HarmonyOS RelativeContainer相关问题

可参考示例：https://gitee.com/harmonyos-cases/cases/blob/master/CommonAppDevelopment/feature/refreshtimeline/README.md

可以参考示例，用onAeraChange获取右侧高度，设置左侧线的高度：

@Component
struct test {
  @State item: string = ''
  @State h: number = 0

  build() {
    Row() {
      Line()
        .stroke('#CCCCCC')
        .startPoint([0, 0])
        .endPoint([0, this.h])
        .stroke(Color.Red)
        .strokeWidth(5)
        .strokeDashArray([10, 3])
        .height(this.h)
        .width(5)
      Column() {
        Text(this.item)
          .width('100%')
          .fontSize(16)
          .textAlign(TextAlign.Center)
          .borderRadius(10)
          .backgroundColor(0xFFFFFF)
        Button('我的')
      }.onAreaChange((oldValue: Area, newValue: Area) => {
        console.info(`Ace: on area change, oldValue is ${JSON.stringify(oldValue)} value is ${JSON.stringify(newValue)}`)
        this.h = newValue.height as number
      })
    }
  }
}

// xxx.ets
@Entry
@Component
struct ListExample {
  private arr: string[] =
    ['xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx', 'xxxxxxxxxx',      'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx']

  build() {
    Column() {
      List({ space: 20, initialIndex: 0 }) {
        ForEach(this.arr, (item: string) => {
          ListItem() {
            test({ item: item })
          }
        }, (item: string) => item)
      }
      .listDirection(Axis.Vertical) // 排列方向
      .scrollBar(BarState.Off)
      .friction(0.6)
      .divider({
        strokeWidth: 2,
        color: 0xFFFFFF,
        startMargin: 20,
        endMargin: 20
      }) // 每行之间的分界线
      .edgeEffect(EdgeEffect.Spring) // 边缘效果设置为Spring
      .onScrollIndex((firstIndex: number, lastIndex: number, centerIndex: number) => {
        console.info('first' + firstIndex)
        console.info('last' + lastIndex)
        console.info('center' + centerIndex)
      })
      .onScrollVisibleContentChange((start: VisibleListContentInfo, end: VisibleListContentInfo) => {
        console.log(' start index: ' + start.index +
          ' start item group area: ' + start.itemGroupArea +
          ' start index in group: ' + start.itemIndexInGroup)
        console.log(' end index: ' + end.index +
          ' end item group area: ' + end.itemGroupArea +
          ' end index in group: ' + end.itemIndexInGroup)
      })
      .onDidScroll((scrollOffset: number, scrollState: ScrollState) => {
        console.info(`onScroll scrollState = ScrollState` + scrollState + `, scrollOffset = ` + scrollOffset)
      })
      .width('90%')
    }
    .width('100%')
    .height('100%')
    .backgroundColor(0xDCDCDC)
    .padding({ top: 5 })
  }
}