int itemCount = dataset.getItemCount(series);
            for (int item = 0; item < itemCount; item++) {
                lvalue = dataset.getStartXValue(series, item);
                uvalue = dataset.getEndXValue(series, item);
                double offset = (uvalue - lvalue) / 2.0;
                lvalue = lvalue - offset;
                uvalue = uvalue - offset;
                minimum = Math.min(minimum, lvalue);
                maximum = Math.max(maximum, uvalue);