/*

* Copyright (c) 2007 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:  Definition of client side stream buffer

*

*/

#ifndef __MENUBUF_H__

#define __MENUBUF_H__

#include "menusrvdef.h"

#include <e32base.h>

#include <s32buf.h>

class RMenu;

/**

 *  Client side stream buffer. Not seekable.

 *  @lib mcsmenu.lib

 *  @since S60 v5.0

 */

NONSHARABLE_CLASS( RMenuBuf ): public RSubSessionBase, public TStreamBuf

    {

public:

    /**

    * Close the object.

    */

    void Close();

    /**

    * Open the object (initially empty).

    * @param aMenu Session to be used.

    * @return Error code.

    */

    TInt Open( RMenu& aMenu );

    /**

    * Open this object using other object.

    * @param aHandle Handle used to open this object.

    * @param aFunction Function.

    * @param aArgs Arguments. Use arg 0 and 1 only;

    * arg 2 and 3 are used internally.

    * @return Error code.

    */

    TInt Open( RMenu& aMenu, TInt aFunction, TIpcArgs& aArgs );

private:

    /**

    * Read data from server.

    * @param aLength The number of bytes read.

    */

    void IpcReadL( TInt& aLength );

    /**

    * Write data to server.

    */

    void IpcWriteL();

    /**

    * Get read lag (number of bytes transferred from server side but not

    * yet read).

    * @return Read lag.

    */

    inline TInt Lag( TRead aArea ) const;

    /**

    * Get write lag (number of bytes written but not yet transferred to

    * server side).

    * @return Write lag.

    */

    inline TInt Lag( TWrite aArea ) const;

// from base class TStreamBuf

    /**

    * Re-fill the intermediate buffer and reset the start and end points

    * of the read area.

    * @param aMaxLength The maximum amount of data required.

    * @return The amount of data available.

    */

    TInt UnderflowL( TInt aMaxLength );

    /**

    * Empty the intermediate buffer and resets the start and end points

    * of the write area.

    */

    void OverflowL();

    /**

    * Synchronise the stream buffer with the stream. In effect, this

    * ensures that buffered data is delivered to the stream.

    * Write lag flushed.

    * Read lag leaves with KErrNotSupported.

    */

    void DoSynchL();

private:    // Data

    TMenuBuf iBuf; ///< Data buffer.

    };

#include "menubuf.inl"

#endif // __MENUBUF_H__