PDFOne .NET
Powerful all-in-one PDF library for .NET

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Home » Newsletter » December 2007

By Raju Sinha

The PDF format does not explicitly specify any header or footer for a page. However, PDFOne .NET provides you the ability to specify your own headers and footers when you create or modify PDF documents. Using this feature, you can use images and formatted text as headers and footers.

When creating a new page using PDFOne .NET, you can specify header and footer sizes using one of the overloaded PDFPage constructors.

public PDFPage(
   PaperKind pageSize,
   float pageHeaderHeight,
   float pageFooterHeight,
   float pageLeftMargin,
   float pageTopMargin,
   float pageRightMargin,
   float pageBottomMargin,
   PDFMeasurementUnit measurementUnit
);

In the following code snippet, an A4-size PDF page has been created with header and footer sizes set at 2 centimeters.

// Create a page with specified header and footer sizes
PDFPage page1 = new PDFPage(
    PaperKind.A4, // A4-size page
    2,            // 2-cm header
    2,            // 2-cm footer
    3,            // 3-cm left margin
    2,            // 2-cm top margin 
    1,            // 1-cm right margin   
    2,            // 2-cm bottom margin   
    PDFMeasurementUnit.Centimeters 
    // measurment units in centimeters
    );

After specifying the sizes of the header and footer regions, you can use the following methods of the PDFDocument class to add text and images.

• AddHeaderImage()
• AddHeaderText()
• AddFooterImage()
• AddFooterText()

In the code snippet below, some text is written to the designated footer region of a page.

// Create a font
PDFFont font1 = new PDFFont(
    StdType1Font.Times_Bold, // Times font
    PDFFontStyle.Fill,       // filled (shaded) glyphs
    15);                     // 15-point size

// Add footer text
page1.AddFooterText(
   "P.T.O",   // footer text
   font1,     // font used to render footer text
   PDFHAlignment.Right,  // horizontal text alignment
   PDFVAlignment.Bottom  // vertical text alignment);

If you want to add a header or footer to a page in an existing PDF document, it is not as straightforward as when you do the same with a new PDF document that you create.

As mentioned earlier, there is no concept of headers and footers in PDF. So, when you need to add a header or footer to an existing page, you need a mechanism to specify where the header or footer needs to be on that page. This would then help the above-mentioned methods to place text or images on the header/footer region that you have designated.

For that purpose, PDFOne .NET provides a CreatePage() event for which you need to register an event handler that will then be used to specify the footer and header regions.

The CreatePage() event fires when a page from the existing document is created in the output file. If the header and footer regions are defined by the event handler, then PDFOne .NET knows exactly where the header or footer needs to be placed on the page when an "add footer" or an "add header" method is subsequently called.

// event
public event PageCreateEventHandler CreatePage();

// delegate
public delegate void PageCreateEventHandler(
   object sender,
   ref PageMargins margins,
   int pageNumber,
   float pageWidthInPoints,
   float pageHeightInPoints);

In the PageCreateEventHandler event handler, you specify the header and footer size with the PageMargins structure parameter. The members of this structure contain values for the header margin, footer margin, top margin, bottom margin, right margin, left margin, and the measurement unit with which these margins are specified.

public struct PageMargins {
  public float leftMargin;
  public float rightMargin;
  public float topMargin;
  public float bottomMargin;
  public PDFMeasurementUnit measurementUnit;
  public float headerHeight;
  public float footerHeight;
}

Now, here is the code snippet that brings it all together.

// A button-click event on a form - create a 
// form, add a button, double-click the button,
// paste this code and run it.
private void button1_Click(
   object sender, System.EventArgs e) {

 // Create a document object 
 PDFDocument doc = new PDFDocument();

 // Register the event handler
 doc.CreatePage +=
        new PageCreateEventHandler(doc_CreatePage);

 // Load an existing PDF document
 doc.Load("Test.pdf");

 // Process each page in the document
 for (int i = 1; i <= doc.GetPageCount(); i++) {
  // Get specified page from the document
  PDFPage page = doc.GetPage(i);
  // Add an image to the header
  page.AddHeaderImage(
        "image1.bmp",
        PDFHAlignment.Center,
        PDFVAlignment.Center);
  // Add formatted text to the header
  page.AddHeaderText(
        "This is Header Text",
        new PDFFont(StdType1Font.Helvetica, 12),
        PDFHAlignment.Left,
        PDFVAlignment.Top);
  // Add an image to the footer
  page.AddFooterImage(
        "image2.bmp",
        PDFHAlignment.Center,
        PDFVAlignment.Center);
  // Add formatted text to the header
  page.AddFooterText(
        "This is Footer Text",
        new PDFFont(StdType1Font.Helvetica, 12),
        PDFHAlignment.Left,
        PDFVAlignment.Top);
 }

 doc.OpenAfterCreate = true;
 doc.Save("Headers_Footers.pdf");
 doc.Close();
}

// Event handler 
private void doc_CreatePage(
   object sender, ref PageMargins margins,
   int pageNumber, float pageWidthInPoints,
   float pageHeightInPoints) {

 // Specify page margins
 margins.topMargin = 0.5f;
 margins.leftMargin = 2;
 margins.bottomMargin = 1;
 margins.rightMargin = 2;

 // Specify header and footer sizes
 margins.headerHeight = 0.5f;
 margins.footerHeight = 1;

 // Specify measurement unit for margins
 margins.measurementUnit =
   PDFMeasurementUnit.Centimeters;
}