// JavaScript Document
 var flag=false; 
function DrawImage(ImgD,imgwidth,imgheight){ 
 var image=new Image(); 
 var iwidth = imgwidth;  //定义允许图片宽度 
 var iheight =imgheight;  //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; 
  } 
  
  } 
 else{ 
  if(image.height>iheight){   
  ImgD.height=iheight; 
  ImgD.width=(image.width*iheight)/image.height;   
  }else{ 
  ImgD.width=image.width;   
  ImgD.height=image.height; 
  } 
  
  } 
 } 
}