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    Nokia Corporation - initial contribution.
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<!DOCTYPE task
  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">
<task id="GUID-44FDDA27-1A5D-42B5-8DE0-D9E88EB75C93" xml:lang="en"><title>Querying
for Sensor Channels</title><shortdesc>You can retrieve a list of sensor channels that are available for
a particular sensor type. Once you get the list of sensor channels that are
active, you can perform any required operations such as configuring sensor
channel properties, controlling sensor channels and so on.</shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>
<steps id="GUID-4DD07DEC-6017-4237-BE46-1D69E5FBD744-GENID-1-10-1-9-1-1-6-1-4-1-4-1-4-1-3-1">
<step id="GUID-EE1655E2-D4C4-4593-A0E1-BD1DFACB0351"><cmd>Create an instance
of <codeph>TSensrvChannelInfo</codeph> and set the required channel type as
the search criteria. For example, to query for all double tapping channels
provided by accelerometer sensor, set the channel type as <codeph>KSensrvChannelTypeIdAccelerometerDoubleTappingData</codeph>.</cmd>
<stepxmp><codeblock xml:space="preserve">TSensrvChannelInfo channelInfo;
channelInfo.iChannelType = KSensrvChannelTypeIdAccelerometerDoubleTappingData;</codeblock></stepxmp>
</step>
<step id="GUID-176936C5-17FE-49A6-A0A7-0E76EB69C5E8"><cmd>Create an instance
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
to query for available sensor channels.</cmd>
<stepxmp><codeblock xml:space="preserve">CSensrvChannelFinder* finder = CSensrvChannelFinder::NewL();
finder-&gt;FindChannelsL(channelList, searchParameters);</codeblock></stepxmp>
</step>
<step id="GUID-9A69E5AD-E938-4092-A8C2-CB65C37C8962-GENID-1-10-1-9-1-1-6-1-4-1-4-1-4-1-3-1-3"><cmd>Create an instance
of <codeph>RSensrvChannelInfoList</codeph> to store the list of sensor channels.</cmd>
<stepxmp><codeblock xml:space="preserve">RSensrvChannelInfoList channelInfoList;</codeblock></stepxmp>
</step>
</steps>
<result id="GUID-F26EFE38-DF01-4531-89AD-191049E31F36">       <p>The <parmname>channelInfoList</parmname> contains
all the double tapping channels that are found. If several matching channels
are found, you can select the required channel by examining the content of
channel information objects inside <parmname>channelInfoList</parmname>.</p> 
   </result>
<example><p>This following code shows how to find double tapping channels
for accelerometer sensor:</p><codeblock xml:space="preserve">.....
......
/Construct a channel finder.
    CSensrvChannelFinder* channelFinder;
    channelFinder = CSensrvChannelFinder::NewL();
    CleanupStack::PushL( channelFinder );
    
    // to store list of found channels.
    RSensrvChannelInfoList channelInfoList;

    //Create and fill channel search criteria.
    //In this example double tapping channel is searched.
    TSensrvChannelInfo channelInfo;
    channelInfo.iChannelType = KSensrvChannelTypeIdAccelerometerDoubleTappingData;

    //Find the double tapping channel
    channelFinder-&gt;FindChannelsL( channelInfoList, channelInfo );

    CleanupStack::PopAndDestroy( channelFinder ); // finder not needed any more

    if( channelInfoList.Count() != 1 )
        {
        //The device does not support double tapping channel or
        //there are several double tapping channels.
        }
    else
        {
        //double tapping channel found 
        }
.....
....
</codeblock></example>
</taskbody></task>