jquery 等比缩放

/*
  * Image preload and auto zoom
  * scaling     是否等比例自动缩放
  * width       图片最大高
  * height      图片最大宽
  * loadpic     加载中的图片路径
  * example $("*").LoadImage(true,w,h);
 */
 jQuery.fn.LoadImage=function(scaling,width,height,loadpic){
     if(loadpic==null)loadpic="../images/loading.gif";
     return this.each(function(){
         var t=$(this);
         var src=$(this).attr("src")
         var img=new Image();
         //alert("Loading...")
         img.src=src;
         //自动缩放图片
         var autoScaling=function(){
             if(scaling){
            
                 if(img.width>0 && img.height>0){
                     if(img.width/img.height>=width/height){
                         if(img.width>width){
                             t.width(width);
                             t.height((img.height*width)/img.width);
                             t.css("margin-top", (height-t.height())/2);
                         }else{
                             t.width(img.width);
                             t.height(img.height);
                             t.css("margin-top", (height-t.height())/2);
                         }
                     }
                     else{
                         if(img.height>height){
                             t.height(height);
                             t.width((img.width*height)/img.height);
                             t.css("margin-top", (height-t.height())/2);
                         }else{
                             t.width(img.width);
                             t.height(img.height);
                             t.css("margin-top", (height-t.height())/2);
                         }
                     }
                 }
                
             }   
         }
         //处理ff下会自动读取缓存图片
         if(img.complete){
             //alert("getToCache!");
             autoScaling();
             return;
         }
         $(this).attr("src","");
         var loading=$("<img alt=\"加载中...\" title=\"图片加载中...\" src=\""+loadpic+"\" />");
        
         t.hide();
         t.after(loading);
         $(img).load(function(){
             autoScaling();
             loading.remove();
             t.attr("src",this.src);
             t.show();
             //alert("finally!")
         });
        
     });
 }