public static IStroke CreateInterpolatingStroke(SPoint[] controlPoints, int numberOfIterations = 1)
        {
            var ps = new PolyStroke(controlPoints);

            ps.NumberOfIterations = numberOfIterations;
            return(new InterpolatingStroke(ps));
        }
        public static IStroke CreateRotatingStroke(SPoint[] controlPoints, double angularSpeed, double radius, int NumberOfIterations = 1)
        {
            var ps = new PolyStroke(controlPoints);

            ps.NumberOfIterations = NumberOfIterations;
            return(new RotatingStroke(
                       ps,
                       angularSpeed, radius));
        }