Custom Circle Render

<!--
  说明：自定义符号渲染的中文示例，数据在页面内生成，可独立运行。
  核心逻辑：map.on(postrender) + getPixelFromCoordinate + 手动绘制路径
  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>自定义符号渲染</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;flex-wrap:wrap;font-size:12px;color:#58606e}
  .bar label{display:flex;gap:5px;align-items:center;cursor:pointer}
  .bar button{font:inherit;padding:3px 9px;border:1px solid #c9ced6;background:#fff;
       border-radius:5px;cursor:pointer;color:#333}
  .bar button:hover{background:#eef2f8}
  .bar input[type=range]{width:110px;vertical-align:middle}
  .bar input[type=text]{font:inherit;padding:2px 6px;border:1px solid #c9ced6;border-radius:4px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3;position:relative}
  .panel{flex:0 0 auto;max-height:34%;overflow:auto;padding:8px 12px;font-size:12px;
       background:#fff;border-top:1px solid #e3e6ea;color:#3d4451}
  .panel pre{margin:0;font-family:Consolas,"Courier New",monospace;font-size:11px;
       white-space:pre-wrap;word-break:break-all;line-height:1.5}
  .ol-attribution{font-size:11px}

</style>
</head>
<body>
<div class="bar">
<label><input type="radio" name="shape" value="star" checked> 星形</label>
<label><input type="radio" name="shape" value="hex"> 六边形</label>
<label><input type="radio" name="shape" value="gear"> 齿轮</label>
<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') {
    var errBox = document.getElementById('map');
    if (errBox) {
      errBox.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;
  var places = [
    [116.4074, 39.9042, '北京', '#1f5fd0'],
    [121.4737, 31.2304, '上海', '#ee602a'],
    [113.2644, 23.1291, '广州', '#26966e'],
    [104.0668, 30.5728, '成都', '#8a5cd6'],
    [108.9398, 34.3416, '西安', '#d4a017'],
    [126.6424, 45.7560, '哈尔滨', '#0f8a9d']
  ];

  var features = places.map(function (p) {
    return new ol.Feature({
      geometry: new ol.geom.Point(fromLonLat([p[0], p[1]])),
      color: p[3]
    });
  });

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

  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'})}), vector],
    view: new ol.View({center: fromLonLat([112, 33]), zoom: 4}),
    controls: ol.control.defaults.defaults({attribution: false, zoom: true, rotate: false})
  });

  var shape = 'star';

  function drawSymbol(ctx, x, y, radius, kind, color) {
    ctx.save();
    ctx.translate(x, y);
    ctx.beginPath();

    var i, angle, r;
    if (kind === 'hex') {
      for (i = 0; i < 6; i++) {
        angle = Math.PI / 6 + i * Math.PI / 3;
        r = radius * 0.95;
        if (i === 0) { ctx.moveTo(Math.cos(angle) * r, Math.sin(angle) * r); }
        else { ctx.lineTo(Math.cos(angle) * r, Math.sin(angle) * r); }
      }
    } else if (kind === 'gear') {
      for (i = 0; i < 16; i++) {
        angle = i * Math.PI / 8;
        r = i % 2 === 0 ? radius : radius * 0.72;
        if (i === 0) { ctx.moveTo(Math.cos(angle) * r, Math.sin(angle) * r); }
        else { ctx.lineTo(Math.cos(angle) * r, Math.sin(angle) * r); }
      }
    } else {
      for (i = 0; i < 10; i++) {
        angle = -Math.PI / 2 + i * Math.PI / 5;
        r = i % 2 === 0 ? radius : radius * 0.45;
        if (i === 0) { ctx.moveTo(Math.cos(angle) * r, Math.sin(angle) * r); }
        else { ctx.lineTo(Math.cos(angle) * r, Math.sin(angle) * r); }
      }
    }

    ctx.closePath();
    ctx.fillStyle = color;
    ctx.fill();
    ctx.lineWidth = 2;
    ctx.strokeStyle = '#ffffff';
    ctx.stroke();
    ctx.restore();
  }

  map.on('postrender', function (evt) {
    var ctx = evt.context;
    if (!ctx) { return; }
    features.forEach(function (f) {
      var coord = f.getGeometry().getCoordinates();
      var px = map.getPixelFromCoordinate(coord);
      if (!px) { return; }
      drawSymbol(ctx, px[0], px[1], 9, shape, f.get('color'));
    });
  });

  Array.prototype.forEach.call(document.querySelectorAll('input[name=shape]'), function (r) {
    r.addEventListener('change', function () {
      shape = this.value;
      document.getElementById('info').textContent = '符号：' +
        (shape === 'star' ? '星形（10 个顶点）' : (shape === 'hex' ? '六边形' : '齿轮（16 个顶点）'));
      map.render();
    });
  });
})();
</script>
</body>
</html>