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 MAUDIOCONTEXT_H

    29 #define MAUDIOCONTEXT_H

    30 

    31 #include <e32base.h>

    32 

    33 #include <a3f/a3fbase.h>

    34 

    35 class MAudioStream;

    36 class MAudioProcessingUnit;

    37 class MAudioContextObserver;

    38 

    39 /**

    40  * An interface to an audio context.

    41  *

    42  * Audio context is a container for a set of logically related audio streams and audio processing units.

    43  * All streams and processing units are created into a context.

    44  * A new context can be created using an instance of CAudioContextFactory.

    45  * When the context is no longer needed, it must be removed using CAudioContextFactory::DeleteAudioContext().

    46  */

    47 class MAudioContext

    48 	{

    49 public:

    50 

    51 	/**

    52 	 * Returns the context identifier.

    53 	 *

    54 	 * @return return the context identifier

    55 	 */

    56 	virtual TAudioContextId ContextId() const = 0;

    57 

    58 	/**

    59 	 * Creates a new audio stream into this context. 

    60 	 *

    61 	 * The stream must be removed using DeleteAudioStream() when it is no longer needed.

    62 	 *

    63 	 * @param aStream on return contains a pointer to the created stream.

    64 	 * @return an error code. KErrNone if successful, otherwise one of the system wide error codes.

    65 	 */

    66 	virtual TInt CreateAudioStream(MAudioStream*& aStream)=0;

    67 

    68 	/**

    69 	 * Deletes an audio stream from this context.

    70 	 *

    71 	 * After removing the stream all references to it will become invalid and must not be used.

    72 	 * At the end of the call, aStream will have been set to NULL. 

    73 	 * Calling DeleteAudioStream() with a parameter whose value is NULL is itself a null operation.

    74 	 * @param aStream a pointer to the stream to Delete.

    75 	 * @return an error code. KErrNone if successful, otherwise one of the system wide error codes.

    76 	 */

    77 	virtual void DeleteAudioStream(MAudioStream*& aStream)=0;

    78 

    79 	/**

    80  	 * Creates a new audio processing unit into this context.

    81 	 *

    82  	 * The processing unit must be removed using DeleteProcessingUnit() when it is no longer needed.

    83 	 *

    84 	 * @param aType the type of the processing unit.

    85 	 * @param aProcessingUnit on return contains a pointer to the created processing unit.

    86 	 * @return an error code. KErrNone if successful, otherwise one of the system wide error codes.

    87 	 */

    88 	virtual TInt CreateAudioProcessingUnit(TUid aTypeId, MAudioProcessingUnit*& aProcessingUnit)=0;

    89 

    90 	/**

    91 	 * Deletes the audio processing unit from this context.

    92 	 *

    93 	 * After removing the processing unit all references to it will become invalid and must not be used.

    94 	 * At the end of the call, aProcessingUnit will have been set to NULL. 

    95 	 * Calling DeleteAudioProcessingUnit() with a parameter whose value is NULL is itself a null operation.

    96 	 * @param aProcessingUnit a pointer to the processing unit to remove.

    97 	 * @return an error code. KErrNone if successful, otherwise one of the system wide error codes.

    98 	 */

    99 	virtual void DeleteAudioProcessingUnit(MAudioProcessingUnit*& aProcessingUnit)=0;

   100 

   101 	/**

   102 	 * Apply changes made to audio components associated with this context. 

   103 	 *

   104 	 * A state change applied to an Audio Stream should be considered "pending" until Commit() is called, 

   105 	 * in that the adaptation merely records that the state setting has been requested and does not seek 

   106 	 * to implement the state change until Commit().

   107 	 *

   108 	 * Commit() can be thought of as an asynchronous call, and completion is signalled by the appropriate 

   109 	 * ContextEvent() callback of MAudioContextObserver.

   110 	 * @return An error code. KErrNone on success. KErrNotReady if SetClientSettings() has not been called.

   111 	 */

   112 	virtual TInt Commit()=0;

   113 

   114 	/**

   115 	 * Forget any pending, requested changes made to this context or its components. 

   116 	 *

   117 	 * Typically called where the client has started to request changes, has yet to call Commit() and changes its mind.

   118 	 *

   119  	 * @return A system wide error code. KErrNone on success. KErrNotReady if called during Commit() cycle.

   120 	 */

   121 	virtual TInt Reset()=0;

   122 

   123 	/**

   124 	 * Sets the client information used by the underlying MMRC. 

   125 	 *

   126 	 * This must be called before any call to Commit(). The client context contains information about the client application 

   127 	 * which is utilising the audio functionality, since this will typically be a different process than is calling A3F.

   128   	 *

   129 	 * @param aSettings Essentially the process Id of the client application, 

   130 	 * the one whose details are used to determine capabilities and policy.

   131 	 * @return an error code. KErrNone for success, otherwise one of the system-wide error codes.	

   132 	 */

   133 	virtual TInt SetClientSettings(const TClientContextSettings& aSettings)=0;

   134 	

   135 	/**

   136 	 * A mechanism to obtain extensions to the Context API.

   137   	 *

   138 	 * @param aType Uid that denotes the type of the interface.

   139 	 * @return the pointer to the specified interface, or NULL if it does not exist. 

   140 	 * Must be cast to correct type by the user.

   141 	 */

   142 	virtual TAny* Interface(TUid aType)=0;

   143 

   144 	/**

   145 	 * Registers an audio context observer.

   146 	 *

   147 	 * The observer will be notified about context state changes.

   148 	 *

   149 	 * @param aObserver the observer reference to register.

   150 	 * @return An error code. KErrNone on success, otherwise one of the system wide error codes.

   151 	 */

   152 	virtual TInt RegisterAudioContextObserver(MAudioContextObserver& aObserver) = 0;

   153 

   154 	/**

   155 	 * Unregisters an audio context observer.

   156 	 *

   157 	 * @param aObserver the observer reference to unregister.

   158   	 * @return An error code. KErrNone on success, otherwise one of the system wide error codes.

   159 	 */

   160 	virtual void UnregisterAudioContextObserver(MAudioContextObserver& aObserver) = 0;

   161 	};

   162 

   163 #endif // MAUDIOCONTEXT_H