Overviewmap

<!--
  示例：鹰眼图控件
  要点：ol.control.OverviewMap 用缩略图显示当前视野，可点击跳转
  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>鹰眼图控件</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 label{display:flex;gap:5px;align-items:center;cursor:pointer}
  .bar b{color:#16181d;font-weight:600}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
  .ol-overviewmap{left:auto;right:8px;bottom:8px}
</style>
</head>
<body>
<div class="bar">
  <label><input type="checkbox" id="open" checked> 展开鹰眼</label>
  <span>鹰眼倍数 <b id="ratio">4</b>×</span>
  <label for="r">调整</label>
  <input type="range" id="r" min="2" max="10" step="1" value="4">
</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 overview = new ol.control.OverviewMap({
    collapsed: false,
    collapsible: true,
    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'}) })
    ],
    tipLabel: '鹰眼图'
  });

  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'}) }),
      new ol.layer.Vector({
        source: new ol.source.Vector({
          features: [[116.32, 39.93], [116.43, 39.94], [116.47, 39.87]].map(function (c) {
            var f = new ol.Feature({ geometry: new ol.geom.Point(ol.proj.fromLonLat(c)) });
            f.setStyle(new ol.style.Style({
              image: new ol.style.Circle({
                radius: 6,
                fill: new ol.style.Fill({ color: '#b42318' }),
                stroke: new ol.style.Stroke({ color: '#ffffff', width: 2 })
              })
            }));
            return f;
          })
        })
      })
    ],
    view: new ol.View({ center: ol.proj.fromLonLat([116.391263, 39.907359]), zoom: 12 }),
    controls: ol.control.defaults.defaults({ rotate: false }).extend([overview])
  });

  var ratio = 4;

  document.getElementById('open').addEventListener('change', function () {
    overview.setCollapsed(!this.checked);
  });

  document.getElementById('r').addEventListener('input', function () {
    ratio = Number(this.value);
    document.getElementById('ratio').textContent = ratio;

    /* 鹰眼图视野倍数由内层 View 的缩放级别决定，直接改内层视图 */
    var ov = overview.getOverviewMap();
    if (ov) {
      var view = ov.getView();
      view.setZoom(map.getView().getZoom() - Math.log2(ratio));
      ov.renderSync();
    }
  });
})();
</script>
</body>
</html>