Composite Layer

<!--
  示例：自定义组合图层
  核心逻辑：继承 CompositeLayer，在 renderLayers 里按 props 拼装多个子图层
  数据：页面内生成的 30 个城市，组合层按人口决定点的颜色与文字大小
  依赖：deck.gl 9.0 · 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>自定义组合图层</title>
<style>
  html,body{height:100%;margin:0;background:#0d1117}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif;color:#e6e8ec}
  .bar{position:relative;z-index:5;flex:0 0 auto;padding:8px 12px;background:#161b22;border-bottom:1px solid #252c36;
       display:flex;gap:14px;align-items:center;font-size:12px;color:#8b93a1;flex-wrap:wrap}
  .bar b{color:#58a6ff;font-weight:600}
  .bar input[type=range]{width:130px}
  .bar label{display:flex;gap:5px;align-items:center;cursor:pointer}
  #cv{flex:1 1 auto;min-height:0;width:100%}
</style>
</head>
<body>
<div class="bar">
  <span>城市 <b id="n">—</b></span>
  <label>人口下限 <input id="p" type="range" min="0" max="2000" step="50" value="0"> <b id="pv">0</b></label>
  <label><input id="t" type="checkbox" checked> 显示名称</label>
</div>
<canvas id="cv"></canvas>
<script src="https://cdn.jsdelivr.net/npm/deck.gl@9.0.35/dist.min.js"></script>
<script>
(function () {
  'use strict';

  if (typeof deck === 'undefined') {
    document.body.innerHTML =
      '<div style="padding:24px;color:#ff8c74">deck.gl 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  var raw = [
    ['北京', 116.39, 39.90, 2189], ['上海', 121.47, 31.23, 2487],
    ['广州', 113.26, 23.12, 1868], ['深圳', 114.06, 22.54, 1756],
    ['成都', 104.06, 30.57, 2094], ['重庆', 106.55, 29.56, 3205],
    ['天津', 117.20, 39.13, 1387], ['武汉', 114.30, 30.59, 1365],
    ['西安', 108.94, 34.34, 1295], ['杭州', 120.15, 30.28, 1194],
    ['南京', 118.80, 32.06, 931], ['郑州', 113.62, 34.75, 1260],
    ['长沙', 112.94, 28.23, 1005], ['沈阳', 123.43, 41.80, 902],
    ['青岛', 120.38, 36.07, 949], ['昆明', 102.71, 25.04, 846],
    ['大连', 121.61, 38.91, 745], ['厦门', 118.09, 24.48, 528],
    ['合肥', 117.28, 31.86, 937], ['福州', 119.30, 26.08, 829],
    ['哈尔滨', 126.64, 45.75, 1001], ['济南', 117.00, 36.65, 920],
    ['南宁', 108.37, 22.82, 874], ['太原', 112.55, 37.87, 530],
    ['石家庄', 114.51, 38.04, 1122], ['贵阳', 106.63, 26.65, 598],
    ['兰州', 103.83, 36.06, 436], ['乌鲁木齐', 87.61, 43.82, 405],
    ['呼和浩特', 111.75, 40.84, 344], ['拉萨', 91.11, 29.65, 87]
  ];

  var data = raw.map(function (d) {
    return { name: d[0], lng: d[1], lat: d[2], pop: d[3] };
  });
  document.getElementById('n').textContent = data.length;

  /* 组合层只需实现 renderLayers，子图层的 id 用 this.id 做前缀保证唯一 */
  class CityLayer extends deck.CompositeLayer {
    renderLayers() {
      var minPop = this.props.minPop || 0;
      var showText = this.props.showText !== false;
      var rows = this.props.data.filter(function (d) { return d.pop >= minPop; });

      var layers = [
        new deck.ScatterplotLayer({
          id: this.id + '-points',
          data: rows,
          getPosition: function (d) { return [d.lng, d.lat]; },
          getRadius: function (d) { return Math.sqrt(d.pop) * 30; },
          radiusUnits: 'meters',
          radiusMinPixels: 4,
          radiusMaxPixels: 22,
          getFillColor: function (d) {
            var t = Math.min(1, d.pop / 3200);
            return [Math.round(90 + 150 * t), Math.round(200 - 120 * t), 200, 190];
          },
          stroked: true,
          getLineColor: [255, 255, 255, 90],
          lineWidthMinPixels: 1,
          pickable: true
        })
      ];

      if (showText) {
        layers.push(new deck.TextLayer({
          id: this.id + '-labels',
          data: rows,
          getPosition: function (d) { return [d.lng, d.lat]; },
          getText: function (d) { return d.name; },
          getSize: function (d) { return d.pop > 1500 ? 15 : 12; },
          getColor: [235, 242, 255],
          getPixelOffset: [0, -16],
          outlineWidth: 2,
          outlineColor: [13, 17, 23, 255],
          fontFamily: 'sans-serif'
        }));
      }

      return layers;
    }
  }

  var cityLayer = new CityLayer({
    id: 'cities',
    data: data,
    minPop: 0,
    showText: true
  });

  var deckgl = new deck.Deck({
    canvas: document.getElementById('cv'),
    width: '100%',
    height: '100%',
    initialViewState: {
      longitude: 108,
      latitude: 34,
      zoom: 3.2,
      pitch: 0,
      bearing: 0
    },
    controller: true,
    layers: [cityLayer],
    getTooltip: function (info) {
      return info.object ? info.object.name + ' · ' + info.object.pop + ' 万' : null;
    }
  });

  document.getElementById('p').addEventListener('input', function () {
    var v = parseInt(this.value, 10);
    document.getElementById('pv').textContent = v;
    cityLayer = cityLayer.clone({ minPop: v });
    deckgl.setProps({ layers: [cityLayer] });
  });

  document.getElementById('t').addEventListener('change', function () {
    cityLayer = cityLayer.clone({ showText: this.checked });
    deckgl.setProps({ layers: [cityLayer] });
  });

  window.__deck = deckgl;
})();
</script>
</body>
</html>