/*

* 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:  An observer interface for the tree data model.

*

*/

#ifndef M_FSTREEOBSERVER_H

#define M_FSTREEOBSERVER_H

/**

 * MFsTreeObserver defines an interface which is used to observe tree events.

 * 

 * Observer of the tree is notified of changes in the tree structure

 * through this interface with appropriate events.

 * 

 * @code

 *

 * @endcode

 *

 * @lib 

 */

NONSHARABLE_CLASS( MFsTreeObserver )

    {

public:

    enum TFsTreeEvent

        {

        /** 

         * Item was added to the tree. 

         * The visible items list should be updated if needed.

         */

        EFsTreeItemAdded,

        /** 

         * Node was added to the tree. 

         * The visible items list should be updated if needed.

         */

        EFsTreeNodeAdded,

        /**

         * Item was removed from the tree.

         * The visible items list should be updated if needed.

         */

        EFsTreeItemRemoved,

        /**

         * Node was removed from the tree.

         * The visible items list should be updated if needed.

         */

        EFsTreeNodeRemoved,

        /**

         * All items will be removed from the tree.

         * The visible items list should be updated..

         */

        EFsTreeRemovedAll,

        /**

         * Item's/Node's data has changed.

         * The visible items list should be updated if needed.

         */

        EFsTreeItemDataChanged,

        /**

         * Item data's visualizer has changed.

         * The visible items list should be updated if needed.

         */

        EFsTreeItemVisualizerChanged

        };

public:

    /**

     * Observer of the tree is notified of changes in the tree structure

     * through this function.

     * 

     * @param aEvent Event which happend in the tree structure.

     * @param aId Id of the node/item associated with the event.

     */

    struct TFsTreeEventParams

        {

        TFsTreeEventParams(TFsTreeItemId aItemId, TFsTreeItemId aTargetNodeId, TInt aIndex ) :

        iItemId(aItemId), iTargetNodeId(aTargetNodeId), iIndex(aIndex) {};

        TFsTreeItemId iItemId;

        TFsTreeItemId iTargetNodeId; 

        TInt iIndex;

        };

    virtual void TreeEventL( const TFsTreeEvent aEvent, 

            const TFsTreeEventParams& aParams ) = 0;

    };

#endif // M_FSTREEOBSERVER_H