Sorry, I misunderstood. I assume that you write an app and want to know API, right? To get coordinate of any pixel, you call method Code: queryCoordinateForPixel(const QPointF p, const QVariant &tag = QVariant()) This method will return immediately and the reply you will get somewhat later (has to go through to other thread and so on) via signal Code: replyCoordinateForPixel(const QPointF pixel, QGeoCoordinate geocoordinate, qreal degLatPerPixel, qreal degLonPerPixel, const QVariant &tag) The signal will carry correct geocoordinate as well as its derivative per pixel (if you wish to apply some sensitivity analysis to the result). See query example at https://github.com/rinigus/mapbox-gl...es-and-signals So, in your case, find pixel coordinates of the pin and ask for its geolocation using queryCoordinateForPixel
queryCoordinateForPixel(const QPointF p, const QVariant &tag = QVariant())
replyCoordinateForPixel(const QPointF pixel, QGeoCoordinate geocoordinate, qreal degLatPerPixel, qreal degLonPerPixel, const QVariant &tag)