vue使用自定义指令v-dialogDrag来控制element ui中el-dialog的拖动缩放，拉伸问题

1 在vue的utils中新建一个dialogDrag.js

import Vue from 'vue'
Vue.directive('dialogDrag', {
  bind(el, binding, vnode, oldVnode) {
    //弹框可拉伸最小宽高
    let minWidth = 400;
    let minHeight = 300;
    //初始非全屏
    let isFullScreen = false;
    //当前宽高
    let nowWidth = 0;
    let nowHight = 0;
    //当前顶部高度
    let nowMarginTop = 0;
    //获取弹框头部（这部分可双击全屏）
    const dialogHeaderEl = el.querySelector('.el-dialog__header');
    //弹窗
    const dragDom = el.querySelector('.el-dialog');
    //给弹窗加上overflow auto；不然缩小时框内的标签可能超出dialog；
    dragDom.style.overflow = "auto";
    //清除选择头部文字效果
    dialogHeaderEl.onselectstart = new Function("return false");  
    //头部加上可拖动cursor
    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 = dragDom.currentStyle || window.getComputedStyle(dragDom, null);

    let moveDown = (e) => {
      // 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;

      // 获取到的值带px 正则匹配替换
      let styL, styT;

      // 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 (sty.left.includes('%')) {
        styL = +document.body.clientWidth * (+sty.left.replace(/\%/g, '') / 100);
        styT = +document.body.clientHeight * (+sty.top.replace(/\%/g, '') / 100);
      } else {
        styL = +sty.left.replace(/px/g, '');
        styT = +sty.top.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`;

        //将此时的位置传出去
        //binding.value({x:e.pageX,y:e.pageY})
      };

      document.onmouseup = function (e) {
        document.onmousemove = null;
        document.onmouseup = null;
      };
    }
    dialogHeaderEl.onmousedown = moveDown;
    //双击头部效果
    dialogHeaderEl.ondblclick = (e) => {
      if (isFullScreen == false) {
        nowHight = dragDom.clientHeight;
        nowWidth = dragDom.clientWidth;
        nowMarginTop = dragDom.style.marginTop;
        dragDom.style.left = 0;
        dragDom.style.top = 0;
        dragDom.style.height = "100VH";
        dragDom.style.width = "100VW";
        dragDom.style.marginTop = 0;
        isFullScreen = true;
        dialogHeaderEl.style.cursor = 'initial';
        dialogHeaderEl.onmousedown = null;
      } else {
        dragDom.style.height = "auto";
        dragDom.style.width = nowWidth + 'px';
        dragDom.style.marginTop = nowMarginTop;
        isFullScreen = false;
        dialogHeaderEl.style.cursor = 'move';
        dialogHeaderEl.onmousedown = moveDown;
      }
    }
    
    //拉伸(右下方)
    let resizeEl=document.createElement("div");
    dragDom.appendChild(resizeEl); 
    //在弹窗右下角加上一个10-10px的控制块
    resizeEl.style.cursor = 'se-resize';
    resizeEl.style.position = 'absolute';
    resizeEl.style.height = '10px';
    resizeEl.style.width = '10px';
    resizeEl.style.right = '0px';
    resizeEl.style.bottom = '0px';
    resizeEl.style.zIndex = '99';
    //鼠标拉伸弹窗
    resizeEl.onmousedown = (e) => {
      // 记录初始x位置
      let clientX = e.clientX;
      // 鼠标按下，计算当前元素距离可视区的距离
      let disX = e.clientX - resizeEl.offsetLeft;
      let disY = e.clientY - resizeEl.offsetTop;

      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
        let x = e.clientX - disX + (e.clientX - clientX);//这里 由于elementUI的dialog控制居中的，所以水平拉伸效果是双倍
        let y = e.clientY - disY;
        //比较是否小于最小宽高
        dragDom.style.width = x > minWidth ? `${x}px` : minWidth + 'px';
        dragDom.style.height = y > minHeight ? `${y}px` : minHeight + 'px';
        };
      //拉伸结束
      document.onmouseup = function (e) {
        document.onmousemove = null;
        document.onmouseup = null;
      };
    }
    
    //拉伸(右边)
    let resizeElR=document.createElement("div");
    dragDom.appendChild(resizeElR); 
    //在弹窗右下角加上一个10-10px的控制块
    resizeElR.style.cursor = 'w-resize';
    resizeElR.style.position = 'absolute';
    resizeElR.style.height = '100%';
    resizeElR.style.width = '10px';
    resizeElR.style.right = '0px';
    resizeElR.style.top = '0px';
    //鼠标拉伸弹窗
    resizeElR.onmousedown = (e) => {
      let elW = dragDom.clientWidth;
      let EloffsetLeft = dragDom.offsetLeft;
      // 记录初始x位置
      let clientX = e.clientX;
      document.onmousemove = function (e) {
        e.preventDefault(); // 移动时禁用默认事件
        //右侧鼠标拖拽位置
        if (clientX > EloffsetLeft + elW - 10 && clientX < EloffsetLeft + elW) {
            //往左拖拽
            if (clientX > e.clientX) {
                if (dragDom.clientWidth < minWidth) {
                } else {
                    dragDom.style.width = elW - (clientX - e.clientX) * 2 + 'px';
                }
            }
            //往右拖拽
            if (clientX < e.clientX) {
                dragDom.style.width = elW + (e.clientX - clientX) * 2 + 'px';
            }
        }
       
