Data Update

<!--
  示例：数据增量更新
  要点：图层 id 不变，每两秒用 concat 追加一批点并保留窗口上限
  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>数据增量更新</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"><span>点位 <b id="n">—</b></span><span>每 2 秒追加 200 个 · 上限 6000</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 MAX = 6000;

  function batch(time) {
    var out = [];
    var n = 200;
    for (var i = 0; i < n; i++) {
      out.push({
        lng: 116.24 + Math.random() * 0.32,
        lat: 39.80 + Math.random() * 0.18,
        t: time,
        v: 30 + Math.random() * 90
      });
    }
    return out;
  }

  var data = batch(0);
  document.getElementById('n').textContent = data.length;

  var base = new deck.ScatterplotLayer({
    id: 'stream',
    data: data,
    getPosition: function (d) { return [d.lng, d.lat]; },
    getRadius: function (d) { return 2 + Math.min(4, (Date.now() - d.t) / 6000); },
    radiusUnits: 'pixels',
    getFillColor: function (d) {
      return d.t === 0 ? [120, 150, 180, 120] : [255, 176, 92, 225];
    },
    updateTriggers: { getRadius: data.length },
    pickable: true
  });

  var 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: [base],
    getTooltip: function (info) {
      if (!info.object) return null;
      return '数值 ' + info.object.v.toFixed(0);
    }
  });

  setInterval(function () {
    data = data.concat(batch(Date.now()));
    if (data.length > MAX) data = data.slice(data.length - MAX);
    document.getElementById('n').textContent = data.length;
    deckgl.setProps({
      layers: [new deck.ScatterplotLayer({
        id: 'stream',
        data: data,
        getPosition: function (d) { return [d.lng, d.lat]; },
        getRadius: function (d) { return 2 + Math.min(4, (Date.now() - d.t) / 6000); },
        radiusUnits: 'pixels',
        getFillColor: function (d) {
          return d.t === 0 ? [120, 150, 180, 120] : [255, 176, 92, 225];
        },
        updateTriggers: { getRadius: data.length },
        pickable: true
      })]
    });
  }, 2000);

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