Google Maps JS API v3 - 如何檢查和顯示多邊形點之間的距離

Question

我正在使用谷歌地圖API來允許用戶在地圖上繪制自定義多邊形。 我需要檢查並顯示每個邊框的長度。

我已經使用Geometry Library和Map Label Library來獲取並顯示多邊形的計算區域（也改變'insert_at'和'set_at'事件），但不幸的是我不知道如何獲得邊框長度。 任何幫助將不勝感激。

二手代碼示例：

var labels = [];
var allOverlays = [];

function setSelection(shape) {
  selectedShape = shape;
  shape.setEditable(true);
}

function initMap() {

 var options = {
    zoom: 14,
    center: {lat: 52.250618, lng: 20.9774}
}

var map = new google.maps.Map(document.getElementById('map'), options);

var drawingManager = new google.maps.drawing.DrawingManager({
 markerOption: {
 draggable: false
 },
 polygonOptions: {
 draggable: false,
 fillColor: '#5C6BC0',
 fillOpacity: 0.45,
 strokeWeight: 0,
 editable: true,
 zIndex: 1
 },
 drawingControl: true,
 drawingControlOptions: {
 position: google.maps.ControlPosition.TOP_CENTER,
 drawingModes: ['circle', 'polygon']
 },
 circleOptions: {
 fillColor: '#5C6BC0',
 fillOpacity: 0.45,
 strokeWeight: 0,
 editable: true,
 zIndex: 1
 },
 map: map
});

function attachPolygonInfoWindow(polygon) {
   var path = polygon.getPath();
   var points = path.getArray();
   var area = (google.maps.geometry.spherical.computeArea(path.getArray())).toFixed(0);
   var bounds = new google.maps.LatLngBounds();
   var i;

   for (i = 0; i < points.length; i++) {
      bounds.extend(points[i]);
   }

   var boundsCenter = bounds.getCenter();
   var mapLabel = new MapLabel({
      map: map,
      fontSize: 20,
      align: 'left'
   });

   if (!labels.length) {
      labels.push(mapLabel)
   }

   showPolygonInfoWindow(labels, boundsCenter, area);
}

function showPolygonInfoWindow(arr, position, text) {
   arr.forEach((el) => {
     el.set('position', position);
     el.set('text', text + 'm2')
   })
}

function removePolygonInfoWindow() {

   for (var i = 0; i < labels.length; i++) {
     labels[i].setMap(null);
   }

   labels = [];
}

google.maps.event.addListener(drawingManager, 'overlaycomplete', function(e) {
   allOverlays.push(e);

   if (e.type != google.maps.drawing.OverlayType.MARKER) {

   drawingManager.setDrawingMode(null);

   var newShape = e.overlay;
   newShape.type = e.type;

   google.maps.event.addListener(newShape, 'click', function() {
       setSelection(newShape);
   });


   if (newShape.type == "polygon") {
     var path = newShape.getPath();

     google.maps.event.addListener(path, 'insert_at', function() {
        attachPolygonInfoWindow(newShape);
     });

     google.maps.event.addListener(path, 'set_at', function() {
        attachPolygonInfoWindow(newShape);
     });

     attachPolygonInfoWindow(newShape);
   }

   setSelection(newShape);
  }
});
}

initMap();

<script src="https://maps.google.com/maps/api/js?sensor=false&libraries=drawing,geometry">
</script>
<script type="text/javascript" src="https://cdn.rawgit.com/googlemaps/js-map-label/gh-pages/src/maplabel.js"></script>

