// 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; 
			} 
		} 
	} 
}