Extent Constrained

<!--
  说明：受限地图范围的中文示例，数据在页面内生成，可独立运行。
  核心逻辑：ol.View 的 extent 选项限制可视范围
  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>受限地图范围</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="checkbox" id="lock" checked> 锁定范围</label>
<button id="fly" type="button">飞向 [96, 28]</button>
<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 ext = ol.proj.transformExtent([115.7, 39.4, 117.2, 40.3], 'EPSG:4326', 'EPSG:3857');
  var info = document.getElementById('info');
  var locked = true;

  var view = new ol.View({
    center: fromLonLat([116.397, 39.909]),
    zoom: 11,
    extent: ext
  });

  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({attribution: false, zoom: true, rotate: false})
  });

  function report() {
    var size = map.getSize();
    if (!size) { return; }
    var ve = view.calculateExtent(size);
    var inside = ve[0] >= ext[0] - 1 && ve[1] >= ext[1] - 1 && ve[2] <= ext[2] + 1 && ve[3] <= ext[3] + 1;
    info.textContent = (locked ? '已锁定' : '自由') + ' · 可视范围 ' +
      ol.proj.toLonLat([ve[0], ve[1]])[0].toFixed(2) + ',' +
      ol.proj.toLonLat([ve[0], ve[1]])[1].toFixed(2) + ' → ' +
      ol.proj.toLonLat([ve[2], ve[3]])[0].toFixed(2) + ',' +
      ol.proj.toLonLat([ve[2], ve[3]])[1].toFixed(2) + (inside ? ' · 未越界' : ' · 已越界');
  }

  function rebuild() {
    var c = view.getCenter();
    var z = view.getZoom();
    view = new ol.View({
      center: c,
      zoom: z,
      extent: locked ? ext : undefined
    });
    map.setView(view);
    view.on('change:center', report);
    view.on('change:resolution', report);
    report();
  }

  document.getElementById('lock').addEventListener('change', function () {
    locked = this.checked;
    rebuild();
  });

  document.getElementById('fly').addEventListener('click', function () {
    view.animate({center: fromLonLat([96, 28]), zoom: 8, duration: 900});
  });

  view.on('change:center', report);
  view.on('change:resolution', report);
  map.on('change:size', report);
  report();
})();
</script>
</body>
</html>