使用純javascript實現放大鏡效果

 本文給大家分享的是使用純javascript實現放大鏡效果的代碼，並附上封裝的步驟，做電商程序的小伙伴們一定不要錯過。

   

jd或者淘寶的具體商品有個放大鏡的效果。雖然網上類似插件琳琅滿目，應用到項目上有諸多不便，自己抽點時間自己寫了個類似插件，積累下代碼，何樂而不為呢!!let‘go:

打算把此特效封裝成個插件，先把最基本的算法實現，然後再一步步封裝吧：

最終實現效果：

html 代碼：

 

代碼如下:
<div id="Magnifier"></div>

 

css 代碼：

 

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

 

貌似什麼都沒有，開始咱們強大的js之旅吧：

javascript 代碼：

 

代碼如下:
function createElement(MagnifierId, sImg, bImg) {
var Magnifier = $(MagnifierId);
Magnifier.style.position = 'relative';
//小圖div
var smallDiv = $Create("div");
smallDiv.setAttribute("id", "small");
smallDiv.style.position = "absolute";
//遮罩層
var mask = $Create("div");
mask.setAttribute("id", "mask");
mask.style.position = "absolute";
//鏡片
var mirror = $Create("div");
mirror.setAttribute("id", "mirror");
mirror.style.opacity = 0.3;
mirror.style.position = "absolute";
mirror.style.display = "none";
//小圖
var smallImg = $Create("img");
smallImg.setAttribute("src", sImg);
smallImg.setAttribute("id", "smallImg");
smallImg.onload = function () {
//如果沒設置放大鏡的height或者width 根據小圖大小設置放大鏡大小
if (!Magnifier.offsetHeight) {
Magnifier.style.width = this.offsetWidth+"px";
Magnifier.style.height = this.offsetHeight + "px";
}
//遮罩層大小和小圖一樣
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);
//視窗
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);
}

 

最後再 onload小小的調用一下：

 

代碼如下:
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();
}

 

效果總算出來了耶，

2. 接下來咱們封裝吧：

Magnifer類代碼：

 

代碼如下:
function Magnifier(
MagnifierId, //放大鏡容器ID
sImg, //小圖片src
bImg, //大圖片src
mirrorStyle, //小圖片裡鏡片樣式，json格式數據
ViewStyle //預覽視窗樣式，json格式數據
) {
var _this = this;
this.MagnifierContainer = null; //容器
this.smallDiv = null; //小圖容器
this.mask = null; //小圖遮罩層
this.mirror = null; //小圖鏡片
this.smallImg = null; //小圖
this.bigDiv = null; //預覽視圖
this.bigImg = null; //大圖
var init = function () {
_this.MagnifierContainer = _this.$(MagnifierId);
_this.createElement(sImg, bImg);
_this.setMagnifierStyle(mirrorStyle, ViewStyle);
_this.MainEvent();
}
init();
}
Magnifier.prototype.createElement = function (sImg, bImg) {
var _this = this;
var $Create = this.$Create;
this.MagnifierContainer.style.position = 'relative'; //脫離文檔流，視情況修改
this.smallDiv = $Create("div");
this.smallDiv.setAttribute("id", "small");
this.smallDiv.style.position = "absolute";
this.mask = $Create("div");
this.mask.setAttribute("id", "mask");
this.mask.style.position = "absolute";
this.mirror = $Create("div");
this.mirror.setAttribute("id", "mirror");
this.mirror.style.opacity = 0.3;
this.mirror.style.position = "absolute";
this.mirror.style.display = "none";
this.smallImg = $Create("img");
this.smallImg.setAttribute("src", sImg);
this.smallImg.setAttribute("id", "smallImg");
this.smallImg.onload = function () {
//如果沒設置放大鏡的height或者width 根據小圖大小設置放大鏡大小<