Marker Pulse

<!--
  示例：标记脉冲动画
  要点：requestAnimationFrame 每帧 setRadius，驱动 Circle 样式外圈扩散
  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>标记脉冲动画</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:12px;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="pause"> 暂停动画</label>
  <span>脉冲点位：天安门</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;

  /* 外圈样式单独持有，便于逐帧改半径 */
  var pulseStyle = new ol.style.Style({
    image: new ol.style.Circle({
      radius: 8,
      fill: new ol.style.Fill({ color: 'rgba(31, 95, 208, 0.25)' }),
      stroke: new ol.style.Stroke({ color: 'rgba(31, 95, 208, 0.65)', width: 2 })
    })
  });

  var pulseFeature = new ol.Feature({
    geometry: new ol.geom.Point(fromLonLat([116.3912, 39.9074])),
    name: '天安门'
  });
  pulseFeature.setStyle(pulseStyle);

  var centerFeature = new ol.Feature({
    geometry: new ol.geom.Point(fromLonLat([116.3912, 39.9074]))
  });

  var others = [
    [116.4106, 39.9147], [116.3800, 39.9005], [116.3966, 39.9182]
  ].map(function (p) {
    return new ol.Feature({ geometry: new ol.geom.Point(fromLonLat(p)) });
  });

  var layer = new ol.layer.Vector({
    source: new ol.source.Vector({ features: others.concat([pulseFeature, centerFeature]) })
  });

  /* 中心实心点用图层默认样式 */
  layer.setStyle(function (feature) {
    if (feature === centerFeature) {
      return new ol.style.Style({
        image: new ol.style.Circle({
          radius: 5,
          fill: new ol.style.Fill({ color: '#1f5fd0' }),
          stroke: new ol.style.Stroke({ color: '#ffffff', width: 2 })
        })
      });
    }
    if (feature === pulseFeature) {
      return pulseStyle;
    }
    return new ol.style.Style({
      image: new ol.style.Circle({
        radius: 5,
        fill: new ol.style.Fill({ color: '#8a919d' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 2 })
      })
    });
  });

  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([116.397, 39.911]),
      zoom: 15
    }),
    controls: ol.control.defaults.defaults({ attribution: false })
  });

  var circle = pulseStyle.getImage();
  var paused = false;
  var start = performance.now();

  document.getElementById('pause').addEventListener('change', function () {
    paused = this.checked;
  });

  function tick(now) {
    if (!paused) {
      var t = (now - start) / 700;
      /* 半径在 8 到 22 之间循环 */
      var r = 15 + 7 * Math.sin(t * Math.PI);
      circle.setRadius(r);
      /* 样式对象不是可观察的，改完半径需要主动重绘 */
      map.render();
    }
    requestAnimationFrame(tick);
  }

  requestAnimationFrame(tick);
})();
</script>
</body>
</html>