Marble does not use GPS through gpsd.

https://bugs.kde.org/show_bug.cgi?id=451656

STEPS TO REPRODUCE

1. Connect u-blox7 GPS connector ( https://www.robotshop.com/en/dfrobot-usb-gps-receiver-compatible-w-raspberry-pilattepandajetson-nano.html ). Open cgps to check it works fine.
2. Open Marble.
3. Select gpsd in Location > Position Tracking.

OBSERVED RESULT

Although the cpgs program shows I have a 2D or 3D FIX and gives me my exact location and GPS-coordinates, Marble keeps on "waiting for current location information...".

EXPECTED RESULT

Marble uses my GPS USB Dongle and detects my position just like the cgps CLI tool.

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Fedora 35 KDE (fully updated through the dnf package manager at 18 March 2022) KDE Plasma Version: 5.24.3 KDE Frameworks Version: 5.91.0 Qt Version: 5.12.2

ADDITIONAL INFORMATION

Marble is started after cgps reported a 2D or 3D FIX.

I have created a test file to play with:

// https://gpsd.io/client-howto.html
// https://gpsd.gitlab.io/gpsd/libgps.html
// $ clang++ -lgps -lQt5Core -std=c++20 -Wall -pedantic -g main.cpp && ./a.out

#include <QtCore/QTime>
#include <libgpsmm.h>

#include <iomanip>
#include <iostream>

// Based on https://gpsd.io/client-howto.html#_c_examples_2
void libgpsmm(gpsmm& gps_rec)
{
    for (;;)
    {
        if (!gps_rec.waiting(1000000)) // 1000000 is 1 second
        {
            continue;
        }

        struct gps_data_t* gpsd_data;

        if ((gpsd_data = gps_rec.read()) == nullptr)
        {
            std::cerr << "GPSD read error." << std::endl;
        }
        else
        {
            const auto latitude{gpsd_data->fix.latitude};
            const auto longitude{gpsd_data->fix.longitude};
            const auto s_vis{gpsd_data->satellites_visible};
            const auto s_used{gpsd_data->satellites_used};
            const auto mode{gpsd_data->fix.mode};

            std::cout << std::setprecision(8) << std::fixed;
            std::cout << "Lat: " << latitude << ", long: " << longitude << ", visible sats: " << s_vis
                      << ", used sats: " << s_used << ", mode: " << mode << std::endl;
        }
    }
}

// Based on Marble source code
void marble(gpsmm& gps_rec)
{
    const int gpsWaitTimeout = 200; // ms

    QTime watchdog;
    watchdog.start();

    while (gps_rec.waiting(0) && watchdog.elapsed() < gpsWaitTimeout)
    {
        gps_data_t* gpsd_data = gps_rec.read();

        if (gpsd_data)
        {
            const auto latitude{gpsd_data->fix.latitude};
            const auto longitude{gpsd_data->fix.longitude};
            const auto s_vis{gpsd_data->satellites_visible};
            const auto s_used{gpsd_data->satellites_used};
            const auto mode{gpsd_data->fix.mode};

            std::cout << std::setprecision(8) << std::fixed;
            std::cout << "Lat: " << latitude << ", long: " << longitude << ", visible sats: " << s_vis
                      << ", used sats: " << s_used << ", mode: " << mode << std::endl;
        }
        else
        {
            std::cerr << "GPSD read error." << std::endl;
        }
    }
}

int main()
{
    std::cout << "Version " << GPSD_API_MAJOR_VERSION << " - " << GPSD_API_MINOR_VERSION << std::endl;

    gpsmm gps_rec("localhost", DEFAULT_GPSD_PORT);

    if (gps_rec.stream(WATCH_ENABLE | WATCH_JSON) == nullptr)
    {
        std::cerr << "No GPSD running." << std::endl;
        return 1;
    }

    // Choose 1:
    //
    // marble(gps_rec);
    // libgpsmm(gps_rec);

    return 0;
}

When executing with a 2D FIX I get the following results:

• When uncommenting marble(gps_rec) only:

$ clang++ -lgps -lQt5Core -std=c++20 -Wall -pedantic -g main.cpp && ./a.out
Version 12 - 0
Lat: nan, long: nan, visible sats: 0, used sats: 0, mode: 0
Lat: nan, long: nan, visible sats: 0, used sats: 0, mode: 0
Lat: nan, long: nan, visible sats: 0, used sats: 0, mode: 0
$

• When uncommenting libgpsmm(gps_rec) only:

$ clang++ -lgps -lQt5Core -std=c++20 -Wall -pedantic -g main.cpp && ./a.out
Version 12 - 0
Lat: nan, long: nan, visible sats: 0, used sats: 0, mode: 0
Lat: nan, long: nan, visible sats: 0, used sats: 0, mode: 0
Lat: nan, long: nan, visible sats: 0, used sats: 0, mode: 0
Lat: 50.12345678, long: 5.12345678, visible sats: 0, used sats: 0, mode: 2
Lat: 50.12345678, long: 5.12345678, visible sats: 10, used sats: 3, mode: 2
Lat: 50.12345678, long: 5.12345678, visible sats: 10, used sats: 3, mode: 2
Lat: 50.12345678, long: 5.12345678, visible sats: 10, used sats: 3, mode: 2
Lat: 50.12345678, long: 5.12345678, visible sats: 10, used sats: 3, mode: 2
Lat: 50.12345678, long: 5.12345678, visible sats: 10, used sats: 3, mode: 2
Lat: 50.12345678, long: 5.12345678, visible sats: 10, used sats: 3, mode: 2
Lat: 50.12345678, long: 5.12345678, visible sats: 10, used sats: 3, mode: 2
Lat: 50.12345678, long: 5.12345678, visible sats: 10, used sats: 3, mode: 2
Lat: 50.12345678, long: 5.12345678, visible sats: 10, used sats: 3, mode: 2
^C
$