START_PAGE only makes the header for the first page - asp.net

Question

I have this code for web development:
protected internal class MyEventHandler : iText.Kernel.Events.IEventHandler
{
public virtual void HandleEvent(iText.Kernel.Events.Event #event)
{
iText.Kernel.Events.PdfDocumentEvent docEvent =
(iText.Kernel.Events.PdfDocumentEvent)#event;
PdfDocument pdfDoc = docEvent.GetDocument();
}
public void onStartPage(
iText.Kernel.Pdf.PdfWriter writer, iText.Layout.Document document)
{
// paragragrap for start pages
…
}
}
…
MyEventHandler StartPage = new MyEventHandler();
pdf.AddEventHandler(iText.Kernel.Events.PdfDocumentEvent.START_PAGE, new MyEventHandler());
StartPage.onStartPage(writer, document);
And other code that adds more to the page.
It only makes the header for the first page.

Answer 1

You are mixing event handling from different iText versions.
In iText 5 you used to implement IPdfPageEvent, often by extending PdfPageEventHelper, and here you had separate methods like
void OnStartPage(PdfWriter writer, Document document)
void OnEndPage(PdfWriter writer, Document document)
etc.
In iText 7 you implement IEventHandler which has only a single method,
void HandleEvent(Event #event)
You either register your event handler only for one event type and, consequentially, know in HandleEvent that the right event arrived, or you determine based on the event type (#event.GetEventType()) which type of event you got and execute the appropriate code.
An example event listener changing page rotation
E.g. in this example the event handler is registered for page starts only
C07E01_EventHandlers.PageRotationEventHandler eventHandler = new PageRotationEventHandler();
pdf.AddEventHandler(PdfDocumentEvent.START_PAGE, eventHandler);
and in its event handling method acts accordingly
public virtual void HandleEvent(Event #event) {
PdfDocumentEvent docEvent = (PdfDocumentEvent)#event;
docEvent.GetPage().Put(PdfName.Rotate, this.rotation);
}
The full example class:
public class C07E01_EventHandlers {
public const String DEST = "../../../results/chapter07/jekyll_hyde_page_orientation.pdf";
public static readonly PdfNumber PORTRAIT = new PdfNumber(0);
public static readonly PdfNumber LANDSCAPE = new PdfNumber(90);
public static readonly PdfNumber INVERTEDPORTRAIT = new PdfNumber(180);
public static readonly PdfNumber SEASCAPE = new PdfNumber(270);
public static void Main(String[] args) {
FileInfo file = new FileInfo(DEST);
file.Directory.Create();
new C07E01_EventHandlers().CreatePdf(DEST);
}
public virtual void CreatePdf(String dest) {
PdfDocument pdf = new PdfDocument(new PdfWriter(dest));
pdf.GetCatalog().SetPageLayout(PdfName.TwoColumnLeft);
C07E01_EventHandlers.PageRotationEventHandler eventHandler = new PageRotationEventHandler();
pdf.AddEventHandler(PdfDocumentEvent.START_PAGE, eventHandler);
Document document = new Document(pdf, PageSize.A8);
document.Add(new Paragraph("Dr. Jekyll"));
eventHandler.SetRotation(INVERTEDPORTRAIT);
document.Add(new AreaBreak());
document.Add(new Paragraph("Mr. Hyde"));
eventHandler.SetRotation(LANDSCAPE);
document.Add(new AreaBreak());
document.Add(new Paragraph("Dr. Jekyll"));
eventHandler.SetRotation(SEASCAPE);
document.Add(new AreaBreak());
document.Add(new Paragraph("Mr. Hyde"));
document.Close();
}
protected internal class PageRotationEventHandler : IEventHandler {
protected internal PdfNumber rotation = C07E01_EventHandlers.PORTRAIT;
public virtual void SetRotation(PdfNumber orientation) {
this.rotation = orientation;
}
public virtual void HandleEvent(Event #event) {
PdfDocumentEvent docEvent = (PdfDocumentEvent)#event;
docEvent.GetPage().Put(PdfName.Rotate, this.rotation);
}
internal PageRotationEventHandler() {
}
}
}
An example page listener adding headers and footers
In comments you asked for an example for header and not rotation a page. For that look e.g. at the iText 7 Jump-Start Tutorial chapter 3 (Using renderers and event handlers) example C03E03_UFO (Java version / C# version) in which an event listener is used to add a background, a watermark, a header, and a footer:
public class C03E03_UFO {
internal static PdfFont helvetica = null;
internal static PdfFont helveticaBold = null;
public static void Main(String[] args) {
helvetica = PdfFontFactory.CreateFont(StandardFonts.HELVETICA);
helveticaBold = PdfFontFactory.CreateFont(StandardFonts.HELVETICA_BOLD);
...
}
protected internal virtual void CreatePdf(String dest) {
//Initialize PDF document
PdfDocument pdf = new PdfDocument(new PdfWriter(dest));
pdf.AddEventHandler(PdfDocumentEvent.END_PAGE, new C03E03_UFO.MyEventHandler(this));
...
}
...
protected internal class MyEventHandler : IEventHandler {
public virtual void HandleEvent(Event #event) {
PdfDocumentEvent docEvent = (PdfDocumentEvent)#event;
PdfDocument pdfDoc = docEvent.GetDocument();
PdfPage page = docEvent.GetPage();
int pageNumber = pdfDoc.GetPageNumber(page);
Rectangle pageSize = page.GetPageSize();
PdfCanvas pdfCanvas = new PdfCanvas(page.NewContentStreamBefore(), page.GetResources(), pdfDoc);
//Set background
Color limeColor = new DeviceCmyk(0.208f, 0, 0.584f, 0);
Color blueColor = new DeviceCmyk(0.445f, 0.0546f, 0, 0.0667f);
pdfCanvas.SaveState()
.SetFillColor(pageNumber % 2 == 1 ? limeColor : blueColor)
.Rectangle(pageSize.GetLeft(), pageSize.GetBottom(), pageSize.GetWidth(), pageSize.GetHeight())
.Fill()
.RestoreState();
//Add header and footer
pdfCanvas.BeginText()
.SetFontAndSize(C03E03_UFO.helvetica, 9)
.MoveText(pageSize.GetWidth() / 2 - 60, pageSize.GetTop() - 20)
.ShowText("THE TRUTH IS OUT THERE")
.MoveText(60, -pageSize.GetTop() + 30)
.ShowText(pageNumber.ToString())
.EndText();
//Add watermark
iText.Layout.Canvas canvas = new iText.Layout.Canvas(pdfCanvas, pdfDoc, page.GetPageSize());
canvas.SetFontColor(ColorConstants.WHITE);
canvas.SetProperty(Property.FONT_SIZE, UnitValue.CreatePointValue(60));
canvas.SetProperty(Property.FONT, C03E03_UFO.helveticaBold);
canvas.ShowTextAligned(new Paragraph("CONFIDENTIAL"), 298, 421, pdfDoc.GetPageNumber(page), TextAlignment.
CENTER, VerticalAlignment.MIDDLE, 45);
pdfCanvas.Release();
}
internal MyEventHandler(C03E03_UFO _enclosing) {
this._enclosing = _enclosing;
}
private readonly C03E03_UFO _enclosing;
}
}
Strictly speaking that example listens to PdfDocumentEvent.END_PAGE instead of PdfDocumentEvent.START_PAGE. That difference shouldn't hurt too much, though.