Modify Scale and Rotate

<!--
  示例：要素缩放与旋转
  要点：ol.geom 的 scale 与 rotate 以中心点为基准，配合 Modify 继续微调
  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>要素缩放与旋转</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 input[type=range]{width:120px}
  .bar b{color:#16181d;font-weight:600}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <label for="scale">缩放 <b id="sv">1.00</b></label>
  <input type="range" id="scale" min="0.4" max="2.2" step="0.05" value="1">
  <label for="rot">旋转 <b id="rv">0°</b></label>
  <input type="range" id="rot" min="-180" max="180" step="5" value="0">
  <span>拖动顶点可继续编辑</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 fromLonLat = ol.proj.fromLonLat;

  var baseRing = [
    [116.355, 39.928], [116.428, 39.940], [116.452, 39.892], [116.390, 39.868], [116.355, 39.928]
  ].map(function (c) { return fromLonLat(c); });

  var geom = new ol.geom.Polygon([baseRing.slice()]);
  var feature = new ol.Feature({ geometry: geom });

  feature.setStyle(new ol.style.Style({
    fill: new ol.style.Fill({ color: 'rgba(47,158,110,0.22)' }),
    stroke: new ol.style.Stroke({ color: '#166b46', width: 2 }),
    image: new ol.style.Circle({
      radius: 5,
      fill: new ol.style.Fill({ color: '#ffffff' }),
      stroke: new ol.style.Stroke({ color: '#166b46', width: 2 })
    })
  }));

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

  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'}) }), new ol.layer.Vector({ source: source })],
    view: new ol.View({ center: fromLonLat([116.40, 39.905]), zoom: 12 }),
    controls: ol.control.defaults.defaults({ rotate: false })
  });

  map.addInteraction(modify);

  /* 缩放与旋转以几何中心为原点累加，先复位再套用，避免误差累积 */
  function apply(scale, degrees) {
    var ring = baseRing.map(function (c) { return c.slice(); });
    geom.setCoordinates([ring]);

    var ext = geom.getExtent();
    var cx = (ext[0] + ext[2]) / 2;
    var cy = (ext[1] + ext[3]) / 2;

    if (scale !== 1) geom.scale(scale, scale, [cx, cy]);
    if (degrees !== 0) geom.rotate(Math.PI * degrees / 180, [cx, cy]);

    document.getElementById('sv').textContent = scale.toFixed(2);
    document.getElementById('rv').textContent = Math.round(degrees) + '°';
  }

  var scaleValue = 1, rotValue = 0;

  document.getElementById('scale').addEventListener('input', function () {
    scaleValue = Number(this.value);
    apply(scaleValue, rotValue);
  });

  document.getElementById('rot').addEventListener('input', function () {
    rotValue = Number(this.value);
    apply(scaleValue, rotValue);
  });
})();
</script>
</body>
</html>