ElementUI的Dialog对话框实现拖拽移动功能

在项目中的directive文件夹里，新建draggable.js，路径是src/directive/draggable.js

import Vue from 'vue'

// v-dialogDrag: 弹窗拖拽
Vue.directive('dialogDrag', {
  bind(el, binding, vnode, oldVnode) {
    const dialogHeaderEl = el.querySelector('.el-dialog__header')
    const dragDom = el.querySelector('.el-dialog')
    dialogHeaderEl.style.cursor = 'move'

    // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
    const sty = (function () {
      if (window.document.currentStyle) {
        return (dom, attr) => dom.currentStyle[attr]
      } else {
        return (dom, attr) => getComputedStyle(dom, false)[attr]
      }
    })()

    dialogHeaderEl.onmousedown = (e) => {
      // 防止拖拽时影响其他元素
      e.preventDefault()

      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - dialogHeaderEl.offsetLeft
      const disY = e.clientY - dialogHeaderEl.offsetTop

      // body当前宽度
      const screenWidth = document.body.clientWidth
      // 可见区域高度(应为body高度，可某些环境下无法获取)
      const screenHeight = document.documentElement.clientHeight
      // 对话框宽度
      const dragDomWidth = dragDom.offsetWidth
      // 对话框高度
      const dragDomheight = dragDom.offsetHeight
      const minDragDomLeft = dragDom.offsetLeft
      const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth
      const minDragDomTop = dragDom.offsetTop
      const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight
      // 获取到的值带px 正则匹配替换
      let styL = sty(dragDom, 'left')
      let styT = sty(dragDom, 'top')

      // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
      if (styL.includes('%')) {
        // eslint-disable-next-line no-useless-escape
        styL = +document.body.clientWidth * (+styL.replace(/\%/g, '') / 100)
        // eslint-disable-next-line no-useless-escape
        styT = +document.body.clientHeight * (+styT.replace(/\%/g, '') / 100)
      } else {
        styL = +styL.replace(/\px/g, '')
        styT = +styT.replace(/\px/g, '')
      }

      document.onmousemove = function(e) {
        // 通过事件委托，计算移动的距离
        const l = e.clientX - disX
        const t = e.clientY - disY

        // 移动当前元素
        dragDom.style.left = `${l + styL}px`
        dragDom.style.top = `${t + styT}px`
      }

      document.onmousemove = (e) => {
        // 通过事件委托，计算移动的距离
        let left = e.clientX - disX
        let top = e.clientY - disY

        // 边界处理
        if (-left > minDragDomLeft) {
          left = -minDragDomLeft
        } else if (left > maxDragDomLeft) {
          left = maxDragDomLeft
        }
        if (-top > minDragDomTop) {
          top = -minDragDomTop
        } else if (top > maxDragDomTop) {
          top = maxDragDomTop
        }

        // 移动当前元素
        dragDom.style.cssText += `;left:${left + styL}px;top:${
          top + styT
        }px;transform:translateX(0)`
      }

      document.onmouseup = () => {
        document.onmousemove = null
        document.onmouseup = null
      }
      return false
    }
  }
})

// v-dialogDragWidth: 弹窗宽度拖大 拖小
Vue.directive('dialogDragWidth', {
  bind(el, binding, vnode, oldVnode) {
    const dragDom = binding.value.$el.querySelector('.el-dialog')

    el.onmousedown = (e) => {
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - el.offsetLeft

      document.onmousemove = function(e) {
        e.preventDefault() // 移动时禁用默认事件

        // 通过事件委托，计算移动的距离
        const l = e.clientX - disX
        dragDom.style.width = `${l}px`
      }

      document.onmouseup = function(e) {
        document.onmousemove = null
        document.onmouseup = null
      }
    }
  }
})

在main.js中引入：

import '@/directive/draggable.js'

使用：

 <el-dialog
  title="可拖拽对话框"
  :visible.sync="modelVisible"
  v-dialogDrag
  :before-close="handleCancel"
  :close-on-click-modal="false">
  <div>我是一个可拖拽的对话框</div>
</el-dialog>