How to set QPainter Background color?

[ChrisW67]

QPainter::setBackground() looks the obvious candidate, but I don't think this method does what you expect. By default background pixels are not painted, leaving whatever was already in the background untouched, i.e. Qt::TransparentMode is the default backgroundMode(). Changing the background mode will only affect the background pixels in areas that are painted in certain ways, and not the canvas in general.

If you want the general base colour of whatever you are painting on (your "It") to be something other than the default then you should fill it with a colour using QPainter::fillRect() (or make sure Qt does it by default).