      };
      //拉伸结束
      document.onmouseup = function (e) {
        document.onmousemove = null;
        document.onmouseup = null;
      };
    }
    
    //拉伸(左边)
    let resizeElL=document.createElement("div");
    dragDom.appendChild(resizeElL); 
    //在弹窗右下角加上一个10-10px的控制块
    resizeElL.style.cursor = 'w-resize';
    resizeElL.style.position = 'absolute';
    resizeElL.style.height = '100%';
    resizeElL.style.width = '10px';
    resizeElL.style.left = '0px';
    resizeElL.style.top = '0px';
    //鼠标拉伸弹窗
    resizeElL.onmousedown = (e) => {
      let elW = dragDom.clientWidth;
      let EloffsetLeft = dragDom.offsetLeft;
      // 记录初始x位置
      let clientX = e.clientX;
      document.onmousemove = function (e) {
        e.preventDefault(); // 移动时禁用默认事件
        //左侧鼠标拖拽位置
        if (clientX > EloffsetLeft && clientX < EloffsetLeft + 10) {
            //往左拖拽
            if (clientX > e.clientX) {
                dragDom.style.width = elW + (clientX - e.clientX) * 2 + 'px';
            }
            //往右拖拽
            if (clientX < e.clientX) {
                if (dragDom.clientWidth < minWidth) {
                } else {
                    dragDom.style.width = elW - (e.clientX - clientX) * 2 + 'px';
        
                }
            }
        }
       
      };
      //拉伸结束
      document.onmouseup = function (e) {
        document.onmousemove = null;
        document.onmouseup = null;
      };
    }
    
    // 拉伸(下边)
    let resizeElB=document.createElement("div");
    dragDom.appendChild(resizeElB); 
    //在弹窗右下角加上一个10-10px的控制块
    resizeElB.style.cursor = 'n-resize';
    resizeElB.style.position = 'absolute';
    resizeElB.style.height = '10px';
    resizeElB.style.width = '100%';
    resizeElB.style.left = '0px';
    resizeElB.style.bottom = '0px';
    //鼠标拉伸弹窗
    resizeElB.onmousedown = (e) => {
     let EloffsetTop = dragDom.offsetTop;
     let ELscrollTop = el.scrollTop;
      let clientY = e.clientY;
      let elH = dragDom.clientHeight;
      document.onmousemove = function (e) {
        e.preventDefault(); // 移动时禁用默认事件
        //底部鼠标拖拽位置
        if (ELscrollTop + clientY > EloffsetTop + elH - 20 && ELscrollTop + clientY < EloffsetTop + elH) {
            //往上拖拽
            if (clientY > e.clientY) {
                if (dragDom.clientHeight < minHeight) {
                } else {
                    dragDom.style.height = elH - (clientY - e.clientY) * 2 + 'px';
                }
            }
            //往下拖拽
            if (clientY < e.clientY) {
                dragDom.style.height = elH + (e.clientY - clientY) * 2 + 'px';
            }
        }
      };
      //拉伸结束
      document.onmouseup = function (e) {
        document.onmousemove = null;
        document.onmouseup = null;
      };
    }
  }
})
/**
 *  注意：如果是el-dialog弹出的表单el-form，最好不要把提交按钮当做el-form-item（elementUI文档是这么用的），放在el-dialog里。
 *  不然按钮会同el-dialog中标签一样被overflow；
*/

2.在main.js中引用

import '@/utils/dialogDrag.js'

3。使用v-dialogDrag指令

<el-dialog v-dialogDrag :title="dialog.title" center :visible.sync="dialog.show" custom-class="lz-el-dialog" width="80%" top="1vh"
                :close-on-click-modal="false">
                <addCustomer ref="addCustomer" :type="dialog.title" @success="getCustomerList"></addCustomer>
                <span slot="footer" class="dialog-footer" >
                    <el-button @click="dialog.show=false" :size="size">取 消</el-button>
                    <el-button type="primary" @click="determine" :size="size" style="margin-left: 30px;">确 定</el-button>
                </span>
            </el-dialog>

4.你可能遇到这样的问题，我只要在弹出层中滚动后，就无法缩放，或者我想让确定和取消按钮始终在底部显示

那么你需要设置css

.el-dialog {
  position: relative;
  margin-bottom: 0!important;
  height: 94vh;overflow: auto;
}
// 弹出对话框 解决缩放问题
.el-dialog__body{padding: 10px;height: calc(100% - 112px);overflow: auto;}