operator unary- method

Radius operator unary- ()

Unary negation operator.

Returns a Radius with the distances negated.

Radiuses with negative values aren't geometrically meaningful, but could occur as part of expressions. For example, negating a radius of one pixel and then adding the result to another radius is equivalent to subtracting a radius of one pixel from the other.

Implementation 

Radius operator -() => new Radius.elliptical(-x, -y);