OpenLayers绘制实际宽度为米的LineString

var map = new ol.Map({
  target: 'map-container',
  view: new ol.View({
    center: [0, 0],
    zoom: 10
  })
});

var vectorLayer = new ol.layer.Vector({
  source: new ol.source.Vector()
});
map.addLayer(vectorLayer);

var draw = new ol.interaction.Draw({
  source: vectorLayer.getSource(),
  type: 'LineString'
});

draw.on('drawend', function(event) {
  var feature = event.feature;
  var geometry = feature.getGeometry();

  // 获取绘制的坐标点数组
  var coordinates = geometry.getCoordinates();

  // 计算线段的实际长度（假设地图投影为Web Mercator）
  var length = ol.Sphere.getLength(geometry, {
    projection: 'EPSG:3857'
  });

  // 将长度转换为米
  var lengthInMeters = length * 111319.9;

  // 在控制台输出线段的实际长度
  console.log('线段的实际长度为：' + lengthInMeters + '米');
});

map.addInteraction(draw);