[Question] How to correctly skip a failed object copying? about pdf-writer HOT 12 CLOSED

Probably not cause by that time some content is already written to the file and its a bit contrary to how pdfwrite doesnt things to go back.
How about you tell me more about why copying failes? Do you have a sample?

(Alternatively you could always work with two pdfs. Do action first on one, if doesnt fail, do on the other one)

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Please check this sample PDF
There is a missing object whose object ID = 16, but is referenced by an annotation object whose object ID = 19, in its "Parent" entry so CopyObject failed in copying source object ID = 19.
Is there any way that i can skip the failed object without writing a temp file (to rollback if failed) for every object copy?

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Well, this is something that PDFWriter should be corrected to handle. i mean, it is a valid possibility.

Gal.

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The ideal result is to skip the object copying on missing objects only.
i.e. for the missing object ID = 16, referenced by the other object (ID = 19) in its "Parent" entry, just skip copying the object whose ID = 16 and keep the destination exactly the same with the source is ideal although the missing condition will still preserve in the destination.

from pdf-writer.

I could make it into copying a null in this case, or create a deleted object entry. We will have to see which would be a more reliable recreation of the origin

from pdf-writer.

Do you mean to assign a deleted object ID (marked as unused in the xRefTable) for a missing object?

from pdf-writer.

that's a good option - if that's what makes 16 missing. is 16 marked as such? is it simply null? whatever it is in the source document...it's probably best to do the same in the target. i'm taking a look now

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What did you mean copying a null? (did you mean to replace the missing object ID with 0 ?) I am not as familiar with PDF spec as you. You are the PDF expert!!!

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yap. committed a solution along this line now. you can try it out. for me it worked well on the sample file, copying the annotation, and i also tried to append a page and it seemed to create a PDF is fine.

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It worked for the sample pdf.
Thank you very much for the solution!

However, do you have a solution for the case that a missing object has no associated deleted entry in the xRefTable?

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Look, it's valid to have deleted elements. the lib should take care of this case. it didn't and thanks to your note it's ok now.
anything else is just invalid. there are plenty possible exceptions. we could have an element pointing to an element it shouldn't (just having a wrong xref). xref table could be providing wrong positions (someone sent me a PDF like that recently). i think failing is a good policy then.

we could be writing another version of the copying method to handle all possible cases and fill up things with deleted elements (for instance, it could just do what i did for all "else" cases), but i feel that sometimes its ok to just fail if the file is invalid.

If you have an actual PDF that bothers you and you think we can figure out a good way out, we can tailor something around it together.

Gal.

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You are right!

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