) = 0;

    /**

     * Enques event to event queue and notifies it asynchronously to

     * the observers. Ownership of the event is transferred to the queue.

     * 

     * @param aEvent the event to enque to the event queue.

     */

    virtual void NotifyEventAsyncL( MESMRFieldEvent* aEvent ) = 0;

    /**

     * Removes event from the event queue.

     * 

     * @param aEvent the event to remove from the event queue.

     */

    virtual void CancelEvent( MESMRFieldEvent* aEvent ) = 0;

protected:

    virtual ~MESMRFieldEventQueue() {}

    };

#endif // MESMRFIELDEVENTQUEUE_H