画圆；

// 画圆
drawCircle(coordinate) {
    let iconFeature = new ol.Feature({
        geometry: new ol.geom.Point(coordinate),
    });
    let vectorLayer_Polygon = new ol.layer.Vector({
        source: new ol.source.Vector({
            features: [iconFeature]
        }),
        style: new ol.style.Style({
            stroke: new ol.style.Stroke({
                color: '#4473ff',
                width: 5
            }),
            image: new ol.style.Circle({    //形状
                radius: 5,
                fill: new ol.style.Fill({
                    color: '#4473ff'
                })
            }),
        })
    });
    this.map.addLayer(vectorLayer_Polygon);
},