HarmonyOS waterflow组件卡片删除缺少动画

// WaterFlowDataSource.ets  
// 实现IDataSource接口的对象，用于瀑布流组件加载数据  
export class WaterFlowDataSource implements IDataSource {  
  dataArray: number[] = []  
  private listeners: DataChangeListener[] = []  
  constructor() {  
    for (let i = 0; i < 100; i++) {  
      this.dataArray.push(i)  
    }  
  }  
  // 获取索引对应的数据  
  public getData(index: number): number {  
    return this.dataArray[index]  
  }  
  // 通知控制器数据重新加载  
  notifyDataReload(): void {  
    this.listeners.forEach(listener => {  
      listener.onDataReloaded()  
    })  
  }  
  // 通知控制器数据增加  
  notifyDataAdd(index: number): void {  
    this.listeners.forEach(listener => {  
      listener.onDataAdd(index)  
    })  
  }  
  // 通知控制器数据变化  
  notifyDataChange(index: number): void {  
    this.listeners.forEach(listener => {  
      listener.onDataChange(index)  
    })  
  }  
  // 通知控制器数据删除  
  notifyDataDelete(index: number): void {  
    this.listeners.forEach(listener => {  
      listener.onDataDelete(index)  
    })  
  }  
  // 通知控制器数据位置变化  
  notifyDataMove(from: number, to: number): void {  
    this.listeners.forEach(listener => {  
      listener.onDataMove(from, to)  
    })  
  }  
  //通知控制器数据批量修改  
  notifyDatasetChange(operations: DataOperation[]): void {  
    this.listeners.forEach(listener => {  
      listener.onDatasetChange(operations);  
    })  
  }  
  // 获取数据总数  
  public totalCount(): number {  
    return this.dataArray.length  
  }  
  // 注册改变数据的控制器  
  registerDataChangeListener(listener: DataChangeListener): void {  
    if (this.listeners.indexOf(listener) < 0) {  
      this.listeners.push(listener)  
    }  
  }  
  // 注销改变数据的控制器  
  unregisterDataChangeListener(listener: DataChangeListener): void {  
    const pos = this.listeners.indexOf(listener)  
    if (pos >= 0) {  
      this.listeners.splice(pos, 1)  
    }  
  }  
  // 增加数据  
  public add1stItem(): void {  
    this.dataArray.splice(0, 0, this.dataArray.length)  
    this.notifyDataAdd(0)  
  }  
  // 在数据尾部增加一个元素  
  public addLastItem(): void {  
    this.dataArray.splice(this.dataArray.length, 0, this.dataArray.length)  
    this.notifyDataAdd(this.dataArray.length - 1)  
  }  
  // 在指定索引位置增加一个元素  
  public addItem(index: number): void {  
    this.dataArray.splice(index, 0, this.dataArray.length)  
    this.notifyDataAdd(index)  
  }  
  // 删除第一个元素  
  public delete1stItem(): void {  
    this.dataArray.splice(0, 1)  
    this.notifyDataDelete(0)  
  }  
  // 删除第二个元素  
  public delete2ndItem(): void {  
    this.dataArray.splice(1, 1)  
    this.notifyDataDelete(1)  
  }  
  // 删除最后一个元素  
  public deleteLastItem(): void {  
    this.dataArray.splice(-1, 1)  
    this.notifyDataDelete(this.dataArray.length)  
  }  
  // 在指定索引位置删除一个元素  
  public deleteItem(index: number): void {  
    this.dataArray.splice(index, 1)  
    this.notifyDatasetChange([{type: DataOperationType.DELETE, index: index, count: 1}])  
  }  
  // 重新加载数据  
  public reload(): void {  
    this.dataArray.splice(1, 1)  
    this.dataArray.splice(3, 2)  
    this.notifyDataReload()  
  }  
}  
@Entry  
@Component  
struct WaterFlowDemo {  
  @State minSize: number = 80  
  @State maxSize: number = 180  
  @State fontSize: number = 24  
  @State colors: number[] = [0xFFC0CB, 0xDA70D6, 0x6B8E23, 0x6A5ACD, 0x00FFFF, 0x00FF7F]  
  scroller: Scroller = new Scroller()  
  dataSource: WaterFlowDataSource = new WaterFlowDataSource()  
  private itemWidthArray: number[] = []  
  private itemHeightArray: number[] = []  
  // 计算FlowItem宽/高  
  getSize() {  
    let ret = Math.floor(Math.random() * this.maxSize)  
    return (ret > this.minSize ? ret : this.minSize)  
  }  
  // 设置FlowItem的宽/高数组  
  setItemSizeArray() {  
    for (let i = 0; i < 100; i++) {  
      this.itemWidthArray.push(this.getSize())  
      this.itemHeightArray.push(this.getSize())  
    }  
  }  
  aboutToAppear() {  
    this.setItemSizeArray()  
  }  
  @Builder  
  itemFoot() {  
    Column() {  
      Text(`Footer`)  
        .fontSize(10)  
        .backgroundColor(Color.Red)  
        .width(50)  
        .height(50)  
        .align(Alignment.Center)  
        .margin({ top: 2 })  
    }  
  }  
  build() {  
    Column({ space: 2 }) {  
      WaterFlow() {  
        LazyForEach(this.dataSource, (item: number) => {  
          FlowItem() {  
            Column() {  
              Text("N" + item).fontSize(12).height('16')  
              Image('res/waterFlowTest(' + item % 5 + ').jpg')  
                .objectFit(ImageFit.Fill)  
                .width('100%')  
                .layoutWeight(1)  
            }  
            .onClick(()=> {  
              animateTo({  
                duration: 300,  
                curve: Curve.Smooth  
              }, ()=> {  
                let index = this.dataSource.dataArray.indexOf(item)  
                this.dataSource.deleteItem(index)  
              })  
            })  
          }  
          .onAppear(() => {  
            // 即将触底时提前增加数据  
            if (item + 20 == this.dataSource.totalCount()) {  
              for (let i = 0; i < 100; i++) {  
                this.dataSource.addLastItem()  
              }  
            }  
          })  
          .width('100%')  
          .height(this.itemHeightArray[item % 100])  
          .backgroundColor(this.colors[item % 5])  
        }, (item: string) => item)  
      }  
      .columnsTemplate("1fr 1fr")  
      .columnsGap(10)  
      .rowsGap(5)  
      .backgroundColor(0xFAEEE0)  
      .width('100%')  
      .height('100%')  
      .onReachStart(() => {  
        console.info('waterFlow reach start')  
      })  
      .onScrollStart(() => {  
        console.info('waterFlow scroll start')  
      })  
      .onScrollStop(() => {  
        console.info('waterFlow scroll stop')  
      })  
      .onScrollFrameBegin((offset: number, state: ScrollState) => {  
        console.info('waterFlow scrollFrameBegin offset: ' + offset + ' state: ' + state.toString())  
        return { offsetRemain: offset }  
      })  
    }  
  }  
}
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