三十三、openlayers官网示例Drawing Features Style——在地图上绘制图形，并修改绘制过程中的颜色

这篇讲的是使用Draw绘制图形时根据绘制形状设置不同颜色。

根据下拉框中的值在styles对象中取对应的颜色对象，new Draw的时候将其设置为style参数。

 const styles = {
      Point: {
        "circle-radius": 5,
        "circle-fill-color": "red",
      },
      LineString: {
        "circle-radius": 5,
        "circle-fill-color": "red",
        "stroke-color": "yellow",
        "stroke-width": 2,
      },
      Polygon: {
        "circle-radius": 5,
        "circle-fill-color": "red",
        "stroke-color": "yellow",
        "stroke-width": 2,
        "fill-color": "blue",
      },
      Circle: {
        "circle-radius": 5,
        "circle-fill-color": "red",
        "stroke-color": "blue",
        "stroke-width": 2,
        "fill-color": "yellow",
      },
    };

    const typeSelect = document.getElementById("type");

    let draw; 
    function addInteraction() {
      const val