MapImageLayer - 在子图层上设置渲染器

MapImageLayer 的子图层属性允许你动态设置地图服务中的图层渲染器。为此，您必须引用服务图层的图层 ID，并将渲染器分配给子图层的渲染器属性。

const layer = new MapImageLayer({
  url: "https://sampleserver6.geosceneonline.cn/arcgis/rest/services/USA/MapServer",
  sublayers: [
    {
      id: 2,
      renderer: {
        type: "simple", // autocasts as new SimpleRenderer()
        symbol: {
          type: "simple-marker", // autocasts as new SimpleMarkerSymbol()
          size: 3,
          color: "white"
        }
      }
    }
  ]
});