Provide position through QGeoPositionInfoSource

JustAJ

Dear all, I am making an application which must show the location of a ship. The actual location comes from outside the application which I am making. To show the location, I want to make use of the LocationDisplay class. So I started a default ArcGIS application in Qt Creator (I tried both a QML and C++ app), and made a class, which is derived from QGeoPositionInfoSource, according to this example, linked by LDanzinger-esristaff, also on this forum. However, I just can't seem to get it to work. It seems I just don't understand it, and to be hones I'm getting a bit frustrated :)

My code is as follows:

#ifndef SHIPPOSITIONSOURCE_H
#define SHIPPOSITIONSOURCE_H

#include <QGeoPositionInfoSource>

class ShipPositionSource : public QGeoPositionInfoSource
{
    Q_OBJECT

public:
    explicit ShipPositionSource(QObject* parent = nullptr);
    ~ShipPositionSource();

    QGeoPositionInfo lastKnownPosition(bool fromSatellitePositioningMethodsOnly = false) const override;
    PositioningMethods supportedPositioningMethods() const override;
    int minimumUpdateInterval() const override;
    QGeoPositionInfoSource::Error error() const override;

public slots:
    void startUpdates() override;
    void stopUpdates() override;
    void requestUpdate(int timeout = 0) override;

    QGeoPositionInfo currentPosition;
    QGeoPositionInfoSource::Error lastError = QGeoPositionInfoSource::NoError;

    bool started;
};

#endif // SHIPPOSITIONSOURCE_H

That was the header, here the source:

#include "shippositionsource.h"

ShipPositionSource::ShipPositionSource(QObject* parent) :
    QGeoPositionInfoSource(parent)
{
    setUpdateInterval(500);
    currentPosition.setCoordinate(QGeoCoordinate(52.920905, 4.862173));
    emit positionUpdated(currentPosition);
}

ShipPositionSource::~ShipPositionSource()
{}

void ShipPositionSource::startUpdates()
{
    if(started)
        return;

    started = true;
    //TODO: start communication with bridge
}

void ShipPositionSource::stopUpdates()
{
    if(!started)
        return;

    started = false;

    //TODO: stop communication with bridge
}

void ShipPositionSource::requestUpdate(int timeout)
{
    Q_UNIMPLEMENTED();
}

QGeoPositionInfo ShipPositionSource::lastKnownPosition(bool fromSatellitePositioningMethodsOnly) const
{
    Q_UNUSED(fromSatellitePositioningMethodsOnly);
    return currentPosition;
}

QGeoPositionInfoSource::PositioningMethods ShipPositionSource::supportedPositioningMethods() const
{
    return QGeoPositionInfoSource::PositioningMethod::NoPositioningMethods;
}

int ShipPositionSource::minimumUpdateInterval() const
{
    return updateInterval();
}

QGeoPositionInfoSource::Error ShipPositionSource::error() const
{
    return lastError;
}

I made a Quick C++ app, called TestProject, and in TestProject.cpp I only edited the TestProject::setMapView method with the following lines:

m_mapView = mapView;
m_mapView->locationDisplay()->setPositionSource(&positionSource);
    m_mapView->locationDisplay()->setAutoPanMode(LocationDisplayAutoPanMode::Recenter);
m_mapView->locationDisplay()->start();
m_mapView->setMap(m_map);

The result is that I don't see any location updated, or the map centering on the position I gave in the constructor. I must be doing something wrong or I don't understand something, but I don't see what. I would be very thankful for hints and tips!

Christian Ehrlicher

@JustAJ said in Provide position through QGeoPositionInfoSource:

locationDisplay

What type of Qt class is this? I think this is no Qt class but on from ESRI ArcGIS runtime SDK ( https://developers.arcgis.com/qt/latest/cpp/api-reference/esri-arcgisruntime-locationdisplay.html ) so you should better ask here as we don't have any experience with this library.
Also - where did you define positionSource - are you sure it's alive after you leave the function (I would guess no)?

JustAJ

@Christian-Ehrlicher said in Provide position through QGeoPositionInfoSource:

@JustAJ said in Provide position through QGeoPositionInfoSource:

locationDisplay

What type of Qt class is this? I think this is no Qt class but on from ESRI ArcGIS runtime SDK ( https://developers.arcgis.com/qt/latest/cpp/api-reference/esri-arcgisruntime-locationdisplay.html ) so you should better ask here as we don't have any experience with this library.
Also - where did you define positionSource - are you sure it's alive after you leave the function (I would guess no)?

I am terribly sorry, I mixed up some stuff. This is indeed from the ArcGIS SDK. I will go ask there.

Yes, positionSource is alive at that position. I defined it as a private attribute of the TestProject class, in the header

Christian Ehrlicher

@JustAJ said in Provide position through QGeoPositionInfoSource:

I defined it as a private attribute of the TestProject class, in the header

I just asked because the other members seems to be prefixed with 'm_'. Also I would check QGeoPositionInfoSource::error() and other functions provided by QGeoPositionInfoSource to see if it is really valid.

JustAJ

@Christian-Ehrlicher said in Provide position through QGeoPositionInfoSource:

@JustAJ said in Provide position through QGeoPositionInfoSource:

I defined it as a private attribute of the TestProject class, in the header

I just asked because the other members seems to be prefixed with 'm_'. Also I would check QGeoPositionInfoSource::error() and other functions provided by QGeoPositionInfoSource to see if it is really valid.

I've worked quite some time in a .NET environment, so I'm not very fond of the prefixes. This code was from an example, which I modified to my preferences.
Regarding the error() method, it is a pure virtual method, so besides my own implementation, no useful information can be gotten.

Christian Ehrlicher

@JustAJ said in Provide position through QGeoPositionInfoSource:

so besides my own implementation

What does this mean? You wrote an own QGeoPositionInfoSource? Did you actually check if it is working correctly?

JustAJ

@Christian-Ehrlicher said in Provide position through QGeoPositionInfoSource:

@JustAJ said in Provide position through QGeoPositionInfoSource:

so besides my own implementation

What does this mean? You wrote an own QGeoPositionInfoSource? Did you actually check if it is working correctly?

I don't think I understand what you mean... I made my own class which inherits from QGeoPositionInfoSource, as you can see in the code I provided. The QGeoPositionInfoSource::error() you mentioned is a pure virtual method, so I cannot use this method to troubleshout if something goes wrong in QGeoPositionInfoSource, that's what I mean.

Christian Ehrlicher

Ok, mixed it up :)