如何使应用一键变灰，你会吗？

@Entry 
@Component 
struct Index { 
  @State message: string = 'Hello World' 
 
  build() { 
    Row() { 
      Column() { 
        Text(this.message) 
          .fontSize(50) 
          .fontWeight(FontWeight.Bold) 
 
        Image($r("app.media.icon")) 
          .autoResize(true) 
          .width(100) 
          .height(100) 
      } 
    } 
    .width('100%') 
    .height('100%') 
    .saturate(0) 
  } 
}