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<!--
  示例：视图状态写入链接
  要点：把 center 与 zoom 写进 URL hash，刷新或分享后还原同样视野
  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>视图状态写入链接</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;color:#16181d}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       display:flex;gap:14px;align-items:center;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar button{padding:4px 10px;border:1px solid #d5dae2;background:#fff;border-radius:4px;cursor:pointer}
  .bar code{font-family:ui-monospace,Menlo,Consolas,monospace;color:#0b3d91;
            overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:360px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <code id="hash">—</code>
  <button id="copy">复制链接</button>
  <button id="reset">复位</button>
</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 (!window.ol) {
    document.getElementById('map').textContent = 'OpenLayers 加载失败，请检查 cdn.jsdelivr.net 是否可访问';
    return;
  }

  var DEFAULT = { zoom: 11, lat: 39.9074, lon: 116.3913 };

  /* 链接格式： #map=zoom/lat/lon */
  function parseHash() {
    var m = /map=([\d.]+)\/([-\d.]+)\/([-\d.]+)/.exec(window.location.hash);
    if (!m) return null;
    return { zoom: Number(m[1]), lat: Number(m[2]), lon: Number(m[3]) };
  }

  var start = parseHash() || DEFAULT;

  var view = new ol.View({
    center: ol.proj.fromLonLat([start.lon, start.lat]),
    zoom: start.zoom,
    maxZoom: 19
  });

  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'}) })],
    view: view,
    controls: ol.control.defaults.defaults({ rotate: false })
  });

  function hashOf() {
    var c = ol.proj.toLonLat(view.getCenter());
    return '#map=' + view.getZoom().toFixed(2) + '/' + c[1].toFixed(4) + '/' + c[0].toFixed(4);
  }

  function sync() {
    var h = hashOf();
    document.getElementById('hash').textContent = h;
    /* replaceState 避免每次移动都往历史记录里塞一条 */
    try {
      window.history.replaceState(null, '', h);
    } catch (e) {
      /* 某些沙箱环境限制改写 history，链接仍在页面里显示 */
    }
  }

  map.on('moveend', sync);
  sync();

  document.getElementById('copy').addEventListener('click', function () {
    var url = window.location.href.split('#')[0] + hashOf();
    var done = function () { this.textContent = '已复制'; }.bind(this);
    if (navigator.clipboard && navigator.clipboard.writeText) {
      navigator.clipboard.writeText(url).then(done, done);
    } else {
      document.getElementById('hash').textContent = url;
    }
  });

  document.getElementById('reset').addEventListener('click', function () {
    view.animate({
      center: ol.proj.fromLonLat([DEFAULT.lon, DEFAULT.lat]),
      zoom: DEFAULT.zoom,
      duration: 500
    });
  });
})();
</script>
</body>
</html>