1 /*

     2 * Copyright (c) 2002, 2003 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

     7 * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description: Property Observer class for handling property change events.

    15  *

    16 */

    17 

    18 

    19 

    20 #ifndef CPROPERTYOBSERVER_H

    21 #define CPROPERTYOBSERVER_H

    22 

    23 // INCLUDES

    24 #include <e32base.h>

    25 #include <e32property.h>

    26 

    27 // CLASS DECLARATION

    28 

    29 /**

    30  * MPropertyChangeHandler.

    31  * Abstract interface for handling property change events.

    32  **/

    33 NONSHARABLE_CLASS( MPropertyChangeHandler )

    34 {

    35  public:

    36     /**

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

    38      *

    39      * @param aCategory  UID of the category.

    40      * @param aKey       changed key

    41      * @param aValue     the new value

    42      *

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

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

    45      **/

    46     virtual void HandlePropertyChange(const TUid& aCategory, const TUint& aKey, const TInt& aValue) = 0;

    47 

    48 };

    49 

    50 

    51 // CLASS DECLARATION

    52 

    53 /**

    54  * ?one_line_short_description.

    55  * ?other_description_lines

    56  *

    57  * @since Series 60 3.0

    58  **/

    59 NONSHARABLE_CLASS(CPropertyObserver) : public CActive

    60 {

    61  public:  // Constructors and destructor

    62     /**

    63      * Two-phased constructor.

    64      * @since Series 60 3.0

    65      * @param ?arg1 ?description

    66      * @param ?arg2 ?description

    67      **/

    68     static CPropertyObserver* NewL(MPropertyChangeHandler& aHandler, const TUid& aCategory, const TUint& aKey, const TBool aSkipValue=EFalse)

    69     {

    70         CPropertyObserver* self = new( ELeave )CPropertyObserver( aHandler, aCategory, aKey, aSkipValue );

    71         CleanupStack::PushL( self );

    72         self->ConstructL();

    73         CleanupStack::Pop( self );

    74         return self;

    75     };

    76 

    77     /**

    78      * Destructor.

    79      **/

    80     ~CPropertyObserver()

    81     {

    82         Deque();

    83         iProperty.Cancel();

    84         iProperty.Close();

    85     };

    86 

    87  private:

    88     /**

    89      * C++ default constructor overload.

    90      **/

    91     CPropertyObserver(MPropertyChangeHandler& aHandler, const TUid& aCategory, const TUint& aKey, const TBool aSkipValue)

    92     : CActive( CActive::EPriorityStandard ),

    93       iCategory( aCategory ),

    94       iKey( aKey ),

    95       iHandler( aHandler ),

    96       iSkipValue( aSkipValue )

    97     {

    98     };

    99 

   100     /**

   101      * By default Symbian 2nd phase constructor is private.

   102      **/

   103     void ConstructL(void)

   104     {

   105         CActiveScheduler::Add( this );

   106 

   107         User::LeaveIfError( iProperty.Attach( iCategory, iKey ) );

   108 

   109         //NotifyCurrentValue(); // notify initial value

   110 

   111         // Start observing...

   112         Subscribe();

   113     };

   114 

   115  protected:  // Functions from base classes

   116     /**

   117      * From CActive ?member_description

   118      **/

   119     inline void RunL(void);

   120 

   121     /**

   122      * From CActive ?member_description

   123      **/

   124     inline void DoCancel(void);

   125 

   126  private:  // New functions

   127     /**

   128      * ?member_description.

   129      * @since Series 60 3.0

   130      **/

   131     inline void Subscribe(void);

   132 

   133     /**

   134      * ?member_description.

   135      * @since Series 60 3.0

   136      **/

   137     inline void NotifyCurrentValue(void);

   138 

   139  private:  // Data

   140     // ?one_line_short_description_of_data

   141     RProperty iProperty;

   142 

   143     // ?one_line_short_description_of_data

   144     const TUid iCategory;

   145 

   146     // ?one_line_short_description_of_data

   147     const TUint iKey;

   148 

   149     // ?one_line_short_description_of_data

   150     MPropertyChangeHandler& iHandler;

   151 

   152     // ?one_line_short_description_of_data

   153     const TBool iSkipValue;

   154 

   155 };

   156 

   157 #include "PropertyObserver.inl"

   158 

   159 #endif  // CPROPERTYOBSERVER_H

   160 

   161 

   162 // End of File