rem: BPoint p(point); p += fOrigin; p.x *= fScale; p.y *= fScale; return p;
add: *x += fOrigin.x; *y += fOrigin.y; *x *= fScale; *y *= fScale;
context: DrawState::Transform(const BPoint& point) const{	BPoint p(point);	p += fOrigin;	p.x *= fScale;	p.y *= fScale;	return p;}