js+jquery實現圖片裁剪功能

現在我們在使用各大網站的個人中心時,都有個上傳個人頭像的功能。用戶在上傳瞭個人照片之後,可能不符合網站的要求,於是要求用戶對照片進行裁剪,最終根據用戶裁剪的尺寸生成頭像。這個功能真是太棒瞭,原來不懂js的時候,感覺很神奇,太神奇瞭。心想哪天要是自己也能搞明白這裡面的技術,那該多牛呀~大傢是不是也有何我一樣的想法呀~哈哈~~

下面我們就來用javascript來實現這個功能吧。

代碼如下:

<!DOCTYPE html>
<html xmlns="https://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(https://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(https://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>
<p class="code">
 <p class="how">使用方法</p>
    <p>$("#container").clip({
  imgC : $("#imgC"),
        blockClass : "block",
        tipsClass  : "tips"       
 });</p>
    <p><span>imgC :</span> 表示裁剪圖片的容器,也就是右邊的圖</p>
    <p><span>blockClass :</span> block的樣式名  也就是頁面上的可以拖動的滑塊的樣式 因為怕和別的頁面上的樣式重名  默認是block</p>
    <p><span>tipsClass  :</span> tips的樣式名   也就是頁面上顯示left width height top的那個span的樣式名 默認是tips</p>
</p>
<ul>
 <li>
     <p id="container"></p>
    </li>
    <li>
     <p id="imgC"></p>
    </li>
</ul>
<script type="text/javascript" src="https://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 = $('<p class="'+this.blockClass+'">\
     <p action="rightDown" class="rRightDown"></p>\
     <p action="leftDown" class="rLeftDown"></p>\
     <p action="rightUp" class="rRightUp"></p>\
     <p action="leftUp" class="rLeftUp"></p>\
     <p action="right" class="rRight"></p>\
   nbsp;  <p action="left" class="rLeft"></p>\
     <p action="up" class="rUp"></p>\
     <p action="down" class="rDown" ></p>\
       </p>')
   .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");
   //這個 每次都要計算 基本dom結構的改變 瀏覽器的縮放 都會讓裡面的值發生改變 
   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), //出現垂直方向滾動條時候 要計算這個 
    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>

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