Add Elements Over PDF Page Main Content

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 = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c=";

    // 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;

    // Set a handler for AfterRenderPdfPageEvent where to add the stamp in each PDF page over the main content
    htmlToPdfConverter.AfterRenderPdfPageEvent += new AfterRenderPdfPageDelegate(htmlToPdfConverter_AfterRenderPdfPageEvent);

    try
    {
        // The buffer to receive the generated PDF document
        byte[] outPdfBuffer = null;

        if (convertUrlRadioButton.Checked)
        {
            string url = urlTextBox.Text;

            // Convert the HTML page given by an URL to a PDF document in a memory buffer
            outPdfBuffer = htmlToPdfConverter.ConvertUrl(url);
        }
        else
        {
            string htmlString = htmlStringTextBox.Text;
            string baseUrl = baseUrlTextBox.Text;

            // Convert a HTML string with a base URL to a PDF document in a memory buffer
            outPdfBuffer = htmlToPdfConverter.ConvertHtml(htmlString, baseUrl);
        }

        // 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=Add_Elements_Over_Main_Content.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
    {
        // Uninstall the handler
        htmlToPdfConverter.AfterRenderPdfPageEvent -= new AfterRenderPdfPageDelegate(htmlToPdfConverter_AfterRenderPdfPageEvent);
    }
}

void htmlToPdfConverter_AfterRenderPdfPageEvent(AfterRenderPdfPageParams eventParams)
{
    if (!addStampCheckBox.Checked)
        return;

    // Get the rendered PDF page
    PdfPage pdfPage = eventParams.Page;

    int pageNumber = eventParams.PageNumber;
    int pageCount = eventParams.PageCount;
    bool isOddPage = pageNumber % 2 != 0;

    // Get the PDF document
    Document pdfDocument = pdfPage.Document;

    // Get the PDF page drawable area width and height
    float pdfPageWidth = pdfPage.ClientRectangle.Width;
    float pdfPageHeight = pdfPage.ClientRectangle.Height;

    // Create a .NET font
    Font timesNewRomanFont = new Font("Times New Roman", 50, GraphicsUnit.Point);

    // Create a PDF font
    PdfFont pdfFont = pdfDocument.AddFont(timesNewRomanFont, true);

    // The stamp text
    string text = String.Format("Stamp on Page {0} of {1}", pageNumber, pageCount);

    // Measure the text 
    float textWidth = pdfFont.GetTextWidth(text);

    // Calculate the PDF page diagonal
    float pdfPageDiagonal = (float)Math.Sqrt(pdfPageWidth * pdfPageWidth + pdfPageHeight * pdfPageHeight);

    // The text location on PDF page diagonal
    float xLocation = (pdfPageDiagonal - textWidth) / 2;

    // Create the stamp as a rotated text element
    TextElement stampTextElement = new TextElement(xLocation, 0, text, pdfFont);
    stampTextElement.ForeColor = isOddPage ? Color.Blue : Color.Green;
    stampTextElement.Rotate((float)(Math.Atan(pdfPageHeight / pdfPageWidth) * (180 / Math.PI)));
    stampTextElement.Opacity = 75;

    // Add the stamp to PDF page
    pdfPage.AddElement(stampTextElement);
}

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 = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c="

    ' 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

    ' Set a handler for AfterRenderPdfPageEvent where to add the stamp in each PDF page over the main content
    AddHandler htmlToPdfConverter.AfterRenderPdfPageEvent, AddressOf htmlToPdfConverter_AfterRenderPdfPageEvent

    Try
        ' The buffer to receive the generated PDF document
        Dim outPdfBuffer() As Byte = Nothing

        If convertUrlRadioButton.Checked Then
            Dim url As String = urlTextBox.Text

            ' Convert the HTML page given by an URL to a PDF document in a memory buffer
            outPdfBuffer = htmlToPdfConverter.ConvertUrl(url)
        Else
            Dim htmlString As String = htmlStringTextBox.Text
            Dim baseUrl As String = baseUrlTextBox.Text

            ' Convert a HTML string with a base URL to a PDF document in a memory buffer
            outPdfBuffer = htmlToPdfConverter.ConvertHtml(htmlString, baseUrl)
        End If

        ' 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=Add_Elements_Over_Main_Content.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
        ' Uninstall the handler
        RemoveHandler htmlToPdfConverter.AfterRenderPdfPageEvent, AddressOf htmlToPdfConverter_AfterRenderPdfPageEvent
    End Try
End Sub

Private Sub htmlToPdfConverter_AfterRenderPdfPageEvent(ByVal eventParams As AfterRenderPdfPageParams)
    If Not addStampCheckBox.Checked Then
        Return
    End If

    ' Get the rendered PDF page
    Dim pdfPage As PdfPage = eventParams.Page

    Dim pageNumber As Integer = eventParams.PageNumber
    Dim pageCount As Integer = eventParams.PageCount
    Dim isOddPage As Boolean = pageNumber Mod 2 <> 0

    ' Get the PDF document
    Dim pdfDocument As Document = pdfPage.Document

    ' Get the PDF page drawable area width and height
    Dim pdfPageWidth As Single = pdfPage.ClientRectangle.Width
    Dim pdfPageHeight As Single = pdfPage.ClientRectangle.Height

    ' Create a .NET font
    Dim timesNewRomanFont As New Font("Times New Roman", 50, GraphicsUnit.Point)

    ' Create a PDF font
    Dim pdfFont As PdfFont = pdfDocument.AddFont(timesNewRomanFont, True)

    ' The stamp text
    Dim text As String = String.Format("Stamp on Page {0} of {1}", pageNumber, pageCount)

    ' Measure the text 
    Dim textWidth As Single = pdfFont.GetTextWidth(text)

    ' Calculate the PDF page diagonal
    Dim pdfPageDiagonal As Single = CSng(Math.Sqrt(pdfPageWidth * pdfPageWidth + pdfPageHeight * pdfPageHeight))

    ' The text location on PDF page diagonal
    Dim xLocation As Single = (pdfPageDiagonal - textWidth) / 2

    ' Create the stamp as a rotated text element
    Dim stampTextElement As New TextElement(xLocation, 0, text, pdfFont)
    stampTextElement.ForeColor = If(isOddPage, Color.Blue, Color.Green)
    stampTextElement.Rotate(CSng(Math.Atan(pdfPageHeight / pdfPageWidth) * (180 / Math.PI)))
    stampTextElement.Opacity = 75

    ' Add the stamp to PDF page
    pdfPage.AddElement(stampTextElement)
End Sub