/*

* Copyright (c) 2006 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:  Observer interface for the tree structure.

*

*/

#ifndef M_AKNTREEOBSERVER_H

#define M_AKNTREEOBSERVER_H

class CAknTree;

class CAknTreeItem;

/**

 *  Observer interface for the tree structure.

 *

 *  Observers of the tree are notified of changes in the tree structure

 *  through this interface with appropriate events.

 *

 *  @lib aknhlist.lib

 *  @since S60 v3.2

 */

class MAknTreeObserver

    {

public:

    /**  Tree events. */

    enum TEvent

        {

        /** New item is added to the tree. */

        EItemAdded,

        /** Item is moved to another location in tree. */

        EItemMoved,

        /** Item is about to be removed from the tree. Observers are notified

            with this event before the item is removed. */

        EItemRemoveBegin,

        /** Item is removed from the tree. */

        EItemRemoveEnd,

        /** Tree node is expanded. */

        ENodeExpanded,

        /** Tree node is collapsed. */

        ENodeCollapsed,

        /** Content of a item is changed (item need to be redrawn if visible). */

        EItemModified,

        /** Tree has been sorted. */

        ETreeSorted

        };

    /**

     * Notification of a tree event. The event is specified as a parameter.

     *

     * @param aEvent Tree event.

     *

     * @param aItem Pointer to the tree item that is concerned by the event.

     *

     * @param aDrawNow @c ETrue, if the view should be redrawn after the

     *      event.

     */

    virtual void HandleTreeEvent( TEvent aEvent, CAknTreeItem* aItem,

        TBool aDrawNow ) = 0;

    };

#endif // M_AKNTREEOBSERVER_H