有一个业务需要用到cesium图层请求完成的回调，翻了好久的文档终于给我找到🌶️。
是Cesium.ImageryProvider类的一个属性readyPromise
效果如下：
Cesium图层请求完成的回调
完整代码如下：
<html lang="en"><head><meta charset="utf-8"><!-- Include the CesiumJS JavaScript and CSS files --><script src="https://cesium.com/downloads/cesiumjs/releases/1.95/Build/Cesium/Cesium.js"></script><link href="https://cesium.com/downloads/cesiumjs/releases/1.95/Build/Cesium/Widgets/widgets.css" rel="stylesheet"><style>.button {width: 80px;height: 30px;background-color: rgba(92, 38, 116, 0.818);cursor: pointer;padding: 10px;color: #fff;text-align: center;line-height: 50px;border-radius: 10px;}</style>
</head><body><div id="cesiumContainer"><span id="addLayer" class="button">添加图层</span><span id="removeLayer" class="button">移除图层</span></div><script type="module">javascript">Cesium.Ion.defaultAccessToken = ';const viewer = new Cesium.Viewer('cesiumContainer', {});viewer.camera.setView({destination: Cesium.Cartesian3.fromDegrees(105, 35, 3456789),orientation: {heading: Cesium.Math.toRadians(360), //方向pitch: Cesium.Math.toRadians(-90), //俯仰角roll: Cesium.Math.toRadians(0),},});let layer = null;// 添加图层(async/await语法糖)async function addLayer() {let url = './assets/lyy.jpg';let rectangleArr = [100.0, 30.0, 110.0, 40.0]const singleTileImageryProvider = new Cesium.SingleTileImageryProvider({url: url,rectangle: new Cesium.Rectangle(...rectangleArr.map(item => Cesium.Math.toRadians(item))),});console.log("开始请求图层");try {// ⭐关键代码⭐const res = await singleTileImageryProvider.readyPromise;if (res) {console.log("图层请求成功");} else {console.log("图层请求失败");}} catch (error) {console.error("图层请求时发生错误:", error);}// 将imageryProvider添加到地图的图层列表中，使得图层可以在地图上显示return viewer.imageryLayers.addImageryProvider(singleTileImageryProvider);}/*// 添加图层(Promise)function addLayer() {return new Promise((resolve, reject) => {let url = './assets/lyy.jpg';let rectangleArr = [100.0, 30.0, 110.0, 40.0];const singleTileImageryProvider = new Cesium.SingleTileImageryProvider({url: url,rectangle: new Cesium.Rectangle(...rectangleArr.map(item => Cesium.Math.toRadians(item))),});console.log("开始请求图层");singleTileImageryProvider.readyPromise.then(res => {if (res) {console.log("图层请求成功");resolve(viewer.imageryLayers.addImageryProvider(singleTileImageryProvider));} else {console.log("图层请求失败");reject(new Error("图层请求失败"));}}).catch(error => {console.error("图层请求时发生错误:", error);reject(error);});});}*/// 移除图层function removeLayer() {viewer.imageryLayers.remove(layer)}// 给按钮添加点击事件document.getElementById("addLayer").onclick = async () => {layer = await addLayer()};document.getElementById("removeLayer").onclick = () => {removeLayer()};</script></div>
</body></html>
