QPicture overflows the bounding rect calculations

void QPicturePaintEngine::writeCmdLength(int pos, const QRectF &r, bool corr)
{
        ....
        // update the calculated bounding rectangle:
        if (br.width() > 0.0 || br.height() > 0.0) {
            int minx = qFloor(br.left());
            int miny = qFloor(br.top());
            int maxx = qCeil(br.right());
            int maxy = qCeil(br.bottom());

            if (d->pic_d->brect.width() > 0 || d->pic_d->brect.height() > 0) {
                minx = qMin(minx, d->pic_d->brect.left());
                miny = qMin(miny, d->pic_d->brect.top());
                maxx = qMax(maxx, d->pic_d->brect.x() + d->pic_d->brect.width());
                maxy = qMax(maxy, d->pic_d->brect.y() + d->pic_d->brect.height());
                d->pic_d->brect = QRect(minx, miny, maxx - minx, maxy - miny);
            } else {
                d->pic_d->brect = QRect(minx, miny, maxx - minx, maxy - miny);
            }
        }
    }
}
 

bool QPicturePaintEngine::end()
{
    ...
    if (d->pic_d->formatMajor >= 4) { // bounding rectangle
        QRect r = static_cast<QPicture *>(d->pdev)->boundingRect();
        d->s << (qint32) r.left() << (qint32) r.top() << (qint32) r.width()
             << (qint32) r.height();
    }