如何使用leaflet.draw从多边形中获取区域字符串 [英] How to get the area string from a polygon using leaflet.draw

问题描述

我正在尝试获取多边形的面积测量值，因此我可以将它们列在地图一侧的表格中，旁边是多边形的名称。这是我试过没有成功的：

I am trying to get the area measurements of polygons so I can list them in a table to the side of the map, next to the name of the polygon. This is what I have tried with no success:

$("#polygon").on("click", function (){
    createPolygon = new L.Draw.Polygon(map, drawControl.options.polygon);
    createPolygon.enable();
}

var polygon = new L.featureGroup();

map.on('draw:created', function (e) {
    var type = e.layerType,
        layer = e.layer;
    if (type === 'polygon') {
      polygons.addLayer(layer);
    }
    var seeArea = createPolygon._getMeasurementString();
   console.log(seeArea);  //Returns null
}

对此有任何帮助赞赏！

推荐答案

您可以访问Leaflet提供的几何实用程序库。

You can access the geometry utility library provided with Leaflet.

var area = L.GeometryUtil.geodesicArea(layer.getLatLngs());

在你的例子中，你试图访问一个控件本身，这就是变量creat ePolygon被分配给。相反，你想要获取绘制的图层区域。

In your example, you are trying to access a control itself, which is what the variable createPolygon is assigned to. Instead, you want to take the area of the layer that got drawn.

map.on('draw:created', function (e) {
  var type = e.layerType,
      layer = e.layer;
  if (type === 'polygon') {
    polygons.addLayer(layer);
    var seeArea = L.GeometryUtil.geodesicArea(layer.getLatLngs());
    console.log(seeArea);
  }
}

一旦你确认你正在获得该区域，你可以将它分配给填充地图旁边表格的变量。

Once you verify you are getting the area, you can just assign it to the variables that populate the table next to the map.

注意：默认区域为squareMeters

Note: area will be in squareMeters by default

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