GeoJSON Filter

<!--
  示例：要素过滤
  要点：按阈值在数据层剔除 GeoJSON 要素，渲染与拾取范围保持一致
  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>要素过滤</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 label{display:flex;align-items:center;gap:5px;cursor:pointer}
  .bar input[type=checkbox]{accent-color:#4f9ef8}
  .bar input[type=range]{width:150px;accent-color:#4f9ef8}
  .bar button{font:inherit;font-size:12px;padding:3px 10px;border-radius:4px;cursor:pointer;
       border:1px solid #2f3947;background:#1d242e;color:#c9d3e0}
  .bar button:hover{background:#26303d}
  #cv{flex:1 1 auto;min-height:0;width:100%;display:block}

</style>
</head>
<body>
<div class="bar">
  <label>阈值 <input id="th" type="range" min="0" max="90" step="5" value="40"> <b id="tv">40</b></label>
  <span>保留 <b id="n">—</b> 个要素</span>
</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 all = [];
  for (var i = 0; i < 90; i++) {
    all.push({
      type: 'Feature',
      properties: { v: Math.round(Math.random() * 100), name: '监测点 ' + (i + 1) },
      geometry: {
        type: 'Point',
        coordinates: [116.24 + Math.random() * 0.32, 39.80 + Math.random() * 0.18]
      }
    });
  }

  var deckgl = null;

  function layersFor(threshold) {
    var kept = all.filter(function (f) { return f.properties.v >= threshold; });
    document.getElementById('n').textContent = kept.length;
    return [
      new deck.GeoJsonLayer({
        id: 'filtered',
        data: { type: 'FeatureCollection', features: kept },
        pointType: 'circle',
        filled: true,
        getPointRadius: 7,
        pointRadiusUnits: 'pixels',
        getFillColor: function (f) {
          return f.properties.v > 75 ? [255, 150, 92, 225] : [92, 180, 255, 215];
        },
        getPointColor: function (f) {
          return f.properties.v > 75 ? [255, 150, 92, 225] : [92, 180, 255, 215];
        },
        stroked: true,
        getLineColor: [12, 20, 32, 210],
        lineWidthUnits: 'pixels',
        getLineWidth: 1.5,
        pickable: true
      })
    ];
  }

  deckgl = new deck.Deck({
    canvas: 'cv',
    width: '100%',
    height: '100%',
    initialViewState: { longitude: 116.40, latitude: 39.89, zoom: 10.2, pitch: 0, bearing: 0 },
    controller: true,
    layers: layersFor(40),
    getTooltip: function (info) {
      if (!info.object) return null;
      return info.object.properties.name + ' · ' + info.object.properties.v;
    }
  });

  document.getElementById('th').addEventListener('input', function (e) {
    var v = parseInt(e.target.value, 10);
    document.getElementById('tv').textContent = v;
    deckgl.setProps({ layers: layersFor(v) });
  });
  window.__deck = deckgl;
})();
</script>
</body>
</html>