HarmonyOS 在waterflow使用lazyForEach刷新数据的时候首页图片会闪一下

使用@reusable 优化

其他实践demo

// Basic implementation of IDataSource to handle data listener

class BasicDataSource<T> implements IDataSource {
  private listeners: DataChangeListener[] = [];

  public totalCount(): number {
    return 0;
  }

  public getData(index: number): T {
    throw Error("not implemented yet");
  }

  // 该方法为框架侧调用，为LazyForEach组件向其数据源处添加listener监听
  registerDataChangeListener(listener: DataChangeListener): void {
    if (this.listeners.indexOf(listener) < 0) {
      console.info('add listener');
      this.listeners.push(listener);
    }
  }

  // 该方法为框架侧调用，为对应的LazyForEach组件在数据源处去除listener监听
  unregisterDataChangeListener(listener: DataChangeListener): void {
    const pos = this.listeners.indexOf(listener);
    if (pos >= 0) {
      console.info('remove listener');
      this.listeners.splice(pos, 1);
    }
  }

  // 通知LazyForEach组件需要重载所有子组件
  notifyDataReload(): void {
    this.listeners.forEach(listener => {
      listener.onDataReloaded();
    })
  }

  // 通知LazyForEach组件需要在index对应索引处添加子组件
  notifyDataAdd(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataAdd(index);
    })
  }



  // 通知LazyForEach组件在index对应索引处数据有变化，需要重建该子组件
  notifyDataChange(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataChange(index);
    })
  }

  // 通知LazyForEach组件需要在index对应索引处删除该子组件
  notifyDataDelete(index: number): void {
    this.listeners.forEach(listener => {
      listener.onDataDelete(index);
    })
  }

  // 通知LazyForEach组件将from索引和to索引处的子组件进行交换
  notifyDataMove(from: number, to: number): void {
    this.listeners.forEach(listener => {
      listener.onDataMove(from, to);
    })
  }
}

@Observed
export class ViewModel {
  id: string = ""
  uuid: string = ""

  constructor(id: string) {
    this.id = id;
    this.uuid = Math.random().toString()
  }
}

export class MyDataSource extends BasicDataSource<ViewModel> {

  static _id: number = -1;
  public dataArray: Array<ViewModel> = [];

  public totalCount(): number {
    // console.log('111---- this.dataArray.length : ' + this.dataArray.length)
    return this.dataArray.length;
  }

  public getData(index: number): ViewModel {
    return this.dataArray[index];
  }

  public loadMoreData(): void {
    let length = this.totalCount()
    console.log('111 --- benfore delete length = ' + length)
    for (let i = 0; i < length; i++) {

      this.notifyDataDelete(0);
    }
    console.log('111 --- after delete')
    this.dataArray.length = 0;
    for (let index = 0; index < 10; index++) {
      MyDataSource._id += 1;
      this.dataArray.push(new ViewModel(MyDataSource._id.toString()))

    }
  }

  public refreshData(): void {
    // this.dataArray.length = 0;
    this.loadMoreData();
  }

  public resetAndRefreshData(): void {
    MyDataSource._id = -1;
    this.dataArray.length = 0;
    this.loadMoreData();
  }

  public notifyDataChangeInRange(start: number, end: number): void {
    for (let i = start; i <= end; i++) {
      super.notifyDataChange(i)
    }
  }
}
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