QVariant cameraInterpolator(const QGeoCameraData &start,
                            const QGeoCameraData &end,
                            qreal progress)
{
    QGeoCameraData result = start;
    QGeoCoordinate from = start.center();
    QGeoCoordinate to = end.center();

    if (from == to) {
        if (progress < 0.5) {
            result.setCenter(from);
        } else {
            result.setCenter(to);
        }
    }
    else {
        QGeoCoordinate coordinateResult = QGeoProjection::coordinateInterpolation(from, to, progress);
        result.setCenter(coordinateResult);
    }

    double sf = 1.0 - progress;
    double ef = progress;

    result.setBearing(sf * start.bearing() + ef * end.bearing());
    result.setTilt(sf * start.tilt() + ef * end.tilt());
    result.setRoll(sf * start.roll() + ef * end.roll());
    result.setZoomLevel(sf * start.zoomLevel() + ef * end.zoomLevel());

    return QVariant::fromValue(result);
}
void QGeoMapController::setTilt(qreal tilt)
{
    QGeoCameraData cd = map_->cameraData();

    if (tilt == cd.tilt())
        return;

    cd.setTilt(tilt);
    map_->setCameraData(cd);
}