Geolocation

<!--
  示例：浏览器定位
  要点：ol.Geolocation 的 change:position / accuracyGeometry 驱动标记与精度圈
  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>浏览器定位</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{padding:4px 10px;border:1px solid #cfd4dc;border-radius:4px;
              background:#fff;cursor:pointer;font-size:12px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <button id="start">开始定位</button>
  <button id="stop">停止</button>
  <button id="sim">模拟定位</button>
  <span id="info">尚未定位</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 view = new ol.View({
    center: ol.proj.fromLonLat([116.3974, 39.9093]),
    zoom: 12
  });

  var accuracyFeature = new ol.Feature();
  var positionFeature = new ol.Feature();

  var layer = new ol.layer.Vector({
    source: new ol.source.Vector({
      features: [accuracyFeature, positionFeature]
    })
  });

  /* 精度圈单独用浅色填充 */
  layer.setStyle(function (feature) {
    if (feature === accuracyFeature) {
      return new ol.style.Style({
        fill: new ol.style.Fill({ color: 'rgba(31, 95, 208, 0.12)' }),
        stroke: new ol.style.Stroke({ color: 'rgba(31, 95, 208, 0.5)', width: 1 })
      });
    }
    return new ol.style.Style({
      image: new ol.style.Circle({
        radius: 7,
        fill: new ol.style.Fill({ color: '#1f5fd0' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 3 })
      })
    });
  });

  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: view,
    controls: ol.control.defaults.defaults({ attribution: false })
  });

  var info = document.getElementById('info');

  var geolocation = new ol.Geolocation({
    projection: 'EPSG:3857',
    trackingOptions: { enableHighAccuracy: true, timeout: 8000 }
  });

  geolocation.on('change:position', function () {
    var pos = geolocation.getPosition();
    if (!pos) {
      return;
    }
    positionFeature.setGeometry(new ol.geom.Point(pos));
    var acc = geolocation.getAccuracy();
    info.textContent = '当前位置精度约 ' + (acc ? acc.toFixed(0) : '—') + ' m';
    view.animate({
      center: pos,
      zoom: Math.max(view.getZoom(), 15),
      duration: 700
    });
  });

  geolocation.on('change:accuracyGeometry', function () {
    accuracyFeature.setGeometry(geolocation.getAccuracyGeometry());
  });

  geolocation.on('error', function (e) {
    info.textContent = '定位失败：' + (e.message || '未获得浏览器授权');
  });

  document.getElementById('start').addEventListener('click', function () {
    geolocation.setTracking(true);
    info.textContent = '正在获取位置…';
  });

  document.getElementById('stop').addEventListener('click', function () {
    geolocation.setTracking(false);
    info.textContent = '已停止追踪';
  });

  document.getElementById('sim').addEventListener('click', function () {
    var center = ol.proj.fromLonLat([116.3912, 39.9074]);
    positionFeature.setGeometry(new ol.geom.Point(center));
    accuracyFeature.setGeometry(
      ol.geom.Polygon.fromCircle(new ol.geom.Circle(center, 180), 48)
    );
    info.textContent = '模拟位置 · 精度约 180 m';
    view.animate({ center: center, zoom: 15, duration: 500 });
  });
})();
</script>
</body>
</html>