element-ui 的 dialog 实现拖拽、水平伸缩、双击头部放大

import Vue from 'vue';

/*
 *  使用：
 *  elementUI 的 dialog 上加上 v-dialogDrag 指令就可以实现弹窗的全屏和拉伸了。
 *  给 dialog 设置 :close-on-click-modal="false" , 禁止点击遮罩层关闭弹出层
 *  如果是 form 表单，不要将提交等按钮放置 el-form-item，以免在上下拉伸时被隐藏
 */

// v-dialogDrag: 弹窗拖拽+水平方向伸缩
Vue.directive('dialogDrag', {
  bind(el, binding, vnode, oldVnode) {
    //弹框可拉伸最小宽高
    const minWidth = 400;
    const 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);

    const 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;
      let 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
    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;
      }
    };

    dragDom.onmousemove = function (e) {
      const moveE = e;
      if (e.clientX > dragDom.offsetLeft + dragDom.clientWidth - 10) {
        dragDom.style.cursor = 'e-resize';
      } else if (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;
        const elW = dragDom.clientWidth;
        const elH = dragDom.clientHeight;
        const EloffsetLeft = dragDom.offsetLeft;
        const EloffsetTop = dragDom.offsetTop;
        dragDom.style.userSelect = 'none';
        const 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;
          };
        }
      };
    };
  },
});