2

我正在折线中工作，我需要获得它的距离。因此，如果有人可以提供帮助，我将不胜感激。

此致。

这是我的代码：

function polyline() {
downloadUrl("xmlPolyline.asp", function(data) {
    var xml = xmlParse(data);
    var markersPath = xml.documentElement.getElementsByTagName("marker");   
    var path = [];


    for (var i = 0; i < markersPath.length; i++) {
    var lat = parseFloat(markersPath[i].getAttribute("lat"));
    var lng = parseFloat(markersPath[i].getAttribute("lng"));
    pointPath = new google.maps.LatLng(lat,lng);


    path.push(pointPath);

}//finish loop

 polyline = new google.maps.Polyline({
  path: path,
  strokeColor: "#FF0000",
  strokeOpacity: 1.0,
  strokeWeight: 2
});


//new polyline

polyline.setMap(map);

}); //end download url

}
4

2 回答 2

12

这很容易 - 使用几何库中的内置函数......

const polyLengthInMeters = google.maps.geometry.spherical.computeLength(yourPolyline.getPath().getArray());

要使用几何库，请在加载地图 api 时声明它

<script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?key={YOUR_KEY}&amp;sensor=false&amp;libraries=geometry"></script>

有关更多信息，请参阅：

Google API 折线参考

谷歌 API mcvArray 参考

Google API 球面几何参考

于 2012-12-27T05:34:27.673 回答
5

“几何”库有一个 computeDistanceBetween 方法。

这将以米为单位返回结果：

var polylineLength = 0;
for (var i = 0; i < markersPath.length; i++) {
  var lat = parseFloat(markersPath[i].getAttribute("lat"));
  var lng = parseFloat(markersPath[i].getAttribute("lng"));
  var pointPath = new google.maps.LatLng(lat,lng);
  path.push(pointPath);
  if (i > 0) polylineLength += google.maps.geometry.spherical.computeDistanceBetween(path[i], path[i-1]);

}
alert("the length of the polyline is "+polylineLength+" meters");

更新：几何库中现在还有一个computeLength ：

computeLength(path[, radius])
参数：
path: Array|MVCArray
radius: number 可选
返回值： number
返回给定路径的长度。

const polyline = new google.maps.Polyline({
    path: polylineCoordinates,
    strokeColor: "#FF0000",
    strokeOpacity: 1.0,
    strokeWeight: 2,
    map: map
  });
var polylineLength = google.maps.geometry.spherical.computeLength(polyline.getPath());

概念证明小提琴

代码片段：

// This example creates a 2-pixel-wide red polyline showing the path of
// a drive from New York, NY to Newark, NJ
function initMap() {
  const map = new google.maps.Map(document.getElementById("map"),{
  center: {lat:40.71248,lng: -74.006200},
  zoom: 10
  });
  const polyline = new google.maps.Polyline({
    path: polylineCoordinates,
    strokeColor: "#FF0000",
    strokeOpacity: 1.0,
    strokeWeight: 2,
    map: map
  });
  var bounds = new google.maps.LatLngBounds();
  for (var i = 0; i < polyline.getPath().getLength(); i++) {
    console.log(polyline.getPath().getAt(i).toUrlValue(6));
    bounds.extend(polyline.getPath().getAt(i));
  }
  map.fitBounds(bounds);
  var polylineLength = google.maps.geometry.spherical.computeLength(polyline.getPath());
  document.getElementById('info').innerHTML = polylineLength.toFixed(2)+" meters, "+(polylineLength/1000).toFixed(2)+" km, "+(polylineLength/1609).toFixed(2)+" miles";
  console.log(polylineLength.toFixed(2)+" meters, "+(polylineLength/1000).toFixed(2)+" km, "+(polylineLength/1609).toFixed(2)+" miles");
}
// per Google Directions service 13.9 mi. About 31 mins
// 13.9 mi = 22.36988 km
const polylineCoordinates = [
{lat:40.712480,lng:-74.006200},
{lat:40.712450,lng:-74.006150},
{lat:40.712310,lng:-74.005810},
{lat:40.712300,lng:-74.005810},
{lat:40.712300,lng:-74.005800},
{lat:40.712290,lng:-74.005790},
{lat:40.712280,lng:-74.005780},
{lat:40.712260,lng:-74.005770},
{lat:40.712250,lng:-74.005770},
{lat:40.712130,lng:-74.005700},
{lat:40.712130,lng:-74.005700},
{lat:40.712090,lng:-74.005830},
{lat:40.712050,lng:-74.005970},
{lat:40.712020,lng:-74.006090},
{lat:40.711980,lng:-74.006230},
{lat:40.711930,lng:-74.006390},
{lat:40.711930,lng:-74.006440},
{lat:40.711830,lng:-74.006810},
{lat:40.711800,lng:-74.006950},
{lat:40.711770,lng:-74.007050},
{lat:40.711690,lng:-74.007420},
{lat:40.711670,lng:-74.007480},
{lat:40.711660,lng:-74.007510},
{lat:40.711660,lng:-74.007550},
{lat:40.711660,lng:-74.007570},
{lat:40.711660,lng:-74.007600},
{lat:40.711660,lng:-74.007650},
{lat:40.711670,lng:-74.007690},
{lat:40.711680,lng:-74.007710},
{lat:40.711690,lng:-74.007740},
{lat:40.711710,lng:-74.007780},
{lat:40.711710,lng:-74.007780},
{lat:40.711750,lng:-74.007840},
{lat:40.711800,lng:-74.007920},
{lat:40.711850,lng:-74.007990},
{lat:40.711870,lng:-74.008010},
{lat:40.711910,lng:-74.008050},
{lat:40.711950,lng:-74.008070},
{lat:40.711970,lng:-74.008090},
{lat:40.712000,lng:-74.008120},
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/* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
#map {
  height: 90%;
}

/* Optional: Makes the sample page fill the window. */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}
<!DOCTYPE html>
<html>
  <head>
    <title>Simple Polylines</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <script
      src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&callback=initMap&libraries=geometry&v=weekly"
      defer
    ></script>
    <!-- jsFiddle will insert css and js -->
  </head>
  <body>
    <div id="info"></div>
    <div id="map"></div>
  </body>
</html>

于 2012-12-26T12:15:50.600 回答