PPI (Plan-position Indicator) creation

I'm attempting to create a PPI to display objects that will be updating their position about every 4 seconds. I'm currently using a QGraphicsView object as a drawing canvas. Can get one object to display, but no more. I may be missing some fundamental concepts associated with refresh/redraw requirements. Would appreciate guidance. Thanks.

Conceptual problem solved. I set up a Frame, used QTimer with redraw, paintEvent, QList<QRectF>. Then painter.eraseRect(), and painter.drawRect().
Probably QFrame is not the appropriate canvas. I'll move the lessons learned to QGraphicsView.