View Padding

<!--
  示例：OpenLayers 视图内边距
  要点：View 的 padding 为浮层预留空间，fit 与 setCenter 都以有效视区为基准
  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>视图内边距</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">
  <button id="fit" type="button">缩放至范围</button>
  <button id="center" type="button">定位到样本点</button>
  <label><input type="checkbox" id="pad" checked> 启用内边距</label>
  <span class="sep"></span>
  <span id="info">padding 170 / 50 / 30 / 150</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 area = new ol.Feature({
    geometry: new ol.geom.Polygon([[
      ol.proj.fromLonLat([116.40, 39.85]),
      ol.proj.fromLonLat([116.62, 39.85]),
      ol.proj.fromLonLat([116.62, 40.02]),
      ol.proj.fromLonLat([116.40, 40.02]),
      ol.proj.fromLonLat([116.40, 39.85])
    ]]),
    name: '样本范围'
  });

  var point = new ol.Feature({
    geometry: new ol.geom.Point(ol.proj.fromLonLat([116.52, 39.95])),
    name: '样本点'
  });

  var vector = new ol.layer.Vector({
    source: new ol.source.Vector({features: [area, point]}),
    style: function (feature) {
      if (feature.getGeometry() instanceof ol.geom.Point) {
        return new ol.style.Style({
          image: new ol.style.Circle({
            radius: 8,
            fill: new ol.style.Fill({color: '#e06a00'}),
            stroke: new ol.style.Stroke({color: '#ffffff', width: 2})
          })
        });
      }
      return new ol.style.Style({
        fill: new ol.style.Fill({color: 'rgba(255, 255, 255, 0.35)'}),
        stroke: new ol.style.Stroke({color: '#319fd3', width: 2})
      });
    }
  });

  var view = new ol.View({
    center: ol.proj.fromLonLat([116.52, 39.95]),
    padding: [170, 50, 30, 150],
    zoom: 10
  });

  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'})}),
      vector
    ],
    view: view
  });

  document.getElementById('fit').addEventListener('click', function () {
    view.fit(area.getGeometry(), {padding: view.getPadding()});
  });

  document.getElementById('center').addEventListener('click', function () {
    view.setCenter(point.getGeometry().getCoordinates());
    view.setZoom(13);
  });

  document.getElementById('pad').addEventListener('change', function () {
    var padding = this.checked ? [170, 50, 30, 150] : [0, 0, 0, 0];
    view.padding = padding;
    view.setPadding(padding);
    document.getElementById('info').textContent =
      'padding ' + padding.join(' / ');
  });

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