Use QPainter to draw on a videoStream

I have a videoStream in a FrameLabel and i want to use QPainter to draw a rectangle on it, But when i do something like this:

Code:

---

void CameraView::paintEvent(QPaintEvent * /*event*/)
{
    QPainter painter(this);
    painter.setPen(Qt::blue);
    painter.drawRect(QRect( 500, 0, 150, 150));
}

---

The rectangle is drawn behind the FrameLabel (i.e. behinde the videoStream)

I would be very grateful if anyone can show me an easy way to go around this.

How is CameraView related to FrameLabel?