Getting the location in Qt

This code snippet demonstrates how to use the Qt Location API.

Article Metadata

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Tested with

Devices(s): Nokia 5800 XpressMusic

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Compatibility

Platform(s): S60 5th Edition, Maemo 5

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Article

Created: tapla (25 May 2010)

Last edited: hamishwillee (11 Oct 2012)

Qt project file

Link the Location module into the project:

CONFIG += mobility
MOBILITY = location

Using the Location module requires the Location capability:

symbian: {
    TARGET.CAPABILITY = Location
}

Header

#include <QGeoPositionInfo>
#include <QGeoPositionInfoSource>
 
 
#include <QDebug>
 
#include <QPointer>
 
// QtMobility namespace 
QTM_USE_NAMESPACE
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public slots:
    /**
     * Called when the current position is updated.
     */
    void positionUpdated(QGeoPositionInfo geoPositionInfo);
´
private:
    /**
     * Obtains the location data source and starts listening for position
     * changes.
     */
    void startGPS();
 
private:
    QPointer<QGeoPositionInfoSource> locationDataSource;
    QGeoPositionInfo myPositionInfo;
}

Source

#include <QGeoCoordinate>
 
void MainWindow::startGPS()
{
    // Obtain the location data source if it is not obtained already
    if (!locationDataSource)
    {
        locationDataSource =
            QGeoPositionInfoSource::createDefaultSource(this);
        // Whenever the location data source signals that the current
        // position is updated, the positionUpdated function is called
        connect(locationDataSource, SIGNAL(positionUpdated(QGeoPositionInfo)),
                      this, SLOT(positionUpdated(QGeoPositionInfo)));
 
        // Start listening for position updates
        locationDataSource->startUpdates();
    }
}
 
void MainWindow::positionUpdated(QGeoPositionInfo geoPositionInfo)
{
    if (geoPositionInfo.isValid())
    {
        // We've got the position. No need to continue the listening.
        locationDataSource->stopUpdates();
 
        // Save the position information into a member variable
        myPositionInfo = geoPositionInfo;
 
        // Get the current location as latitude and longitude
        QGeoCoordinate geoCoordinate = geoPositionInfo.coordinate();
        qreal latitude = geoCoordinate.latitude();
        qreal longitude = geoCoordinate.longitude();
        qDebug() << QString("Latitude: %1 Longitude: %2").arg(latitude).arg(longitude);
    }
}

Postconditions

Current location is obtained and printed on the screen.

See also

• CS001615 - Setting up Qt Mobility