js+jquery实现图片裁剪功能

现在我们在使用各大网站的个人中心时，都有个上传个人头像的功能。用户在上传了个人照片之后，可能不符合网站的要求，于是要求用户对照片进行裁剪，最终根据用户裁剪的尺寸生成头像。这个功能真是太棒了，原来不懂js的时候，感觉很神奇，太神奇了。心想哪天要是自己也能搞明白这里面的技术，那该多牛呀~大家是不是也有何我一样的想法呀~哈哈~~

下面我们就来用javascript来实现这个功能吧。

代码如下:

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>clip</title>
<style type="text/css">
*{ padding:0; margin:0;}
ul{ list-style-type:none; overflow:hidden; zoom:1; width:1000px; margin:30px auto; }
li{ float:left; width:500px;}
#container{width:480px; height:480px; margin:0 auto; border:1px solid #999; position:relative;background:url(http://images.cnblogs.com/cnblogs_com/wtcsy/192373/r_xx.jpg);}
#container .block{height:100px; width:100px; border:1px solid #000000; position:absolute; left:50px; top:50px; background:#fff;filter:alpha(opacity=30);opacity:0.3; cursor:move;}
#container .tips{ position:absolute; padding:5px; border:1px solid #ccc;background:#fff;filter:alpha(opacity=60);opacity:0.6; display:none; font-size:12px; color:#333; ;}
.tips span{ display:inline-block;zoom:1; width:28px;}
.rRightDown,.rLeftDown,.rLeftUp,.rRightUp,.rRight,.rLeft,.rUp,.rDown{
position:absolute;background:#f00;width:6px;height:6px;z-index:5;font-size:0;}
.rLeftDown,.rRightUp{cursor:ne-resize;}
.rRightDown,.rLeftUp{cursor:nw-resize;}
.rRight,.rLeft{cursor:e-resize;}
.rUp,.rDown{cursor:n-resize;}
.rRightDown{ bottom:-3px; right:-3px;}
.rLeftDown{ bottom:-3px; left:-3px;}
.rRightUp{ top:-3px; right:-3px;}
.rLeftUp{ top:-3px; left:-3px;}
.rRight{ right:-3px; top:50%}
.rLeft{ left:-3px; top:50%}
.rUp{ top:-3px; left:50%}
.rDown{ bottom:-3px; left:50%}
#imgC{ border:1px solid #CCC; width:0; height:0; margin:0 auto;background:url(http://images.cnblogs.com/cnblogs_com/wtcsy/192373/r_xx.jpg);}
.code {
    background: none repeat scroll 0 0 #E3F4F9;
    border: 1px solid #BAE2F0;
    font: 12px "Courier New",Courier,monospace;
    margin: 30px auto;
    padding: 10px 10px 40px;
 width:980px;
}
.code p{ height:24px; line-height:24px;}
.code span{ display:inline-block;zoom:1; margin-right:5px; width:85px; font-weight:bold; color:#00F}
</style>
</head>
<body>
<div class="code">
 <div class="how">使用方法</div>
    <p>$("#container").clip({
  imgC : $("#imgC"),
        blockClass : "block",
        tipsClass  : "tips"       
 });</p>
    <p><span>imgC :</span> 表示裁剪图片的容器,也就是右边的图</p>
    <p><span>blockClass :</span> block的样式名  也就是页面上的可以拖动的滑块的样式 因为怕和别的页面上的样式重名  默认是block</p>
    <p><span>tipsClass  :</span> tips的样式名   也就是页面上显示left width height top的那个span的样式名 默认是tips</p>
</div>
<ul>
 <li>
     <div id="container"></div>
    </li>
    <li>
     <div id="imgC"></div>
    </li>
</ul>
<script type="text/javascript" src="http://common.cnblogs.com/script/jquery.js"></script>
<script type="text/javascript">
(function(){
 var dBody = document.body,
  dDoc = document.documentElement,
  ie   = $.browser.msie;
 ie&&($.browser.version=="6.0")
  &&document.execCommand("BackgroundImageCache", false, true); 
 var  clip =  function(options){
  this.init.call(this,options); 
 }
 clip.prototype = {
  options :{
   moveCallBack : function(){},
   blockClass : "block",
   tipsClass  : "tips"
  },
  init : function(options){   
   $.extend(this,this.options,options||{});
   if(!this.container || !this.imgC){
    return;
   }
   this.container = $(this.container);
   var self = this;
   this.block = $('<div class="'+this.blockClass+'">\
     <div action="rightDown" class="rRightDown"></div>\
     <div action="leftDown" class="rLeftDown"></div>\
     <div action="rightUp" class="rRightUp"></div>\
     <div action="leftUp" class="rLeftUp"></div>\
     <div action="right" class="rRight"></div>\
     <div action="left" class="rLeft"></div>\
     <div action="up" class="rUp"></div>\
     <div action="down" class="rDown" ></div>\
       </div>')
   .bind("mousedown.r",function(e){self.start(e)})
   .appendTo(this.container[0]);
   this.tips = $('<span class="'+this.tipsClass+'" />').appendTo(this.container[0]);
   this.setImg();
  },
  setImg : function(){
   var block = this.block;
   var left  = block.css("left"),
    top   = block.css("top"),
    height = block.height(),
    width  = block.width();
   this.imgC.css({
    height: height,
    width : width,
    "background-position" : "-"+left+" -"+top
   });
   this.tips.html("left:<span>"+parseInt(left) + "</span>top:<span>" + +parseInt(top) + "</span>width:<span>"+width+ "</span>height:<span>"+height+"</span>");
  },
  start : function(e){      
   var $elem     = $(e.target),
    block     = this.block,
    self      = this,
    move      = false,
    container = this.container,
    action    = $elem.attr("action");
   //这个 每次都要计算 基本dom结构的改变 浏览器的缩放 都会让里面的值发生改变 
   this.offset = $.extend({height:container.height(),width:container.width()},container.offset());
   this.blockOriginal = {height:block.height(),width:block.width(),left:parseInt(block.css("left")),top:parseInt(block.css("top"))};
   if(action){
    this.fun = this[action];    
   }else{
    this.x = e.clientX - this.offset.left - this.blockOriginal.left ;
    this.y = e.clientY - this.offset.top - this.blockOriginal.top;
    move = true;
   }   
   ie
    &&this.block[0].setCapture();
   this.tips.show();
   $(document)
    .bind("mousemove.r",function(e){self.move(e,move)})
    .bind("mouseup.r",function(){self.end()});   
  },
  end  : function(){
   $(document)
    .unbind("mousemove.r")
    .unbind("mouseup.r");
   ie 
    &&this.block[0].releaseCapture();
   this.tips.hide(); 
  },
  move : function(e,isMove){
   window.getSelection
    ? window.getSelection().removeAllRanges()
    : document.selection.empty();
    
