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 

    28 #ifndef MAUDIOSTREAMOBSERVER_H

    29 #define MAUDIOSTREAMOBSERVER_H

    30 

    31 #include <e32base.h>

    32 #include <a3f/a3fbase.h>

    33 #include <a3f/maudiostream.h>

    34 

    35 /**

    36  * An interface to a set of AudioStream callback functions.

    37  *

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

    39  * AudioStream.

    40  *

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

    42  * that is interested in observing the AudioStream operation. The functions

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

    44  * processing audio.

    45  */

    46 class MAudioStreamObserver

    47 	{

    48 public:

    49 	/**

    50 	 * Handles audio stream state change event.

    51 	 *

    52 	 * @param aStream A reference to the stream whose state changed.

    53 	 * @param aReason A set of values describing why the state change occurred 

    54 	 * corresponding to the system-wide error codes. The value will be KErrNone on successful calls.

    55 	 * @param aNewState indicating the state in which the audio stream has changed.

    56 	 */

    57 	virtual void StateEvent(MAudioStream& aStream , TInt aReason, TAudioState aNewState)=0;

    58 

    59 	/**

    60 	 * Notifies that adding of processing unit to the stream has been completed successfully or otherwise.

    61 	 *

    62 	 * if the processing unit is added succesfully, then it must be removed from the

    63 	 * stream before the processing unit is removed from the context or before the stream is removed.

    64 	 *

    65 	 * @param aStream A reference to the stream to which the processing unit was added.

    66 	 * @param aInstance a pointer to the processing unit instance.

    67 	 * @param aError an error code. KErrNone on success. Otherwise one of the system wide error codes.

    68 	 */

    69 	virtual void AddProcessingUnitComplete(MAudioStream& aStream, MAudioProcessingUnit* aInstance, TInt aError)=0;

    70 

    71 	/**

    72 	 * Notifies that removing of processing unit from the stream has been completed

    73 	 * successfully or otherwise.

    74 	 * 

    75 	 * if the processing unit has been added succesfully, then it must be removed

    76 	 * from the stream, before the processing unit is removed from the

    77 	 * context or before the stream is removed.

    78 	 * 

    79 	 * @param aStream A reference to the stream from which the processing unit has been removed.

    80 	 * @param aType the processing unit type.

    81 	 * @param aInstance a pointer to the processing unit instance.

    82 	 * @param aError an error code. KErrNone on success. Otherwise one of the system wide error codes.

    83 	 */

    84 	virtual void RemoveProcessingUnitComplete(MAudioStream& aStream, MAudioProcessingUnit* aInstance, TInt aError)=0;

    85 

    86 	/**

    87 	 * Call-back indicating that is the last buffer has been processed by the sink.

    88 	 *

    89 	 * @param aStream A reference to the stream.

    90 	 */

    91 	virtual void ProcessingFinished (MAudioStream& aStream)=0;

    92 

    93 	/**

    94 	 * Signals completion of a Flush() operation.

    95 	 *

    96 	 * @param aStream A reference to the stream on which Flush() was called.  

    97 	 * @param aError an error code. KErrAbort if the associated stream has been unloaded, and the buffers cease to exist.

    98 	 */

    99 	virtual void FlushComplete (MAudioStream& aStream, TInt aError) = 0;

   100 

   101 	};

   102 

   103 #endif // MAUDIOSTREAMOBSERVER_H