html
<link type="text/css" href="style.css" rel="stylesheet" />
<script type="text/javascript" src="FreeZoomer.js"></script>
<div style="height:500px;line-height:500px;text-align:center;padding:100px;">
<img id="test" class="free-zoomer" src="demo-small.jpg" data-img-big="demo-big.jpg" style="border:10px solid #CCC;margin:1px;padding:10px;" />
</div>FreeZoomer.js
//作者：dabai QQ2500152288
//用途：图片放大镜
//用法：
/*
* <img src="小图.jpg" class="free-zoomer" data-img-big="大图.jpg" />
*
*/
var zoomerViewPanelId = "free-zoomer-view-panel";
function FreeZoomer(img) {
var rect = null; //当前图片四个角坐标
var ready = false; //状态，是否已经加载完成大图
var panel = null; //大图容器
var bigImg = null; //大图对象
var bigRect = null; //大图坐标
var widthMultiple = 1; //宽度倍数，大图的宽度/小图的宽度
var heightMultiple = 1; //高度倍数，大图的高度/小图的高度
var viewWidth = 0; //放大镜容器宽度
var viewHeight = 0;//放大镜容器高度
img.onmouseover = function (event) {
rect = GetAbsolutePosition(img);
panel = ShowViewPanel(rect.right, rect.top);
viewHeight = GetHeight(panel);
viewWidth = GetWidth(panel);
var src = img.getAttribute("data-img-big");
bigImg = new Image();
bigImg.src = src;
//自定义函数，当图片加载完成后，运行
bigImg.Loaded = function () {
ready = true;
panel.innerHTML = "";
panel.appendChild(bigImg);
bigRect = GetAbsolutePosition(bigImg);
panel.className = "";
widthMultiple = GetWidth(bigImg) / GetWidth(img);
heightMultiple = GetHeight(bigImg) / GetHeight(img);
}
if (bigImg.complete) {
bigImg.Loaded();
}
else {
bigImg.onload = function () {
bigImg.Loaded();
}
}
};
img.onmousemove = function (event) {
if (ready && (rect != null)) {//不要问我为什么要rect!=null,我也不知道，ie6下会报错。。估计是还没给rect设置值，已经触发move事件
event = event ? event : window.event;
var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft;
var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
var relativeScrollLeft = Math.abs((rect.left - scrollLeft - event.clientX) * widthMultiple);
if (relativeScrollLeft > (viewWidth / 2)) {
relativeScrollLeft = relativeScrollLeft - (viewWidth / 2);
}
else {
relativeScrollLeft = 0;
}
var relativeScrollTop = Math.abs((rect.top - scrollTop - event.clientY) * heightMultiple);
if (relativeScrollTop > (viewHeight / 2)) {
relativeScrollTop = relativeScrollTop - (viewHeight / 2);
}
else {
relativeScrollTop = 0;
}
panel.scrollLeft = relativeScrollLeft;
panel.scrollTop = relativeScrollTop;
}
};
img.onmouseout = function (event) {
HideViewPanel();
}
}
//获取放大容器
function GetViewPanel() {
var panel = document.getElementById(zoomerViewPanelId);
if (panel == null) {
panel = document.createElement("div");
panel.id = zoomerViewPanelId;
document.body.appendChild(panel);
}
return panel;
}
//显示放大器
function ShowViewPanel(left, top) {
var panel = GetViewPanel();
panel.style.left = (left + 10) + "px";
panel.style.top = top + "px";
panel.style.display = "block";
panel.className = "loading";
return panel;
}
//隐藏放大容器
function HideViewPanel() {
var panel = document.getElementById(zoomerViewPanelId);
if (panel != null) {
panel.style.display = "none";
}
}
//获取对象高度
function GetHeight(ele) {
var paddingTop = parseInt(ele.style.paddingTop);
if (!paddingTop) {
paddingTop = 0;
}
var paddingBottom = parseInt(ele.style.paddingBottom);
if (!paddingBottom) {
paddingBottom = 0;
}
return ele.clientHeight - paddingTop - paddingBottom;
}
//获取对象宽度
function GetWidth(ele) {
var paddingLeft = parseInt(ele.style.paddingLeft);
if (!paddingLeft) {
paddingLeft = 0;
}
var paddingRight = parseInt(ele.style.paddingRight);
if (!paddingRight) {
paddingRight = 0;
}
return ele.clientWidth - paddingLeft - paddingRight;
}
//获取对象坐标
function GetAbsolutePosition(ele) {
var rect = ele.getBoundingClientRect();
var padding = GetPadding(ele);
var border = GetBorder(ele);
var position = {};
var scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft;
var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
position.left = rect.left + padding.left + border.left + scrollLeft;
position.top = rect.top + padding.top + border.top + scrollTop;
position.bottom = rect.bottom - padding.bottom - border.bottom + scrollTop;
position.right = rect.right - padding.right - border.right + scrollLeft;
return position;
}
//获取对象4个边距
function GetPadding(ele) {
var padding = {};
padding.top = parseInt(ele.style.paddingTop);
if (!padding.top) {
padding.top = 0;
}
padding.bottom = parseInt(ele.style.paddingBottom);
if (!padding.bottom) {
padding.bottom = 0;
}
padding.left = parseInt(ele.style.paddingLeft);
if (!padding.left) {
padding.left = 0;
}
padding.right = parseInt(ele.style.paddingRight);
if (!padding.right) {
padding.right = 0;
}
return padding;
}
//获取对象4个边框
function GetBorder(ele) {
var border = {};
border.top = parseInt(ele.style.borderTop);
if (!border.top) {
border.top = 0;
}
border.bottom = parseInt(ele.style.borderBottom);
if (!border.bottom) {
border.bottom = 0;
}
border.left = parseInt(ele.style.borderLeft);
if (!border.left) {
border.left = 0;
}
border.right = parseInt(ele.style.borderRight);
if (!border.right) {
border.right = 0;
}
return border;
}
//查找是否带有className
function hasClass(element, className) { return new RegExp("(^|\\s)" + className + "(\\s|$)").test(element.className); }
//初始化各图片放大镜
function InitFreeZoomer() {
var imgs = document.getElementsByTagName("img");
for (var i = 0; i < imgs.length; i++) {
var img = imgs[i];
if (hasClass(img, "free-zoomer")) {
FreeZoomer(img);
}
}
}
//加载事件
function AddEventListener(obj, eventName, func) {
if (obj.addEventListener) {
obj.addEventListener(eventName, func, false);
}
else {
if (obj.attachEvent) {
obj.attachEvent("on" + eventName, func)
}
else {
alert("FreeZoomer无法加载事件！");
}
}
}
AddEventListener(window, "load", InitFreeZoomer);style.css
#free-zoomer-view-panel {
position:absolute;
width:300px;
height:300px;
border:1px solid #CCC;
overflow:hidden;
z-index:9999;
}
#free-zoomer-view-panel img {
position:absolute;
left:0px;
top:0px;
}
.loading {
background-image:url("loading.gif");
background-repeat:no-repeat;
background-position:center center;
}
img.free-zoomer {
cursor:zoom-in;
}