Listening for Channel Changes

The sensor channel APIs enable you to receive notifications when a sensor channel is added or removed. This ensures that you are informed of changes to sensor channels whenever there is a change. For example, you can receive notifications when a specific proximity sensor channel is added.

1. Create a channel listener implementation for the MSensrvChannelListener interface.

           class ChannelListener:public MSensrvChannelListener
       {
       public:    
       void ChannelChangeDetected(const TSensrvChannelInfo &aDetectedChannel, TSensrvChannelChangeType aChangeType)
           {
           ...
            //Implementation
           }
       void ChannelDetectionError(CSensrvChannelFinder aChannelFinder, TSensrvErrorSeverity aError)
           {
           ...
            //Implementation
           }
       void GetChannelListenerInterfaceL(TUid aInterfaceUid, TAny *aInterface)
           {
           ...
            //Implementation
           }
       };
          

2. Start channel listening by passing an instance of the channel listener implementation, using CSensrvChannelFinder::SetChannelListenerL() function.

           //Instance of the channel listener implementation
   ChannelListener channelListener;
   //Channel search parameters
   TSensrvChannelInfo &searchParameters
   ...
   CSensrvChannelFinder* finder = CSensrvChannelFinder::NewLC();
   ...
   channel->SetChannelListenerL(channelListener, searchParameters);
   ...
          

   This listens for channels that meet the supplied search parameters. When a channel change occurs, a ChannelChangeDetected notification is delivered through the MSensrvChannelListener interface.

3. Stop channel listening by passing a NULL parameter to the CSensrvChannelFinder::SetChannelListenerL() function.

           ChannelListener channelListener=NULL;
   finder->SetChannelListenerL(channelListener, searchParameters);