Curve ???

void Grafik::paintEvent(QPaintEvent *event){    QLineF line;    QPainter painter;    painter.begin(this->viewport());    painter.setRenderHint(QPainter::Antialiasing, true);    painter.setPen(QPen(Qt::black));    painter.drawLine(this->width()/2,0,this->width()/2,221);    painter.drawLine(0,this->height()/2,401,this->height()/2);    int j = 1;    if(noktalar != NULL){        for(double i=1.0;i<=this->viewport()->geometry().width();i+=0.01)        {            painter.setPen(Qt::red);            line = QLineF (i-1.0,points[j-1],i,points[j]);            painter.drawLine(line);            j++;        }    }    painter.end();}