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1 <?xml version="1.0" encoding="utf-8"?> |
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2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
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3 <!-- This component and the accompanying materials are made available under the terms of the License |
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4 "Eclipse Public License v1.0" which accompanies this distribution, |
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5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
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6 <!-- Initial Contributors: |
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7 Nokia Corporation - initial contribution. |
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8 Contributors: |
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9 --> |
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10 <!DOCTYPE task |
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11 PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd"> |
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12 <task id="GUID-09E44FE5-6BEE-49FF-8BBF-CBB3C066EE10" xml:lang="en"><title>Listening |
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13 for Channel Changes</title><shortdesc>The sensor channel APIs enable you to receive notifications when |
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14 a sensor channel is added or removed. This ensures that you are informed of |
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15 changes to sensor channels whenever there is a change. For example, you can |
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16 receive notifications when a specific proximity sensor channel is added.</shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody> |
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17 <prereq id="GUID-03B31784-B731-43C4-B2DC-38DD4898AE22"> <p>Before listening |
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18 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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19 the sensor channel</xref>.</p> </prereq> |
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20 <steps id="GUID-4DD07DEC-6017-4237-BE46-1D69E5FBD744-GENID-1-8-1-9-1-1-6-1-4-1-4-1-9-1-3-2"> |
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21 <step id="GUID-B454B117-4FC5-4B19-B512-7B4A213E4C51"><cmd>Create a channel |
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22 listener implementation for the <parmname>MSensrvChannelListener</parmname> interface.</cmd> |
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23 <stepxmp><codeblock xml:space="preserve">class ChannelListener:public MSensrvChannelListener |
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24 { |
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25 public: |
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26 void ChannelChangeDetected(const TSensrvChannelInfo &aDetectedChannel, TSensrvChannelChangeType aChangeType) |
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27 { |
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28 ... |
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29 //Implementation |
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30 } |
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31 void ChannelDetectionError(CSensrvChannelFinder aChannelFinder, TSensrvErrorSeverity aError) |
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32 { |
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33 ... |
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34 //Implementation |
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35 } |
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36 void GetChannelListenerInterfaceL(TUid aInterfaceUid, TAny *aInterface) |
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37 { |
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38 ... |
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39 //Implementation |
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40 } |
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41 };</codeblock></stepxmp> |
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42 </step> |
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43 <step id="GUID-CB0E18F1-21C3-4B51-88C8-ABCBD083304D"><cmd>Start channel listening |
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44 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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45 <stepxmp><codeblock xml:space="preserve">//Instance of the channel listener implementation |
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46 ChannelListener channelListener; |
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47 //Channel search parameters |
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48 TSensrvChannelInfo &searchParameters |
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49 ... |
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50 CSensrvChannelFinder* finder = CSensrvChannelFinder::NewLC(); |
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51 ... |
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52 channel->SetChannelListenerL(channelListener, searchParameters); |
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53 ...</codeblock></stepxmp> |
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54 <info><p>This listens for channels that meet the supplied search parameters. |
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55 When a channel change occurs, a <parmname>ChannelChangeDetected</parmname> notification |
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56 is delivered through the <parmname>MSensrvChannelListener</parmname> interface.</p></info> |
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57 </step> |
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58 <step id="GUID-E9FF2158-0E82-4AB8-A9C0-8FE5A2651FE8"><cmd>Stop channel listening |
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59 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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60 <stepxmp><codeblock xml:space="preserve">ChannelListener channelListener=NULL; |
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61 finder->SetChannelListenerL(channelListener, searchParameters);</codeblock></stepxmp> |
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62 </step> |
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63 </steps> |
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64 </taskbody></task> |