The graphics context provides the color, line styles, etc... See the gtk and postscript backends for examples of mapping the graphics context attributes (cap styles, join styles, line widths, colors) to a particular backend. In GTK this is done by wrapping a gtk.gdk.GC object and forwarding the appropriate calls to it using a dictionary mapping styles to gdk constants. In Postscript, all the work is done by the renderer, mapping line styles to postscript calls. The base GraphicsContext stores colors as a RGB tuple on the unit interval, eg, (0.5, 0.0, 1.0). You will probably need to map this to colors appropriate for your backend. Eg, see the ColorManager class for the GTK backend. If it's more appropriate to do the mapping at the renderer level (as in the postscript backend), you don't need to override any of the GC methods. If it's more approritate to wrap an instance (as in the GTK backend) and do the mapping here, you'll need to override several of the setter methods.