QPainter and QPen

void painter::paintEvent(QPaintEvent *e)
{
    QPainter pt(this);
    QPen pen1(Qt::black);
    pen1.setWidth(2);

    QPen pen2(Qt::red);
    pen2.setWidth(5);

    QPoint p1;
    p1.setX(10);
    p1.setY(10);

    QPoint p2;
    p2.setX(200);
    p2.setY(500);

    pt.setPen(pen1);
    pt.drawLine(p1,p2);

    pt.setPen(pen2);
    pt.drawPoint(p1);
    pt.drawPoint(p2);

}