HarmonyOS 获取text高度

可以通过onAreaChange获取

参考链接：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/ts-universal-component-area-change-event-V5#onareachange

参考demo：

// xxx.ets
@Entry
@Component
struct ListExample {
  private arr: number[] = [0, 1, 2]
  text1:string = 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'
  build() {
    Column() {
      List({ space: 20, initialIndex: 0 }) {
        ForEach(this.arr, (item: number) => {
          ListItem() {
            Text( item+': '+this.text1)
              .width('100%').height(100).fontSize(16)
              .textAlign(TextAlign.Center).borderRadius(10).backgroundColor(0xFFFFFF)
              .onAreaChange((oldValue, newValue) => {
                let textHeight = newValue.height.valueOf() as number
                console.info('textHeight '+ item + ' :' + textHeight)
              })
          }
        }, (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 })
  }
}