Scaleline Indiana East

<!--
  示例：英制比例尺
  要点：ScaleLine 的 units 决定刻度单位，英制投影下用 imperial 才对应英尺英里
  依赖：OpenLayers 10.3.1 · jsDelivr CDN（底图 OSM，无 Key）
  替代：官方用印第安纳东部英尺投影，这里保留公制底图并用 imperial 刻度对照
-->
<!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>英制比例尺</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 select,.bar input{font-size:12px;padding:2px 4px}
  .bar b{color:#16181d;font-weight:600}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <label>刻度单位
    <select id="u">
      <option value="metric">metric（米 / 公里）</option>
      <option value="imperial" selected>imperial（英尺 / 英里）</option>
      <option value="us">us（美制英尺 / 英里）</option>
      <option value="nautical">nautical（海里）</option>
    </select>
  </label>
  <span>当前分辨率 <b id="res">—</b> m/px</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 (!window.ol) {
    document.getElementById('map').textContent = 'OpenLayers 加载失败，请检查 cdn.jsdelivr.net 是否可访问';
    return;
  }

  var view = new ol.View({
    center: ol.proj.fromLonLat([-86.15, 39.77]),
    zoom: 11,
    minZoom: 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'}) })],
    view: view,
    controls: ol.control.defaults.defaults({ attribution: false, rotate: false })
  });

  var scaleBar = new ol.control.ScaleLine({
    units: 'imperial',
    bar: true,
    steps: 4,
    text: false,
    minWidth: 120
  });
  map.addControl(scaleBar);

  function refresh() {
    var res = view.getResolution() * view.getProjection().getMetersPerUnit();
    document.getElementById('res').textContent = res.toFixed(1);
  }
  view.on('change:resolution', refresh);
  refresh();

  document.getElementById('u').addEventListener('change', function () {
    scaleBar.setUnits(this.value);
  });
})();
</script>
</body>
</html>