Modify Interaction

<!--
  示例：修改要素
  要点：Modify 交互拖动顶点，modifyend 中统计外环顶点数，setCoordinates 还原
  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>修改要素</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}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       display:flex;gap:10px;align-items:center;font-size:12px;color:#58606e}
  .bar button{padding:4px 10px;border:1px solid #cfd4dc;border-radius:4px;
              background:#fff;cursor:pointer;font-size:12px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <span>拖动顶点或边线中点改变形状</span>
  <span id="info">顶点数 4</span>
  <button id="reset">还原形状</button>
</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').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 original = [
    fromLonLat([116.380, 39.902]),
    fromLonLat([116.418, 39.902]),
    fromLonLat([116.424, 39.926]),
    fromLonLat([116.384, 39.924]),
    fromLonLat([116.380, 39.902])
  ];

  var geometry = new ol.geom.Polygon([original]);
  var feature = new ol.Feature({ geometry: geometry, name: '编辑区' });

  var source = new ol.source.Vector({ features: [feature] });

  var layer = new ol.layer.Vector({
    source: source,
    style: new ol.style.Style({
      fill: new ol.style.Fill({ color: 'rgba(31, 95, 208, 0.2)' }),
      stroke: new ol.style.Stroke({ color: '#1f5fd0', width: 2 }),
      image: new ol.style.Circle({
        radius: 5,
        fill: new ol.style.Fill({ color: '#ffffff' }),
        stroke: new ol.style.Stroke({ color: '#1f5fd0', width: 2 })
      })
    })
  });

  var modify = new ol.interaction.Modify({ source: source });

  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: fromLonLat([116.402, 39.914]),
      zoom: 13
    }),
    controls: ol.control.defaults.defaults({ attribution: false })
  });

  map.addInteraction(modify);

  var info = document.getElementById('info');

  function report() {
    var ring = geometry.getCoordinates()[0];
    /* 首尾闭合点重复，减去 1 */
    info.textContent = '顶点数 ' + (ring.length - 1);
  }

  modify.on('modifyend', report);
  report();

  document.getElementById('reset').addEventListener('click', function () {
    geometry.setCoordinates([original.slice()]);
    report();
  });
})();
</script>
</body>
</html>