An interface for figure sets with that have their contents defined
geometrically. The geometry of the set is a Shape, and the contents
of the set is somehow determined by that shape. A number of the
methods defined here are optional, so implementors are not obliged
to implement them. For example, some implementations might not
allow the geometry to be changed, so they can throw an exception on
the setGeometry(), freshFigures(), and staleFigures() methods.
Get the geometry. The client must not modify the
void setGeometry(java.awt.Shape geometry)
Set the geometry. All previously-obtained iterators
are invalid and must be discarded. This is an optional
operation. Implementors may choose to throw an exception
if the particular Shape class passed in as the geometry
is not suitable.