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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-44FDDA27-1A5D-42B5-8DE0-D9E88EB75C93" xml:lang="en"><title>Querying |
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13 for Sensor Channels</title><shortdesc>You can retrieve a list of sensor channels that are available for |
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14 a particular sensor type. Once you get the list of sensor channels that are |
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15 active, you can perform any required operations such as configuring sensor |
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16 channel properties, controlling sensor channels and so on.</shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody> |
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17 <steps id="GUID-4DD07DEC-6017-4237-BE46-1D69E5FBD744-GENID-1-8-1-9-1-1-6-1-4-1-4-1-4-1-3-1"> |
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18 <step id="GUID-EE1655E2-D4C4-4593-A0E1-BD1DFACB0351"><cmd>Create an instance |
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19 of <codeph>TSensrvChannelInfo</codeph> and set the required channel type as |
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20 the search criteria. For example, to query for all double tapping channels |
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21 provided by accelerometer sensor, set the channel type as <codeph>KSensrvChannelTypeIdAccelerometerDoubleTappingData</codeph>.</cmd> |
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22 <stepxmp><codeblock xml:space="preserve">TSensrvChannelInfo channelInfo; |
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23 channelInfo.iChannelType = KSensrvChannelTypeIdAccelerometerDoubleTappingData;</codeblock></stepxmp> |
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24 </step> |
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25 <step id="GUID-176936C5-17FE-49A6-A0A7-0E76EB69C5E8"><cmd>Create an instance |
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26 of <codeph>CSensrvChannelFinder</codeph> class and use the <xref href="GUID-5F108D03-C8A6-3EF9-B103-2E8916633602.dita#GUID-5F108D03-C8A6-3EF9-B103-2E8916633602/GUID-E58BAF1B-57AA-3E85-A4F9-8C6C29043FBD"><apiname>CSensrvChannelFinder::FindChannelsL()</apiname></xref> function |
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27 to query for available sensor channels.</cmd> |
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28 <stepxmp><codeblock xml:space="preserve">CSensrvChannelFinder* finder = CSensrvChannelFinder::NewL(); |
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29 finder->FindChannelsL(channelList, searchParameters);</codeblock></stepxmp> |
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30 </step> |
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31 <step id="GUID-9A69E5AD-E938-4092-A8C2-CB65C37C8962-GENID-1-8-1-9-1-1-6-1-4-1-4-1-4-1-3-1-3"><cmd>Create an instance |
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32 of <codeph>RSensrvChannelInfoList</codeph> to store the list of sensor channels.</cmd> |
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33 <stepxmp><codeblock xml:space="preserve">RSensrvChannelInfoList channelInfoList;</codeblock></stepxmp> |
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34 </step> |
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35 </steps> |
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36 <result id="GUID-F26EFE38-DF01-4531-89AD-191049E31F36"> <p>The <parmname>channelInfoList</parmname> contains |
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37 all the double tapping channels that are found. If several matching channels |
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38 are found, you can select the required channel by examining the content of |
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39 channel information objects inside <parmname>channelInfoList</parmname>.</p> |
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40 </result> |
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41 <example><p>This following code shows how to find double tapping channels |
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42 for accelerometer sensor:</p><codeblock xml:space="preserve">..... |
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43 ...... |
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44 /Construct a channel finder. |
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45 CSensrvChannelFinder* channelFinder; |
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46 channelFinder = CSensrvChannelFinder::NewL(); |
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47 CleanupStack::PushL( channelFinder ); |
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48 |
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49 // to store list of found channels. |
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50 RSensrvChannelInfoList channelInfoList; |
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51 |
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52 //Create and fill channel search criteria. |
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53 //In this example double tapping channel is searched. |
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54 TSensrvChannelInfo channelInfo; |
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55 channelInfo.iChannelType = KSensrvChannelTypeIdAccelerometerDoubleTappingData; |
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56 |
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57 //Find the double tapping channel |
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58 channelFinder->FindChannelsL( channelInfoList, channelInfo ); |
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59 |
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60 CleanupStack::PopAndDestroy( channelFinder ); // finder not needed any more |
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61 |
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62 if( channelInfoList.Count() != 1 ) |
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63 { |
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64 //The device does not support double tapping channel or |
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65 //there are several double tapping channels. |
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66 } |
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67 else |
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68 { |
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69 //double tapping channel found |
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70 } |
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71 ..... |
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72 .... |
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73 </codeblock></example> |
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74 </taskbody></task> |