//執(zhí)行初始函數(shù)
init();
function init() {
    //創(chuàng)建一個碎片容器
    var frag = document.createDocumentFragment();
    document.body.style.margin = "0px";
    //創(chuàng)建左側(cè)圖片容器
    var ul=createE("ul",{
        width: "260px",
        height: "400px",
        backgroundImage: "url(./img/3.jpg)",
        borderRight: "1px solid #000",
        borderBottom: "1px solid #000",
        listStyle: "none",
        padding: "0px",
        margin: "0px",
        opacity: ".3",
        position: "absolute"
    })
    //創(chuàng)建li,顯示圖片中的邊框
    var li=createE("li",{
        width: "51px",
        height: "79px",
        borderLeft: "1px solid #000",
        borderTop: "1px solid #000",
        padding: "0px",
        margin: "0px",
        float: "left"
    })
    //循環(huán)，將li復(fù)制插入到ul中
    for (i = 0; i < 25; i++) {
        ul.appendChild(li.cloneNode(false));
    }
    //將ul插入到碎片容器中
    frag.appendChild(ul);
    //創(chuàng)建右側(cè)圖片容器,因?yàn)閕mg要相對body定位，所以它的父容器不能有定位屬性
    var div=createE("div",{
        width: "302px",
        height: "302px",
        border: "1px solid #000",
        marginLeft: "400px"
    })
    //創(chuàng)建圖片標(biāo)簽
    for (var j = 0; j < 5; j++) {
        for (var k = 0; k < 5; k++) {
            var img=createE("img",{
                width: "52px",
                height: "80px",
                position: "absolute",
                left: Math.floor(Math.random() * 250) + 400 + "px",
                top: Math.floor(Math.random() * 220) + "px"
            })
            img.src = "./img/img" + j + "-" + k + ".jpg";
            //圖片偵聽mouseHandler事件
            img.addEventListener("mousedown", mouseHandler);
            div.appendChild(img);
        }
    }
    //將div插入到碎片容器中，再將frag插入到body中
    frag.appendChild(div);
    document.body.appendChild(frag);
}
//鼠標(biāo)事件
function mouseHandler(e) {
    switch (e.type) {
        case "mousedown":
            //清除點(diǎn)擊后移動圖片的默認(rèn)效果
            e.preventDefault();
            console.log(this.src.match(/img\/img(.*)\.jpg/))
            //獲取到圖片路徑中的數(shù)字，計算圖片正確的位置坐標(biāo)
            var imgSrc = this.src.match(/img\/img(.*)\.jpg/)[1].split("-");
            var rightL=imgSrc[1]*52;
            var rightTop=imgSrc[0]*80;
            //如果圖片正確放入，直接跳出
            if (this.style.left===rightL+"px" && this.style.top===rightTop+"px") return;
            //將當(dāng)前圖片的z-index設(shè)為最大
            this.style.zIndex = "999";
            //將e.offsetX、e.offsetY、當(dāng)前點(diǎn)擊圖片對象存入到document中
            document.x = e.offsetX;
            document.y = e.offsetY;
            document.elem = this;
            document.rightL=rightL;
            document.rightTop=rightTop;
            //document偵聽mousemove事件和mouseup事件
            document.addEventListener("mousemove", mouseHandler);
            document.addEventListener("mouseup", mouseHandler);
            break;
        case "mousemove":
            //自動吸附的距離大小
            var gap = 20;
            //設(shè)置當(dāng)前的圖片跟著鼠標(biāo)移動而移動
            let x=e.clientX - this.x;
            let y=e.clientY - this.y;
            this.elem.style.left = x + "px";
            this.elem.style.top = y + "px";
            //如果當(dāng)前圖片的位置坐標(biāo)在一定范圍內(nèi)，則讓它自動吸附
            if (x>=this.rightL-gap &&x<=this.rightL+gap&&
                y>=this.rightTop-gap &&y<=this.rightTop+gap) {
                this.elem.style.left = this.rightL + "px";
                this.elem.style.top = this.rightTop + "px";
            }
            break;
        case "mouseup":
            //鼠標(biāo)松開的時候，將當(dāng)前圖片的z-index改小
            this.elem.style.zIndex = "10";
            //鼠標(biāo)松開后，移除document的mousemove和mouseup事件,清空數(shù)據(jù)，防止內(nèi)容泄露
            this.removeEventListener("mousemove", mouseHandler);
            this.removeEventListener("mouseup", mouseHandler);
            this.elem=null;
            break;
    }
}
//創(chuàng)建標(biāo)簽
function createE(elem,styleData){
    var elem=document.createElement(elem);
    for(var prep in styleData){
        elem.style[prep]=styleData[prep];
    }
    return elem;
}