window.onload=function()
{               
ResetAllImg(160,120);
}
function ResetAllImg(width,height)  
{  
      var img_vh=height; //定义最大高度  
      var img_vw=width; //定义最大宽度  
      var imgn=document.getElementsByTagName("img");  
      for (var i=0;i<imgn.length;i++) {  
      if(imgn[i].height>img_vh || imgn[i].width>img_vw)  
      {  
         DrawImage(imgn[i],img_vw,img_vh);  
       }  
    }  
}  
 
function DrawImage(ImgD,FitWidth,FitHeight){  
     var image=new Image();   
     image.src=ImgD.src;  
     if(image.width>0 && image.height>0){  
        if(image.width/image.height>= FitWidth/FitHeight){  
           if(image.width>FitWidth){  
              ImgD.width=FitWidth;  
              ImgD.height=(image.height*FitWidth)/image.width;  
           }else{  
              ImgD.width=image.width;  
              ImgD.height=image.height;  
           }  
       } else{  
          if(image.height>FitHeight){  
             ImgD.height=FitHeight;  
             ImgD.width=(image.width*FitHeight)/image.height;  
          }else{  
             ImgD.width=image.width;  
             ImgD.height=image.height;  
      }  
     }  
   }  
}