/*
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需求：实现一个拖拽指令，可在父元素区域任意拖拽元素。
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思路：
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1、设置需要拖拽的元素为absolute，其父元素为relative。
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2、鼠标按下(onmousedown)时记录目标元素当前的 left 和 top 值。
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3、鼠标移动(onmousemove)时计算每次移动的横向距离和纵向距离的变化值，并改变元素的 left 和 top 值
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4、鼠标松开(onmouseup)时完成一次拖拽
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使用：在 Dom 上加上 v-draggable 即可
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<div class="dialog-model" v-draggable></div>
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*/
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import type { Directive } from "vue";
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interface ElType extends HTMLElement {
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parentNode: any;
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}
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const draggable: Directive = {
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mounted: function (el: ElType) {
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el.style.cursor = "move";
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el.style.position = "absolute";
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el.onmousedown = function (e) {
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let disX = e.pageX - el.offsetLeft;
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let disY = e.pageY - el.offsetTop;
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document.onmousemove = function (e) {
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let x = e.pageX - disX;
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let y = e.pageY - disY;
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let maxX = el.parentNode.offsetWidth - el.offsetWidth;
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let maxY = el.parentNode.offsetHeight - el.offsetHeight;
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if (x < 0) {
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x = 0;
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} else if (x > maxX) {
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x = maxX;
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}
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if (y < 0) {
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y = 0;
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} else if (y > maxY) {
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y = maxY;
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}
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el.style.left = x + "px";
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el.style.top = y + "px";
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};
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document.onmouseup = function () {
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document.onmousemove = document.onmouseup = null;
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};
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};
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}
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};
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export default draggable;
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