如何动态设置组件属性的值

Text('test') 
  .backgroundColor(this.flag ? Color.Red : Color.Transparent) 
  .onClick(() => this.flag = !this.flag)

@Entry 
@Component 
struct Index { 
  @State message: string = 'Hello World'; 
  @State widthSize: number = 400; 
  @State heightSize: number = 200; 
 
  build() { 
    Row() { 
      Column() { 
        Text(this.message) 
          .fontSize(50) 
          .fontWeight(FontWeight.Bold) 
        Button() 
          .onClick(() => { 
            this.widthSize = 800; 
            this.heightSize = 400; 
          }) 
      } 
      .width(this.widthSize) 
      .backgroundColor(Color.Orange) 
    } 
    .height(this.heightSize) 
  } 
}