//ͼƭ����������   
var flag = false;   
   function drawimage(imgd, iwidth, iheight) {   
	   //����(ͼƭ,����ŀ��,����ĸ߶�)   
	   var image = new image();   
	   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;   
		}   
	}   
}