Vector Label Decluttering

<!--
  示例：OpenLayers 标签避让
  要点：declutter 开启后标签自动避让重叠，缩放时优先保留重要标注
  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>标签避让</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 select,.bar input[type=range]{font-size:12px}
  .bar .val{font-family:ui-monospace,Consolas,monospace;color:#1f5fd0;min-width:44px}
  .bar .sep{width:1px;height:16px;background:#d8dce2}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <label><input type="checkbox" id="declutter" checked> 标签避让</label>
  <span class="sep"></span>
  <span id="info">20 个地块 · declutter 开启</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') {
    document.getElementById('map').textContent = 'OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net';
    return;
  }


  var features = [];
  for (var row = 0; row < 4; ++row) {
    for (var col = 0; col < 5; ++col) {
      var lon = 116.350 + col * 0.011;
      var lat = 39.880 + row * 0.011;
      features.push(new ol.Feature({
        geometry: new ol.geom.Polygon([[
          ol.proj.fromLonLat([lon, lat]),
          ol.proj.fromLonLat([lon + 0.010, lat]),
          ol.proj.fromLonLat([lon + 0.010, lat + 0.010]),
          ol.proj.fromLonLat([lon, lat + 0.010]),
          ol.proj.fromLonLat([lon, lat])
        ]]),
        name: '片区 ' + (row + 1) + '-' + (col + 1) + ' 号地块'
      }));
    }
  }

  var labelStyle = new ol.style.Style({
    text: new ol.style.Text({
      font: '12px sans-serif',
      overflow: true,
      fill: new ol.style.Fill({color: '#17212c'}),
      stroke: new ol.style.Stroke({color: '#ffffff', width: 3})
    })
  });

  var areaStyle = new ol.style.Style({
    fill: new ol.style.Fill({color: 'rgba(255, 255, 255, 0.55)'}),
    stroke: new ol.style.Stroke({color: '#7b9bbb', width: 1})
  });

  var vector = new ol.layer.Vector({
    source: new ol.source.Vector({features: features}),
    declutter: true,
    style: function (feature) {
      labelStyle.getText().setText(feature.get('name'));
      return [areaStyle, labelStyle];
    }
  });

  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'}), opacity: 0.8}),
      vector
    ],
    view: new ol.View({
      center: ol.proj.fromLonLat([116.375, 39.900]),
      zoom: 14
    })
  });

  document.getElementById('declutter').addEventListener('change', function () {
    vector.setDeclutter(this.checked);
    document.getElementById('info').textContent =
      '20 个地块 · declutter ' + (this.checked ? '开启' : '关闭');
  });

})();
</script>
</body>
</html>