HarmonyOS 如何在ArkTS组件中动态控制是否使用组件的某个属性

class MyButtonModifier implements AttributeModifier<ButtonAttribute> {  
  isDark: boolean = false  
  applyNormalAttribute(instance: ButtonAttribute): void {  
    if (this.isDark) {  
      instance.backgroundColor(Color.Black)  
    } else {  
      instance.backgroundColor(Color.Red)  
    }  
  }  
}  
  
@Entry  
@Component  
struct attributeDemo {  
  @State modifier: MyButtonModifier = new MyButtonModifier()  
  
  build() {  
    Row() {  
      Column() {  
        Button("Button")  
          .attributeModifier(this.modifier)  
          .onClick(() => {  
            this.modifier.isDark = !this.modifier.isDark  
          })  
      }  
      .width('100%')  
    }  
    .height('100%')  
  }  
}