convert gridview to pdf

using (StringWriter sw = new StringWriter())
            {
                using (HtmlTextWriter hw = new HtmlTextWriter(sw))
                {
                    GridView1.AllowPaging = false;
                   
                    this.DataBind();
                    GridView1.RenderControl(hw);
                    StringReader sr = new StringReader(sw.ToString());
                    Document pdfdoc = new Document(PageSize.A2, 10f, 10f, 10f, 0f);
                    HTMLWorker htmlparser = new HTMLWorker(pdfdoc);
                    PdfWriter.GetInstance(pdfdoc, Response.OutputStream);
                    pdfdoc.Open();
                    htmlparser.Parse(sr);
                    pdfdoc.Close();

                    Response.ContentType = "Application/pdf";
                    Response.AddHeader("content-disposition"attachemnt;FileName=Spj");
                    Response.Cache.SetCacheability(HttpCacheability.NoCache);
                    Response.Write(pdfdoc);
                    Response.End();



                }
            }