Repaint the graphical. Area specified the area (in the coordinate system
of the current device) that needs to be repainted. Area is guaranteed to
overlap with graphical<-area,
the bounding box of the pixels affected by this graphical.
This method is called by the graphical infra-structure of XPCE and
should never be called directly. See also graphical->draw
and
graphical->compute.
This method may be redefined to create custom graphical
objects. It is not obligatory for the redefinition to call the method of
the super-class. The definition should not apply paint outside the graphical<-area
of the graphical. If there is no simple way to avoid this, use graphical->clip
and graphical->unclip
to ensure this.
The definition can use graphical->draw
to paint other graphical
objects or one or more of the primitive drawing operations listed below:
The pen, colours, etc. may be manipulated using the following
methods:
The User Guide (Programming in PCE/Prolog) provides further
documentation on redefining graphicals.
Another common approach to create custom graphics is by subclassing
class device to define
compound graphicals.
