HarmonyOS 自定义tab，子页面无法监听到tab切换？

Question

自定义tab，子页面无法监听到tab切换，见如下代码《TestTabsPage.ets》

@Builder
 function JhkPageMain(index: number) {
  pageMain({currentIndex: index})
}

@Component
struct pageMain {
  @Prop @Watch('onCountUpdated') currentIndex: number = 0;
  @State total: number = 0;
  @State txt: string = '默认显示';
  // @Watch 回调
  onCountUpdated(propName: string): void {
    console.log('输出：currentIndex',this.currentIndex)
    console.log('输出：total',this.total)
    if (this.total != this.currentIndex) {
      this.txt = 'pageMain组件隐藏了'
    }else{
      this.txt = 'pageMain组件重新显示了'
    }
  }

  build() {
    Text(this.txt)
  }
}

@Builder
function JhkPageNews(index: number) {
  pageNews()
}

@Component
struct pageNews {
  build() {
    Column().width('100%').height('100%').backgroundColor('#ff0033cb')
  }
}


@Builder
function JhkPageMine(index: number) {
  pageMine()
}

@Component
struct pageMine {
  build() {
    Column().width('100%').height('100%').backgroundColor('#ffcb0018')
  }
}

@Builder
export function JhkTestTabsPage() {
  BuildPage()
}

@Component
struct BuildPage {
  contentBuilderList: WrappedBuilder<[number]>[] =
    [
      wrapBuilder(JhkPageMain),
      wrapBuilder(JhkPageNews),
      wrapBuilder(JhkPageMine),
    ];

  build() {
    tabsBuildPage({
      contentBuilderList: this.contentBuilderList
    })
  }
}

@Component
struct tabsBuildPage {
  @State fontColor: string = '#182431'
  @State selectedFontColor: string = '#007DFF'
  @State currentIndex: number = 0
  @State contentBuilderList: WrappedBuilder<[number]>[] = []
  private controller: TabsController = new TabsController()

  @Builder tabBuilder(index: number, name: string) {
    Column() {
      Text(name)
        .fontColor(this.currentIndex === index ? this.selectedFontColor : this.fontColor)
        .fontSize(16)
        .fontWeight(this.currentIndex === index ? 500 : 400)
        .lineHeight(22)
        .margin({ top: 17, bottom: 7 })
      Divider()
        .strokeWidth(2)
        .color('#007DFF')
        .opacity(this.currentIndex === index ? 1 : 0)
    }.width('100%')
  }

  build() {
    Column() {
      Tabs({ barPosition: BarPosition.Start, index: this.currentIndex, controller: this.controller }) {
        ForEach(this.contentBuilderList, (itemBuilder: WrappedBuilder<[number]>, index: number) => {
          TabContent() {
            itemBuilder.builder(index);
          }
          .tabBar(this.tabBuilder(index, `${index}`))
        })
      }
      .vertical(false)
      .barMode(BarMode.Fixed)
      .barWidth(360)
      .barHeight(56)
      .animationDuration(400)
      .onChange((index: number) => {
        this.currentIndex = index
      })
      .width(360)
      .height(296)
      .margin({ top: 52 })
      .backgroundColor('#F1F3F5')
    }.width('100%')
  }
}

Answer 1

请参考此demo：

class CurrentIndex {
  public currentIndex: number = 0;

  // constructor(currentIndex: number) {
  //   this.currentIndex = currentIndex;
  // }
}

@Builder
function JhkPageMain($$: CurrentIndex) {
  pageMain({currentIndex: $$.currentIndex})
}

@Component
struct pageMain {
  @Prop @Watch('onCountUpdated') currentIndex: number;
  @State total: number = 0;
  @State txt: string = '默认显示';

  aboutToAppear(): void {
    console.log('输出：',JSON.stringify(this.currentIndex))
  }

  // @Watch 回调
  onCountUpdated(propName: string): void {
    console.log('输出：currentIndex',this.currentIndex)
    console.log('输出：total',this.total)
    if (this.total != this.currentIndex) {
      this.txt = 'pageMain组件隐藏了'
    }else{
      this.txt = 'pageMain组件重新显示了'
    }
  }

  build() {
    Column(){
      Text(this.txt)
    }
  }
}

@Builder
function JhkPageNews(index: CurrentIndex) {
  pageNews()
}

@Component
struct pageNews {
  build() {
    Column().width('100%').height('100%').backgroundColor('#ff0033cb')
  }
}


@Builder
function JhkPageMine(index: CurrentIndex) {
  pageMine()
}

@Component
struct pageMine {
  build() {
    Column().width('100%').height('100%').backgroundColor('#ffcb0018')
  }
}

@Builder
export function JhkTestTabsPage() {
  BuildPage()
}

@Component
struct BuildPage {
  contentBuilderList: WrappedBuilder<[CurrentIndex]>[] =
    [
      wrapBuilder(JhkPageMain),
      wrapBuilder(JhkPageNews),
      wrapBuilder(JhkPageMine),
    ];

  build() {
    tabsBuildPage({
      contentBuilderList: this.contentBuilderList
    })
  }
}

@Component
struct tabsBuildPage {
  @State fontColor: string = '#182431'
  @State selectedFontColor: string = '#007DFF'
  @State currentIndex: CurrentIndex = new CurrentIndex()
  @State contentBuilderList: WrappedBuilder<[CurrentIndex]>[] = []
  private controller: TabsController = new TabsController()

  @Builder tabBuilder(index: number, name: string) {
    Column() {
      Text(name)
        .fontColor(this.currentIndex.currentIndex === index ? this.selectedFontColor : this.fontColor)
        .fontSize(16)
        .fontWeight(this.currentIndex.currentIndex === index ? 500 : 400)
        .lineHeight(22)
        .margin({ top: 17, bottom: 7 })
      Divider()
        .strokeWidth(2)
        .color('#007DFF')
        .opacity(this.currentIndex.currentIndex === index ? 1 : 0)
    }.width('100%')
  }

  build() {
    Column() {
      Tabs({ barPosition: BarPosition.Start, index: this.currentIndex.currentIndex, controller: this.controller }) {
        ForEach(this.contentBuilderList, (itemBuilder: WrappedBuilder<[CurrentIndex]>, index: number) => {
          TabContent() {
            itemBuilder.builder({ currentIndex: this.currentIndex.currentIndex });
          }
          .tabBar(this.tabBuilder(index, `${index}`))
        })
      }
      .vertical(false)
      .barMode(BarMode.Fixed)
      .barWidth(360)
      .barHeight(56)
      .animationDuration(400)
      .onChange((index: number) => {
        this.currentIndex.currentIndex = index
      })
      .width(360)
      .height(296)
      .margin({ top: 52 })
      .backgroundColor('#F1F3F5')
    }.width('100%')
  }
}

@Entry
@Component
struct Page {

  build() {
    Column(){
      JhkTestTabsPage()
    }
  }
}