HarmonyOS 鸿蒙Next怎么动态设置某个组件添加浮层overlay？

参考如下demo

import web_webview from '@ohos.web.webview'

@Entry
@Component
struct Index {
  controller: web_webview.WebviewController = new web_webview.WebviewController()
  @State overlayShow:boolean = false
  @Builder
  overlay1() {
    Image($r('app.media.icon'))
      .width('100%')
      .height('100%')
      .opacity(this.overlayShow?0:0.3)
      .hitTestBehavior(HitTestMode.Transparent)
  }

  build() {
    Column() {
      Button('打开/关闭浮层'))
        .onClick(() => {
          this.overlayShow = !this.overlayShow
        })
      Web({ src: $rawfile("local1.html"), controller: this.controller })
        .layoutWeight(1)
        .overlay(this.overlay1(), { align: Alignment.Center })
    }.width('100%').height('100%')
  }
}