Grid

<!--
  示例：网格生成 — 用 turf.hexGrid 在研究范围内铺六边形统计单元
  核心逻辑：cellSize 以公里传入，滑块调整后重新生成整个网格
  依赖：Turf.js 7 · 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>网格生成</title>
<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;color:#16181d;background:#fff}
  .bar{flex:0 0 auto;display:flex;gap:12px;align-items:center;padding:8px 12px;
       background:#f6f7f9;border-bottom:1px solid #e3e6ea;font-size:12px;color:#58606e;flex-wrap:wrap}
  .bar input[type=range]{width:170px}
  .bar b{color:#16181d;font-weight:600}
  svg{flex:1 1 auto;min-height:0;width:100%;display:block;background:#fbfcfd}
  .out{flex:0 0 auto;display:flex;gap:22px;flex-wrap:wrap;padding:8px 12px;
       border-top:1px solid #e3e6ea;
       font-family:ui-monospace,Consolas,monospace;font-size:11.5px;color:#3a4250}
  .out b{color:#1f5fd0}
</style>
</head>
<body>
<div class="bar">
  <label>单元尺寸 <input id="size" type="range" min="1" max="5" step="0.5" value="2"> <b id="sv">2.0 km</b></label>
  <span>范围约 20 × 16 km</span>
</div>
<svg id="stage" viewBox="0 0 640 320" preserveAspectRatio="xMidYMid meet"></svg>
<div class="out">
  <span>单元数 <b id="n">—</b></span>
  <span>单格面积 <span id="cell">—</span></span>
  <span>范围面积 <span id="total">—</span></span>
</div>
<script src="https://cdn.jsdelivr.net/npm/@turf/turf@7/turf.min.js"></script>
<script>
(function () {
  'use strict';

  if (typeof turf === 'undefined') {
    document.body.innerHTML =
      '<div style="padding:24px;color:#b42318">Turf.js 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  var BOX = [116.260, 39.840, 116.500, 39.980];
  var W = 640, H = 320, PAD = 20;
  var stage = document.getElementById('stage');
  var slider = document.getElementById('size');

  var kx = Math.cos(((BOX[1] + BOX[3]) / 2) * Math.PI / 180);
  var x0 = BOX[0] * kx, x1 = BOX[2] * kx;
  var y0 = BOX[1], y1 = BOX[3];
  var s = Math.min((W - PAD * 2) / (x1 - x0), (H - PAD * 2) / (y1 - y0));
  var ox = (W - (x1 - x0) * s) / 2;
  var oy = (H - (y1 - y0) * s) / 2;

  function pr(c) {
    return [(c[0] * kx - x0) * s + ox, (y1 - c[1]) * s + oy];
  }

  function ringPath(ring) {
    var d = '';
    for (var i = 0; i < ring.length; i++) {
      var p = pr(ring[i]);
      d += (i ? 'L' : 'M') + p[0].toFixed(1) + ' ' + p[1].toFixed(1);
    }
    return d + 'Z';
  }

  function draw() {
    var size = parseFloat(slider.value);
    var grid = turf.hexGrid(BOX, size, { units: 'kilometers' });

    var parts = ['<rect x="0" y="0" width="640" height="320" fill="none" stroke="#e3e6ea"/>'];

    grid.features.forEach(function (cell) {
      parts.push('<path d="' + ringPath(cell.geometry.coordinates[0]) +
                 '" fill="rgba(31,95,208,0.05)" stroke="#1f5fd0" ' +
                 'stroke-width="0.9" stroke-opacity="0.55"/>');
    });

    var b = turf.bboxPolygon(BOX);
    parts.push('<path d="' + ringPath(b.geometry.coordinates[0]) +
               '" fill="none" stroke="#c2410c" stroke-width="1.5" stroke-dasharray="6 4"/>');

    stage.innerHTML = parts.join('');

    var total = turf.area(b);
    var cellArea = grid.features.length ? turf.area(grid.features[0]) : 0;

    document.getElementById('sv').textContent = size.toFixed(1) + ' km';
    document.getElementById('n').textContent = grid.features.length;
    document.getElementById('cell').textContent = (cellArea / 1e6).toFixed(3) + ' km²';
    document.getElementById('total').textContent = (total / 1e6).toFixed(1) + ' km²';
  }

  slider.addEventListener('input', draw);
  draw();
})();
</script>
</body>
</html>