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.

Before listening for channel changes, you must open the sensor channel .

  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);