diff -r 43e37759235e -r 51a74ef9ed63 Symbian3/SDK/Source/GUID-83630B57-D842-4B60-8AF0-D2965251DE29.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Symbian3/SDK/Source/GUID-83630B57-D842-4B60-8AF0-D2965251DE29.dita Wed Mar 31 11:11:55 2010 +0100 @@ -0,0 +1,98 @@ + + + + + +Retrieving +Channel PropertiesA sensor channel is associated with properties such as channel +availability status, data transmission rate, data format and so on. Also, +each field in the data type supplied by a sensor channel can have its own +properties. The channel properties can be retrieved using the CSensrvChannel::GetPropertyL() and CSensrvChannel::GetAllPropertiesL() functions. +

Before retrieving +channel properties, you must open +the sensor channel.

 +

A channel property +is referenced by its property id and an index. The parameters of the CSensrvChannel::GetPropertyL() are +listed with their meanings in the following table.

+ + + +Parameter +Meaning + + + + +First parameter +specifies the id of the property to retrieve. + + +Second parameter +is an index that specifies the property to be retrieved, if there are +several properties associated with a particular property id. + + +Third parameter + is a TSensrvProperty that is passed by reference +and populated by CSensrvChannel::GetPropertyL(). + + + +

The following list shows the different possible values of the index +:

    +

  • When the property id is for a simple property, that is, there is only +one property item for the id (for example, KSensrvPropIdChannelAccuracy), +the second parameter must be specified as ESensrvSingleProperty.

    • +

  • When the given property id has an array of TSensrvProperty items, +the index parameter indicates which item in the array to retrieve. One such +case is when you want to retrieve a property of a particular data field that +is supplied by the channel. For example, if you want to find out if the X +axis of the accelerometer is enabled, you must specify KSensrvPropIdAxisActive as +the property id, and TSensrvAccelerometerAxisData::iAxisX as +the index. For details, see Array +Properties.

    • +

  • When the given property id has an array of TSensrvProperty items, +information about the array can be retrieved by specifying ESensrvArrayPropertyInfo as +the index parameter. For example, when a channel can provide data at discrete +data rates, the information for each data rate is stored in a TSensrvProperty item. +You can use KSensrvPropIdDataRate as the property id +and ESensrvArrayPropertyInfo as the index to retrieve +the property item that contains this information.

    • +
 + +Create an instance +of TSensrvProperty. +TSensrvProperty property; +

Each channel property is encapsulated by the TSensrvProperty class. +Therefore, the details of the retrieved property can be accessed using the +functions of the TSensrvProperty class.

 + +Use the CSensrvChannel::GetPropertyL() function +to retrieve the property item for a particular property id. For example, to +check for the accuracy of a channel, pass the KSensrvPropIdChannelAccuracy as +a property id. +... + +CSensrvChannel* iSensorChannel; +.... +iSensorChannel->GetPropertyL( KSensrvPropIdChannelAccuracy, + KSensrvItemIndexNone, + property ); + +.... + You can retrieve all the properties associated with a particular +sensor channel using the CSensrvChannel::GetAllPropertiesL() function. + + +
    +
  • End the session with the sensor channel using the CSensrvChannel::CloseChannel() function.
    • +
  • You can set the required channel properties. For details, see Setting +Channel Properties.
    • +
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