vue基于element的模态框放大缩小可拖动

封装的js文件

import Vue from 'vue';
import bigPic from '../assets/images/bigChange.png';
// v-dialogDrag: 弹窗拖拽属性
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'); 
    // 全屏按钮 
    dialogHeaderEl.insertAdjacentHTML('beforeEnd', '<div class="bigbtn"><div class="changeBig"></div><div class="changeSmall"></div></div>'); 
    const bigBtn = el.querySelector('.bigbtn'); 
    const changeBig = el.querySelector('.changeBig'); 
    const changeSmall = el.querySelector('.changeSmall');
    //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;
 
    //双击头部全屏效果
 
    bigBtn.onclick = (e) => {
      if (isFullScreen == false) { 
        changeBig.style.display = 'none'; 
        changeSmall.style.display = 'block';
        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 {
 
        changeBig.style.display = 'block'; 
        changeSmall.style.display = 'none';
        dragDom.style.height = "auto"; 
        dragDom.style.width = nowWidth + 'px'; 
        dragDom.style.marginTop = nowMarginTop; 
        isFullScreen = false; 
        dialogHeaderEl.style.cursor = 'move';
 
        dialogHeaderEl.onmousedown = moveDown;
 
      }
 
    }
 
    dragDom.onmousemove = function (e) {
      // console.log(dialogHeaderEl,dragDom.querySelector('.el-dialog__body'), 123);
      let moveE = e;
 
      if (e.clientX > dragDom.offsetLeft + dragDom.clientWidth - 10 || dragDom.offsetLeft + 10 > e.clientX) {
         dragDom.style.cursor = 'w-resize';
      } else if (el.scrollTop + e.clientY > dragDom.offsetTop + dragDom.clientHeight - 10) { 
        dragDom.style.cursor = 's-resize'; 
      } else { 
        dragDom.style.cursor = 'default'; 
        dragDom.onmousedown = null;
 
      }
 
      dragDom.onmousedown = (e) => { 
        const clientX = e.clientX; 
        const clientY = e.clientY; 
        let elW = dragDom.clientWidth; 
        let elH = dragDom.clientHeight; 
        let EloffsetLeft = dragDom.offsetLeft;
        let EloffsetTop = dragDom.offsetTop;
        dragDom.style.userSelect = 'none';
        let ELscrollTop = el.scrollTop;
 
        //判断点击的位置是不是为头部
 
        if (clientX > EloffsetLeft && clientX < EloffsetLeft + elW && clientY > EloffsetTop && clientY < EloffsetTop + 100) {
 
          //如果是头部在此就不做任何动作，以上有绑定dialogHeaderEl.onmousedown = moveDown;
 
        } else {
 
          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';
 
                }
 
              }
 
            }
 
            //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';
 
              }
 
            }
 
            //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;
 
          };
 
        }
 
      }
 
    }
  }
})

来源：https://www.jb51.net/article/212304.htm