HarmonyOS 如何实现半屏展开

@Entry 
@Component 
struct SideBarContainerDemo { 
  @State arr: string[] = ['通用设置', '举报反馈', '关于我们'] 
  @State current: number = 1 
  @State showSideBar: boolean = false 
  @State showFlag: Visibility = Visibility.Hidden; 
  // 延迟关闭侧边栏，让自定义的出场动画显示 
  cancel() { 
    this.showFlag = Visibility.Hidden 
    setTimeout(() => { 
      this.showSideBar = !this.showSideBar 
    }, 1000) 
  } 
  build() { 
    SideBarContainer(SideBarContainerType.Overlay) { 
      Column() { 
        ForEach(this.arr, (item: number) => { 
          Column({ space: 5 }) { 
            Text(item+'') 
              .fontSize(25) 
              .fontColor(this.current === item ? '#0A59F7' : '#999') 
              .fontFamily('source-sans-pro,cursive,sans-serif') 
          } 
          .onClick(() => { 
            this.current = item 
          }) 
        }, (item: string) => item) 
      } 
      .visibility(this.showFlag) 
      .transition(TransitionEffect.OPACITY.animation({ duration: 500 }) 
        .combine(TransitionEffect.translate({ x: -100 }))) 
      .width('100%') 
      .justifyContent(FlexAlign.SpaceEvenly) 
      .backgroundColor(Color.Pink) 
      Column() { 
        Button('打开侧边栏').onClick(() => { 
          this.showFlag = Visibility.Visible 
          this.showSideBar = true 
        }) 
        Button('关闭侧边栏').onClick(() => { 
          this.cancel() 
        }) 
      } 
      .backgroundColor(Color.Green) 
      .gesture( 
        TapGesture({ count: 2 }) 
          .onAction((event?: GestureEvent) => { 
            if (event) { 
              this.cancel() 
            } 
          }) 
      ) 
    } 
    .sideBarPosition(SideBarPosition.Start) 
    .showSideBar(this.showSideBar) 
    .showControlButton(false) 
    .sideBarWidth(300) 
    .minSideBarWidth(50) 
    .maxSideBarWidth(300) 
    .minContentWidth(0) 
    .onChange((value: boolean) => { 
      console.info('status:' + value) 
    }) 
  } 
}
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