HarmonyOS list的item拖拽到底部的时候，list无法向上滚动

import curves from '@ohos.curves'; 
import Curves from '@ohos.curves' 
// xxx.ets 
@Entry 
@Component 
struct ListItemExample { 
  @State private arr: number[] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] 
  @State dragItem: number = -1 
  @State scaleItem: number = -1 
  @State neighborItem: number = -1 
  @State neighborScale: number = -1 
  private dragRefOffset: number = 0 
  @State offsetX: number = 0 
  @State offsetY: number = 0 
  private ITEM_INTV: number = 120 
 
  private listScroller: ListScroller = new ListScroller() 
  // list组件规格 
  private listArea: Area = { 
    width: 0, 
    height: 0, 
    position: {}, 
    globalPosition: {} 
  } 
 
  scaleSelect(item: number): number { 
    if (this.scaleItem == item) { 
      return 1.05 
    } else if (this.neighborItem == item) { 
      return this.neighborScale 
    } else { 
      return 1 
    } 
  } 
  itemMove(index: number, newIndex: number): void { 
    let tmp = this.arr.splice(index, 1) 
    this.arr.splice(newIndex, 0, tmp[0]) 
  } 
  build() { 
    Stack() { 
      List({ space: 20, initialIndex: 0, scroller: this.listScroller }) { 
        ForEach(this.arr, (item: number) => { 
          ListItem() { 
            Text('' + item) 
              .width('100%') 
              .height(100) 
              .fontSize(16) 
              .textAlign(TextAlign.Center) 
              .borderRadius(10) 
              .backgroundColor(0xFFFFFF) 
              .shadow(this.scaleItem == item ? { radius: 70, color: '#15000000', offsetX: 0, offsetY: 0 } : 
                { radius: 0, color: '#15000000', offsetX: 0, offsetY: 0 }) 
              .animation({ curve: Curve.Sharp, duration: 300 }) 
          } 
          .margin({ left: 12, right: 12 }) 
          .scale({ x: this.scaleSelect(item), y: this.scaleSelect(item) }) 
          .zIndex(this.dragItem == item ? 1 : 0) 
          .translate(this.dragItem == item ? { y: this.offsetY } : { y: 0 }) 
          .gesture( 
            // 以下组合手势为顺序识别，当长按手势事件未正常触发时则不会触发拖动手势事件 
            GestureGroup(GestureMode.Sequence, 
              LongPressGesture({ repeat: true }) 
                .onAction((event?: GestureEvent) => { 
                  animateTo({ curve: Curve.Friction, duration: 300 }, () => { 
                    this.scaleItem = item 
                  }) 
                }) 
                .onActionEnd(() => { 
                  animateTo({ curve: Curve.Friction, duration: 300 }, () => { 
                    this.scaleItem = -1 
                  }) 
                }), 
              PanGesture({ fingers: 1, direction: null, distance: 0 }) 
                .onActionStart(() => { 
                  this.dragItem = item 
                  this.dragRefOffset = 0 
                }) 
                .onActionUpdate((event: GestureEvent) => { 
                  this.offsetY = event.offsetY - this.dragRefOffset 
                  // console.log('Y:' + this.offsetY.toString()) 
                  this.neighborItem = -1 
                  let index = this.arr.indexOf(item) 
                  let curveValue = Curves.initCurve(Curve.Sharp) 
                  let value: number = 0 
                  //根据位移计算相邻项的缩放 
                  if (this.offsetY < 0) { 
                    value = curveValue.interpolate(-this.offsetY / this.ITEM_INTV) 
                    this.neighborItem = this.arr[index-1] 
                    this.neighborScale = 1 - value / 20; 
                    console.log('neighborScale:' + this.neighborScale.toString()) 
                  } else if (this.offsetY > 0) { 
                    value = curveValue.interpolate(this.offsetY / this.ITEM_INTV) 
                    this.neighborItem = this.arr[index+1] 
                    this.neighborScale = 1 - value / 20; 
                  } 
 
                  // 防止offsetY触发越界逻辑 
                  if (index === 0) { 
                    this.offsetY = Math.max(0, this.offsetY) 
                  } else if (index === this.arr.length - 1) { 
                    this.offsetY = Math.min(0, this.offsetY) 
                  } 
                  // 获取手指信息 
                  let fingerInfo = event.fingerList[0] 
                  let clickPercentY = (fingerInfo.globalY - Number(this.listArea.globalPosition.y)) / Number(this.listArea.height) 
                  let curListOffset = this.listScroller.currentOffset() 
                  // 根据触摸区域百分比确定自动上滑/下滑 
                  if (clickPercentY > 0.8 && !this.listScroller.isAtEnd()) { 
                    // 触摸到最底部加速滚动 
                    let scrollVelocity = clickPercentY > 0.9 ? 4 : 2 
                    this.listScroller.scrollTo({xOffset: 0, yOffset: curListOffset.yOffset += scrollVelocity}) 
                    this.dragRefOffset -= scrollVelocity 
                  } else if (clickPercentY < 0.2 && (index !== 0 || this.offsetY > 0)) { 
                    // 触摸到最顶部加速滚动 
                    let scrollVelocity = clickPercentY < 0.1 ? 4 : 2 
                    this.listScroller.scrollTo({xOffset: 0, yOffset: curListOffset.yOffset -= scrollVelocity}) 
                    this.dragRefOffset += scrollVelocity 
                  } 
 
                  //根据位移交换排序 
                  if (this.offsetY > this.ITEM_INTV / 2) { 
                    animateTo({ curve: curves.interpolatingSpring(0, 1, 400, 38) }, () => { 
                      this.offsetY -= this.ITEM_INTV 
                      this.dragRefOffset += this.ITEM_INTV 
                      this.itemMove(index, index + 1) 
                    }) 
                  } else if (this.offsetY < -this.ITEM_INTV / 2) { 
                    animateTo({ curve: curves.interpolatingSpring(0, 1, 400, 38) }, () => { 
                      this.offsetY += this.ITEM_INTV 
                      this.dragRefOffset -= this.ITEM_INTV 
                      this.itemMove(index, index - 1) 
                    }) 
                  } 
                }) 
                .onActionEnd((event: GestureEvent) => { 
                  animateTo({ curve: curves.interpolatingSpring(0, 1, 400, 38) }, () => { 
                    this.dragItem = -1 
                    this.neighborItem = -1 
                  }) 
                  animateTo({ 
                    curve: curves.interpolatingSpring(14, 1, 170, 17), delay: 150 
                  }, () => { 
                    this.scaleItem = -1 
                  }) 
                }) 
            ) 
              .onCancel(() => { 
                animateTo({ curve: curves.interpolatingSpring(0, 1, 400, 38) }, () => { 
                  this.dragItem = -1 
                  this.neighborItem = -1 
                }) 
                animateTo({ 
                  curve: curves.interpolatingSpring(14, 1, 170, 17), delay: 150 
                }, () => { 
                  this.scaleItem = -1 
                }) 
              }) 
          ) 
        }, (item: number) => item.toString()) 
      } 
      .onAreaChange((oldValue: Area, newValue: Area) => { 
        this.listArea = newValue 
      }) 
    }.width('100%').height('100%').backgroundColor(0xDCDCDC).padding({ top: 5 }) 
  } 
}