h5实现放大镜效果的代码

来源：浪柱娱乐
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最近公司做的艺术品放大效果，和以往的淘宝放大镜效果有些不同，这个需要在本图上放大
<html>
<head>
 <meta charset="UTF-8">
 <style type="text/css">
 *{margin:0;padding:0}
 .demo{width: 680px;height: 480px;position:relative;background:#333;margin:20px auto;overflow:hidden;}
 .small_box{position:absolute;/*left:100px;*/top: 0;/*height: 480px;*/}
 .big_box{width: 100px;height: 100px;border:1px solid #999;background:url(./images/cc.jpg) no-repeat;position:absolute;top: 0;left: 0;border-radius:50%;cursor:none;display:none;box-shadow: 0px 0px 8px #000;}
 </style>
</head>
<body>
 <p id="demo" class="demo">
 <img id="small_box" class="small_box" src="images/cc.jpg"/>
 <p id="big_box" class="big_box">
 </p>
 </p>
 <script type="text/javascript" src="./js/jquery-1.10.1.min.js"></script>
 <script type="text/javascript">
 $(function(){
 (function(a){function d(b){var c=b||window.event,d=[].slice.call(arguments,1),e=0,f=!0,g=0,h=0;return b=a.event.fix(c),b.type="mousewheel",c.wheelDelta&&(e=c.wheelDelta/120),c.detail&&(e=-c.detail/3),h=e,c.axis!==undefined&&c.axis===c.HORIZONTAL_AXIS&&(h=0,g=-1*e),c.wheelDeltaY!==undefined&&(h=c.wheelDeltaY/120),c.wheelDeltaX!==undefined&&(g=-1*c.wheelDeltaX/120),d.unshift(b,e,g,h),(a.event.dispatch||a.event.handle).apply(this,d)}var b=["DOMMouseScroll","mousewheel"];if(a.event.fixHooks)for(var c=b.length;c;)a.event.fixHooks[b[--c]]=a.event.mouseHooks;a.event.special.mousewheel={setup:function(){if(this.addEventListener)for(var a=b.length;a;)this.addEventListener(b[--a],d,!1);else this.onmousewheel=d},teardown:function(){if(this.removeEventListener)for(var a=b.length;a;)this.removeEventListener(b[--a],d,!1);else this.onmousewheel=null}},a.fn.extend({mousewheel:function(a){return a?this.bind("mousewheel",a):this.trigger("mousewheel")},unmousewheel:function(a){return this.unbind("mousewheel",a)}})})(jQuery)
 // 画原本的宽高
 var origin_img = new Image();
 origin_img.src = $('.small_box').attr('src');
 var origin_w = origin_img.width;
 var origin_h = origin_img.height;
 // 计算画缩放的宽高
 var now_h = 480;
 var now_w = (origin_w/origin_h)*now_h;
 $('.small_box').css({'left':(680 -now_w)/2+'px','height':now_h+'px'})
 console.log($('.small_box').offset().left);
 $('#demo')[0].onmousemove = function(ev){
 var _event=ev||window.event;
 var x = _event.pageX||_event.clientX,
 y = _event.pageY||_event.clientY;
 var left=x- $('#big_box').width()/2 - $('.demo').offset().left ;
 var top=y - $('#big_box').width()/2 - $('.demo').offset().top ;
 $('#big_box')[0].style.left = left+ 'px';
 $('#big_box')[0].style.top = top + 'px';
 var percentX = ($('.small_box').offset().left -x)/now_w;
 var percentY = ($('.small_box').offset().top -y)/now_h;
 $('.big_box').css({
 'background-position-x':percentX*origin_w + $('#big_box').width()/2+'px',
 'background-position-y':percentY*origin_h + $('#big_box').height()/2+'px'
 })
 }
 // 滚轮滚动
 $('.big_box').on('mousewheel',function(_event,delta){
 var x = _event.pageX||_event.clientX,
 y = _event.pageY||_event.clientY;
 var left=x- $('#big_box').width()/2 - $('.demo').offset().left ;
 var top=y - $('#big_box').width()/2 - $('.demo').offset().top ;
 var targe_w = $(this).width();
 var targe_h = $(this).height();
 if (delta>0) {
 targe_w += 3;
 targe_h += 3;
 $('#big_box')[0].style.left = left -3+ 'px';
 $('#big_box')[0].style.top = top -3 + 'px';
 }else{
 targe_w -= 3;
 targe_h -= 3;
 $('#big_box')[0].style.left = left +3+ 'px';
 $('#big_box')[0].style.top = top +3 + 'px';
 }
 $(this).width(targe_w);
 $(this).height(targe_h);
 })
 //显示放大镜
 $('.demo').on('mouseover',function(){
 $('#big_box').show();
 });
 $('.demo').on('mouseout',function(){
 $('#big_box').hide();
 });
 })
 </script>
 <br/> <br/> <br/> <br/> <br/>
</body>
</html>