Can I watermark XFA PDF using iText (commercial or not)?

Question

Well, after spending quite some time playing with this, I think I may have found a solution soon after I posted the question. Bit embarrassing but hey, it seems to work now.

I don't want to delete the question yet, in case someone wants the details. Basically, I tried again point (c) but in the XML I put back I used an embedded image. So, it seems I can change the XFA template master page using iText. More testing to follow ...

=========================

The problem: Apply watermark to a PDF XFA (dynamic or not). At the end the PDF should still be an XFA and should have all its security settings intact. I don't have control over the PDFs coming in.

The question: Can I use iText 5 to do that? If yes, is it via PdfStamper.getUnderContent() or via XfaForm.setXfa() or something else ? The first 2 didn't work for me yet.

I wonder if it's some XFA detail that I am missing (i.e. when I try to replace the XML), not sure how the XFA is actually protected from changes. Do I need to generate some UUID, encrypt some things, something about signatures ...

Btw, if I take the PDF generated by iText after replacing the XML, then open and save in LC, the watermark shows

thanks, Cristian

========================

Anyway, that's the short version of my question. If you think you can help and/or are interested in more details ...

I know this or similar questions came up before but what I have tried so far didn't work for me. I also admit I am not a IText, XFA or PDF Standard expert. I browsed a number of forums posts, the Itext book, browsed the specs, no luck yet.

The PDF input has no regular usage rights, no security. When opened in Acrobat it will show the restrictions on Changing Document/Document Assembly/Adding templates but I have a feeling all XFAs have that. Nothing comes back from the following ...

    System.out.println(" permissions " + reader.getPermissions());
    System.out.println(" usage rights " + reader.hasUsageRights());
    System.out.println(" viewer pref" + reader.getSimpleViewerPreferences());

Here are some of the things I have been through:

a) doing in it LC (https://forums.adobe.com/thread/496558)

This works. If I try to place an image on the master page, then it shows as watermark on all pages when saved from LC.

b) trying to write under using iText (https://sourceforge.net/p/itext/mailman/message/17225398/)

I found a post from '07 suggesting using pdfStamper.getUnderContent(). The thread does not seem to conclude if it did work eventually for the person asking

For me, the code works for a simple PDF, but not for XFA

PdfContentByte under = pdfStamper.getUnderContent(1);
under.beginText();
BaseFont FONT = BaseFont.createFont("c:/windows/fonts/times.ttf", BaseFont.WINANSI, BaseFont.EMBEDDED);
under.setFontAndSize(FONT, 40);
under.showTextAligned(Element.ALIGN_CENTER, "TEST_TEXT", 200, 600, 45);
under.endText();

c) generate the XML and replace it using iText (Some pdf file watermark does not show using iText)

After reading the post above and section 8.6 from itext in action, it seemed this is the correct path, so:

1. I create a simple XFA using LiveCycle
2. Save as xfa1.pdf and extract xml (using iText) to xfa1.xml
3. in LC add an image to the masterpage and save as xfa2.pdf
4. open xfa2.pdf and notice the watermark is present
5. extract XML from xfa2 to xfa2.xml and compare to xfa1.xml - notice the image element
6. either place the image element in original XML or use xfa2.xml and replace the XFA in original xfa1.pdf using iText, let's call it xfa3_itext;

Relevant code:

XfaForm xfa = new XfaForm(reader);
DocumentBuilderFactory fact = DocumentBuilderFactory.newInstance();
fact.setNamespaceAware(true);
DocumentBuilder db = fact.newDocumentBuilder();
Document doc = db.parse(new FileInputStream(xml));
xfa.setDomDocument(doc);
xfa.setChanged(true);
XfaForm.setXfa(xfa, stamper.getReader(), stamper.getWriter());

I have tried with a sample PDF that was provided by a customer and with a simple XFA form created in LiveCycle Designer, no luck. If I open xfa3_itext in LiveCycle it does the watermark and if I save it again from LiveCycle as dynamic XFA PDF, the new PDF shows the watermark.

phew, that is a long post ... sorry.

thanks for reading and for any feedback