ElementUI的Dialog弹窗实现拖拽移动功能

在项目中使用el-dialog中发现不能够拖拽移动，因此网上找了相关资料，使用自定义指令实现拖拽功能。

1、创建自定义指令：

新建文件directive/el-drag-dialog/index.js

import drag from "./drag";

const install = function (Vue) {
  Vue.directive("el-drag-dialog", drag);
};
if (window.Vue) {
  window["el-drag-dialog"] = drag;
  Vue.use(install);
}

drag.install = install;
export default drag;

新建文件directive/el-drag-dialog/drag.js

export default {
  bind(el, binding, vnode) {
    const dialogHeaderEl = el.querySelector(".el-dialog__header");
    const dragDom = el.querySelector(".el-dialog");
    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 getStyle = (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 dragDomWidth = dragDom.offsetWidth;
      const dragDomheight = dragDom.offsetHeight;

      const screenWidth = document.body.clientWidth;
      const screenHeight = document.body.clientHeight;

      const minDragDomLeft = dragDom.offsetLeft;
      const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth;

      const minDragDomTop = dragDom.offsetTop;
      const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight;

      // 获取到的值带px 正则匹配替换
      let styL = getStyle(dragDom, "left");
      let styT = getStyle(dragDom, "top");

      if (styL.includes("%")) {
        styL = +document.body.clientWidth * (+styL.replace(/%/g, "") / 100);
        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 (-top > minDragDomTop) {
          top = -minDragDomTop;
        } else if (top > maxDragDomTop) {
          top = maxDragDomTop;
        }

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

        // emit onDrag event
        vnode.child.$emit("dragDialog");
      };

      document.onmouseup = function () {
        document.onmousemove = null;
        document.onmouseup = null;
      };
    };
  },
};

2、引入自定义指令

import elDragDialog from "@/directive/el-drag-dialog";

directives: {
    elDragDialog
},

3、使用自定义指令（v-el-darg-dialog）

<el-dialog
      v-el-drag-dialog
      title="提示"
      :visible.sync="dialogVisible"
      width="30%"
      :before-close="handleClose"
      v-if="dialogVisible"
    >
      <span>这是一段信息</span>
      <span slot="footer" class="dialog-footer">
        <el-button @click="dialogVisible = false">取 消</el-button>
        <el-button type="primary" @click="dialogVisible = false"
          >确 定</el-button
        >
      </span>
    </el-dialog>

其中v-el-drag-dialog为自定义指令，v-if主要为了处理每次打开弹框都在中间位置。

4、完整代码：

<template>
  <div>
    <el-button @click="dialogVisible = true">打开弹框</el-button>
    <el-dialog
      v-el-drag-dialog
      title="提示"
      :visible.sync="dialogVisible"
      width="30%"
      :before-close="handleClose"
      v-if="dialogVisible"
    >
      <span>这是一段信息</span>
      <span slot="footer" class="dialog-footer">
        <el-button @click="dialogVisible = false">取 消</el-button>
        <el-button type="primary" @click="dialogVisible = false"
          >确 定</el-button
        >
      </span>
    </el-dialog>
  </div>
</template>

<script>
import elDragDialog from "@/directive/el-drag-dialog";
export default {
  name: "DialogView",
  directives: {
    elDragDialog,
  },
  data() {
    return {
      dialogVisible: false,
    };
  },
  methods: {
    handleClose() {
      this.dialogVisible = false;
    },
  },
};
</script>

5、效果