想做一个从相册取得照片，先用OffScreenCanvas裁剪，通过wx.canvasToTempFilePath拿到裁剪后图片地址，然后再显示到wxxl中的<image>的功能，

在社区查询说要在image.onload方法中执行wx.canvasToTempFilePath才能拿到地址，但是我的image.onload方法不执行，是什么原因？

通过以下代码创建了Image对象

const image = this.data.offscreenCanvas.createImage()

然后给通过以下代码给image传入从相册拿到的图片地址，为什么image.onload不执行呢？

image.onLoad =  () => {
    console.log("image.onLoad 为什么不执行？")
}        
image.src = imageUrl

-------- 以下是完整代码 ------------

Page({


    /**
     * 页面的初始数据
     */
    data: {
        imagePath: '',
        clipedImagePath: '',
        offscreenCanvas: null,
        renderingContext: null,
        canvasWidth: 0,
        canvasHeight: 0,
        canvasHWRatio: 0.0,
    },


    onLoad(){
       
        this.data.canvasHWRatio = 1.427


        var windowWidth = wx.getSystemInfoSync().windowWidth
        var pixelRatio = wx.getSystemInfoSync().pixelRatio


        this.data.canvasWidth = windowWidth * pixelRatio
        this.data.canvasHeight = Math.ceil(this.data.canvasWidth * this.data.canvasHWRatio)


        this.initCanvas()
    },


    /* 从相册选择照片 */
    tapChoose(){
        const that = this
        wx.chooseMedia({
            count: 1,
            mediaType: ['image'],
            sourceType: ['album'],
            maxDuration: 30,
            camera: 'back',
            success(res) {
              console.log("tempFiles = ")
              console.log(res.tempFiles)
              that.setData({
                  imagePath: res.tempFiles[0].tempFilePath
              })
              that.getClipedImagePath(res.tempFiles[0].tempFilePath)
            }
          })
    },

    /*  初始化 OffscreenCanvas */
    initCanvas(){
        // 创建离屏 2D canvas 实例
        const offscreenCanvas = wx.createOffscreenCanvas({type: '2d', width: this.data.canvasWidth, height: this.data.canvasHeight})
        // 获取 context。注意这里必须要与创建时的 type 一致
        const renderingContext = offscreenCanvas.getContext('2d')
        this.data.offscreenCanvas = offscreenCanvas
        this.data.renderingContext = renderingContext
    },


    getClipedImagePath(imageUrl){
        console.log("getClipedImagePath 执行")

        // 创建一个图片
        const image = this.data.offscreenCanvas.createImage()
        // 等待图片加载
        image.onLoad =  () => {
            console.log("image.onLoad 为什么不执行？")
        }
        image.src = imageUrl
        
    }
})