Quadkey

<!--
  示例：Quadkey 瓦片索引
  核心逻辑：QuadkeyLayer 用四叉树编码定位瓦片，无需瓦片服务即可着色
  数据：页面内由经纬度反算 zoom 4~6 的 quadkey，并随机赋一个热度
  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>Quadkey 瓦片索引</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}
  #cv{flex:1 1 auto;min-height:0;width:100%}
</style>
</head>
<body>
<div class="bar">
  <span>瓦片 <b id="n">—</b></span>
  <span>编码级别 <b>4–6</b></span>
  <span>悬停查看 quadkey</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;
  }

  /* 经纬度转瓦片行列号，再用四个象限拼出 quadkey */
  function lngLatToTile(lng, lat, z) {
    var n = Math.pow(2, z);
    var x = Math.floor((lng + 180) / 360 * n);
    var s = Math.sin(lat * Math.PI / 180);
    var y = Math.floor((0.5 - Math.log((1 + s) / (1 - s)) / (4 * Math.PI)) * n);
    return [
      Math.max(0, Math.min(n - 1, x)),
      Math.max(0, Math.min(n - 1, y))
    ];
  }

  function tileToQuadkey(x, y, z) {
    var q = '';
    for (var i = z; i > 0; i--) {
      var d = 0;
      var mask = 1 << (i - 1);
      if ((x & mask) !== 0) d += 1;
      if ((y & mask) !== 0) d += 2;
      q += d;
    }
    return q;
  }

  /* 在中国范围内撒点，每个点落在一张瓦片上，同一瓦片只保留一次 */
  var seen = {};
  var data = [];
  var levels = [4, 5, 6];

  for (var i = 0; i < 900; i++) {
    var lng = 74 + Math.random() * 60;
    var lat = 18 + Math.random() * 35;
    var z = levels[i % levels.length];
    var t = lngLatToTile(lng, lat, z);
    var key = z + '/' + t[0] + '/' + t[1];
    if (seen[key]) continue;
    seen[key] = true;

    /* 让热度呈现东西差异，着色才有层次 */
    var heat = Math.random() * 0.6 + (lng - 74) / 60 * 0.4;

    data.push({
      quadkey: tileToQuadkey(t[0], t[1], z),
      z: z,
      heat: heat
    });
  }

  document.getElementById('n').textContent = data.length;

  var layer = new deck.QuadkeyLayer({
    id: 'quadkeys',
    data: data,
    getQuadkey: function (d) { return d.quadkey; },
    /* 低级别瓦片画得高一点，避免同一位置被完全盖住 */
    getElevation: function (d) { return (7 - d.z) * 30000; },
    elevationScale: 1,
    getFillColor: function (d) {
      return [
        Math.round(40 + 210 * d.heat),
        Math.round(120 + 80 * d.heat),
        Math.round(220 - 150 * d.heat),
        190
      ];
    },
    stroked: true,
    getLineColor: [255, 255, 255, 40],
    lineWidthMinPixels: 1,
    pickable: true
  });

  var deckgl = new deck.Deck({
    canvas: document.getElementById('cv'),
    width: '100%',
    height: '100%',
    initialViewState: {
      longitude: 104,
      latitude: 34,
      zoom: 3.4,
      pitch: 45,
      bearing: -10,
      maxPitch: 70
    },
    controller: true,
    layers: [layer],
    getTooltip: function (info) {
      if (!info.object) return null;
      return info.object.quadkey + ' · 级别 ' + info.object.z +
        ' · 热度 ' + info.object.heat.toFixed(2);
    }
  });

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