HarmonyOS Tabs的TabBar需要居左显示，改如何开发局部

请参考 ：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/ts-container-tabs-V5#示例9

demo如下：

import ComponentUtils from '@ohos.arkui.UIContext';
@Entry
@Component
struct tabsAnimation {
  @State tabArray: Array<number> = [0, 1, 2, 3, 4]
  @State focusIndex: number = 0
  @State pre: number = 0
  @State index: number = 0
  private controller: TabsController = new TabsController()
  @State test: boolean = false
  @State animationDuration: number = 300
  @State indicatorLeftMargin: number = 0
  @State indicatorWidth: number = 0
  private tabsWidth: number = 0
  private tabWidth: number = 0;
  private scrollerForScroll: Scroller = new Scroller()
  private componentUtils: ComponentUtils.ComponentUtils = this.getUIContext().getComponentUtils()
  // 单独的页签
  @Builder
  Tab(tabName: string, tabItem: number, tabIndex: number) {
    Row({ space: 20 }) {
      Text(tabName)
        .fontSize(18)
        .fontColor(tabIndex === this.focusIndex ? Color.Blue : Color.Black)
        .id(tabIndex.toString())
        .onAreaChange((oldValue: Area, newValue: Area) => {
          if (this.focusIndex === tabIndex && (this.indicatorLeftMargin === 0 || this.indicatorWidth === 0)) {
            if (newValue.position.x != undefined) {
              let positionX = Number.parseFloat(newValue.position.x.toString())
              this.indicatorLeftMargin = Number.isNaN(positionX) ? 0 : positionX
            }
            let width = Number.parseFloat(newValue.width.toString())
            this.tabWidth = Number.isNaN(width) ? 0 : width
            this.indicatorWidth = this.tabWidth
          }
        })
    }
    .justifyContent(FlexAlign.Center)
    .constraintSize({ minWidth: 35 })
    .width(100)
    .height(30)
    .onClick(() => {
      this.controller.changeIndex(tabIndex)
      this.focusIndex = tabIndex
    })
    .backgroundColor("#ffb7b7b7")
  }
  @Builder
  textTest(textName: string) {
    Row({ space: 20 }) {
      Text(textName).fontSize(18)
    }
    .justifyContent(FlexAlign.Center)
    .constraintSize({ minWidth: 35 })
    .height(30)
    .backgroundColor("#ffb7b7b7")
  }
  build() {
    Column() {
      Stack({ alignContent: Alignment.TopStart }) {
        Column() {
          // 页签
          Row({ space: 8 }) {
            List({ space: 20, initialIndex: 0, scroller: this.scrollerForScroll }) {
              ForEach(this.tabArray, (item: number, index: number) => {
                ListItem() {
                  this.Tab("页签 " + item, item, index)
                }
              }, (item: string) => item)
            }
            .listDirection(Axis.Horizontal)
            .height(30)
            .width('80%')
            .friction(0.6)
            .alignListItem(ListItemAlign.Start)
            .scrollBar(BarState.Off)
            .width('80%')
            .backgroundColor("#ffb7b7b7")
            .onScroll((xOffset: number, yOffset: number) => {
              this.indicatorLeftMargin -= xOffset
            })
            this.textTest('更多1')
          }
          .alignItems(VerticalAlign.Bottom)
          .width('100%')
          .backgroundColor("#ffb7b7b7")
        }
        .alignItems(HorizontalAlign.Start)
        .width('100%')
        Column()
          .height(2)
          .width(this.indicatorWidth)
          .margin({ left: this.indicatorLeftMargin, top: 30 })
          .backgroundColor(Color.Blue)
      }
      .height(40)
      .width('100%')
      .backgroundColor("#ffb7b7b7")
      //tabs
      Tabs({ barPosition: BarPosition.Start, controller: this.controller }) {
        ForEach(this.tabArray, (item: number, index: number) => {
          TabContent() {
            Text('我是页面 ' + item + " 的内容")
              .height(300)
              .width('100%')
              .fontSize(30)
          }
          .backgroundColor(Color.White)
        }, (item: string) => item)
      }
      .onAreaChange((oldValue: Area, newValue: Area) => {
        let width = Number.parseFloat(newValue.width.toString())
        this.tabsWidth = Number.isNaN(width) ? 0 : width
      })
      .width('100%')
      .barHeight(0)
      .animationDuration(100)
      .onChange((index: number) => {
        console.log('foo change')
        this.focusIndex = index
        this.scrollerForScroll.scrollToIndex(index - 1, true)
      })
      .onAnimationStart((index: number, targetIndex: number, event: TabsAnimationEvent) => {
        // 切换动画开始时触发该回调。下划线跟着页面一起滑动
        this.focusIndex = targetIndex
        let targetIndexInfo = this.getTextInfo(targetIndex)
        this.startAnimateTo(this.animationDuration, targetIndexInfo.left, targetIndexInfo.width)
      })
      .onAnimationEnd((index: number, event: TabsAnimationEvent) => {
        // 切换动画结束时触发该回调。下划线动画停止。
        let currentIndicatorInfo = this.getCurrentIndicatorInfo(index, event)
        this.startAnimateTo(0, currentIndicatorInfo.left, currentIndicatorInfo.width)
      })
      .onGestureSwipe((index: number, event: TabsAnimationEvent) => {
        // 在页面跟手滑动过程中，逐帧触发该回调。
        let currentIndicatorInfo = this.getCurrentIndicatorInfo(index, event)
        this.focusIndex = currentIndicatorInfo.index
        this.indicatorLeftMargin = currentIndicatorInfo.left
        this.tabWidth = currentIndicatorInfo.width
        this.indicatorWidth = currentIndicatorInfo.width
      })
    }
    .height('100%')
  }
  private getTextInfo(index: number): Record<string, number> {
    let rectangle = this.componentUtils.getRectangleById(index.toString())
    return { 'left': px2vp(rectangle.windowOffset.x), 'width': px2vp(rectangle.size.width) }
  }
  private getCurrentIndicatorInfo(index: number, event: TabsAnimationEvent): Record<string, number> {
    let nextIndex = index
    if (index > 0 && event.currentOffset > 0) {
      nextIndex--
    } else if (index < 4 && event.currentOffset < 0) {
      nextIndex++
    }
    let indexInfo = this.getTextInfo(index)
    let nextIndexInfo = this.getTextInfo(nextIndex)
    let swipeRatio = Math.abs(event.currentOffset / this.tabsWidth)
    let currentIndex = swipeRatio > 0.5 ? nextIndex : index // 页面滑动超过一半，tabBar切换到下一页。
    let currentLeft = indexInfo.left + (nextIndexInfo.left - indexInfo.left) * swipeRatio
    let currentWidth = indexInfo.width + (nextIndexInfo.width - indexInfo.width) * swipeRatio
    return { 'index': currentIndex, 'left': currentLeft, 'width': currentWidth }
  }
  private startAnimateTo(duration: number, leftMargin: number, width: number) {
    animateTo({
      duration: duration, // 动画时长
      curve: Curve.Linear, // 动画曲线
      iterations: 1, // 播放次数
      playMode: PlayMode.Normal, // 动画模式
      onFinish: () => {
        console.info('play end')
      }
    }, () => {
      this.indicatorLeftMargin = leftMargin
      this.tabWidth = width
      this.indicatorWidth = width
    })
  }
}