WMS Custom Proj

<!--
  说明：WMS 请求参数生成的中文示例，数据在页面内生成，可独立运行。
  核心逻辑：calculateExtent + transformExtent + 版本化 BBOX 轴序拼接
  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>WMS 请求参数生成</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 button{font:inherit;padding:3px 9px;border:1px solid #c9ced6;background:#fff;
       border-radius:5px;cursor:pointer;color:#333}
  .bar button:hover{background:#eef2f8}
  .bar input[type=range]{width:110px;vertical-align:middle}
  .bar input[type=text]{font:inherit;padding:2px 6px;border:1px solid #c9ced6;border-radius:4px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3;position:relative}
  .panel{flex:0 0 auto;max-height:34%;overflow:auto;padding:8px 12px;font-size:12px;
       background:#fff;border-top:1px solid #e3e6ea;color:#3d4451}
  .panel pre{margin:0;font-family:Consolas,"Courier New",monospace;font-size:11px;
       white-space:pre-wrap;word-break:break-all;line-height:1.5}
  .ol-attribution{font-size:11px}

</style>
</head>
<body>
<div class="bar">
<label>版本 <select id="ver">
  <option value="1.1.1">WMS 1.1.1</option>
  <option value="1.3.0">WMS 1.3.0</option>
</select></label>
<label>图层 <input type="text" id="layer" value="demo:china" size="14"></label>
<span id="info">—</span>
</div>
<div id="map"></div>
<div class="panel">
  <pre id="wms-url">—</pre>
</div>
<script src="https://cdn.jsdelivr.net/npm/ol@10.3.1/dist/ol.js"></script>
<script>
(function () {
  'use strict';

  if (typeof ol === 'undefined') {
    var errBox = document.getElementById('map');
    if (errBox) {
      errBox.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 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: fromLonLat([112, 32]), zoom: 4}),
    controls: ol.control.defaults.defaults({attribution: false, zoom: true, rotate: false})
  });

  var info = document.getElementById('info');
  var ver = document.getElementById('ver');
  var layerInput = document.getElementById('layer');
  var out = document.getElementById('wms-url');

  function pad(v) {
    return v.toFixed(4);
  }

  function update() {
    var size = map.getSize();
    if (!size) { return; }

    var ext = map.getView().calculateExtent(size);
    var ll = ol.proj.transformExtent(ext, 'EPSG:3857', 'EPSG:4326');
    var version = ver.value;

    /* 1.1.1 用 SRS 且轴序为 lon,lat；1.3.0 用 CRS 且轴序为 lat,lon */
    var bbox = version === '1.3.0'
      ? [ll[1], ll[0], ll[3], ll[2]]
      : [ll[0], ll[1], ll[2], ll[3]];

    var url = 'https://wms.example.org/geoserver/wms' +
      '?SERVICE=WMS&VERSION=' + version + '&REQUEST=GetMap' +
      '&LAYERS=' + encodeURIComponent(layerInput.value || 'demo:layer') +
      '&STYLES=' +
      (version === '1.3.0' ? '&CRS=EPSG:4326' : '&SRS=EPSG:4326') +
      '&BBOX=' + bbox.map(pad).join(',') +
      '&WIDTH=' + Math.round(size[0]) + '&HEIGHT=' + Math.round(size[1]) +
      '&FORMAT=image/png&TRANSPARENT=TRUE';

    out.textContent = url;
    info.textContent = 'WMS ' + version + ' · 视口 ' + Math.round(size[0]) + ' × ' +
      Math.round(size[1]) + ' px · 分辨率 ' +
      map.getView().getResolution().toFixed(1) + ' 米/像素';
  }

  map.on('moveend', update);
  map.on('change:size', update);
  ver.addEventListener('change', update);
  layerInput.addEventListener('input', update);

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