ArkTS布局组件实现瀑布流式布局

export class WaterFlowDataSource implements IDataSource { 
  private 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): any { 
    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.onDataAdded(index) 
    }) 
  } 
  
  // 通知控制器数据变化 
  notifyDataChange(index: number): void { 
    this.listeners.forEach(listener => { 
      listener.onDataChanged(index) 
    }) 
  } 
  
  // 通知控制器数据删除 
  notifyDataDelete(index: number): void { 
    this.listeners.forEach(listener => { 
      listener.onDataDeleted(index) 
    }) 
  } 
  
  // 通知控制器数据位置变化 
  notifyDataMove(from: number, to: number): void { 
    this.listeners.forEach(listener => { 
      listener.onDataMoved(from, to) 
    }) 
  } 
  
  // 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) 
  } 
  
  // 重新加载数据 
  public Reload(): void { 
    this.dataArray.splice(1, 1) 
    this.dataArray.splice(3, 2) 
    this.notifyDataReload() 
  } 
}

import { WaterFlowDataSource } from '../model/WaterFlowDataSource' 
@Entry 
@Component 
struct WaterflowDemo { 
  @State minSize: number = 100 
  @State maxSize: number = 150 
  scroller: Scroller = new Scroller() 
  datasource: WaterFlowDataSource = new WaterFlowDataSource() 
  private itemHeightArray: number[] = [] 
  
  // 计算flow item宽/高 
  getSize() { 
    let ret = Math.floor(Math.random() * this.maxSize) 
    return (ret > this.minSize ? ret : this.minSize) 
  } 
  
  // 保存flow item宽/高 
  getItemSizeArray() { 
    for (let i = 0; i < 20; i++) { 
      this.itemHeightArray.push(this.getSize()) 
    } 
  } 
  
  aboutToAppear() { 
    this.getItemSizeArray() 
    this.datasource. 
  } 
  
  build() { 
    Column({ space: 2 }) { 
      WaterFlow({  scroller: this.scroller }) { 
        LazyForEach(this.datasource, (item: number) => { 
          FlowItem() { 
            Text(item.toString()) 
              .width('100%') 
              .height('100%') 
              .backgroundColor(0xFFFFFF) 
              .borderRadius(15) 
              .fontSize(16) 
              .textAlign(TextAlign.Center) 
              .margin({ top: 10 }) 
          } 
          .width('100%') 
          .height(this.itemHeightArray[item]) 
        }, item => item) 
      } 
      .columnsTemplate("1fr 1fr") 
      .columnsGap(10) 
      .rowsGap(5) 
      .backgroundColor(0xFAEEE0) 
      .width('100%') 
      .height('100%') 
      .layoutDirection(FlexDirection.Column) 
    } 
  } 
}