double value = plot.getValue(this.datasetIndex);
            DialScale scale = plot.getScaleForDataset(this.datasetIndex);
            double angle = scale.valueToAngle(value);
        
            Arc2D arc1 = new Arc2D.Double(lengthRect, angle, 0, Arc2D.OPEN);
            Point2D pt1 = arc1.getEndPoint();