Adding PDF Page Headers with iTextSharp

Updated 2012-01-16.

A common question on the iText mailing list; probably because it's not a simple, one-step process.

The recommended method is to create a class that inherits from PdfPageEventHelper, which you should be able to guess, allows you to handle numerous document events. Since the goal is to add a header to every page of the PDF document, the following ASP.NET web forms example is implemented using the following steps:

Create a class in the code-behind file that overrides PdfPageEventHelper.
Override the OnEndPage() method to write the page header content. You should not use OnStartPage() to write header content - you should only override the method to initialize class members.
Instantiate a PdfPTable within the OnEndPage() method so everything is nicely formatted. We throw in an Image object, since that's also a popular question.
Attach an instance object of our newly created class to PdfWriter's PageEvent property.

On to the code. First the class that inherits from PdfPageEventHelper, nested in your code-behind class:

  private class MyPageEventHandler : PdfPageEventHelper {
/*
 * We use a __single__ Image instance that's assigned __once__;
 * the image bytes added **ONCE** to the PDF file. If you create 
 * separate Image instances in OnEndPage()/OnEndPage(), for example,
 * you'll end up with a much bigger file size.
 */      
    public Image ImageHeader {get; set;}

    public override void OnEndPage(PdfWriter writer, Document document) {
// cell height 
      float cellHeight = document.TopMargin;
// PDF document size      
      Rectangle page = document.PageSize;

// create two column table
      PdfPTable head = new PdfPTable(2);
      head.TotalWidth = page.Width;

// add image; PdfPCell() overload sizes image to fit cell
      PdfPCell c = new PdfPCell(ImageHeader, true);
      c.HorizontalAlignment = Element.ALIGN_RIGHT;
      c.FixedHeight = cellHeight;
      c.Border = PdfPCell.NO_BORDER;
      head.AddCell(c);

// add the header text
      c = new PdfPCell( new Phrase(
        DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ss") + " GMT",
        new Font(Font.FontFamily.COURIER, 8)
      ));
      c.Border = PdfPCell.NO_BORDER;
      c.VerticalAlignment = Element.ALIGN_BOTTOM;
      c.FixedHeight = cellHeight;
      head.AddCell(c);
      
// since the table header is implemented using a PdfPTable, we call
// WriteSelectedRows(), which requires absolute positions!
      head.WriteSelectedRows(
        0, -1,  // first/last row; -1 flags all write all rows
        0,      // left offset
        // ** bottom** yPos of the table
        page.Height - cellHeight + head.TotalHeight,
        writer.DirectContent
      );
    }
  }

In the button's event handler you stream the PDF to the client using this method:

  private void _streamPdf() {
    using (Document document = new Document()) {
      PdfWriter writer = PdfWriter.GetInstance(
        document, Response.OutputStream
      );
      
// the image we're using for the page header      
      Image imageHeader = Image.GetInstance(Request.MapPath(
        "~/kyouyuu/image/kuujinbo2.gif"
      ));
      
// instantiate the custom PdfPageEventHelper
      MyPageEventHandler e = new MyPageEventHandler() { 
        ImageHeader = imageHeader
      };
// and add it to the PdfWriter
      writer.PageEvent = e;
      document.Open();
      
// finally we add some pages with text to show the headers are working
      string text = filler.Text;
      for (int k = 0; k < 8; ++k) {
        text += " " + text;
        Paragraph p = new Paragraph(text);
        p.SpacingBefore = 8f;
        document.Add(p);
      }
    }

The inline comments should be self-explanatory.

Enter a sentence to fill the PDF document:

Yes, just like the Generating PDFs with iTextSharp page, the PDF is being dynamically created on each POST.

Adding PDF Page Headers with iTextSharp

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