Icon Canvas

<!--
  示例：Canvas 图标符号
  要点：离屏 Canvas 画水滴并 toDataURL，交给 ol.style.Icon，anchor 设为 [0.5, 1]
  依赖：OpenLayers 10.3.1 · jsDelivr CDN
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta name="robots" content="noindex,follow">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Canvas 图标符号</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@10.3.1/ol.css">
<style>
  html,body{height:100%;margin:0}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       display:flex;gap:10px;align-items:center;font-size:12px;color:#58606e}
  .bar label{display:flex;gap:5px;align-items:center;cursor:pointer}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <label><input type="checkbox" id="scaleUp"> 放大图标</label>
  <span>水滴符号由 Canvas 现场绘制</span>
</div>
<div id="map"></div>
<script src="https://cdn.jsdelivr.net/npm/ol@10.3.1/dist/ol.js"></script>
<script>
(function () {
  'use strict';

  if (typeof ol === 'undefined') {
    document.getElementById('map').innerHTML =
      '<div style="padding:20px;color:#b42318">OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  /* 离屏 Canvas 绘制水滴形状 */
  function makePinDataUrl() {
    var c = document.createElement('canvas');
    c.width = 32;
    c.height = 44;
    var ctx = c.getContext('2d');

    ctx.beginPath();
    ctx.moveTo(16, 42);
    ctx.quadraticCurveTo(1, 20, 16, 2);
    ctx.quadraticCurveTo(31, 20, 16, 42);
    ctx.closePath();
    ctx.fillStyle = '#1f5fd0';
    ctx.fill();
    ctx.lineWidth = 2;
    ctx.strokeStyle = '#ffffff';
    ctx.stroke();

    ctx.beginPath();
    ctx.arc(16, 16, 5.5, 0, Math.PI * 2);
    ctx.fillStyle = '#ffffff';
    ctx.fill();

    return c.toDataURL();
  }

  var pinUrl = makePinDataUrl();
  var scale = 1;

  var raw = [
    [116.3800, 39.9005, '西单'],
    [116.3912, 39.9074, '天安门'],
    [116.4106, 39.9147, '王府井'],
    [116.4200, 39.9220, '东四'],
    [116.3966, 39.9182, '景山']
  ];

  var features = raw.map(function (p) {
    return new ol.Feature({
      geometry: new ol.geom.Point(ol.proj.fromLonLat([p[0], p[1]])),
      name: p[2]
    });
  });

  var layer = new ol.layer.Vector({
    source: new ol.source.Vector({ features: features })
  });

  function buildStyle(feature) {
    return new ol.style.Style({
      image: new ol.style.Icon({
        src: pinUrl,
        anchor: [0.5, 1],
        scale: scale
      }),
      text: new ol.style.Text({
        text: feature.get('name'),
        font: '500 11px sans-serif',
        offsetY: 14,
        fill: new ol.style.Fill({ color: '#16181d' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 3 })
      })
    });
  }

  layer.setStyle(buildStyle);

  new ol.Map({
    target: 'map',
    layers: [new ol.layer.Tile({ source: new ol.source.XYZ({url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}', attributions: 'Tiles © Esri'}) }), layer],
    view: new ol.View({
      center: ol.proj.fromLonLat([116.398, 39.911]),
      zoom: 14
    }),
    controls: ol.control.defaults.defaults({ attribution: false })
  });

  document.getElementById('scaleUp').addEventListener('change', function () {
    scale = this.checked ? 1.4 : 1;
    layer.setStyle(buildStyle);
  });
})();
</script>
</body>
</html>