/*

* Copyright (c) 2007-2010 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:  Callback wrapper for Publish and Subscribe

*

*/

#ifndef CAMPROPERTYWATCHER_H

#define CAMPROPERTYWATCHER_H

//  INCLUDES

#include <e32base.h>

#include <e32property.h>

// FORWARD DECLARATIONS

class MPropertyObserver;

// CLASS DECLARATION

/**

*  Class to watch for value changes on a property

*

*  @since 2.8

*/

class CCamPropertyWatcher : public CActive

	{

public: // Constructors and destructor

    /**

    * Symbian OS two-phased constructor

    * @since 2.8

    * @param aPropertyObserver The observer, notified when the value changes

    * @param aCategory the category of the property

    * @param aKey the identifier of the property

    */      

    static CCamPropertyWatcher* NewL( MPropertyObserver& aPropertyObserver, 

                                      const TUid& aCategory, 

                                      const TUint aKey );

    /**

    * Destructor.

    * @since 2.8

    */

    ~CCamPropertyWatcher();

public: // New methods

    /**

    * Register a need for notification of value changes

    * @since 2.8

    */

    void Subscribe();

    /**

    * Return the current value of the property

    * @since 2.8

    * @param aValue Reference to an integer that will receive the current 

    *                 value of the property

    * @return KErrNone if successful otherwise another of the system-wide error 

    *                 codes 

    */

	TInt Get( TInt& aValue );

private: // new methods

    /**

    * C++ default constructor.

    * @since 2.8

    * @param aPropertyObserver Reference to observer of change events

    * @param aCategory category of the property

    * @param aKey identifier of the property

    */

    CCamPropertyWatcher( MPropertyObserver& aPropertyObserver, 

                         const TUid& aCategory, 

                         const TUint aKey );

    /**

    * Symbian 2nd phase constructor.

    * @since 2.8

    */

    void ConstructL();

public: // methods from base classes

	/**

    * From CActive

    * @since 2.8

    */

    void RunL();

private:

    /**

    * From CActive

    * @since 2.8

    */

    void DoCancel();

private:

    MPropertyObserver& iPropertyObserver;   // observer informed of change events

    RProperty iProperty;                    // handle to the property

    TUid iCategory;                         // category of the property

    TUint iKey;                             // identifier of the property

	};

#endif // CAMPROPERTYWATCHER_H

// End of File