HarmonyOS 怎么动态设置某个组件添加浮层overlay？

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%')  
  }  
}