CS000913 - Listening for rotation sensor data events

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ID	CS000913	Creation date	April 22, 2008
Platform	S60 3rd Edition, MR	Tested on devices	Nokia N95 8GB
Category	Symbian C++	Subcategory	Hardware, Sensor

Keywords (APIs, classes, methods, functions): CRRSensorApi, TRRSensorInfo, CRRSensorApi::NewL(), CRRSensorApi::AddDataListener(), CRRSensorApi::RemoveDataListener(), MRRSensorDataListener::HandleDataEventL()

Overview

This code snippet demonstrates how to listen for data events produced by the rotation sensor of the device. In practice, the control implements the MRRSensorDataListener interface which enables it to listen to the data events. Whenever a data event occurs, the MRRSensorDataListener::HandleDataEventL() function is called.

Note: In order to use the code, you need to install the sensor plug-in for your SDK.

This snippet can be self-signed.

MMP file

The following libraries are required:

LIBRARY  RRSensorApi.lib

Header file

#include <RRSensorApi.h>

// Rotation sensor UID
const TInt KRotationSensorUID = 0x303E;

class CMyControl : public CCoeControl, public MRRSensorDataListener
    {
    // ...
 
    private:  // Functions from base classes
        /**
         * From MRRSensorDataListener.
         * Callback function for receiving sensor data events.
         *
         * @param aSensor identifies the sensor that created the event.
         * @param aEvent contains data about created event.
         */
        void HandleDataEventL(TRRSensorInfo aSensor, TRRSensorEvent aEvent);
 
    private:
        /**
         * Initializes and registers the rotation sensor listener.
         */
        void RegisterSensors();
 
        /**
         * Unregisters the rotation sensor listener.
         */
        void UnregisterSensors();
 
    private:  // Data
        CRRSensorApi* iRotationSensor;
    }

Source file

#include <RRSensorApi.h>

void CMyControl::ConstructL(const TRect& aRect)
    {
    // ...
 
    // Initialize and register the rotation sensor listener
    RegisterSensors();
 
    // ...
    }

CMyControl::~CMyControl()
    {
    // ...
 
    // Unregister the rotation sensor listener
    UnregisterSensors();
 
    // ...
    }

/**
 * Initializes and registers the rotation sensor listener.
 */
void CMyControl::RegisterSensors()
    {
    RArray<TRRSensorInfo> sensorList;
    CleanupClosePushL(sensorList);
 
    // Retrieve list of available sensors
    CRRSensorApi::FindSensorsL(sensorList);
 
    // Get number of sensors available
    TInt sensorCount = sensorList.Count();
 
    for (TInt i = 0; i < sensorCount; i++)
        {
        // We are interested only in the rotation sensor now
        if (sensorList[i].iSensorId == KRotationSensorUID)
            {
            iRotationSensor = CRRSensorApi::NewL(sensorList[i]);
 
            // Register this control as rotation data listener
            iRotationSensor->AddDataListener(this);
 
            break;
            }
        }
 
    CleanupStack::PopAndDestroy();  // sensorList
    }

/**
 * Unregisters the rotation sensor listener.
 */
void CMyControl::UnregisterSensors()
    {
    // Unregister rotation data listener
    iRotationSensor->RemoveDataListener();
    delete iRotationSensor;
    iRotationSensor = NULL;
    }

/**
 * Gets called whenever a data event occurs.
 */
void CMyControl::HandleDataEventL(TRRSensorInfo aSensor, TRRSensorEvent aEvent)
    {
    // A data event occurred. Handle it.
    // ...
    }

Postconditions

Whenever a data event occurs, the CMyControl::HandleDataEventL() function is called.

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