How to introduce multiple PdfPageEventHelper instances?

I have to generate a large amount of different types of documents using the iTextSharp library that all have things in common.

5th November 2015
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Some have common headers, page counts, watermarks my initial thought was to have different PdfPageEventHelper subclasses for example WatermarkPdfPageEventHelper, OrderHeaderPdfPageEventHelper, PageNumberPdfPageEventHelper, and so on, and apply them when necessary to compose the documents but PageEvent is not really an event but an instance of only one IPdfEvent, what is the correct way to implement this?

Posted on StackOverflow on Mar 6, 2013 by Marc

Page events can be cumulative. In iText (Java), you can do this:

writer.setPageEvent(watermarkevent);
writer.setPageEvent(headerevent);
writer.setPageEvent(footerevent);

Internally, a PdfPageEventForwarder is created. This object will make sure that each event is triggered in the order you added them.

When you want to remove the events, you just need to do this:

writer.setPageEvent(null);

In your case, you could create your own PdfPageEventForwarder instances, creating different combinations of page events.

I'm pretty sure you can do the same thing in iTextSharp although there may be slight differences in the class and method names.

That is the solution I was looking for, thanks. The PageEvent thing is not very intuitive. In the c# version of the library it's a property and not a method so one expects to be holding a reference of a IPdfPageEvent instance.


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