如何显示所有工具提示文本的线条系列圆项目符号相交Amcharts 4？

chart.cursor = new am4charts.XYCursor();
chart.cursor.behavior = "none";

var series = chart.series.push(new am4charts.LineSeries());
series.dataFields.valueY = "value";
series.dataFields.categoryX = "category";
series.tooltipText = "{valueY}";
series.tooltip.pointerOrientation = "vertical";
series.tooltip.background.cornerRadius = 20;
series.tooltip.background.fillOpacity = 0.5;
series.tooltip.label.padding(12, 12, 12, 12);

series.adapter.add("tooltipY", function(tooltipY, target) {
  if (target.tooltipX < chart.pixelWidth / 2) {
    return tooltipY;
  }
  else {
    return tooltipY - target.tooltipY - target.tooltip.pixelHeight;
  }
});