Hi,
page is set updated because the annotations array is updated and the
array is always saved inside (not as an object).
acroform is updated because fields is a direct object and fields is
modified.
Yes, it might make sense to fine-tune this, i.e. to set the update flag
only if fields / annotations are added.
The problem is that this code segment is very difficult, we have seen
many weird problems (similar to yours!) that can't be discovered in
automated tests.
One risk I remember/suspect is that when we don't mark certain parts as
updated, then dependent modified objects aren't updated either. There
must be a "path" to the modified objects.
Could you share the PDF files? (upload to sharehoster) Are you signing
both with PDFBox or only one with it and the other with another product?
Tilman
Am 17.02.2021 um 11:01 schrieb Waldemar Dick:
Dear all,
I have a problem when signing a PDF document twice, which already has
signature form fields pre-placed on the document.
The problem is visible, when the document is signed the second time.
The signatures are correct, but Acrobat says, that there was a change
in the document structure before the second signature was created.
Message is something like this: “Form Fields with Property Changes >
Field Person_1 on page 5”.
I know, that this doesn’t change the validity of the signature itself,
but still it is not nice and people are insecure, what it exactly means.
Looking into the COS structure of the PDF, I see that there are more
objects written (in the incremental save), than actually changed.
Two objects stand out:
a) the AcroForm dictionary
b) the Page dictionary
Both objects are the exactly the same from the beginning, but still
are written with every signature applied.
I had a working workaround in the past, where I changed the AcroForm
/Annots entry to a object reference. This worked some time ago, but
not anymore.
We currently use PDFBox 2.0.19, I updated to 2.0.22 with no success.
Two questions:
a) Why are the AcroForm and Pages objects marked as changed, when
there are no changes?
b) Can I somehow try to remove the “needToBeUpdated” flag, before a
incremental save. I tried, but fail to find the right time to do so.
c) When I mark the COSArray referenced by AcroForm /Annots to
"direct=false”, it is ignored in the COSWriter.
COSWriter#visitFromArray never checks, if the array is direct or not.
But I am pretty sure, that this worked some time ago.
Happy about any pointers, what I can try next to fix the problem.
Kind regards,
Waldemar
