sl@0: /*
sl@0: * Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: * All rights reserved.
sl@0: * This component and the accompanying materials are made available
sl@0: * under the terms of "Eclipse Public License v1.0"
sl@0: * which accompanies this distribution, and is available
sl@0: * at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: *
sl@0: * Initial Contributors:
sl@0: * Nokia Corporation - initial contribution.
sl@0: *
sl@0: * Contributors:
sl@0: *
sl@0: * Description:
sl@0: *
sl@0: */
sl@0: 
sl@0: 
sl@0: 
sl@0: 
sl@0: /**
sl@0:  @file
sl@0:  @publishedPartner
sl@0:  @released
sl@0: */
sl@0: 
sl@0: #ifndef MAUDIOGAINCONTROLOBSERVER_H
sl@0: #define MAUDIOGAINCONTROLOBSERVER_H
sl@0: 
sl@0: #include <e32base.h>
sl@0: #include <a3f/a3fbase.h>
sl@0: #include <a3f/maudiogaincontrol.h>
sl@0: 
sl@0: /**
sl@0:  *  An interface to a set of AudioGainControl callback functions.
sl@0:  *
sl@0:  *  this serves as the method of communication between the client and the
sl@0:  *  AudioGainControl.
sl@0:  *
sl@0:  *  The class is a mixin and is intended to be inherited by the client class
sl@0:  *  that is interested in observing the Gain operations. The functions
sl@0:  *  encapsulated by this class are called when specific events occur while
sl@0:  *  processing audio.
sl@0:  *
sl@0:  */
sl@0: class MAudioGainControlObserver
sl@0: 	{
sl@0: public:
sl@0: 
sl@0: 	/**
sl@0: 	* Notifies the observer that the max ramp time supported by the gain
sl@0: 	* control has changed.
sl@0: 	*
sl@0: 	* @param aGain a reference to GainControl whose max ramp time changed.
sl@0: 	*/
sl@0: 	virtual void MaxRampTimeChanged(MAudioGainControl& aGain)=0;
sl@0: 
sl@0: 	/**
sl@0: 	* Notifies the observer that the maximum gain value supported by the
sl@0: 	* gain control has changed.
sl@0: 	*
sl@0: 	* @param aGain a reference to GainControl whose max gain changed.
sl@0: 	*/
sl@0: 	virtual void MaxGainChanged(MAudioGainControl& aGain)=0;
sl@0: 
sl@0: 	/**
sl@0: 	* Notifies the observer that the gain has changed, 
sl@0: 	* due to request from the client or otherwise.  
sl@0: 	* If gain change by the client cannot be fulfilled, 
sl@0: 	* a gain change with an error code other than KErrNone will be issued.
sl@0: 	* @param aGain	a reference to the gain control whose gain has changed.
sl@0: 	* @return aError		an error code. 
sl@0: 	* KErrNone if the gain change was requested by the client and was completed successfully.
sl@0: 	* KErrNotSupported if the SetGain() call referred to non-existent channels.
sl@0: 	* KErrArgument if aGain of less than 0 or larger than max gain, 
sl@0: 	* the same channel is specified multiple times, 
sl@0: 	* or aRampDuration is less than 0 or greater than max ramp duration.
sl@0: 	* KErrA3fUnsupportedRamp if the ramp operation requested is not supported, 
sl@0: 	* or the Uid value supplies is unknown.
sl@0: 	* Other system-wide errors are also possible. They will indicate that the gain change failed.
sl@0: 	* Note that these errors could alternatively be returned by the associated SetGain() call.
sl@0: 	*/
sl@0: 	virtual void GainChanged(MAudioGainControl& aGain, TInt aError)=0;
sl@0: 
sl@0: 	};
sl@0: 
sl@0: #endif // MAUDIOGAINCONTROLOBSERVER_H