//图片按比例
//onload="DrawImage(this,400,30)" 
var flag=false; 
function DrawImage(ImgD,intWidth,intHeight){ 
  var image=new Image(); 
  var iwidth = intWidth;  //定义允许图片宽度 
  var iheight = intHeight;  //定义允许图片高度 
  image.src=ImgD.src; 
  if(image.width>0 && image.height>0){ 
   flag=true; 
   if(image.width/image.height>= iwidth/iheight){ 
    if(image.width>iwidth){   
    ImgD.width=iwidth; 
    ImgD.height=(image.height*iwidth)/image.width; 
    }else{ 
    ImgD.width=image.width;   
    ImgD.height=image.height; 
    } 
    //ImgD.alt=image.width+"×"+image.height; 
    } 
   else{ 
    if(image.height>iheight){   
    ImgD.height=iheight; 
    ImgD.width=(image.width*iheight)/image.height;      
    }else{ 
    ImgD.width=image.width;   
    ImgD.height=image.height; 
    } 
    //ImgD.alt=image.width+"×"+image.height; 
    } 
   } 
}