Select Features

<!--
  示例：点选要素
  要点：ol.interaction.Select 自带选中集合，select 事件里读属性
  依赖：OpenLayers 10.3.1 · jsDelivr CDN（底图 OSM，无 Key）
-->
<!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>点选要素</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:16px;align-items:center;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar b{color:#16181d;font-weight:600}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <span>选中 <b id="nm">—</b></span>
  <span>类型 <b id="tp">—</b></span>
  <span>面积 <b id="ar">—</b></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 ZONES = [
    ['西单商圈', 116.36, 39.909, 'poly'],
    ['王府井商圈', 116.411, 39.913, 'poly'],
    ['国贸中心', 116.455, 39.908, 'poly'],
    ['中关村', 116.316, 39.983, 'poly'],
    ['望京', 116.470, 40.000, 'poly'],
    ['北京南站', 116.378, 39.865, 'poly'],
    ['朝阳公园', 116.478, 39.944, 'poly']
  ];

  function polyFor(lon, lat) {
    var d = 0.012;
    return new ol.geom.Polygon([[
      ol.proj.fromLonLat([lon - d, lat - d * 0.7]),
      ol.proj.fromLonLat([lon + d, lat - d * 0.7]),
      ol.proj.fromLonLat([lon + d, lat + d * 0.7]),
      ol.proj.fromLonLat([lon - d, lat + d * 0.7]),
      ol.proj.fromLonLat([lon - d, lat - d * 0.7])
    ]]);
  }

  var feats = ZONES.map(function (z, i) {
    var f = new ol.Feature({
      geometry: polyFor(z[1], z[2]),
      name: z[0],
      kind: i % 2 === 0 ? '商业' : '交通'
    });
    return f;
  });

  var layer = new ol.layer.Vector({
    source: new ol.source.Vector({ features: feats }),
    style: function (f) {
      return new ol.style.Style({
        fill: new ol.style.Fill({ color: 'rgba(31,95,208,.16)' }),
        stroke: new ol.style.Stroke({ color: '#1f5fd0', width: 2 }),
        text: new ol.style.Text({
          text: f.get('name'),
          font: '500 12px sans-serif',
          fill: new ol.style.Fill({ color: '#16181d' }),
          stroke: new ol.style.Stroke({ color: '#fff', width: 3 })
        })
      });
    }
  });

  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'}) }), layer],
    view: new ol.View({ center: ol.proj.fromLonLat([116.40, 39.94]), zoom: 12 }),
    controls: ol.control.defaults.defaults({ attribution: false, rotate: false })
  });

  var select = new ol.interaction.Select({
    style: new ol.style.Style({
      fill: new ol.style.Fill({ color: 'rgba(214,69,69,.28)' }),
      stroke: new ol.style.Stroke({ color: '#d64545', width: 3 }),
      text: new ol.style.Text({
        text: '',
        font: '600 12px sans-serif'
      })
    })
  });

  select.getFeatures().on('add', function (e) {
    var f = e.element;
    document.getElementById('nm').textContent = f.get('name');
    document.getElementById('tp').textContent = f.get('kind');
    var area = ol.sphere.getArea(f.getGeometry()) / 1e6;
    document.getElementById('ar').textContent = area.toFixed(2) + ' km²';
  });

  select.getFeatures().on('remove', function () {
    document.getElementById('nm').textContent = '—';
    document.getElementById('tp').textContent = '—';
    document.getElementById('ar').textContent = '—';
  });

  map.addInteraction(select);
  select.getFeatures().clear();
})();
</script>
</body>
</html>