Vector Tile Selection

<!--
  示例：OpenLayers 矢量瓦片选择
  要点：共享同一矢量瓦片源的选择图层，用要素 id 记录选中集合并重绘高亮
  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>矢量瓦片选择</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">
  <label>选择方式
    <select id="type">
      <option value="singleselect-click">单选（点击）</option>
      <option value="singleselect-hover">单选（悬停）</option>
      <option value="multiselect-click">多选（点击）</option>
    </select>
  </label>
  <span class="sep"></span>
  <span id="info">已选 0 个</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 selection = {};

  var baseStyle = new ol.style.Style({
    fill: new ol.style.Fill({color: 'rgba(40, 55, 70, 0.72)'}),
    stroke: new ol.style.Stroke({color: 'rgba(220, 230, 240, 0.7)', width: 1})
  });

  var selectedStyle = new ol.style.Style({
    fill: new ol.style.Fill({color: 'rgba(200, 30, 30, 0.45)'}),
    stroke: new ol.style.Stroke({color: 'rgba(200, 30, 30, 0.95)', width: 2})
  });

  var tileFormat = {
    getType: function () {
      return 'arraybuffer';
    },
    readProjection: function () {
      return 'EPSG:3857';
    },
    readFeatures: function (buffer, options) {
      var info = JSON.parse(new TextDecoder().decode(buffer));
      var extent = options.extent;
      var w = extent[2] - extent[0];
      var h = extent[3] - extent[1];

      function box(x1, y1, x2, y2) {
        return [
          [extent[0] + x1 * w, extent[1] + y1 * h],
          [extent[0] + x2 * w, extent[1] + y1 * h],
          [extent[0] + x2 * w, extent[1] + y2 * h],
          [extent[0] + x1 * w, extent[1] + y2 * h],
          [extent[0] + x1 * w, extent[1] + y1 * h]
        ];
      }

      var features = [];
      for (var i = 0; i < 3; ++i) {
        var feature = new ol.Feature({
          geometry: new ol.geom.Polygon([box(
            0.10 + i * 0.28, 0.18 + (i % 2) * 0.20,
            0.33 + i * 0.28, 0.62 + (i % 2) * 0.20
          )]),
          name: '要素 ' + (i + 1) + ' · ' + info.z + '/' + info.x + '/' + info.y
        });
        feature.setId(info.z + ':' + info.x + ':' + info.y + ':' + i);
        features.push(feature);
      }
      return features;
    }
  };

  var source = new ol.source.VectorTile({
    format: tileFormat,
    tileUrlFunction: function (tileCoord) {
      return 'data:application/json;charset=utf-8,' + encodeURIComponent(
        JSON.stringify({z: tileCoord[0], x: tileCoord[1], y: tileCoord[2]})
      );
    },
    maxZoom: 14,
    transition: 0
  });

  var vtLayer = new ol.layer.VectorTile({
    source: source,
    style: baseStyle
  });

  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'}), opacity: 0.35}),
      vtLayer
    ],
    view: new ol.View({
      center: ol.proj.fromLonLat([116.391, 39.907]),
      zoom: 11
    })
  });

  var selectionLayer = new ol.layer.VectorTile({
    map: map,
    renderMode: 'vector',
    source: source,
    style: function (feature) {
      return feature.getId() in selection ? selectedStyle : undefined;
    }
  });

  var selectElement = document.getElementById('type');

  function updateInfo() {
    document.getElementById('info').textContent =
      '已选 ' + Object.keys(selection).length + ' 个';
  }

  map.on(['click', 'pointermove'], function (event) {
    if ((selectElement.value === 'singleselect-hover' && event.type !== 'pointermove') ||
        (selectElement.value !== 'singleselect-hover' && event.type === 'pointermove')) {
      return;
    }
    vtLayer.getFeatures(event.pixel).then(function (features) {
      if (!features.length) {
        selection = {};
        selectionLayer.changed();
        updateInfo();
        return;
      }
      var feature = features[0];
      var fid = feature.getId();
      if (selectElement.value.indexOf('singleselect') === 0) {
        selection = {};
      }
      selection[fid] = feature;
      selectionLayer.changed();
      updateInfo();
    });
  });

  updateInfo();

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