html to pdf conversion

string filename = string.Empty;
        private void button1_Click(object sender, EventArgs e)
        {
            DialogResult result = openFileDialog1.ShowDialog();
            if (result == DialogResult.OK)
            {
                textBox1.Text = openFileDialog1.FileName;
                filename = textBox1.Text;

            }
        }

private void button2_Click(object sender, EventArgs e)
        {
            using (StreamReader reader = new StreamReader(filename))
            {
                String line = reader.ReadToEnd();
                Html2PDF(line);
            }


        }
        protected void Html2PDF(string PDFText)
        {
            //HttpContext context = HttpContext.Current;
            StringReader reader = new StringReader(PDFText);

            //Create PDF document 
            Document document = new Document(PageSize.A4);
            HTMLWorker parser = new HTMLWorker(document);

            string PDF_FileName = Path.GetFileNameWithoutExtension(filename) + ".pdf";
            PdfWriter.GetInstance(document, new FileStream(PDF_FileName, FileMode.Create));
            document.Open();

            try
            {
                parser.Parse(reader);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
            finally
            {
                document.Close();
                MessageBox.Show("PDF File Generated Successfully...");
            }

        }