/*

* Copyright (c) 2006-2009 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:  Composer Plug-in ECom interface

*

*/

#ifndef __CCOMPOSERPLUGIN_H__

#define __CCOMPOSERPLUGIN_H__

#include <e32base.h>

#include <ecom.h>

#include <badesca.h>

#include <mdesession.h>

/** @var Uid for this interface */

const TUid KCComposerPluginInterfaceUid = { 0x2000717E };

 /**

 * Composer Plug-in ECom interface definition. Composer plug-in implementation

 * needs to inherit this class and implement the pure virtual methods which exist 

 * in this interface.

 *

 * Example:

 *

 * class CMyVideoComposerPlugin: public CComposerPlugin

 *     {

 *     protected:

 *         void SetObservers();    

 *         void RemoveObservers();

 * 

 *         // Because CComposerPlugin inherits MMdEObjectObserver

 *         void HandleObjectNotification(CMdESession& aSession, 

 *				TObserverNotificationType aType,

 *				const RArray<TItemId>& aObjectIdArray);

 *     

 *     private:

 *         // Active object which does the actual binary writing

 *         // so that this interface and its observers remain responsive

 *         CMyVideoComposerAO* iVideoComposerAO;       

 *     }

 *

 * void SetObservers()

 *     {

 *	   // We want to listen to changes in Video metadata objects

 *     // and setup an observer for this  

 *     CMdENamespaceDef& defaultNamespace = iSession->GetDefaultNamespaceDefL();

 *     CMdEObjectDef& videoDef = 

 *        defaultNamespace.GetObjectDefL( MdeConstants::Video::KVideoObject );

 *     CMdELogicCondition* condition = CMdELogicCondition::NewL( ELogicConditionOperatorAnd );

 *     condition->AddObjectConditionL( videoDef );

 *       

 *     // iSession is reference to CMdESession which is always set in CComposerPlugin::SetSession()

 *     iSession->AddObjectObserverL( *this, condition, ENotifyModify, &defaultNamespace );

 *     }

 * 

 * void RemoveObservers()

 *     {

 *     iSession->RemoveObjectObserverL( *this )

 *     }

 *

 * void CComposerImagePlugin::HandleObjectNotification(CMdESession& aSession, 

 *		TObserverNotificationType aType, const RArray<TItemId>& aObjectIdArray)

 *     {

 *     // We give ID-array of changed Video objects to our active object

 *     // which adds then to a its internal queue and processes them one-by-one 

 *     // with different RunL-calls so that we don't stuck the thread by composing

 *     // for example 1000 binary files in a row.

 *     iVideoComposerAO->AddToQueue( aObjectIdArray );

 *     }

 */

class CComposerPlugin : public CBase, public MMdEObjectObserver

    {

    public:

        /**

         * Construction.

         *

         * @param aUid  Implementation UID which plug-in to invoke.

         */

        IMPORT_C static CComposerPlugin* NewL( const TUid& aUid );

        /**

         * Lists all available implementations which satisfy this given interface.

         * 

         * @param aImplInfoArray  Reference to a list which will be populated with 

         *                        plug-in implementation details. 

         */

        IMPORT_C static void ListImplementationsL(RImplInfoPtrArray& aImplInfoArray);

        /**

         * Destructor.

         */ 

        IMPORT_C virtual ~CComposerPlugin();

        /**

         * Sets Mde session to be used.

         * 

         * @param aSession  Open MdE session to utilize in the Composer plug-in

         */

        IMPORT_C void SetSession( CMdESession& aSession );

        /**

         * Unsets Mde session.

         */

        IMPORT_C void RemoveSession();

        /**

         * Checks if composing is completed.

         *

         * @return  Whether composing is on-going

         */

        virtual TBool IsComposingComplete() = 0;

    protected:

        /**

         * Sets observers to be notified. Called by the interface itself when

         * SetSession method is called from Harvester server side.

         */

        virtual void SetObservers() = 0;

        /**

         * Unsets observers. Called by the interface itself when

         * RemoveSession method is called from Harvester server side.

         */

        virtual void RemoveObservers() = 0;

    protected:

        /* Pointer to Mde session used by the plugin */

    CMdESession* iSession;

    private:

        /* Identification on cleanup */

        TUid iDtor_ID_Key;

    };

#endif // __CCOMPOSERPLUGIN_H__