double x0 = dataset.getXValue(series, Math.max(item - 1, 0));
        double y0 = dataset.getYValue(series, Math.max(item - 1, 0));
        if (Double.isNaN(y0)) {
            y0 = 0.0;
        }
        double transX0 = domainAxis.valueToJava2D(x0, dataArea, 
                plot.getDomainAxisEdge());
        double transY0 = rangeAxis.valueToJava2D(y0, dataArea, 
                plot.getRangeAxisEdge());