HTML代码：
<!DOCTYPE html>
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.0/jquery.min.js"></script>
<link rel="stylesheet" href="style.css" type="text/css" />
<script type='text/javascript' src='script.js'></script>
</head>
<body>
<img id="back" name="back" src="back.jpg" alt = "背景"/>
<div>
<div id="larger" class="size_btn"><img src="+.png" alt="+"></div>
<div id="smaller" class="size_btn"><img src="-.png" alt="+"></div>
</div>
</body>
</html>
JS代码：
$(document).ready(function(){
/******** 先将图片居中并完全显示 ********/
var proportion = 1;
if($(window).width() / $('#back').width() < $(window).height() / $('#back').height())
proportion = $(window).width()/$('#back').width();
else
proportion = $(window).height()/$('#back').height();
var back_width = $('#back').width() * proportion;
var back_height = $('#back').height() * proportion;
var back_left = ($(window).width() - back_width)/2;
var back_top = ($(window).height() - back_height)/2;
$('#back').width(back_width);
$('#back').height(back_height);
$("#back").offset({left:back_left,top:back_top});
//放大缩小操作时的尺寸变化
var sizeX = back_width/10;
var sizeY = back_height/10;
//放大缩小操作时的位置变化
var moveX = sizeX/2;
var moveY = sizeY/2;
//点击放大按钮
$('#larger').click(function(){
$('#back').height("+=" + sizeX);
$('#back').width("+=" + sizeY);
$("#back").offset(function(n,c){
newPos = new Object();
newPos.left = c.left-moveX;
newPos.top = c.top-moveY;
return newPos;
});
});
//点击缩小按钮
$('#smaller').click(function(){
$('#back').height("-=" + sizeX);
$('#back').width("-=" + sizeY);
$("#back").offset(function(n,c){
newPos = new Object();
newPos.left = c.left + moveX;
newPos.top = c.top + moveY;
return newPos;
});
});
//点击图片
$('#back').click(function(event){
var x=($(window).width()/2) - event.clientX + $("#back").offset().left;
var y=($(window).height()/2) - event.clientY + $("#back").offset().top;
$("#back").animate({left:x,top:y});
});
});
css代码：
#back{
left: 0px;
top: 0px;
position:absolute;
z-index:-1;
}
.size_btn{
position:absolute;
height:30px;
30px;
}
#larger{
}
#smaller{
top:60px;
}
最终效果：
点击放大按钮：
点击图片的任意位置：
