js-放大镜效果

jd或者淘宝的具体商品有个放大镜的效果。虽然网上类似插件琳琅满目，应用到项目上有诸多不便，自己抽点时间自己写了个类似插件，积累下代码，何乐而不为呢!!let‘go:

1. 打算把此特效封装成个插件，先把最基本的算法实现，然后再一步步封装吧：

最终实现效果：

html 代码：

<div id="Magnifier"></div>

View Code

CSS 代码：

 <style>        * {            margin: 0;            padding: 0;        }    </style>

View Code

貌似什么都没有，开始咱们强大的js之旅吧：

javascript 代码：

  function createElement(MagnifierId, sImg, bImg) {            var Magnifier = $(MagnifierId);            Magnifier.style.position = 'relative';            //小图div            var smallDiv = $Create("div");            smallDiv.setAttribute("id", "small");            smallDiv.style.position = "absolute";                       //遮罩层            var mask = $Create("div");            mask.setAttribute("id", "mask");            mask.style.position = "absolute";            //镜片            var mirror = $Create("div");            mirror.setAttribute("id", "mirror");            mirror.style.opacity = 0.3;            mirror.style.position = "absolute";            mirror.style.display = "none";            //小图            var smallImg = $Create("img");            smallImg.setAttribute("src", sImg);            smallImg.setAttribute("id", "smallImg");            smallImg.onload = function () {                //如果没设置放大镜的height或者width 根据小图大小设置放大镜大小                if (!Magnifier.offsetHeight) {                    Magnifier.style.width = this.offsetWidth+"px";                    Magnifier.style.height = this.offsetHeight + "px";                }                //遮罩层大小和小图一样                mask.style.opacity = "0";                mask.style.width = this.width + 'px';                mask.style.height = this.height + "px";                mask.style.zIndex = 2;                bigDiv.style.left = this.width + 5 + "px";                bigDiv.style.top = "-5px";            }            smallDiv.appendChild(mask);            smallDiv.appendChild(mirror);            smallDiv.appendChild(smallImg);            //视窗            var bigDiv = $Create("div");            bigDiv.setAttribute("id", "big");            bigDiv.style.position = "absolute";            bigDiv.style.overflow = "hidden";            bigDiv.style.display = "none";            var bigImg = $Create("img");            bigImg.setAttribute("src", bImg);            bigImg.setAttribute("id", "bigImg");            bigImg.style.position = "absolute";            bigDiv.appendChild(bigImg);            Magnifier.appendChild(smallDiv);            Magnifier.appendChild(bigDiv);        }        function setMagnifierStyle(mirrorStyle,shichuangStyle) {                            //mirror            for (var item in mirrorStyle) {                mirror.style[item] = mirrorStyle[item];            }            for (var item in shichuangStyle) {                $("big").style[item] = shichuangStyle[item];            }                   }        function registerEvent() {            $("mask").onmouSEOver = function () {                $("big").style.display = "block";                mirror.style.display = "block";            }            $("mask").onmouseout = function () {                $("big").style.display = "none";                mirror.style.display = "none";            }            $("mask").onmousemove = function (evt) {                var oEvent = evt || event;                var disX = oEvent.offsetX;                var disY = oEvent.offsetY;                var mirrorLeft = disX - mirror.offsetWidth / 2;                var mirrorTop = disY - mirror.offsetHeight / 2;                if (mirrorLeft < 0) {                    mirrorLeft = 0;                }                else if (mirrorLeft > mask.offsetWidth - mirror.offsetWidth) {                    mirrorLeft = mask.offsetWidth - mirror.offsetWidth;                }                if (mirrorTop < 0) {                    mirrorTop = 0;                }                else if (mirrorTop > mask.offsetHeight - mirror.offsetHeight) {                    mirrorTop = mask.offsetHeight - mirror.offsetHeight;                }                mirror.style.top = mirrorTop + "px";                mirror.style.left = mirrorLeft + "px";                var paX = mirrorTop / (mask.offsetHeight - mirror.offsetHeight);                var paY = mirrorLeft / (mask.offsetWidth - mirror.offsetWidth);                $("bigImg").style.top = -paX * ($("bigImg").offsetHeight - $("big").offsetHeight) + "px";                $("bigImg").style.left = -paY * ($("bigImg").offsetWidth - $("big").offsetWidth) + "px";            }        }        function $(id) {            return document.getElementById(id);        }        function $Create(type) {            return document.createElement(type);        }

View Code

最后再 onload小小的调用一下：

 window.onload = function () {            createElement("Magnifier", "images/Magnifier/small.jpg", "images/Magnifier/big.jpg");            setMagnifierStyle({ "width": "30px", "height": "30px", "backgroundColor": "#fff" }, { "width": "250px", "height": "250px" });            registerEvent();        }

View Code

效果总算出来了耶，

2. 接下来咱们封装吧：

Magnifer类代码：

        function Magnifier(            MagnifierId,                            //放大镜容器ID            sImg,                                   //小图片src            bImg,                                   //大图片src            mirrorStyle,                            //小图片里镜片样式，json格式数据            ViewStyle                               //预览视窗样式，json格式数据            ) {            var _this = this;            this.MagnifierContainer = null;         //容器            this.smallDiv = null;                   //小图容器            this.mask = null;                       //小图遮罩层            this.mirror = null;                     //小图镜片            this.smallImg = null;                   //小图            this.bigDiv = null;                     //预览视图            this.bigImg = null;                     //大图            var init = function () {                _this.MagnifierContain