/**************************************************
* 用法：<img src="1.jpg" class="zoom" big="1.jpg">
<script>zoom({width:300,height:300});</script> width,height是放大显示的区域
**************************************************/
//定义所有的变量，方法
var zoom = function(o){
var d = document,
db=document.body,
timgs=d.getElementsByTagName('img'),
opt = {
width:200,
height:200,
offset:20,
float:'right',
minWidth:100
},
div = d.createElement('div'),
divup = d.createElement('div'),
//获取元素的定位,x,y
getXY = function(el){
var r={t:0,l:0},
ua = navigator.userAgent.toLowerCase(),
add = function(t,l){r.l+=l,r.t+=t},
p = el;
if(el&&el!=db){
//el.getBoundingClientRect,获得元素的左，上，右和下分别相对浏览器视窗的位置
if(el.getBoundingClientRect){
var b = el.getBoundingClientRect();
add(b.top + Math.max(d.body.scrollTop,d.documentElement.scrollTop),
b.left+Math.max(d.body.scrollLeft,d.documentElement.scrollLeft));
add(-d.documentElement.clientTop,-d.documentElement.clientLeft);
}else{
while(p){
add(p.offsetTop,p.offsetLeft);
p = p.offsetParent;
}
p = el.parentNode;
while (p && p != db) {
add(-p.scrollTop,-p.scrollLeft);
p = p.parentNode;
}
}
}
return r;
},
//重新设置div的宽高
extend = function(t,s){
for(var p in s){
t[p] = s[p];
};
};
div.id='zoomdiv',divup.id = 'zoomup';
div.innerHTML = '<img id="bigimg" src="" />';
db.appendChild(div);
extend(opt,o);
function leave(obj,e){
var e=e||event;
/*alert(obj);
alert(e.currentTarget);*/
//火狐，opera专用，e.currentTarget是火狐，opera专用的属性
if (e.currentTarget) {
//relatedTarget对于 mouseout 事件来说，该属性是离开目标时，鼠标指针进入的节点。
//e.relatedTarget != obj，当移入子元素的时候，会出现相等
if (e.relatedTarget != obj) {
if (obj != e.relatedTarget.parentNode) {
div.style.display = divup.style.display = 'none';
db.onmousemove = null;
}
}
} else {//ie专用
if (e.toElement != obj) {
if (obj != e.toElement.parentNode) {
div.style.display = divup.style.display = 'none';
db.onmousemove = null;
}
}
}
};
for(var i=0,ci;ci=timgs[i++];){
if(ci.className=='zoom'){
ci.onmouseover = function(e){
this.parentNode.appendChild(divup);
var bimg=d.getElementById('bigimg'),bwidth,bheight,sx,sy,
width = this.offsetWidth,
height = this.offsetHeight,
top=getXY(this).t,
left = getXY(this).l,
tWidth,tLeft,sWidth;
//当鼠标移过的时候，开始载入大图
bimg.src = this.getAttribute('big');
if(!bimg.complete){
bimg.onload=showBimg;
}else{
showBimg();
}
function showBimg(){
div.style.display = 'block';
bwidth = bimg.width,
bheight = bimg.height,
sx = bwidth/width,sy = bheight/height;
tLeft =opt.float=='right'?opt.offset+width+left:left-opt.offset-opt.width,
sWidth = window.innerWidth||(d.documentElement.clientWidth);
//如果浏览器宽度不够，则自动适应显示div的宽度
if(tLeft+opt.width+5>sWidth){
tWidth = sWidth - 5 - tLeft;
//此句式比较特殊
tWidth<opt.minWidth&&(tLeft = left-opt.offset-opt.width,tWidth=0);
};
//设置div,divup的宽高和位置
extend(div.style,{
left:tLeft +'px',
top:top+'px',
width
tWidth||opt.width)+'px',
height
pt.height+'px'
});
extend(divup.style,{
width
tWidth||opt.width)/sx+'px',
height
pt.height/sy+'px',
display:'block'
});
db.onmousemove = function(e){
var e = e || event,
//显示非IE的鼠标位置，然后是IE的
x=e.pageX||(e.clientX+(d.documentElement.scrollLeft||db.scrollLeft)),
y=e.pageY||(e.clientY+(d.documentElement.scrollTop||db.scrollTop)),
//X,Y相对于原始图片的位置
scrolly = y - divup.offsetHeight/2 - top,
scrollx = x - divup.offsetWidth/2 - left;
//如果鼠标接近边界的时候，相对位置将不再随鼠标发生变化
scrolly = y - divup.offsetHeight/2 < top ? 0 : y + divup.offsetHeight/2>height+top ? height - divup.offsetHeight : scrolly;
scrollx = x - divup.offsetWidth/2 < left ? 0 : x + divup.offsetWidth/2>width+left ? width - divup.offsetWidth : scrollx;
div.scrollTop = scrolly*sy;
div.scrollLeft = scrollx*sx;
extend(divup.style,{top:scrolly+'px',left:scrollx+'px'});
}
};
};
ci.parentNode.onmouseout =function(event){leave(this,event)};
}
};
}
