[xep-support] Re: XEP 4.23 NullPointerException

[uwe.goersch at lhind.dlh.de]

Hi Alexey,

We are tried to fix this issue within iText but until now without success.

It seems that viewing the Adobe Acrobat PDF viewer displays the PDF file “a1_attachment-1-page-3.pdf” without an error. I think that in such a case, it would be better if XEP would create a PDF image rather than not create a PDF image. Do you think you can do this in XEP? That would help us a lot. Thank you very much in advance for your support!

Best regards,
Uwe Goersch

Von: Xep-support [mailto:xep-support-bounces at renderx.com] Im Auftrag von Alexey Gagarinov
Gesendet: Samstag, 2. September 2017 02:50
An: STRECKWALDT, TILL <till.streckwaldt at lhind.dlh.de>
Cc: RenderX Community Support List <xep-support at renderx.com>
Betreff: [xep-support] Re: XEP 4.23 NullPointerException

Hi Till,
when using XEP 4.23 to create a PDF file with an additional PDF attachment, there is a NullPointerException and the resulting PDF cannot be read.


It's a 'a1_attachment-1-page-3.pdf' that cause the NPE.

This PDF file is a TOC and contains links.
Each link itself is an annotations with a GoTo action (in terms of PDF Specification).
In more simple words: you click on the link and will be forwarded to some place on other page.

A PDF splitting software (iText in your case) correctly removes all objects from other pages, but keeps the "hanging" links.
By "hanging" I mean an indirect PDF object reference without the PDF object itself.
For example,

<</D[20 0 R/XYZ 52 715 0.0]/S/GoTo>>

 where 20 0 R is the indirect reference to another page, but the obj #20 (20 0 R) itself is absent in the PDF file.

In such a case XEP fails to create a PDF image.
And, in my opinion, it's the most reasonable behavior -- no PDF image when parsing of the PDF is failed.
Not with NPE, of course :) -- it's our fault, I will fix.

I believe it's worth to ping iText about removing "hanging" indirect objects for links (PDF Annots) during splitting a PDF file.

---
With best regards,
  Alexey Gagarinov
RenderX



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