geospatial/leaflet_gradient.html at master · edjdavid/geospatial · GitHub

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<!DOCTYPE html>
<html>
<head>
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/leaflet/1.6.0/leaflet.css">
  <style>
    html, body {
      margin: 0;
      padding: 0;
      width: 100vw;
      height: 100vh;
    }

    #map {
      width: 100vw;
      height: 100vh;
    }
  </style>
</head>
<body>
  <div id="map"></div>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/leaflet/1.6.0/leaflet.js"></script>
  <script>
    const map = L.map("map").setView([14.0100298, 120.9965796], 16);
    const osmTl = L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
      attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
    }).addTo(map);

    // create a SVG radial gradient
    // create a temporary marker to get the default marker layer
    let circleMarker = L.circle([14.0100298, 120.9965796], {
      radius: 1
    }).addTo(map);

    // get a reference to the SVG element
    const svg = circleMarker.getElement().farthestViewportElement
    const defs = svg.querySelector('defs') || svg.insertBefore( document.createElementNS(svg.namespaceURI,'defs'), svg.firstChild);
    circleMarker.remove()
    function createGradient(svgElem, id, stops) {
      const radGrad = document.createElementNS(svg.namespaceURI, "radialGradient");
      radGrad.setAttribute("id", id);
      for (let s of stops) {
        const stop = document.createElementNS(svg.namespaceURI, "stop");
        for (let k in s) {
          stop.setAttribute(k, s[k]);
        }
        radGrad.appendChild(stop);
      }
      defs.appendChild(radGrad);
    }
    createGradient(svg, "radgrad", [
      {offset: "0%", "stop-color": "#f00"},
      {offset: "80%", "stop-color": "orange"},
      {offset: "100%", "stop-color": "#ff0"},
    ]);
    // end radial gradient creation

    L.circle([14.0100298, 120.9965796], {
      fillColor: "url(#radgrad)", // id of the radial gradient
      fillOpacity: 0.7,
      stroke: false,
      radius: 1000
    }).addTo(map);
  </script>
</body>
</html>