<?xml version="1.0" encoding="utf-8"?>+
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<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->+
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<!-- This component and the accompanying materials are made available under the terms of the License +
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"Eclipse Public License v1.0" which accompanies this distribution, +
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and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->+
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<!-- Initial Contributors:+
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    Nokia Corporation - initial contribution.+
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Contributors: +
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-->+
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<!DOCTYPE task+
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  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">+
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<task id="GUID-09E44FE5-6BEE-49FF-8BBF-CBB3C066EE10" xml:lang="en"><title>Listening+
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for Channel Changes</title><shortdesc>The sensor channel APIs enable you to receive notifications when+
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a sensor channel is added or removed. This ensures that you are informed of+
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changes to sensor channels whenever there is a change. For example, you can+
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receive notifications when a specific proximity sensor channel is added.</shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>+
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<prereq id="GUID-03B31784-B731-43C4-B2DC-38DD4898AE22">       <p>Before listening+
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for channel changes, you must <xref href="GUID-4B709839-8EEF-4AD2-9868-9AF0176B1E5B.dita#GUID-4B709839-8EEF-4AD2-9868-9AF0176B1E5B/GUID-FBBD3A8B-F240-4DC0-B516-3A51FDD86A88">open+
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the sensor channel</xref>.</p>     </prereq>+
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<steps id="GUID-4DD07DEC-6017-4237-BE46-1D69E5FBD744-GENID-1-10-1-9-1-1-8-1-4-1-5-1-9-1-3-2">+
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<step id="GUID-B454B117-4FC5-4B19-B512-7B4A213E4C51"><cmd>Create a channel+
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listener implementation for the <parmname>MSensrvChannelListener</parmname> interface.</cmd>+
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<stepxmp><codeblock xml:space="preserve">class ChannelListener:public MSensrvChannelListener+
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    {+
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    public:    +
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    void ChannelChangeDetected(const TSensrvChannelInfo &amp;aDetectedChannel, TSensrvChannelChangeType aChangeType)+
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        {+
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        ...+
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         //Implementation+
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        }+
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    void ChannelDetectionError(CSensrvChannelFinder aChannelFinder, TSensrvErrorSeverity aError)+
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        {+
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        ...+
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         //Implementation+
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        }+
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    void GetChannelListenerInterfaceL(TUid aInterfaceUid, TAny *aInterface)+
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        {+
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        ...+
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         //Implementation+
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        }+
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    };</codeblock></stepxmp>+
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</step>+
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<step id="GUID-CB0E18F1-21C3-4B51-88C8-ABCBD083304D"><cmd>Start channel listening+
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by passing an instance of the channel listener implementation, using <xref href="GUID-5F108D03-C8A6-3EF9-B103-2E8916633602.dita#GUID-5F108D03-C8A6-3EF9-B103-2E8916633602/GUID-FFB9A53F-CAD2-3CC7-9FAD-D254E15F83CF"><apiname>CSensrvChannelFinder::SetChannelListenerL()</apiname></xref> function.</cmd>+
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<stepxmp><codeblock xml:space="preserve">//Instance of the channel listener implementation+
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ChannelListener channelListener;+
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//Channel search parameters+
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TSensrvChannelInfo &amp;searchParameters+
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...+
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CSensrvChannelFinder* finder = CSensrvChannelFinder::NewLC();+
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...+
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channel-&gt;SetChannelListenerL(channelListener, searchParameters);+
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...</codeblock></stepxmp>+
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<info><p>This listens for channels that meet the supplied search parameters.+
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When a channel change occurs, a <parmname>ChannelChangeDetected</parmname> notification+
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is delivered through the <parmname>MSensrvChannelListener</parmname> interface.</p></info>+
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</step>+
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<step id="GUID-E9FF2158-0E82-4AB8-A9C0-8FE5A2651FE8"><cmd>Stop channel listening+
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by passing a NULL parameter to the <xref href="GUID-5F108D03-C8A6-3EF9-B103-2E8916633602.dita#GUID-5F108D03-C8A6-3EF9-B103-2E8916633602/GUID-FFB9A53F-CAD2-3CC7-9FAD-D254E15F83CF"><apiname>CSensrvChannelFinder::SetChannelListenerL()</apiname></xref> function.</cmd>+
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<stepxmp><codeblock xml:space="preserve">ChannelListener channelListener=NULL;+
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finder-&gt;SetChannelListenerL(channelListener, searchParameters);</codeblock></stepxmp>+
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</step>+
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</steps>+
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</taskbody></task>+
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