AmCharts：我如何检查图表是否被隐藏？

Question

我只在我的图表中获得了一个气球，我想检查是否隐藏了它所属的图形，但是是否隐藏了任何图形。如何检查此属性？

function adjustBalloonText(graphDataItem, graph){
    var data = graphDataItem.dataContext;
    var date = ""; //some kind of getDateInScrollbar here
    console.log(graphDataItem);
    var distance = data.distance; // some kind of getGraphsValue here
    var duration = ""; // some kind of getGraphsValue here as well
    return distance;
}

请帮帮我。