/*

* Copyright (c) 2007-2008 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:    The event observer interface

 *

*/

#ifndef __MSHWENGINEOBSERVER_H__

#define __MSHWENGINEOBSERVER_H__

// INCLUDES

#include <e32std.h>

#include <e32base.h>

// CLASS DECLARATION

/**

 *  MShwEventObserver

 */

class MShwEngineObserver

	{

	protected:

		/**

		 * Destructor. Dont allow deleting objects through this interface.

		 */

		virtual ~MShwEngineObserver() {};

	public: // the API

		/**

		 * This notification is called once the engine is started,

		 * meaning that the slideshow is running.

		 */

		virtual void EngineStartedL() = 0;

		/**

		 * This notification is called once the engine is paused,

		 * meaning that the slideshow is frozen.

		 */

		virtual void EnginePausedL() = 0;

		/**

		 * This notification is called once the engine is resumed,

		 * meaning that the slideshow is re-running after a pause

		 */

		virtual void EngineResumedL() = 0;

		/**

         * This notification is called once the selection key, EngineLSKPressedL

         * pressed.

         */

        virtual void EngineToggleUiStateL() = 0;

        /**

         * LSk pressed.

         */

        virtual void EngineLSKPressedL() = 0;

        /**

         * This notification is called when there is such an error during 

         * slideshow that it cannot continue, for example all items got removed.

         * This method is allowed to leave, in which case slideshow engine panics

         * with EEngineFatalError. This is ok as in case of error all we can do is

         * try to exit slideshow, either easy way or hard way :)

         * @exception EEngineFatalError if this method does leave.

         */

        virtual void ErrorDuringSlideshowL() = 0;

	};

#endif // __MSHWENGINEOBSERVER_H__