通过自定义指令实现一个可拖拽的dialog

1. 编写一个 util.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) {

      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;

          };

        }

      }

    }

  }

})

2. 在 main.js 中引用

    import "../libs/utils"

3. 在 el-dialog 组件中使用

<el-button type="text" @click="dialogVisible = true" v-dialogDrag> 点击打开 Dialog</el-button>