Imagery Canvas Tile

<!--
  示例：用 canvas 画一张地图当影像底图
  要点：SingleTileImageryProvider 把一张图铺到指定经纬矩形，图层 alpha 可调
  依赖：CesiumJS 1.121 · jsDelivr CDN，图像由 2D canvas 绘制并转 dataURL
-->
<!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>canvas 单张影像</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/cesium@1.121.0/Build/Cesium/Widgets/widgets.css">
<style>
  html,body{height:100%;margin:0}
  body{background:#0e1116;color:#e6e8ec;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  #c{height:100%}
  .hud{position:absolute;left:12px;top:12px;z-index:5;background:rgba(23,28,35,.9);
       border:1px solid #2a313b;border-radius:6px;padding:9px 12px;font-size:12px;
       color:#a2a9b6;max-width:250px}
  .hud b{color:#e6e8ec;font-weight:600}
  .hud .row{margin-top:6px}
  input[type=range]{width:100%}
  .cesium-viewer-bottom .cesium-widget-credits,.cesium-viewer-animationContainer,
  .cesium-viewer-timelineContainer{display:none!important}
</style>
</head>
<body>
<div id="c"></div>
<div class="hud">
  <div><b>canvas 底图</b></div>
  <div class="row">图层透明度 <span id="aVal">1.00</span></div>
  <div class="row"><input id="alpha" type="range" min="0" max="1" step="0.05" value="1"></div>
  <div class="row">1024 × 768 · 覆盖 115.8~117.0°E</div>
</div>
<script src="https://cdn.jsdelivr.net/npm/cesium@1.121.0/Build/Cesium/Cesium.js"></script>
<script>
(function () {
  'use strict';

  var viewer = new Cesium.Viewer('c', {
    baseLayer: false,
    baseLayerPicker: false, geocoder: false, homeButton: false,
    sceneModePicker: false, navigationHelpButton: false,
    animation: false, timeline: false, fullscreenButton: false,
    infoBox: false, selectionIndicator: false
  });

  var scene = viewer.scene;
  scene.globe.baseColor = Cesium.Color.fromCssColorString('#16202c');
  scene.backgroundColor = Cesium.Color.fromCssColorString('#0e1116');
  scene.skyBox.show = false;
  scene.sun.show = false;
  scene.moon.show = false;
  if (scene.skyAtmosphere) scene.skyAtmosphere.show = false;

  /* ---------- 画一张示意地图 ---------- */
  function drawMap() {
    var W = 1024, H = 768;
    var c = document.createElement('canvas');
    c.width = W; c.height = H;
    var ctx = c.getContext('2d');

    ctx.fillStyle = '#1b2634';
    ctx.fillRect(0, 0, W, H);

    /* 水系 */
    ctx.fillStyle = '#173346';
    ctx.beginPath();
    ctx.moveTo(0, 520);
    ctx.bezierCurveTo(220, 470, 380, 620, 620, 560);
    ctx.bezierCurveTo(800, 520, 900, 600, W, 560);
    ctx.lineTo(W, H); ctx.lineTo(0, H); ctx.closePath();
    ctx.fill();

    /* 街区网格 */
    ctx.strokeStyle = 'rgba(90,120,155,0.35)';
    ctx.lineWidth = 1;
    for (var x = 40; x < W; x += 64) {
      ctx.beginPath(); ctx.moveTo(x, 0); ctx.lineTo(x, H); ctx.stroke();
    }
    for (var y = 40; y < H; y += 64) {
      ctx.beginPath(); ctx.moveTo(0, y); ctx.lineTo(W, y); ctx.stroke();
    }

    /* 主干道 */
    ctx.strokeStyle = '#3f5a78';
    ctx.lineWidth = 10;
    ctx.beginPath();
    ctx.moveTo(0, 300);
    ctx.bezierCurveTo(300, 260, 500, 360, W, 300);
    ctx.stroke();
    ctx.beginPath();
    ctx.moveTo(420, 0);
    ctx.bezierCurveTo(460, 260, 380, 520, 440, H);
    ctx.stroke();

    ctx.strokeStyle = 'rgba(255,177,61,0.85)';
    ctx.lineWidth = 3;
    ctx.beginPath();
    ctx.moveTo(0, 300);
    ctx.bezierCurveTo(300, 260, 500, 360, W, 300);
    ctx.stroke();

    /* 绿地 */
    ctx.fillStyle = 'rgba(60,130,110,0.55)';
    ctx.beginPath();
    ctx.arc(760, 180, 90, 0, Math.PI * 2);
    ctx.fill();

    /* 标注 */
    ctx.fillStyle = '#cfd9e6';
    ctx.font = '600 26px "Microsoft YaHei", sans-serif';
    ctx.fillText('示意影像', 40, 70);
    ctx.font = '18px "Microsoft YaHei", sans-serif';
    ctx.fillStyle = '#8fa3b8';
    ctx.fillText('canvas 生成 · 非真实地图', 40, 104);

    return c.toDataURL('image/png');
  }

  var rectangle = Cesium.Rectangle.fromDegrees(115.8, 39.5, 117.0, 40.3);

  var provider = new Cesium.SingleTileImageryProvider({
    url: drawMap(),
    rectangle: rectangle,
    credit: 'canvas 生成'
  });

  var layer = viewer.imageryLayers.addImageryProvider(provider);

  /* 边界线，标出影像覆盖范围 */
  var corners = [
    Cesium.Cartesian3.fromDegrees(115.8, 39.5),
    Cesium.Cartesian3.fromDegrees(117.0, 39.5),
    Cesium.Cartesian3.fromDegrees(117.0, 40.3),
    Cesium.Cartesian3.fromDegrees(115.8, 40.3)
  ];
  viewer.entities.add({
    polyline: {
      positions: corners.concat([corners[0]]),
      width: 2,
      material: new Cesium.PolylineDashMaterialProperty({
        color: Cesium.Color.fromCssColorString('#ffb13d'),
        dashLength: 20
      }),
      clampToGround: true
    }
  });

  document.getElementById('alpha').addEventListener('input', function () {
    layer.alpha = parseFloat(this.value);
    document.getElementById('aVal').textContent = parseFloat(this.value).toFixed(2);
  });

  viewer.camera.flyTo({
    destination: Cesium.Cartesian3.fromDegrees(116.4, 39.2, 420000),
    orientation: {
      heading: 0,
      pitch: Cesium.Math.toRadians(-78),
      roll: 0
    },
    duration: 0
  });
})();
</script>
</body>
</html>