在amcharts v4中为每个气泡生成图例

// 创建图表实例
var chart = am4core.create("chartdiv", am4charts.XYChart);

// 设置图表数据

// 创建气泡系列
var series = chart.series.push(new am4charts.MapImageSeries());

// 创建气泡图
var bubble = series.mapImages.template;
bubble.propertyFields.latitude = "latitude";
bubble.propertyFields.longitude = "longitude";
bubble.propertyFields.radius = "size";

// 创建图例
var legend = new am4charts.Legend();
chart.legend = legend;

// 配置图例
legend.itemContainers.template.clickable = false;
legend.itemContainers.template.focusable = false;
legend.position = "right";

// 设置气泡图例标记
var markerTemplate = legend.markers.template;
markerTemplate.width = 15;
markerTemplate.height = 15;

// 添加气泡图例项
var legendData = chart.series.getIndex(0).dataItems;
for (var i = 0; i < legendData.length; i++) {
  var legendItem = legend.createItem();
  legendItem.label.text = legendData[i].name;
  legendItem.marker.template.copyFrom(markerTemplate);
  legendItem.marker.template.fill = legendData[i].fill;
  legendItem.marker.template.stroke = legendData[i].stroke;
}