如何实现类似keyframes的效果

@Entry 
@Component 
struct AnimateToExample { 
  @State widthSize: number = 250; 
  @State heightSize: number = 100; 
  @State rotateAngle: number = 0; 
  private flag: boolean = true; 
  @State opacityValue: number = 1; 
 
  build() { 
    Column() { 
      Button('change size') 
        .width(this.widthSize) 
        .height(this.heightSize) 
        .margin(30) 
        .opacity(this.opacityValue) 
        .onClick(() => { 
          if (this.flag) { 
            animateTo({ 
              duration: 2000, 
              curve: Curve.EaseOut, 
              iterations: 1, 
              playMode: PlayMode.Normal, 
              onFinish: () => { 
                animateTo({ 
                  duration: 2000, 
                  curve: Curve.EaseOut, 
                  iterations: 1, 
                  playMode: PlayMode.Normal, 
                  onFinish: () => { 
                  } 
                }, () => { 
                  this.opacityValue = 0.2; 
                }) 
              } 
            }, () => { 
              this.opacityValue = 0.5; 
            }) 
          } 
        }) 
    }.width('100%').margin({ top: 5 }) 
  } 
}