How to implement drag and drop sorting function in uniapp

How to implement drag-and-drop sorting function in uniapp

Drag-and-drop sorting is a common user interaction method that allows users to change the order of elements by dragging them. In uniapp, we can implement the drag and drop sorting function by using the component library and some basic drag events. The following will introduce in detail how to implement the drag and drop sorting function in uniapp, with code examples.

Step 1: Create a basic list page

First, we need to create a basic list page to display the elements that need to be sorted. You can use the 89c662c6f8b87e82add978948dc499d2 tag to create a list, and each list item can be represented by the 89c662c6f8b87e82add978948dc499d2 or dc6dce4a544fdca2df29d5ac0ea9906b tag. In the 89c662c6f8b87e82add978948dc499d2 tag, add a @touchstart event and a @touchmove event to handle the interaction logic during the dragging process.

Code example:

<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>

Step 2: Process the drag sorting logic

In the handleTouchMove method, we can implement it based on the drag displacement Exchange of elements. First, calculate the index of the currently dragged element and the index of the element at the target position. Then, swap their positions in the list and update the list data. Finally, set currentIndex to -1, indicating the end of dragging.

Code example:

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
    }
  },
},

Step 3: Add drag release event

For a better user experience, we can also add a @touchend Event, used to handle the logic when dragging and releasing. In the handleTouchMove method, when the event type is touchend, set currentIndex to -1, indicating the end of dragging.

Code example:

<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>

To sum up, by adding basic drag events and swap position logic, we can implement the drag sorting function in uniapp. During the dragging process, we can modify the style and interactive effects according to actual needs to improve the user experience. I hope this article can help you implement drag-and-drop sorting function!

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