HarmonyOS List第一个可见的ListItem

@Entry  
@Component  
struct ListExample {  
  private arr: (number | string)[] =  
    [0, '概览', '周边', 3, 4, '房源', 6, 7, '小区', 9, 10, 11, 12, 13, 14, 15]  
  private tabArr: string[] = ['概览', '周边', '房源', '小区']  
  @State currentIndex: number = 0  
  build() {  
    Column() {  
      Row() {  
        ForEach(this.tabArr, (item: string, index: number) => {  
          Text(item)  
            .fontColor(this.currentIndex === index ? Color.Blue : '')  
        })  
      }  
      .width('100%')  
      .padding({ left: 20 })  
      .alignItems(VerticalAlign.Top)  
  
      List({ space: 20, initialIndex: 0 }) {  
        ForEach(this.arr, (item: number) => {  
          ListItem() {  
            Text('' + item)  
              .width('100%')  
              .height(100)  
              .fontSize(16)  
              .textAlign(TextAlign.Center)  
              .borderRadius(10)  
              .backgroundColor(0xFFFFFF)  
          }  
        }, (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)  
        if (firstIndex == 1) {  
          this.currentIndex = 0  
        } else if (firstIndex == 2) {  
          this.currentIndex = 1  
        } else if (firstIndex == 5) {  
          this.currentIndex = 2  
        } else if (firstIndex == 8) {  
          this.currentIndex = 3  
        }  
      })  
      .width('90%')  
    }.width('100%').height('100%').backgroundColor(0xDCDCDC).padding({ top: 5 })  
  }  
}