工作示例Codepen

我想在每個邊框的邊上顯示每個邊框的長度。

Answer 1

我的建議是當你創建中心標簽時，也要處理通過多邊形的路徑，計算它們的長度和中心; 然后為每個創建MapLabel對象並將其放置在側面的中心。 就像是：

for (var i=0; i<polygon.getPath().getLength(); i++) {
  // for each side in path, compute center and length
  var start = polygon.getPath().getAt(i);
  var end = polygon.getPath().getAt(i<polygon.getPath().getLength()-1 ? i+1 : 0);
  var sideLength = google.maps.geometry.spherical.computeDistanceBetween(start,end);
  var sideCenter = google.maps.geometry.spherical.interpolate(start, end, 0.5);
  var sideLabel = new MapLabel({
    map: map,
    fontSize: 20,
    align: "center"
  });
  sideLabel.set("position", sideCenter);
  sideLabel.set("text", sideLength.toFixed(2)+"m");
  polygon.labels.push(sideLabel);
}

概念證明小提琴

代碼段：

 var labels = []; var allOverlays = []; function setSelection(shape) { selectedShape = shape; shape.setEditable(true); } function initMap() { var options = { zoom: 14, center: { lat: 52.250618, lng: 20.9774 } }; var map = new google.maps.Map(document.getElementById("map"), options); var drawingManager = new google.maps.drawing.DrawingManager({ polygonOptions: { draggable: false, fillColor: "#5C6BC0", fillOpacity: 0.45, strokeWeight: 0, editable: true, zIndex: 1 }, drawingControl: true, drawingControlOptions: { position: google.maps.ControlPosition.TOP_CENTER, drawingModes: ["polygon"] }, map: map, drawingMode: 'polygon' }); function attachPolygonInfoWindow(polygon) { if (!polygon.labels) polygon.labels = []; for (var i = 0; i < polygon.labels.length; i++) { polygon.labels[i].setMap(null); } polygon.labels = []; var path = polygon.getPath(); var points = path.getArray(); var area = google.maps.geometry.spherical .computeArea(path.getArray()) .toFixed(0); var bounds = new google.maps.LatLngBounds(); var i; for (i = 0; i < points.length; i++) { bounds.extend(points[i]); } var boundsCenter = bounds.getCenter(); var centerLabel = new MapLabel({ map: map, fontSize: 20, align: "left" }); polygon.labels.push(centerLabel); centerLabel.set("position", bounds.getCenter()); centerLabel.set("text", area + "m2"); if (path.getLength() < 2) return; for (var i = 0; i < polygon.getPath().getLength(); i++) { // for each side in path, compute center and length var start = polygon.getPath().getAt(i); var end = polygon.getPath().getAt(i < polygon.getPath().getLength() - 1 ? i + 1 : 0); var sideLength = google.maps.geometry.spherical.computeDistanceBetween(start, end); var sideCenter = google.maps.geometry.spherical.interpolate(start, end, 0.5); var sideLabel = new MapLabel({ map: map, fontSize: 20, align: "center" }); sideLabel.set("position", sideCenter); sideLabel.set("text", sideLength.toFixed(2) + "m"); polygon.labels.push(sideLabel); } } function removePolygonInfoWindow() { for (var i = 0; i < labels.length; i++) { labels[i].setMap(null); } labels = []; } google.maps.event.addListener(drawingManager, "overlaycomplete", function(e) { allOverlays.push(e); if (e.type != google.maps.drawing.OverlayType.MARKER) { drawingManager.setDrawingMode(null); var newShape = e.overlay; newShape.type = e.type; google.maps.event.addListener(newShape, "click", function() { setSelection(newShape); }); if (newShape.type == "polygon") { var path = newShape.getPath(); google.maps.event.addListener(path, "insert_at", function() { attachPolygonInfoWindow(newShape); }); google.maps.event.addListener(path, "set_at", function() { attachPolygonInfoWindow(newShape); }); attachPolygonInfoWindow(newShape); } setSelection(newShape); } }); } initMap(); 

 html, body, #map { height: 100%; margin: 0; padding: 0; } 

 <div id="map"></div> <!-- Replace the value of the key parameter with your own API key. --> <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&libraries=drawing"></script> <script src="https://cdn.jsdelivr.net/npm/js-map-label@1.0.1/src/maplabel.js"></script>