turf-center

Calculates the absolute center point of all features.

<!doctype html>
<html lang="en">
  <head>
    <link rel="stylesheet" href="https://rawcdn.githack.com/openlayers/openlayers.github.io/master/en/v5.3.0/css/ol.css" type="text/css">
    <link rel="stylesheet" href="assets/css/styles.css" type="text/css">
    <script src="//cdn.jsdelivr.net/npm/@turf/turf@5/turf.min.js"></script>
    <script src="https://rawcdn.githack.com/openlayers/openlayers.github.io/master/en/v5.3.0/build/ol.js"></script>
    <script src="assets/js/es6-promise.min.js"></script>
    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL,fetch"></script>
    <script src="assets/js/helpers.js"></script>
    <title>Turf and OpenLayers 3 - Center</title>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script type="text/javascript">

      // Declare a source for points and drawing
      var vectorSourceCenter = new ol.source.Vector();
      var vectorSourcePoints = new ol.source.Vector();

      var pointsStyle = [new ol.style.Style({
        image: new ol.style.Circle({
          stroke: new ol.style.Stroke({
            color: 'white'
          }),
          fill: new ol.style.Fill({
            color: '#1f6b75'
          }),
          radius: 4
        })
      })];

      var centerStyle = [new ol.style.Style({
        image: new ol.style.Circle({
          stroke: new ol.style.Stroke({
            color: 'white'
          }),
          fill: new ol.style.Fill({
            color: 'black'
          }),
          radius: 5
        })
      })];

      var vectorLayerCenter = new ol.layer.Vector({
        source: vectorSourceCenter,
        style: centerStyle
      });

      var vectorLayerPoints = new ol.layer.Vector({
        source: vectorSourcePoints,
        style: pointsStyle
      });

      // Instanciate a map and add layers
      var map = new ol.Map({
        target: 'map',
        layers: [
          new ol.layer.Tile({
            source: new ol.source.OSM()
          }),
          vectorLayerPoints,
          vectorLayerCenter
        ],
        view: new ol.View({
          center: ol.proj.transform(
            [-1.5603, 47.2383],
            'EPSG:4326',
            'EPSG:3857'
          ),
          zoom: 11
        })
      });

      fetch('assets/data/key_shop_with_name_nantes_area.geojson').then(function(response) {
        return response.json().then(function(points_fc) {
          console.log(points_fc);

          var centerPoint = turf.center(points_fc);
          console.log(centerPoint);
          vectorSourceCenter.addFeatures(geojsonToFeatures(centerPoint, {
            featureProjection: 'EPSG:3857'
          }));

          vectorSourcePoints.addFeatures(geojsonToFeatures(points_fc, {
            featureProjection: 'EPSG:3857'
          }));

        });
      });
    </script>
  </body>
</html>

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