Qt Creator compile error for QSensor - qt

Question

I'm new to Qt/Symbian development (I come from an iOS background), and I can't make sense of this compiler error:
Firstly, this is the error I'm getting:
/Users/Dave/AR-build-simulator/../QtSDK/Simulator/QtMobility/gcc/include/QtSensors/qsensor.h:-1: In member function 'QtMobility::QMagnetometerReading& QtMobility::QMagnetometerReading::operator=(const QtMobility::QMagnetometerReading&)':
Here is my header file:
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QtGui/QMainWindow>
#include <QSystemDeviceInfo>
#include <QGeoPositionInfoSource>
#include <QGeoCoordinate>
#include <QGeoPositionInfo>
#include <QMagnetometer>
QTM_USE_NAMESPACE
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
enum ScreenOrientation {
ScreenOrientationLockPortrait,
ScreenOrientationLockLandscape,
ScreenOrientationAuto
};
explicit MainWindow(QWidget *parent = 0);
virtual ~MainWindow();
// Note that this will only have an effect on Symbian and Fremantle.
void setOrientation(ScreenOrientation orientation);
void showExpanded();
private slots:
void positionUpdated(QGeoPositionInfo gpsPos);
void magnetometerReadingChanged(QMagnetometerReading mr);
private:
Ui::MainWindow *ui;
void setupGeneral();
QGeoPositionInfoSource *m_location;
QGeoCoordinate m_coordinate;
QMagnetometer *m_magnetometer;
QMagnetometerReading m_magnetometerReading;
};
#endif // MAINWINDOW_H
Here is the implementation file:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtCore/QCoreApplication>
#include <qgeopositioninfosource.h>
#include <QMessageBox>
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent), ui(new Ui::MainWindow)
{
ui->setupUi(this);
setupGeneral();
}
void MainWindow::setupGeneral()
{
m_location = QGeoPositionInfoSource::createDefaultSource(this);
//Listen to gps position changes
QObject::connect(m_location, SIGNAL(positionUpdated(QGeoPositionInfo)), this,SLOT(positionUpdated(QGeoPositionInfo)));
//Start listening to GPS position updates
m_location->startUpdates();
//Start listening to magnetometer updates
m_magnetometer = new QMagnetometer(this);
connect(m_magnetometer, SIGNAL(readingChanged(QMagnetometerReading)), this, SLOT(magnetometerReadingChanged(QMagnetometerReading)));
m_magnetometer->start();
}
void MainWindow::positionUpdated(QGeoPositionInfo gpsPos){
m_coordinate = gpsPos.coordinate();
if (m_coordinate.isValid()) {
m_location->stopUpdates();
QString longitude;
QString latitude;
longitude.setNum(m_coordinate.longitude());
latitude.setNum(m_coordinate.latitude());
QMessageBox::information(this,"latitude",latitude);
} else {
QMessageBox::information(this, "GPS Info", "Coordinator is not valid...");
}
}
void MainWindow::magnetometerReadingChanged(QMagnetometerReading mr) {
QMessageBox::information(this, "Magnetometer info", "got magnetometer reading...");
m_magnetometerReading = mr;
//m_magnetometerReading = new QMagnetometerReading(this);
//m_magnetometerReading->copyValuesFrom(mr);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::setOrientation(ScreenOrientation orientation)
{
#if defined(Q_OS_SYMBIAN)
// If the version of Qt on the device is < 4.7.2, that attribute won't work
if (orientation != ScreenOrientationAuto) {
const QStringList v = QString::fromAscii(qVersion()).split(QLatin1Char('.'));
if (v.count() == 3 && (v.at(0).toInt() << 16 | v.at(1).toInt() << 8 | v.at(2).toInt()) < 0x040702) {
qWarning("Screen orientation locking only supported with Qt 4.7.2 and above");
return;
}
}
#endif // Q_OS_SYMBIAN
Qt::WidgetAttribute attribute;
switch (orientation) {
#if QT_VERSION < 0x040702
// Qt < 4.7.2 does not yet have the Qt::WA_*Orientation attributes
case ScreenOrientationLockPortrait:
attribute = static_cast<Qt::WidgetAttribute>(128);
break;
case ScreenOrientationLockLandscape:
attribute = static_cast<Qt::WidgetAttribute>(129);
break;
default:
case ScreenOrientationAuto:
attribute = static_cast<Qt::WidgetAttribute>(130);
break;
#else // QT_VERSION < 0x040702
case ScreenOrientationLockPortrait:
attribute = Qt::WA_LockPortraitOrientation;
break;
case ScreenOrientationLockLandscape:
attribute = Qt::WA_LockLandscapeOrientation;
break;
default:
case ScreenOrientationAuto:
attribute = Qt::WA_AutoOrientation;
break;
#endif // QT_VERSION < 0x040702
};
setAttribute(attribute, true);
}
void MainWindow::showExpanded()
{
#ifdef Q_OS_SYMBIAN
showFullScreen();
#elif defined(Q_WS_MAEMO_5)
showMaximized();
#else
show();
#endif
}
If anybody could explain to me what is going wrong, I'd be very grateful.

Answer 1

According to the documentation(here) readingChanged signal does not have any parameters. You should use
connect(m_magnetometer, SIGNAL(readingChanged()), this, SLOT(magnetometerReadingChanged())); and then acquire the reading from the reading property.