如何获取窗口截图并显示在Image中？

import { window } from '@kit.ArkUI';
import { common } from '@kit.AbilityKit';
import { image } from '@kit.ImageKit';

let context = getContext(this) as common.UIAbilityContext;
let windowClass: window.Window
window.getLastWindow(context, (err, data) => {
//获取window实例
  windowClass = data
})

Button("aaaa")
  .onClick(()=>{
    windowClass.snapshot().then((img: image.PixelMap) => {
      this.image = img
    })
  })
Image(this.image)
  .width(150)
  .height(200)
  .margin(20)
  .borderWidth(1)