Icon

<!--
  说明：图标符号
  核心逻辑：同一 Canvas 图标配不同 anchor，对比中心锚点与底部锚点的落位差异
  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>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;flex-wrap:wrap}
  .bar button{font:inherit;padding:4px 10px;border:1px solid #c9d0da;border-radius:5px;
              background:#fff;color:#1f2a37;cursor:pointer}
  #info{margin-left:auto}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <button id="swap">切换图标</button>
  <span>左：中心锚点 · 右：底部锚点</span>
  <span id="info">—</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;
  }

  var fromLonLat = ol.proj.fromLonLat;

  function pin(color) {
    var canvas = document.createElement('canvas');
    canvas.width = 30;
    canvas.height = 42;
    var ctx = canvas.getContext('2d');
    ctx.beginPath();
    ctx.moveTo(15, 41);
    ctx.bezierCurveTo(3, 25, 1, 20, 1, 14);
    ctx.arc(15, 14, 14, Math.PI, 0);
    ctx.bezierCurveTo(29, 20, 27, 25, 15, 41);
    ctx.closePath();
    ctx.fillStyle = color;
    ctx.fill();
    ctx.strokeStyle = '#ffffff';
    ctx.lineWidth = 2;
    ctx.stroke();
    ctx.beginPath();
    ctx.arc(15, 14, 5, 0, Math.PI * 2);
    ctx.fillStyle = '#ffffff';
    ctx.fill();
    return canvas.toDataURL();
  }

  function dot(color) {
    var canvas = document.createElement('canvas');
    canvas.width = 30;
    canvas.height = 30;
    var ctx = canvas.getContext('2d');
    ctx.beginPath();
    ctx.arc(15, 15, 13, 0, Math.PI * 2);
    ctx.fillStyle = color;
    ctx.fill();
    ctx.strokeStyle = '#ffffff';
    ctx.lineWidth = 3;
    ctx.stroke();
    return canvas.toDataURL();
  }

  var pinUrl = pin('#1f5fd0');
  var dotUrl = dot('#e06a3b');
  var usePin = true;

  var centerFeature = new ol.Feature({ geometry: new ol.geom.Point(fromLonLat([116.37, 39.90])) });
  var bottomFeature = new ol.Feature({ geometry: new ol.geom.Point(fromLonLat([116.41, 39.90])) });

  function styleFn(feature) {
    var isCenter = feature === centerFeature;
    return new ol.style.Style({
      image: new ol.style.Icon({
        src: usePin ? pinUrl : dotUrl,
        anchor: isCenter ? [0.5, 0.5] : [0.5, 1]
      }),
      text: new ol.style.Text({
        text: isCenter ? 'anchor [0.5, 0.5]' : 'anchor [0.5, 1]',
        font: '600 11px sans-serif',
        offsetY: isCenter ? 26 : 8,
        fill: new ol.style.Fill({ color: '#16181d' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 3 })
      })
    });
  }

  var layer = new ol.layer.Vector({
    source: new ol.source.Vector({ features: [centerFeature, bottomFeature] }),
    style: styleFn
  });

  var map = 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: fromLonLat([116.39, 39.90]), zoom: 13, minZoom: 2, maxZoom: 19 }),
    controls: ol.control.defaults.defaults({ attribution: false, rotate: false })
  });

  document.getElementById('swap').addEventListener('click', function () {
    usePin = !usePin;
    layer.changed();
    document.getElementById('info').textContent = usePin ? '当前：图钉图标' : '当前：圆形图标';
  });

  document.getElementById('info').textContent = '当前：图钉图标';
})();
</script>
</body>
</html>