Question

In my QGraphicsView, I display a map. I need to display a horizontal ruler and a vertical ruler on the top edge and left edge respectfully.

The map needs to scrolled but the above rulers should be displayed at their fixed positions, but change their scale values.

I tried to implement this using drawForeground method. Due to the maps large size I only paint the visible area. So I need to update() every time scrolling is done. But this result sometimes flickers.

I feel it would be best to have separate layer like approach.

What is the best way to approach the problem?

Answer 1

I just changed ViewportUpdateMode of the graphics view to FullViewportUpdate to get away from flicker.

You can use SmartViewportUpdate for somewhat good results also.

The downside is, during animations, this takes more process power.