Pinch Zoom

<!--
  示例：双指缩放
  要点：PinchZoom 交互随默认交互一起创建，可单独移除观察差异
  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>双指缩放</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 button{padding:4px 10px;border:1px solid #d5dae2;background:#fff;border-radius:4px;cursor:pointer}
  .bar b{color:#16181d;font-weight:600}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3}
</style>
</head>
<body>
<div class="bar">
  <label><input type="checkbox" id="enabled" checked> 启用双指缩放</label>
  <button id="sim">模拟双指放大</button>
  <span>缩放 <b id="z">—</b></span>
  <span>触屏设备可直接双指操作；桌面端用按钮模拟</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 pinch = new ol.interaction.PinchZoom({ duration: 200 });

  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'}) })],
    view: new ol.View({ center: ol.proj.fromLonLat([116.391263, 39.907359]), zoom: 11, maxZoom: 19 }),
    controls: ol.control.defaults.defaults({ rotate: false })
  });

  /* 默认交互里已含 PinchZoom，先移除再按需挂上自己实例，便于开关 */
  map.getInteractions().getArray().slice().forEach(function (i) {
    if (i instanceof ol.interaction.PinchZoom) map.removeInteraction(i);
  });
  map.addInteraction(pinch);

  function report() {
    document.getElementById('z').textContent = map.getView().getZoom().toFixed(2);
  }

  map.on('moveend', report);
  report();

  document.getElementById('enabled').addEventListener('change', function () {
    if (this.checked) {
      map.addInteraction(pinch);
    } else {
      map.removeInteraction(pinch);
    }
  });

  /* 桌面端没有双指手势，用动画模拟同样的缩放过程 */
  document.getElementById('sim').addEventListener('click', function () {
    var view = map.getView();
    var target = Math.min(19, view.getZoom() + 1);
    view.animate({ zoom: target, duration: 200 });
    setTimeout(report, 260);
  });
})();
</script>
</body>
</html>