HarmonyOS 如何使用自定义组件继承来实现组件的曝光统计

参考示例如下：

import { ListItemModifier } from '@ohos.arkui.modifier';
import { TAG } from '@ohos/hypium/src/Constant';

class MyButtonModifier implements AttributeModifier<ListItemModifier> {
  applyNormalAttribute(instance: ListItemModifier): void {
    instance
      .onVisibleAreaChange([0.0, 1.0], (isVisible: boolean, currentRatio: number) => {
        console.info('Test Text isVisible: ' + isVisible + ', currentRatio:' + currentRatio)
        if (isVisible && currentRatio >= 1.0) {
          this.onCompletelyVisible();
          console.info('Test Text is fully visible. currentRatio:' + currentRatio)
        }

        if (!isVisible && currentRatio <= 0.0) {
          console.info('Test Text is completely invisible.')
        }
      })
  }
  onCompletelyVisible() {
    // console.info(TAG,
    // `completely visible, ref-${this.channel?.id}, ${this.itemIndex}, ${printChannelItemBean(this.itemData)} `)
    // const pageInfo = buildPageInfo(this.itemData, this.channel, this.itemIndex.toString())
    // sendPageInfo(pageInfo)
  }
}

@Entry
@Component
struct MyModifier_isVisiable_ListItem {
  private arr: number[] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
  @State modifier: MyButtonModifier = new MyButtonModifier()

  build() {
    Column() {
      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)
          }
          .attributeModifier(this.modifier)
        }, (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 })
  }
}
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