<template>
    <div></div>
</template>

<script>
/*

*  使用方法

*  将以下代码复制到一个js文件中，然后在入口文件main.js中import引入即可；

*  给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


export default  {
    init(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;
        
                    }
        
                }
        
                return;  //以下功能影响弹窗中其他内容的操作
                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;
        
                            };
        
                        }
        
                    }
        
                }
        
            }
        
        })
    }
}



</script>