uniappにドラッグ＆ドロップの並べ替え機能を実装する方法

<template>
  <view class="list">
    <view class="item" v-for="(item, index) in list" :key="item.id"
      @touchstart="handleTouchStart(index)" @touchmove="handleTouchMove(index)">
      {{ item.name }}
    </view>
  </view>
</template>

<script>
export default {
  data() {
    return {
      list: [
        { id: 1, name: '元素1' },
        { id: 2, name: '元素2' },
        { id: 3, name: '元素3' },
        { id: 4, name: '元素4' },
        { id: 5, name: '元素5' },
      ],
      startX: 0,
      startY: 0,
      currentIndex: -1,
    }
  },
  methods: {
    handleTouchStart(index) {
      this.currentIndex = index
      this.startX = event.changedTouches[0].clientX
      this.startY = event.changedTouches[0].clientY
    },
    handleTouchMove(index) {
      let moveX = event.changedTouches[0].clientX
      let moveY = event.changedTouches[0].clientY
      let offsetX = moveX - this.startX
      let offsetY = moveY - this.startY

      // 拖拽过程中可以根据 offsetX 和 offsetY 实现一些交互效果，例如改变元素的位置、颜色等
    },
  },
}
</script>

<style>
.item {
  width: 100%;
  height: 100px;
  line-height: 100px;
  text-align: center;
  border: 1px solid #ccc;
  margin-bottom: 10px;
}
</style>

methods: {
  handleTouchMove(index) {
    let moveX = event.changedTouches[0].clientX
    let moveY = event.changedTouches[0].clientY
    let offsetX = moveX - this.startX
    let offsetY = moveY - this.startY

    // 计算当前拖拽的元素索引和目标位置元素的索引
    let dragIndex = this.currentIndex
    let targetIndex = Math.floor((index * offsetY) / 100)

    // 交换元素的位置
    if (targetIndex >= 0 && targetIndex < this.list.length && targetIndex !== dragIndex) {
      let dragItem = this.list[dragIndex]
      this.list.splice(dragIndex, 1)
      this.list.splice(targetIndex, 0, dragItem)
      this.currentIndex = targetIndex
    }

    // 将 currentIndex 设为 -1，表示拖拽结束
    if (event.type === 'touchend') {
      this.currentIndex = -1
    }
  },
},

<template>
  <view class="list" @touchend="handleTouchMove(-1)">
    <!-- 列表元素 -->
  </view>
</template>

<script>
// 其他代码
methods: {
  // 其他方法
  handleTouchMove(index) {
    // 其他逻辑

    // 将 currentIndex 设为 -1，表示拖拽结束
    if (event.type === 'touchend') {
      this.currentIndex = -1
    }
  },
},
</script>