Data Tiles

<!--
  说明：从零生成数据瓦片的中文示例，数据在页面内生成，可独立运行。
  核心逻辑：网格切分 + 确定性数值 + 色带样式 + 层级切换
  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>从零生成数据瓦片</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 button{font:inherit;padding:3px 9px;border:1px solid #c9ced6;background:#fff;
       border-radius:5px;cursor:pointer;color:#333}
  .bar button:hover{background:#eef2f8}
  .bar input[type=range]{width:110px;vertical-align:middle}
  .bar input[type=text]{font:inherit;padding:2px 6px;border:1px solid #c9ced6;border-radius:4px}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3;position:relative}
  .panel{flex:0 0 auto;max-height:34%;overflow:auto;padding:8px 12px;font-size:12px;
       background:#fff;border-top:1px solid #e3e6ea;color:#3d4451}
  .panel pre{margin:0;font-family:Consolas,"Courier New",monospace;font-size:11px;
       white-space:pre-wrap;word-break:break-all;line-height:1.5}
  .ol-attribution{font-size:11px}

</style>
</head>
<body>
<div class="bar">
<label>细分层级 <input type="range" id="lvl" min="6" max="9" value="7"></label>
<span id="info">—</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') {
    var errBox = document.getElementById('map');
    if (errBox) {
      errBox.innerHTML = '<div style="padding:20px;color:#b42318">OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    }
    return;
  }

  var fromLonLat = ol.proj.fromLonLat;
  var extent = ol.proj.transformExtent([115.9, 39.5, 116.9, 40.4], 'EPSG:4326', 'EPSG:3857');
  var source = new ol.source.Vector();

  function ramp(t) {
    if (t < 0.5) {
      var k = t / 0.5;
      return [Math.round(40 + 90 * k), Math.round(110 + 80 * k), Math.round(180 - 60 * k)];
    }
    var k2 = (t - 0.5) / 0.5;
    return [Math.round(190 + 50 * k2), Math.round(190 - 40 * k2), Math.round(70 - 40 * k2)];
  }

  var layer = new ol.layer.Vector({
    source: source,
    style: function (feature) {
      var c = ramp(feature.get('value'));
      return new ol.style.Style({
        fill: new ol.style.Fill({color: 'rgb(' + c[0] + ',' + c[1] + ',' + c[2] + ')'}),
        stroke: new ol.style.Stroke({color: 'rgba(255,255,255,0.55)', width: 1})
      });
    }
  });

  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'})}), layer],
    view: new ol.View({center: fromLonLat([116.4, 39.95]), zoom: 10}),
    controls: ol.control.defaults.defaults({attribution: false, zoom: true, rotate: false})
  });

  var info = document.getElementById('info');
  var lvl = document.getElementById('lvl');

  function rebuild() {
    var level = +lvl.value;
    var cols = Math.pow(2, level - 6) * 2;
    var rows = Math.round(cols * 0.62);
    source.clear();

    var dx = (extent[2] - extent[0]) / cols;
    var dy = (extent[3] - extent[1]) / rows;
    var minV = 1;
    var maxV = 0;

    for (var r = 0; r < rows; r++) {
      for (var c = 0; c < cols; c++) {
        var seed = Math.sin((r + 1) * 12.9898 + (c + 1) * 78.233) * 43758.5453;
        var v = Math.abs(seed - Math.floor(seed));
        var x0 = extent[0] + c * dx;
        var y0 = extent[1] + r * dy;
        var ring = [[x0, y0], [x0 + dx, y0], [x0 + dx, y0 + dy], [x0, y0 + dy], [x0, y0]];
        source.addFeature(new ol.Feature({
          geometry: new ol.geom.Polygon([ring]),
          value: v
        }));
        if (v < minV) { minV = v; }
        if (v > maxV) { maxV = v; }
      }
    }

    info.textContent = '网格 ' + cols + ' × ' + rows + ' = ' +
      (cols * rows) + ' 块 · 值域 ' + minV.toFixed(2) + ' ~ ' + maxV.toFixed(2);
  }

  lvl.addEventListener('input', rebuild);
  rebuild();
})();
</script>
</body>
</html>