/*

* Copyright (c) 2002 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: 

 *

*/

#ifndef CPROPERTYOBSERVER_H

#define CPROPERTYOBSERVER_H

// INCLUDES

#include <e32base.h>

#include <e32property.h>

// CLASS DECLARATION

/**

 * MPropertyChangeHandler.

 * Abstract interface for handling property change events.

 **/

NONSHARABLE_CLASS( MPropertyChangeHandler )

{

 public:

    /**

     * This is a callback function which is called when a property is changed.

     *

     * @param aCategory  UID of the category.

     * @param aKey       changed key

     * @param aValue     the new value

     *

     * Note! references aKey and aValue are only valid while executing

     * HandlePropertyChange(). After that the data in which they refer can change.

     **/

    virtual void HandlePropertyChange(const TUid& aCategory,

                                      const TUint& aKey,

                                      const TInt& aValue) = 0;

};

// CLASS DECLARATION

/**

 * ?one_line_short_description.

 * ?other_description_lines

 *

 * @lib ?

 * @since Series 60 3.0

 **/

NONSHARABLE_CLASS(CPropertyObserver) : public CActive

{

 public:  // Constructors and destructor

    /**

     * Two-phased constructor.

     * @since Series 60 3.0

     * @param MPropertyChangeHandler aHandler

     * @param aCategory

     * @param aKey

     **/

    static CPropertyObserver* NewL(MPropertyChangeHandler& aHandler,

                                   const TUid& aCategory,

                                   const TUint& aKey);

    /**

     * Destructor.

     **/

    ~CPropertyObserver();

 private:

    /**

     * C++ default constructor overload.

     **/

    CPropertyObserver(MPropertyChangeHandler& aHandler,

                      const TUid& aCategory,

                      const TUint& aKey);

    /**

     * By default Symbian 2nd phase constructor is private.

     **/

    void ConstructL();

 protected:  // Functions from base classes

    /**

     * From CActive

     **/

    void RunL();

    /**

     * From CActive

     **/

    void DoCancel();

 private:  // New functions

    /**

     * @since Series 60 3.0

     **/

    void Subscribe();

    /**

     * @since Series 60 3.0

     **/

    void NotifyCurrentValue();

 private:  // Data

    // Owns

    RProperty iProperty;

    // Observed PubSub category

    const TUid iCategory;

    // Observed key

    const TUint iKey;

    // Refs. Interface towards observants

    MPropertyChangeHandler& iHandler;

};

#endif  // CPROPERTYOBSERVER_H

// End of File