QCompass in QT Quick mobile App

[Phips04]

Hi everyone,
I'm actually creating an mobile application for my android tablet in QT Quick.
The application now needs to read data from the QCompass sensor.
I tried this:

Header file - backend.h:

Code file - backend.cpp:

Image and Backend implementation:

Timer implementation:

My goal is to assign the heading retrieved via "backend.NumericHeading" to the rotation property of the image.
Every time I run this, android terminates my app, and tells that the app was paused for some reason (no details).
Thanks for your help.

[Phips04]

I tried this now, it runs fine, but checkValue is never triggered.

Backend::Backend(QObject *parent) : QObject(parent)
{
compass = new QCompass(this);

connect(compass, SIGNAL(readingChanged()), this, SLOT(checkReading()));

compass->start();

Value = 45;

}

void Backend::checkReading()
{
Value = 180;
}

[jsulm]

@Phips04 said in QCompass in QT Quick mobile App:

connect(compass, SIGNAL(readingChanged()), this, SLOT(checkReading()));

You should use new connect syntax:

connect(compass, &QCompass::readingChanged, this, &Backend::checkReading);

You should also connect a slot to https://doc.qt.io/qt-5/qsensor.html#sensorError and check whether you get any errors.
And I think your app has to request access rights to read from the sensors.

[Phips04]

@jsulm Just tried the new syntax, the app runs without interruptions but checkReading is never entered.
I registerd a slot for sensorError, the affected function is never called to.
Since the QMagnetometer sensor doesn't work to I think the reason for this problem could be the access rights. I checked the list of permissions in the AndroidMainfest.xml file, but I didn't find any entry which I think could match this.
Do you know one?

[jsulm]

@Phips04 said in QCompass in QT Quick mobile App:

Do you know one?

Check https://stackoverflow.com/questions/20497087/manifest-xml-when-using-sensors
and https://developer.android.com/guide/topics/sensors/sensors_position

[Phips04]

I added the <uses-permission/> statements to my AndroidManifest.xml file, but the testing's outcomes stayed the same.

@jsulm said in QCompass in QT Quick mobile App:

https://developer.android.com/guide/topics/sensors/sensors_position

The android NDK seems to offer a SensorManager class. Is it necessary in Qt to use QSensorManager?. I didn't figure out the way of how to use it yet.

[jsulm]

@Phips04 said in QCompass in QT Quick mobile App:

Is it necessary in Qt to use QSensorManager?

Should not, but I'm not expert in this area.

[Phips04]

Deploying this code on Windows doesn't change the situation, just checked this out.