如何自定义弹窗的弹出动画和关闭动画

// 弹窗交互 
@CustomDialog 
struct CustomDialogExample { 
  controller: CustomDialogController 
  @State showFlag: Visibility = Visibility.Visible; 
  
  build() { 
    Column() { 
      Button("关闭弹窗") 
    } 
    .width("100%") 
    .height(400) 
    .backgroundColor(Color.Gray) 
    .onClick(() => { 
      this.cancel(); 
    }) 
    .visibility(this.showFlag) 
设置动画事件为200ms ，设置组件转场时插入的起点和删除的终点为屏幕以下100vp 
    .transition(TransitionEffect.OPACITY.animation({ duration: 200 }).combine(TransitionEffect.translate({ y: 100 }))) 
  } 
  
//在删除的时候需要注意， 
//设置弹窗为隐藏，此时弹出向下退出的动效生效，再设置延时关闭弹窗。 
  cancel() { 
    this.showFlag = Visibility.Hidden 
    setTimeout(() => { 
      this.controller.close() 
    }, 200) 
  } 
} 
  
@Entry 
@Component 
struct CustomDialogUser { 
  dialogController: CustomDialogController = new CustomDialogController({ 
    builder: CustomDialogExample(), 
    autoCancel: false, 
    customStyle: true 
  }) 
  
  build() { 
    Column() { 
      Button('click me') 
        .onClick(() => { 
          this.dialogController.open() 
        }) 
    } 
    .width('100%') 
    .height('100%') 
  } 
}

dialogController: CustomDialogController | null = new CustomDialogController({
    builder: renderHospitalCustomDialogBuilder(),
    autoCancel: true,
    customStyle: true,
    alignment: DialogAlignment.Bottom,
    cornerRadius: 10,
    width: '100%',
  })

Column() {
}.borderRadius({
      topLeft: 20,
      topRight: 20
    })
    .linearGradient({colors: [['#efe3c7', 0], ['#ffffff', 1]]})
    .visibility(this.showFlag)
    .transition(TransitionEffect.OPACITY.animation({ duration: 800 }).combine(TransitionEffect.translate({ y: 1000 })))