private void btnPrintPdf_Click(object sender, EventArgs e)
{
    if (pdfFileTextBox.Text.Trim().Equals(String.Empty))
    {
        MessageBox.Show("Please choose a source PDF file", "Choose PDF file", MessageBoxButtons.OK);
        return;
    }

    // the source pdf file
    string pdfFileName = pdfFileTextBox.Text.Trim();

    // start page number
    int startPageNumber = int.Parse(textBoxStartPage.Text.Trim());
    // end page number
    // when it is 0 the conversion will continue up to the end of document
    int endPageNumber = 0;
    if (textBoxEndPage.Text.Trim() != String.Empty)
        endPageNumber = int.Parse(textBoxEndPage.Text.Trim());

    // create the PDF printer 
    PdfPrint pdfPrint = new PdfPrint();

    // set the license key
    pdfPrint.LicenseKey = "OrSltaGgtaW1o7ultaaku6Snu6ysrKy1pQ==";

    // set the document name
    pdfPrint.DocumentName = "PDF Silent Printing";

    // enable or disable color printing
    pdfPrint.DefaultPageSettings.Color = cbPrintColor.Checked;

    // set the PDF printing color and resolution
    pdfPrint.Color = GetSelectedPrintColor();
    pdfPrint.Resolution = int.Parse(textBoxResolution.Text);

    // select the printer
    string selectedPrinterName = GetSelectedPrinterName();
    if (selectedPrinterName != null)
        pdfPrint.PrinterSettings.PrinterName = selectedPrinterName;

    // set paper size
    PaperSize selectedPaperSize = GetSelectedPaperSize();
    if (selectedPaperSize != null)
        pdfPrint.DefaultPageSettings.PaperSize = selectedPaperSize;

    // set paper orientation
    pdfPrint.DefaultPageSettings.Landscape = GetSelectedPageOrientation() == "Landscape";

    // set paper margins 
    pdfPrint.DefaultPageSettings.Margins = new Margins((int)(float.Parse(leftMarginTextBox.Text) * 100),
        (int)(float.Parse(rightMarginTextBox.Text) * 100),
        (int)(float.Parse(topMarginTextBox.Text) * 100),
        (int)(float.Parse(bottomMarginTextBox.Text) * 100));

    // the demo output directory
    string outputDirectory = Path.Combine(Application.StartupPath, @"DemoFiles\Output");

    Cursor = Cursors.WaitCursor;

    try
    {
        pdfPrint.Print(pdfFileName, startPageNumber, endPageNumber);
    }
    catch (Exception ex)
    {
        // The conversion failed
        MessageBox.Show(String.Format("An error occurred. {0}", ex.Message), "Error");
        return;
    }
    finally
    {
        Cursor = Cursors.Arrow;
    }

    MessageBox.Show("Print Completed", "Print Completed", MessageBoxButtons.OK);
}