private void convertToPdfButton_Click(object sender, EventArgs e)
{
    // Create a HTML to PDF converter object with default settings
    HtmlToPdfConverter htmlToPdfConverter = new HtmlToPdfConverter();

    // Set license key received after purchase to use the converter in licensed mode
    // Leave it not set to use the converter in demo mode
    htmlToPdfConverter.LicenseKey = "fvDh8eDx4fHg4P/h8eLg/+Dj/+jo6Og=";

    Cursor = Cursors.WaitCursor;

    // Convert HTML to PDF using the settings above
    string outPdfFile = @"DemoAppFiles\Output\HTML_to_PDF\File_Links_and_Attachments.pdf";
    Document pdfDocument = null;
    try
    {   
        string htmlWithLinksAndAttachMarkers = htmlStringTextBox.Text;
        string baseUrl = baseUrlTextBox.Text;

        // Convert a HTML string with markers for file links and attachments to a PDF document object
        pdfDocument = htmlToPdfConverter.ConvertHtmlToPdfDocumentObject(htmlWithLinksAndAttachMarkers, baseUrl);

        // Display the attachments panel when the PDF document is opened in a PDF viewer
        pdfDocument.ViewerPreferences.PageMode = ViewerPageMode.UseAttachments;

        // Create File Links

        // Make the HTML element with 'file_link_text' mapping ID a link to an external file
        HtmlElementMapping fileLinkTextMapping = htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult.GetElementByMappingId("file_link_text");
        if (fileLinkTextMapping != null)
        {
            PdfPage fileLinkTextPage = fileLinkTextMapping.PdfRectangles[0].PdfPage;
            RectangleF fileLinkTextRectangle = fileLinkTextMapping.PdfRectangles[0].Rectangle;

            string filePath = @"..\..\Input\Attach_Files\Linked_External_File.txt";

            // Create the file link
            FileLinkElement fileLinkTextElement = new FileLinkElement(fileLinkTextRectangle, filePath);
            fileLinkTextPage.AddElement(fileLinkTextElement);
        }

        // Make the HTML element with 'file_link_img' ID a link to an external file
        HtmlElementMapping fileLinkImgMapping = htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult.GetElementByMappingId("file_link_image");
        if (fileLinkImgMapping != null)
        {
            PdfPage fileLinkImgPage = fileLinkImgMapping.PdfRectangles[0].PdfPage;
            RectangleF fileLinkImgRectangle = fileLinkImgMapping.PdfRectangles[0].Rectangle;

            string filePath = @"..\..\Input\Attach_Files\Linked_External_File.txt";

            // Create the file link
            FileLinkElement fileLinkImgElement = new FileLinkElement(fileLinkImgRectangle, filePath);
            fileLinkImgPage.AddElement(fileLinkImgElement);
        }

        // Create File Attachments

        // Create an attachment from a file without icon
        string fileAttachmentPath = @"DemoAppFiles\Input\Attach_Files\Attachment_File.txt";
        pdfDocument.AddFileAttachment(fileAttachmentPath, "Attachment from File");

        // Create an attachment from a stream without icon
        string fileStreamAttachmentPath = @"DemoAppFiles\Input\Attach_Files\Attachment_Stream.txt";
        System.IO.FileStream attachmentStream = new System.IO.FileStream(fileStreamAttachmentPath, System.IO.FileMode.Open, System.IO.FileAccess.Read);
        pdfDocument.AddFileAttachment(attachmentStream, "Attachment_Stream.txt", "Attachment from Stream");

        // Create an attachment from file with paperclip icon in PDF
        HtmlElementMapping attachFromFileIconMapping = htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult.GetElementByMappingId("attach_from_file_icon");
        if (attachFromFileIconMapping != null)
        {
            PdfPage attachFromFilePage = attachFromFileIconMapping.PdfRectangles[0].PdfPage;
            RectangleF attachFromFileIconRectangle = attachFromFileIconMapping.PdfRectangles[0].Rectangle;

            string fileAttachmentWithIconPath = @"DemoAppFiles\Input\Attach_Files\Attachment_File_Icon.txt";

            // Create the attachment from file
            FileAttachmentElement attachFromFileElement = new FileAttachmentElement(attachFromFileIconRectangle, fileAttachmentWithIconPath);
            attachFromFileElement.IconType = FileAttachmentIcon.Paperclip;
            attachFromFileElement.Text = "Attachment from File with Paperclip Icon";
            attachFromFileElement.IconColor = Color.Blue;
            attachFromFilePage.AddElement(attachFromFileElement);
        }

        // Create an attachment from stream with pushpin icon in PDF
        System.IO.FileStream attachmentStreamWithIcon = null;
        HtmlElementMapping attachFromStreamIconMapping = htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult.GetElementByMappingId("attach_from_stream_icon");
        if (attachFromStreamIconMapping != null)
        {
            PdfPage attachFromStreamPage = attachFromStreamIconMapping.PdfRectangles[0].PdfPage;
            RectangleF attachFromStreamIconRectangle = attachFromStreamIconMapping.PdfRectangles[0].Rectangle;
                    
            string fileStreamAttachmentWithIconPath = @"DemoAppFiles\Input\Attach_Files\Attachment_Stream_Icon.txt";

            attachmentStreamWithIcon = new System.IO.FileStream(fileStreamAttachmentWithIconPath, System.IO.FileMode.Open, System.IO.FileAccess.Read);

            // Create the attachment from stream
            FileAttachmentElement attachFromStreamElement = new FileAttachmentElement(attachFromStreamIconRectangle, attachmentStreamWithIcon, "Attachment_Stream_Icon.txt");
            attachFromStreamElement.IconType = FileAttachmentIcon.PushPin;
            attachFromStreamElement.Text = "Attachment from Stream with Pushpin Icon";
            attachFromStreamElement.IconColor = Color.Green;
            attachFromStreamPage.AddElement(attachFromStreamElement);
        }
                
        // Save the PDF document in a memory buffer
        byte[] outPdfBuffer = pdfDocument.Save();

        // Write the memory buffer in a PDF file
        System.IO.File.WriteAllBytes(outPdfFile, outPdfBuffer);
    }
    catch (Exception ex)
    {
        // The HTML to PDF conversion failed
        MessageBox.Show(String.Format("HTML to PDF Error. {0}", ex.Message));
        return;
    }
    finally
    {
        // Close the PDF document
        if (pdfDocument != null)
            pdfDocument.Close();

        Cursor = Cursors.Arrow;
    }

    // Open the created PDF document in default PDF viewer
    try
    {
        System.Diagnostics.Process.Start(outPdfFile);
    }
    catch (Exception ex)
    {
        MessageBox.Show(String.Format("Cannot open created PDF file '{0}'. {1}", outPdfFile, ex.Message));
    }
}