Add Watermarks and Stamps to Generated PDF Document

protected 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=";

    // Set an adddional delay in seconds to wait for JavaScript or AJAX calls after page load completed
    // Set this property to 0 if you don't need to wait for such asynchcronous operations to finish
    htmlToPdfConverter.ConversionDelay = 2;

    Document pdfDocument = null;
    try
    {
        // Convert a HTML page to a PDF document object
        pdfDocument = htmlToPdfConverter.ConvertUrlToPdfDocumentObject(urlTextBox.Text);

        // Get the stamp width and height
        float stampWidth = float.Parse(stampWidthTextBox.Text);
        float stampHeight = float.Parse(stampHeightTextBox.Text);

        // Center the stamp at the top of PDF page
        float stampXLocation = (pdfDocument.Pages[0].ClientRectangle.Width - stampWidth) / 2;
        float stampYLocation = 0;

        RectangleF stampRectangle = new RectangleF(stampXLocation, stampYLocation, stampWidth, stampHeight);

        // Create the stamp template to be repeated in each PDF page
        Template stampTemplate = pdfDocument.AddTemplate(stampRectangle);

        // Create the HTML element to add in stamp template
        HtmlToPdfElement stampHtmlElement = new HtmlToPdfElement(htmlStringTextBox.Text, baseUrlTextBox.Text);

        // Set the HTML viewer width for the HTML added in stamp
        stampHtmlElement.HtmlViewerWidth = 600;
        // Fit the HTML content in stamp template
        stampHtmlElement.FitWidth = true;
        stampHtmlElement.FitHeight = true;

        // Add HTML to stamp template
        stampTemplate.AddElement(stampHtmlElement);

        // Save the PDF document in a memory buffer
        byte[] outPdfBuffer = pdfDocument.Save();

        // Send the PDF as response to browser

        // Set response content type
        Response.AddHeader("Content-Type", "application/pdf");

        // Instruct the browser to open the PDF file as an attachment or inline
        Response.AddHeader("Content-Disposition", String.Format("attachment; filename=Watermarks_and_Stamps.pdf; size={0}", outPdfBuffer.Length.ToString()));

        // Write the PDF document buffer to HTTP response
        Response.BinaryWrite(outPdfBuffer);

        // End the HTTP response and stop the current page processing
        Response.End();
    }
    finally
    {
        // Close the PDF document
        if (pdfDocument != null)
            pdfDocument.Close();
    }
}

Protected Sub convertToPdfButton_Click(ByVal sender As Object, ByVal e As EventArgs)
    ' Create a HTML to PDF converter object with default settings
    Dim htmlToPdfConverter As 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="

    ' Set an adddional delay in seconds to wait for JavaScript or AJAX calls after page load completed
    ' Set this property to 0 if you don't need to wait for such asynchcronous operations to finish
    htmlToPdfConverter.ConversionDelay = 2

    Dim pdfDocument As Document = Nothing
    Try
        ' Convert a HTML page to a PDF document object
        pdfDocument = htmlToPdfConverter.ConvertUrlToPdfDocumentObject(urlTextBox.Text)

        ' Get the stamp width and height
        Dim stampWidth As Single = Single.Parse(stampWidthTextBox.Text)
        Dim stampHeight As Single = Single.Parse(stampHeightTextBox.Text)

        ' Center the stamp at the top of PDF page
        Dim stampXLocation As Single = (pdfDocument.Pages(0).ClientRectangle.Width - stampWidth) / 2
        Dim stampYLocation As Single = 0

        Dim stampRectangle As New RectangleF(stampXLocation, stampYLocation, stampWidth, stampHeight)

        ' Create the stamp template to be repeated in each PDF page
        Dim stampTemplate As Template = pdfDocument.AddTemplate(stampRectangle)

        ' Create the HTML element to add in stamp template
        Dim stampHtmlElement As New HtmlToPdfElement(htmlStringTextBox.Text, baseUrlTextBox.Text)

        ' Set the HTML viewer width for the HTML added in stamp
        stampHtmlElement.HtmlViewerWidth = 600
        ' Fit the HTML content in stamp template
        stampHtmlElement.FitWidth = True
        stampHtmlElement.FitHeight = True

        ' Add HTML to stamp template
        stampTemplate.AddElement(stampHtmlElement)

        ' Save the PDF document in a memory buffer
        Dim outPdfBuffer() As Byte = pdfDocument.Save()

        ' Send the PDF as response to browser

        ' Set response content type
        Response.AddHeader("Content-Type", "application/pdf")

        ' Instruct the browser to open the PDF file as an attachment or inline
        Response.AddHeader("Content-Disposition", String.Format("attachment; filename=Watermarks_and_Stamps.pdf; size={0}", outPdfBuffer.Length.ToString()))

        ' Write the PDF document buffer to HTTP response
        Response.BinaryWrite(outPdfBuffer)

        ' End the HTTP response and stop the current page processing
        Response.End()
    Finally
        ' Close the PDF document
        If pdfDocument IsNot Nothing Then
            pdfDocument.Close()
        End If
    End Try
End Sub