HarmonyOS 鸿蒙Next 在ArkTS中，如何实现一个支持拖拽排序的列表组件？

可以参考：

import curves from '@ohos.curves';
import { hilog } from '@kit.PerformanceAnalysisKit';
@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
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 }) {
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(
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
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;
hilog.info(0X0000, ‘testTag’, ‘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;
}
//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())
}
}.width(‘100%’).height(‘100%’).backgroundColor(0xDCDCDC).padding({ top: 5 })
}
}