Searching for GPS devices using Symbian C++

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Article Metadata

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Tested with

Devices(s): Nokia E90 Communicator, Nokia N95

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Compatibility

Platform(s): S60 3rd Edition
S60 3rd Edition, FP1

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Article

Keywords: RPositionServer, TPositionModuleId, TPositionModuleStatus

Created: tepaa (08 Feb 2008)

Last edited: jasfox (25 Apr 2013)

Overview

The following example goes through the GPS devices of the mobile phone and selects the device used for GPS positioning.

If the code finds both an external Bluetooth GPS device and an internal GPS device, it selects the internal one.

MMP file

The following capabilities and libraries are required:

CAPABILITY Location

LIBRARY Lbs.lib

Header file

#include <lbs.h>

Source file

// Finds and selects GPS device
TPositionModuleId CYourClass::GetPositionModuleId()
    {
    TInt error = KErrNone;
 
    RPositionServer ps; // TODO: Move to the class member variable
    error = ps.Connect();
    if (error != KErrNone)
        {
        return KNullUid;
        }
 
    TUint numModules = 0;
    error = ps.GetNumModules(numModules);
    if (error != KErrNone)
        {
        ps.Close(); // TODO: No need to close RPositionServer if it is moved
                    // to class member variable, then it must close in class
                    // destructor.
        return KNullUid;
        }
 
    TPositionModuleId currentModuleId = KNullUid;
    TPositionModuleId selectedModuleId = KNullUid;
    for (TInt moduleIndex = 0; moduleIndex < numModules; moduleIndex++)
        {
        TPositionModuleInfo moduleInfo;
        error = ps.GetModuleInfoByIndex(moduleIndex, moduleInfo);
        if (error != KErrNone)
            {
            ps.Close(); // TODO: No need to close RPositionServer if it is
                        // moved to class member variable, then it must close
                        // in class destructor.
            return selectedModuleId;
            }
 
        currentModuleId = moduleInfo.ModuleId();
 
        TPositionModuleStatus moduleStatus;
        error = ps.GetModuleStatus(moduleStatus, currentModuleId);
        if (error != KErrNone ||
        moduleStatus.DeviceStatus() == TPositionModuleStatus::EDeviceDisabled)
            {
            continue;
            }
 
        TPositionModuleInfo::TDeviceLocation deviceLoc =
            moduleInfo.DeviceLocation();
        if (deviceLoc == TPositionModuleInfo::EDeviceInternal)
            {
            if (selectedModuleId == KNullUid)
                {
                // Found first internal position module, select that
                selectedModuleId = currentModuleId;
                }
            else
                {
                // Check external module should be switched to internal
                TPositionModuleInfo selectedModuleInfo;
                error = ps.GetModuleInfoById(selectedModuleId,
                    selectedModuleInfo);
                if (error == KErrNone && selectedModuleInfo.DeviceLocation()
                == TPositionModuleInfo::EDeviceExternal)
                    {
                    // Change external device to internal
                    selectedModuleId = currentModuleId;
                    }
                }
            }
        else if (deviceLoc == TPositionModuleInfo::EDeviceExternal)
            {
            // Just pick the first external device, if none is currently
            // selected
            if (selectedModuleId == KNullUid)
                {
                // Found first enternal position module, select that
                selectedModuleId = currentModuleId;
                }
            }
        }
 
    ps.Close(); // TODO: No need to close RPositionServer if it is moved to
                // class member variable, then it must close in class
                // destructor.
    return selectedModuleId;
    }
 
 
// Use selected GPS device
void CYourClass::OpenPositioner(TPositionModuleId aDevice)
    {
    RPositioner positioner;    // TODO: Move to the class member variable
    RPositionServer ps;        // TODO: Move to the class member variable
 
    if (aDevice != KNullUid)
        {
        if (ps.Connect() == KErrNone)
            {
            // Selected GPS device goes as 'aDevice' parameter
            positioner.Open(ps,aDevice);
            ...
            positioner.Close();
            ps.Close();
            }
        }
    }