HarmonyOS 实现Tabs 后面添加更多标志的功能

import componentUtils from '@ohos.ArkUI.componentUtils';

@Entry
@Component
struct TabsExample22 {
  @State tabArray: Array<number> = [0, 1, 2]
  private controller: TabsController = new TabsController()
  @State currentIndex: number = 0
  @State animationDuration: number = 300
  @State indicatorLeftMargin: number = 0
  @State indicatorWidth: number = 0
  private tabsWidth: number = 0

  // 单独的页签
  @Builder
  Tab(tabName: string, tabItem: number, tabIndex: number) {
    Row({ space: 20 }) {
      Text(tabName).fontSize(18)
        .fontColor(tabItem === this.currentIndex ? Color.Red : Color.Black)
        .id(tabIndex.toString())
        .onAreaChange((oldValue: Area, newValue: Area) => {
          if (this.currentIndex === 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
          }
        })
    }
    .justifyContent(FlexAlign.Center)
    .constraintSize({ minWidth: 35 })
    .width(80)
    .height(35)
    .borderRadius({ topLeft: 10, topRight: 10 })
    .onClick(() => {
      this.controller.changeIndex(tabIndex)
      this.currentIndex = tabIndex
    })

  }

  build() {
    Column() {
      // 页签
      Stack({ alignContent: Alignment.TopStart }) {
        Scroll() {
          Row() {
            ForEach(this.tabArray, (item: number, index: number) => {
              this.Tab("页签 " + item, item, index)
            })


            Text('+')
              .width(36)
              .height(50)
              .fontSize(28)
              .borderRadius(5)
              .margin({ left: 88 })
              .padding({ left: 5, bottom: 2 })
          }
          .justifyContent(FlexAlign.Start)
        }
        .align(Alignment.Start)
        .scrollable(ScrollDirection.Horizontal)
        .scrollBar(BarState.Off)
        .width('100%')

        Column()
          .width(this.indicatorWidth)
          .height(2)
          .backgroundColor(Color.Red)
          .borderRadius(2)
          .margin({ left: this.indicatorLeftMargin, top: 38 })
      }
      .width('100%')
      .width('100%')

      //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.Pink)
        })
      }
      .onAreaChange((oldValue: Area, newValue: Area) => {
        let width = Number.parseFloat(newValue.width.toString())
        this.tabsWidth = Number.isNaN(width) ? 0 : width
      })
      .barWidth('100%')
      .barHeight(0)
      .width('100%')
      .height('100%')
      .backgroundColor('#F1F3F5')
      .animationDuration(this.animationDuration)
      .onChange((index: number) => {
        this.currentIndex = index // 监听索引index的变化，实现页签内容的切换。
      })
      .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，同时宽度渐变。
        this.currentIndex = 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.currentIndex = currentIndicatorInfo.index
        this.indicatorLeftMargin = currentIndicatorInfo.left
        this.indicatorWidth = currentIndicatorInfo.width
      })
    }
    .height('100%')
  }

  // 获取组件大小、位置、平移缩放旋转及仿射矩阵属性信息。
  private getTextInfo(index: number): Record<string, number> {
    let modePosition: componentUtils.ComponentInfo = componentUtils.getRectangleById(index.toString());
    return { 'left': px2vp(modePosition.windowOffset.x), 'width': px2vp(modePosition.size.width) }
  }

  private getCurrentIndicatorInfo(index: number, event: TabsAnimationEvent): Record<string, number> {
    let nextIndex = index
    if (index > 0 && event.currentOffset > 0) {
      nextIndex--
    } else if (index < 3 && 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.indicatorWidth = width
    })
  }
}
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