element ui +vue2 实现el-dialog拖动放大弹窗

1、在libs文件夹内创建dialog.js

dialog.js内容如下：

import Vue from 'vue';
// v-dialogDrag: 弹窗拖拽属性
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';
    dialogHeaderEl.style.cssText += ';cursor:move;';
    dragDom.style.cssText += ';top:0px;';

    // 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 => {
      // 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;
      const screenWidth = document.body.clientWidth; // body当前宽度
      const screenHeight = document.documentElement.clientHeight; // 可见区域高度(应为body高度，可某些环境下无法获取)
      const dragDomWidth = dragDom.offsetWidth; // 对话框宽度
      const dragDomheight = dragDom.offsetHeight; // 对话框高度
      const minDragDomLeft = dragDom.offsetLeft;
      const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth;
      const minDragDomTop = dragDom.offsetTop;
      const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight;//鼠标按下后的位置
      // 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
        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(dragDomheight<screenHeight){//可视区域小于弹窗高度
          if (-top > minDragDomTop) {
            top = -minDragDomTop;
          } else if (top > maxDragDomTop) {
            top = maxDragDomTop;  
          }
        }else{
          if (-top > minDragDomTop) {//限制顶部
            top = -minDragDomTop;
          }else if(e.clientY > dragDomheight-150){//限制底部
            // console.log(22222222,dragDomheight,e.clientY)
            top = dragDomheight-150
          }
          // console.log('弹窗高出可是区域')
        }
        

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

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

2、在main.js里引入

import draggable from '@/libs/dialog';
Vue.use(draggable)

3、使用

<el-dialog
        v-dialogDrag
        :modal="false"
        :visible.sync="formDialogVisible"
        :close-on-click-modal="false"
        top="20px"
        width="60%"
        :show-close="true"
        title="title"
        :fullscreen="dialogFull"
      >
		<template slot="title">
          <div class="avue-crud__dialog__header">
            <span class="el-dialog__title">
              <span
                style="
                  width: 3px;
                  height: 20px;
                  margin-right: 5px;
                  margin-top: 2px;
                  float: left;
                "></span>
              title
            </span>
            <div class="avue-crud__dialog__menu"
              @click="dialogFull ? (dialogFull = false) : (dialogFull = true)" >
              <i class="el-icon-full-screen"></i>
            </div>
          </div>
        </template>
        <template>
          <div class="dialogMapping">
          	内容
          </div>
        </template>
</el-dialog>



export default {
data() {
    return {
      dialogFull: false,
      formDialogVisible: true
    }
}
}