1 /*

     2 * Copyright (c) 2006-2009 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:

    15 *

    16 */

    17 

    18 

    19 

    20 

    21 /**

    22  @file

    23  @publishedPartner

    24  @released

    25 */

    26 

    27 #ifndef MAUDIOGAINCONTROLOBSERVER_H

    28 #define MAUDIOGAINCONTROLOBSERVER_H

    29 

    30 #include <e32base.h>

    31 #include <a3f/a3fbase.h>

    32 #include <a3f/maudiogaincontrol.h>

    33 

    34 /**

    35  *  An interface to a set of AudioGainControl callback functions.

    36  *

    37  *  this serves as the method of communication between the client and the

    38  *  AudioGainControl.

    39  *

    40  *  The class is a mixin and is intended to be inherited by the client class

    41  *  that is interested in observing the Gain operations. The functions

    42  *  encapsulated by this class are called when specific events occur while

    43  *  processing audio.

    44  *

    45  */

    46 class MAudioGainControlObserver

    47 	{

    48 public:

    49 

    50 	/**

    51 	* Notifies the observer that the max ramp time supported by the gain

    52 	* control has changed.

    53 	*

    54 	* @param aGain a reference to GainControl whose max ramp time changed.

    55 	*/

    56 	virtual void MaxRampTimeChanged(MAudioGainControl& aGain)=0;

    57 

    58 	/**

    59 	* Notifies the observer that the maximum gain value supported by the

    60 	* gain control has changed.

    61 	*

    62 	* @param aGain a reference to GainControl whose max gain changed.

    63 	*/

    64 	virtual void MaxGainChanged(MAudioGainControl& aGain)=0;

    65 

    66 	/**

    67 	* Notifies the observer that the gain has changed, 

    68 	* due to request from the client or otherwise.  

    69 	* If gain change by the client cannot be fulfilled, 

    70 	* a gain change with an error code other than KErrNone will be issued.

    71 	* @param aGain	a reference to the gain control whose gain has changed.

    72 	* @return aError		an error code. 

    73 	* KErrNone if the gain change was requested by the client and was completed successfully.

    74 	* KErrNotSupported if the SetGain() call referred to non-existent channels.

    75 	* KErrArgument if aGain of less than 0 or larger than max gain, 

    76 	* the same channel is specified multiple times, 

    77 	* or aRampDuration is less than 0 or greater than max ramp duration.

    78 	* KErrA3fUnsupportedRamp if the ramp operation requested is not supported, 

    79 	* or the Uid value supplies is unknown.

    80 	* Other system-wide errors are also possible. They will indicate that the gain change failed.

    81 	* Note that these errors could alternatively be returned by the associated SetGain() call.

    82 	*/

    83 	virtual void GainChanged(MAudioGainControl& aGain, TInt aError)=0;

    84 

    85 	};

    86 

    87 #endif // MAUDIOGAINCONTROLOBSERVER_H