vue自定义指令之面板拖拽的实现

<div v-drag="'refName'"></div>

directives: {  drag: {   // 使用bind会有可能没有渲染完成   inserted: function(el, binding, vnode) {    const _el = el; //获取当前元素    const ref = vnode.context.$refs[binding.value]; // 判断基于移动的是哪一个盒子    const masterNode = ref ? ref : document; // 用于绑定事件    const masterBody = ref ? ref : document.body; // 用于获取高和宽    const mgl = _el.offsetLeft;    const mgt = _el.offsetTop;    const maxWidth = masterBody.clientWidth;    const maxHeight = masterBody.clientHeight;    const elWidth = _el.clientWidth;    const elHeight = _el.clientHeight;    let positionX = 0,     positionY = 0;    _el.onmousedown = e => {     //算出鼠标相对元素的位置，加上的值是margin的值     let disX = e.clientX - _el.offsetLeft + mgl;      let disY = e.clientY - _el.offsetTop + mgt;     masterNode.onmousemove = e => {      //用鼠标的位置减去鼠标相对元素的位置，得到元素的位置      let left = e.clientX - disX;      let top = e.clientY - disY;      // 绑定的值不能滑出基于盒子的范围      left < 0 && (left = 0);      left > (maxWidth - elWidth - mgl) && (left = maxWidth - elWidth - mgl);      top < 0 && (top = 0);      top > (maxHeight - elHeight - mgt) && (top = maxHeight - elHeight - mgt);      //绑定元素位置到positionX和positionY上面      positionX = top;      positionY = left;            //移动当前元素      _el.style.left = left + "px";      _el.style.top = top + "px";     };     // 这里是鼠标超出基于盒子范围之后再松开，会监听不到     document.onmouseup = e => {      masterNode.onmousemove = null;      document.onmouseup = null;     };    };   }  } }