   var block = this.block; 
   if(isMove){
    var left = Math.max(0,e.clientX - this.offset.left - this.x);
    left = Math.min(left,this.offset.width - this.blockOriginal.width);
    var top = Math.max(0,e.clientY - this.offset.top - this.y);
    top = Math.min(top,this.offset.height - this.blockOriginal.height);
    block.css({left:left,top:top});    
   }else{
    var offset = this.fun(e);
    block.css(offset);
   }
   
   this.setImg();
   this.moveCallBack();
  },
  down : function(e){
   var blockOriginal = this.blockOriginal,
    sTop = Math.max(dBody.scrollTop,dDoc.scrollTop), //出现垂直方向滚动条时候 要计算这个 
    offset = this.offset;
    
   if(e.clientY-offset.top>=blockOriginal.top-sTop){
    var height = Math.min(offset.height - blockOriginal.top,e.clientY-offset.top-blockOriginal.top+sTop),
     top = blockOriginal.top;
   }else{
    var height = Math.min(offset.top+blockOriginal.top-e.clientY-sTop,blockOriginal.top),
     top = Math.max(e.clientY - offset.top+sTop,0);
   }
   return {height:height, top:top};
  },
  up : function(e){
   var blockOriginal = this.blockOriginal,
    sTop = Math.max(dBody.scrollTop,dDoc.scrollTop),
    offset = this.offset;
   if(e.clientY-offset.top-blockOriginal.height<=blockOriginal.top-sTop){
    var top = Math.max(e.clientY-offset.top+sTop,0),
     maxHeight = blockOriginal.top + blockOriginal.height,
     height = Math.min(maxHeight,blockOriginal.top + blockOriginal.height -(e.clientY-offset.top)-sTop);     
   }else{
    var height = Math.min(e.clientY-offset.top-blockOriginal.top-blockOriginal.height+sTop,offset.height-blockOriginal.top-blockOriginal.height),
     top = blockOriginal.top+blockOriginal.height;  
   }
   return {height:height, top:top};
  },
  left : function(e){
   var blockOriginal = this.blockOriginal,
    offset = this.offset;
    
   if(e.clientX - offset.left - blockOriginal.width - blockOriginal.left<=0){
    var left  = Math.max(e.clientX - offset.left,0),
     width = Math.min(blockOriginal.left + blockOriginal.width,blockOriginal.left + blockOriginal.width -(e.clientX-offset.left));
   }else{
    var width = Math.min(e.clientX-offset.left-blockOriginal.left-blockOriginal.width,offset.width-blockOriginal.left-blockOriginal.width),
     left  = blockOriginal.left + blockOriginal.width;
   }
   return {left : left,  width : width};
  },
  right : function(e){
   var blockOriginal = this.blockOriginal,
    offset = this.offset;
   if(e.clientX-offset.left>=blockOriginal.left){
    var width = Math.min(offset.width - blockOriginal.left,e.clientX - offset.left - blockOriginal.left),
     left  = blockOriginal.left;
   }else{
    var width = Math.min(offset.left + blockOriginal.left - e.clientX,blockOriginal.left),
     left  = Math.max(e.clientX - offset.left,0);
   }
   return {left : left,  width : width};
  },
  rightDown : function(e){
   return $.extend(this.right(e),this.down(e));  
  },
  leftDown : function(e){
   return $.extend(this.left(e),this.down(e));
  },
  rightUp : function(e){
   return $.extend(this.right(e),this.up(e));
  },
  leftUp : function(e){
   return $.extend(this.left(e),this.up(e));
  },
  getValue : function(){
   var block = this.block;
   return {
    left   : parseInt(block.css("left")),
    top    : parseInt(block.css("top")),
    width  : block.width(),
    height : block.height()
   }
  }
 }
 $.fn.clip = function(options){
  options.container = this;
  return new clip(options);
 }
})();
 xx = $("#container").clip({
  imgC : $("#imgC")
 })
</script>
</body>
</html>

是不是很炫酷啊，小伙伴们，学学本示例的思路吧。