2 * Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
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".
9 * Initial Contributors:
10 * Nokia Corporation - initial contribution.
28 #ifndef MAUDIOCONTEXT_H
29 #define MAUDIOCONTEXT_H
33 #include <a3f/a3fbase.h>
36 class MAudioProcessingUnit;
37 class MAudioContextObserver;
40 * An interface to an audio context.
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().
52 * Returns the context identifier.
54 * @return return the context identifier
56 virtual TAudioContextId ContextId() const = 0;
59 * Creates a new audio stream into this context.
61 * The stream must be removed using DeleteAudioStream() when it is no longer needed.
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.
66 virtual TInt CreateAudioStream(MAudioStream*& aStream)=0;
69 * Deletes an audio stream from this context.
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.
77 virtual void DeleteAudioStream(MAudioStream*& aStream)=0;
80 * Creates a new audio processing unit into this context.
82 * The processing unit must be removed using DeleteProcessingUnit() when it is no longer needed.
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.
88 virtual TInt CreateAudioProcessingUnit(TUid aTypeId, MAudioProcessingUnit*& aProcessingUnit)=0;
91 * Deletes the audio processing unit from this context.
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.
99 virtual void DeleteAudioProcessingUnit(MAudioProcessingUnit*& aProcessingUnit)=0;
102 * Apply changes made to audio components associated with this context.
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().
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.
112 virtual TInt Commit()=0;
115 * Forget any pending, requested changes made to this context or its components.
117 * Typically called where the client has started to request changes, has yet to call Commit() and changes its mind.
119 * @return A system wide error code. KErrNone on success. KErrNotReady if called during Commit() cycle.
121 virtual TInt Reset()=0;
124 * Sets the client information used by the underlying MMRC.
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.
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.
133 virtual TInt SetClientSettings(const TClientContextSettings& aSettings)=0;
136 * A mechanism to obtain extensions to the Context API.
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.
142 virtual TAny* Interface(TUid aType)=0;
145 * Registers an audio context observer.
147 * The observer will be notified about context state changes.
149 * @param aObserver the observer reference to register.
150 * @return An error code. KErrNone on success, otherwise one of the system wide error codes.
152 virtual TInt RegisterAudioContextObserver(MAudioContextObserver& aObserver) = 0;
155 * Unregisters an audio context observer.
157 * @param aObserver the observer reference to unregister.
158 * @return An error code. KErrNone on success, otherwise one of the system wide error codes.
160 virtual void UnregisterAudioContextObserver(MAudioContextObserver& aObserver) = 0;
163 #endif // MAUDIOCONTEXT_H