HarmonyOS 自定义的TabItem的坐标怎么获取？

export class TabBarDataType {  
  id: number;  
  selectedIcon: ResourceStr;  
  defaultIcon: ResourceStr;  
  
  constructor(id: number, selectedIcon: ResourceStr, defaultIcon: ResourceStr) {  
    this.id = id;  
    this.selectedIcon = selectedIcon;  
    this.defaultIcon = defaultIcon;  
  }  
}  
  
export const TABINFO: TabBarDataType[] = [  
  new TabBarDataType(0, $r('app.media.ic_product01'), $r('app.media.ic_product_normal')),  
  new TabBarDataType(1, $r('app.media.ic_product01'), $r('app.media.ic_product_normal')),  
  new TabBarDataType(2, $r('app.media.ic_product01'), $r('app.media.ic_product_normal')),  
  new TabBarDataType(3, $r('app.media.ic_product01'), $r('app.media.ic_product_normal')),  
  new TabBarDataType(4, $r('app.media.ic_product01'), $r('app.media.ic_product_normal')),  
  new TabBarDataType(5, $r('app.media.ic_product01'), $r('app.media.ic_product_normal')),  
  
];  
  
@Entry  
@Component  
struct TabViewDemo {  
  @Provide selectedIndex: number = 0; // 初始化被选定的tabBar下标  
  private controller: TabsController = new TabsController(); // 初始化Tab控制器  
  
  build() {  
    Column() {  
      // 自定义TabBar组件  
      CustomTabBar({ selectedIndex: $selectedIndex })  
      Tabs({ index: this.selectedIndex, barPosition: BarPosition.End, controller: this.controller }) {  
        ForEach(TABINFO, (item: TabBarDataType, tabIndex: number) => {  
          // 单独一个TabBar组件  
          TabContent() {  
            Text("tab" + item.id).fontSize(26)  
          }  
        })  
      }  
      .vertical(false)  
      .scrollable(true)  
      .layoutWeight(1)  
      .backgroundColor('#ffdbd9d9')  
      .barHeight(0)  
      .onChange((index: number) => {  
        this.selectedIndex = index;  
      })  
    }.width("100%").height("100%")  
  }  
}  
  
@Component  
struct CustomTabBar {  
  @Link @Watch("scrollTo") selectedIndex: number; // 初始化被选定的tabBar下标  
  private scrollerForScroll: Scroller = new Scroller()  
  private scrollerForList: Scroller = new Scroller()  
  
  scrollTo() {  
    this.scrollerForList.scrollToIndex(this.selectedIndex, false, ScrollAlign.CENTER)  
  }  
  
  build() {  
    Scroll() {  
      Row() {  
        List({ space: 20, scroller: this.scrollerForList }) {  
          ForEach(TABINFO, (item: TabBarDataType, tabIndex: number) => {  
            // 单独一个TabBar组件  
            TabItem({  
              tabBarIndex: tabIndex,  
              selectedIndex: $selectedIndex,  
            })  
          })  
        }.width('100%').listDirection(Axis.Horizontal)  
        .scrollBar(BarState.Off)  
      }  
    }  
    .scrollBar(BarState.Off)  
    .scrollable(ScrollDirection.Horizontal)  
    .height(60)  
  }  
}  
  
@Component  
struct TabItem {  
  @Prop tabBarIndex: number; // tabBar下标  
  @Link selectedIndex: number; // 初始化被选定的tabBar下标  
  
  build() {  
    Column() {  
      Column() {  
        // 通过被选中的tabBar下标值和tabBar的默认下标值来改变图片显示  
        Image(this.selectedIndex === this.tabBarIndex ? TABINFO[this.tabBarIndex].selectedIcon :  
        TABINFO[this.tabBarIndex].defaultIcon)  
          .interpolation(ImageInterpolation.High)  
          .size(  
            { width: 28, height: 28 })  
      }  
      .width(37)  
      .height(37)  
      .justifyContent(FlexAlign.Center)  
    }  
    .width(60)  
    .onClick(() => {  
      // 更新被选中的tabBar下标  
      this.selectedIndex = this.tabBarIndex;  
    })  
  }  
}