... Only cannon.cpp differs from the previous chapter. lcdrange.h contains the LCDRange class definition . ... Makefile contains some rules for generating the meta object information necessary for signal/slot creation. void CannonField::paintEvent( QPaintEvent * ) { QPainter p; QBrush brush( blue ); QPen pen( NoPen ); . In order to paint our widget, we use a QPainter. ... The translate() function translates the coordinate system of the QPainter, i.e. moves it by an offset. ...