question: public double lengthToJava2D ( double length , Rectangle2D area , RectangleEdge edge ) { double zero = valueToJava2D ( 0.0 , area , edge ) ; double l = valueToJava2D ( length , area , edge ) ; return Math . abs ( l - zero ) ; }
target:  Converts a length in data coordinates into the corresponding length in Java2D coordinates.