Feature Request: PDF/A

[pieteckhart]

I may have a future need to output PDF/A.
Is this something that can be easily added?

I haven't done a lot of research about it yet because it's not entirely sure if we are going to need it, but if needed I'm also willing to take a swing at it.

My initial understanding was that it's "just" a subset of pdf but after some further digging it seems more complicated than that.

Thanks for this great library!

Edit: Related to #6 ?

[pieteckhart]

I'm now a bit more sure that i'm going to need this feature.
If I understand correctly i need PDF/A1-b as a minimum for my usecase.

See: https://en.wikipedia.org/wiki/PDF/A#Conformance_levels_and_versions

I will discuss internally if we are possibly going to invest by contributing to this library or if we will go for a commercial solution that already supports PDF/A.

In the meantime i would love to have @jhaygood86 take on this feature.

I think just marking the PDF as PDF/A would go a long way if you use a tool like Vera (https://verapdf.org/software/) to check if the resulting pdf is actually compliant.
See: https://docs.pdfsharp.net/PDFsharp/Topics/PDF-Features/Archiving.html

Attached is validation report from Vera for a random PDF file i created using PeachPdf. It seems that you need to avoid things like transparency and certain fonts for PDF/A
veraPDF-tempHTMLReport3801525450511849940.html

[pieteckhart]

The original PDFsharp library has some PDF/A support but I'm guessing the codebases have diverted a lot since the Xamarin port and the port to PeachPDF.

https://github.com/empira/PDFsharp/blob/master/src/foundation/src/PDFsharp/tests/PdfSharp.Tests/Pdf/pdf-a/PdfATests.cs