1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/os/mm/devsound/a3facf/inc/maudiocontextobserver.h	Fri Jun 15 03:10:57 2012 +0200
     1.3 @@ -0,0 +1,97 @@
     1.4 +/*
     1.5 +* Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).
     1.6 +* All rights reserved.
     1.7 +* This component and the accompanying materials are made available
     1.8 +* under the terms of "Eclipse Public License v1.0"
     1.9 +* which accompanies this distribution, and is available
    1.10 +* at the URL "http://www.eclipse.org/legal/epl-v10.html".
    1.11 +*
    1.12 +* Initial Contributors:
    1.13 +* Nokia Corporation - initial contribution.
    1.14 +*
    1.15 +* Contributors:
    1.16 +*
    1.17 +* Description:
    1.18 +*
    1.19 +*/
    1.20 +
    1.21 +
    1.22 +
    1.23 +
    1.24 +/**
    1.25 + @file
    1.26 + @publishedPartner 
    1.27 + @released
    1.28 +*/
    1.29 +
    1.30 +#ifndef MAUDIOCONTEXTOBSERVER_H
    1.31 +#define MAUDIOCONTEXTOBSERVER_H
    1.32 +
    1.33 +#include <a3f/a3fbase.h>
    1.34 +
    1.35 +const TUid KUidA3FContextCommitUpdate		= {0x1028343E};
    1.36 +const TUid KUidA3FContextPreEmptedCommit	= {0x1028343F};
    1.37 +const TUid KUidA3FContextPreEmption			= {0x10283440};
    1.38 +const TUid KUidA3FContextPreEmptionUpdate	= {0x10283441};
    1.39 +const TUid KUidA3FContextUpdateComplete		= {0x10283442};
    1.40 +const TUid KUidA3FContextAbort				= {0x10283443};
    1.41 +
    1.42 +/**
    1.43 + * KUidA3FContextCommitUpdate - Follows a Commit() call. Signals that Commit() has been successfully received by MMRC 
    1.44 + * and that update callbacks are about to follow.  Note will still be called if MMRC rejects the request for policy reasons 
    1.45 + * – in which case, the callbacks will show the original value. 
    1.46 + *if aError is not KErrNone, then the implementation tried to apply the change but this failed 
    1.47 + * so that the implementation is “rolled-back” to the previous. However, KErrAbort says that this roll-back failed, 
    1.48 + * and streams have been placed in a Dead state.
    1.49 + *
    1.50 + * KUidA3FContextPreEmptedCommit -  Follows a Commit() call, but signals that that MMRC is doing a simultaneous pre-emption. 
    1.51 + * Update callbacks are about to follow, but these relate to the pre-emption. The original request is lost.
    1.52 + * An error of KErrAbort says that the change MMRC requested failed, and typically streams are placed in a “Dead” mode.
    1.53 + *
    1.54 + * KUidA3FContextPreEmption -  Initial indication to the client that it is to be pre-empted. 
    1.55 + * The client should treat the Context and its Components as “locked” – see below. 
    1.56 + *
    1.57 + * KUidA3FContextPreEmptionUpdate - Will follow a KUidA3FContextPreEmption and indicates that callbacks 
    1.58 + * are about to start to indicate the update. An error of KErrAbort says that the change MMRC requested failed, 
    1.59 + * and typically streams are placed in a “Dead” mode.
    1.60 + * 
    1.61 + * KUidA3FContextUpdateComplete - Signals that all callbacks are complete – Commit() can be called again, if required.
    1.62 + *
    1.63 + * KUidA3FContextAbort - Error occurred due to the commit or pre-emption cycle itself – 
    1.64 + * that is something to do with the associated message passing mechanism etc. 
    1.65 + * this terminates the whole cycle, whatever the current state. It should leave the context in a “reasonable state” 
    1.66 + *– usually the original state.  aError gives the associated reason for this.
    1.67 + */
    1.68 +
    1.69 +/*
    1.70 + * Following Commit() or ContextEvent(KUidA3FContextPreEmption), the associated Context should be considered “locked” 
    1.71 + * until the receipt of events KUidA3FContextCommitUpdate, KUidA3FContextPreEmptedCommit or KUidA3FContextPreEmptionUpdate. 
    1.72 + * By locked it is meant that no changes shall be requested by the Client from the Context nor its associated Components, 
    1.73 + * nor Commit() called.
    1.74 + *
    1.75 + * Following events KUidA3FContextCommitUpdate, KUidA3FContextPreEmptedCommit or KUidA3FContextPreEmptionUpdate, 
    1.76 + * the Client can be requested changes to the Context and associated Components, but Commit() cannot be called.
    1.77 + * 
    1.78 + * Following event KUidA3FContextUpdateComplete Commit() can be called.
    1.79 + *
    1.80 + * Following the receipt of event KUidA3FContextPreEmptedCommit or KUidA3FPreEmptionUpdate, 
    1.81 + * any pending requested changes to the Context or its Components are lost – there is an implied call to MAudioContext::Reset(). 
    1.82 + */
    1.83 +
    1.84 +
    1.85 +/**
    1.86 + * Defines the interface for observing context states.
    1.87 + */
    1.88 +class MAudioContextObserver
    1.89 +	{
    1.90 +public:
    1.91 +	/**
    1.92 +	 * Callback to context observer to show progression through Commit() and pre-emption cycles.
    1.93 +	 *
    1.94 +	 * @param a Uid giving the specific event.
    1.95 +	 * @param  an error code. KErrNone if successful, otherwise one of the system wide error codes.
    1.96 +	*/
    1.97 +	virtual void ContextEvent(TUid aEvent, TInt aError)=0;
    1.98 +	};
    1.99 +
   1.100 +#endif // MAUDIOCONTEXTOBSERVER_H