HarmonyOS tabs组件在只有少量tab的时，怎么设置让tab居中

参考示例如下：

import { componentUtils, display } from '@kit.ArkUI';
import curves from '@ohos.curves';

@Entry
@Component
struct Index {
  @State text: string = ''
  textInputController: TextInputController = new TextInputController()
  @State tabArray: Array<number> = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
  @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 scrollController: Scroller = new Scroller();
  private animationCurve: ICurve = curves.interpolatingSpring(7, 1, 328, 34); // 动画曲线

  aboutToAppear(): void {

  }

  // 单独的页签
  @Builder
  Tab(tabName: string, tabItem: number, tabIndex: number) {
    Row({ space: 7 }) {
      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.indicatorWidth = Number.isNaN(width) ? 0 : width
          }
        })
        .border(this.focusIndex == tabIndex ? {
          width: {
            left: 0,
            right: 0,
            top: 0,
            bottom: 2
          },
          color: { bottom: Color.Blue },
          radius: 0,
          style: {
            bottom: BorderStyle.Solid,
          }
        } : null)
    }
    .justifyContent(FlexAlign.Start)
    .constraintSize({ minWidth: 35 })
    .width(100)
    .height(30)
    .onClick(() => {
      console.debug("maotest onclick " + tabIndex)
      this.controller.changeIndex(tabIndex)
      this.focusIndex = tabIndex
    })
    .backgroundColor("#ffb7b7b7")
  }

  build() {
    Column() {
      Stack({ alignContent: Alignment.TopStart }) {
        Column() {
          // 页签
          Row({ space: 8 }) {
            Scroll(this.scrollController) {
              Row() {
                ForEach(this.tabArray, (item: number, index: number) => {
                  this.Tab("页签 " + item, item, index)
                })
              }
              .justifyContent(FlexAlign.Start)
            }
            .align(Alignment.Start)
            .scrollable(ScrollDirection.Horizontal)
            .scrollBar(BarState.Off)
            .width('100%')
            .backgroundColor("#ffb7b7b7")
            .onScrollFrameBegin((offset: number) => {
              let modePosition: componentUtils.ComponentInfo =
                componentUtils.getRectangleById(this.focusIndex.toString());
              try {
                this.indicatorLeftMargin = px2vp(modePosition.windowOffset.x);
              } catch (error) {
                console.error("")
              }
              return { offsetRemain: offset };
            })

          }
          .alignItems(VerticalAlign.Bottom)
          .width('100%')
          .backgroundColor("#ffb7b7b7")

        }
        .alignItems(HorizontalAlign.Start)
        .width('100%')


        Column()
          .height(10)
          .width("20%")
          .margin({ left: '80%', top: 28 })
          .backgroundColor("#ffb7b7b7")
      }
      .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 + " 的内容的内容的内容的内容的内容的内容的内容的内容的内容的内容的内容的内容的内容")
              .height(300)
              .width('100%')
              .fontSize(30)
          }
          .backgroundColor(Color.Blue)
        })
      }
      .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
      })
      .onAnimationStart((index: number, targetIndex: number, event: TabsAnimationEvent) => {
        console.debug("maotest onAnimationStart event.currentOffset: " + event.currentOffset)
        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)
        console.debug("maotest onAnimationEnd left: " + currentIndicatorInfo.left + ", widtch:" +
        currentIndicatorInfo.width)

        this.scrollIntoView(currentIndicatorInfo.index);
      })

      .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
        console.debug("maotest onGestureSwipe focusIndex: " + this.focusIndex
          + ", indicatorLeftMargin: " + this.indicatorLeftMargin + ", indicatorWidth: " + this.indicatorWidth)
      })
    }
    .height('100%')
  }

  private scrollIntoView(currentIndex: number): void {
    const indexInfo = this.getTextInfo(currentIndex);
    let tabPositionLeft = indexInfo.left;
    let tabWidth = indexInfo.width;
    // 获取屏幕宽度，单位vp
    const screenWidth = this.getDisplayWidth();
    //当前滚动的偏移量
    const currentOffsetX: number = this.scrollController.currentOffset().xOffset;

    // 将页签bar定位在正中间
    this.scrollController.scrollTo({
      xOffset: currentOffsetX + tabPositionLeft - screenWidth / 2 + tabWidth / 2,
      yOffset: 0,
      animation: {
        duration: this.animationDuration,
        // 动画曲线
        curve: this.animationCurve,
      }
    });
  }

  // 获取屏幕宽度，单位vp
  private getDisplayWidth(): number {
    const displayInfo = display.getDefaultDisplaySync()
    return displayInfo != null ? px2vp(displayInfo.width) : 0;
  }

  private getTextInfo(index: number): Record<string, number> {
    let modePosition: componentUtils.ComponentInfo = componentUtils.getRectangleById(index.toString());
    try {
      return { 'left': px2vp(modePosition.windowOffset.x), 'width': px2vp(modePosition.size.width) }
    } catch (error) {
      return { 'left': 0, 'width': 0 }
    }
  }

  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)
    console.info('maotest event.currentOffset:' + event.currentOffset + 'nextIndex:' + nextIndex + ', index: ' + index +
      ", swipeRatio: " + swipeRatio)
    console.info('maotest nextIndex:' + nextIndex + ', index: ' + index + ", swipeRatio: " + swipeRatio)
    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
    this.focusIndex = currentIndex
    console.info('maotest index:' + currentIndex, 'left:' + currentLeft, 'width:' + currentWidth)
    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
    })
  }
}
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