/*

* 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:     

*

*/

#ifndef HGSCROLLBUFFEROBSERVERIFACE_H_

#define HGSCROLLBUFFEROBSERVERIFACE_H_

#include <e32base.h>

#include <ganes/HgBufferOwnerIface.h>

/**

 * Buffer observer interface. 

 */

class MHgScrollBufferObserver : public MHgBufferOwner 

    {

public:

    /**

     * The direction of request.

     */

    enum THgScrollDirection

        {

        EHgBufferNoMove, // Request initiated by adding or removing an item 

        EHgBufferReset, // Full buffer reset

        EHgBufferScrollUp, // Request items before the buffer

        EHgBufferScrollDown // Request items after the buffer

        };

public:

    /**

     * Buffer position changed. 

     * The items between the aBufferStart and aBufferEnd should be loaded as soon as possible.

     * 

     * @param aBufferStart The index of the first item in buffer.

     * @param aBufferEnd The index of the last item in buffer.

     * @param aDirection Scroll direction.

     */

    virtual void Request(TInt aRequestStart, TInt aRequestEnd, THgScrollDirection aDirection) = 0 ;

    };

#endif // HGSCROLLBUFFEROBSERVERIFACE_H_