I am making a simple brushing/drawing interface with QGraphicsScene.

The strokes are made with addEllipse with various brush sizes and styles, like Qt::Dense{1:7}Pattern.

The problem is when a brush is drawn over already painted pixels with a different pattern. It seems like it is painting the union between the two patterns, making the area completely black (using a black colour of the brush) or some denser pattern.

What I want is to replace the old pattern with the new brush. Any ideas on how I can do this?