const QRegularExpression regx(QStringLiteral(R"**((?:(X)([-+]?\d*\.?\d+)\s*(Y)([-+]?\d*\.?\d+))|(?:(X)([-+]?\d*\.?\d+))|(?:(Y)([-+]?\d*\.?\d+)))**"));
QTextStream in(&file);
while(!in.atEnd()) {
    QString line = in.readLine();
    const QRegularExpressionMatch reMatch = regx.match(line);
    if(reMatch.hasMatch()){
        if(reMatch.lastCapturedIndex()==4){ // matched both X and Y
            const double lx = reMatch.captured(2).toDouble();
            const double ly = reMatch.captured(4).toDouble();
            qDebug()<<"X : " << lx << " ly" << ly;
            if(lx<minX)
                minX=lx;
            else if (lx>maxX)
                maxX=lx;
            if(ly<minY)
                minY=ly;
            else if (ly>maxY)
                maxY=ly;
        }
        else if(reMatch.captured(1).compare(QLatin1String("X"),Qt::CaseInsensitive)==0){ // matched X
            const double lx = reMatch.captured(2).toDouble();
            qDebug()<<"X : " << lx;
            if(lx<minX)
                minX=lx;
            else if (lx>maxX)
                maxX=lx;
        }
        else {// matched Y
            const double ly = reMatch.captured(2).toDouble();
            qDebug() << " ly" << ly;
            if(ly<minY)
                minY=ly;
            else if (ly>maxY)
                maxY=ly;
        }
    }
}