At its core, graphics painting requires two things: something that knows how to paint and something that can be painted on. Qt defines the
QPainter class as the former and the
QPaintDevice as the interface for classes for the latter. You'll seldom instantiate each, but you use both of these classes a lot if you're doing graphics programming; typically, you'll have an instance of a subclass of
QPaintDevice, ask it for its associated
QPainter, and then use
QPainter to perform your drawing. This can happen when you're writing a widget; you'll be passed a
QPainter subclass, for example, when you need to paint the widget's contents.
There are several subclasses of
QWidget: This class and its ...