var flag = false;
function DrawImage(ImgD,width,height)
{ 
        var image = new Image();
        var iwidth = width;  //定义允许图片宽度 
        var iheight = height;  //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;
            }
        } 
}