怎么让文本框在禁用时变灰？

@Entry
@Component
struct test{
  @State isUsable: boolean = true

  build() {
    Column(){
      TextInput()
        .focusable(this.isUsable)
        .backgroundColor(this.isUsable ?Color.Pink : Color.Gray )
      Button("禁用文本框")
        .onClick(()=>{
          this.isUsable = !this.isUsable
        })
    }
  }
}