Embedded files support (Factur-X 1.07 / ZUGFeRD 2.3)

[fooman]

This PR should get merged after #788 - fixes #578, #684

The changes proposed in this PR allow the generation of compliant Factur-X 1.07 / ZUGFeRD 2.3 pdfs that embed additional invoice information as XML.

To achieve this one additional insertion point inside the XMP section for PDF/A extension has been added as well as methods to directly insert embedded files without the need to use annotations.

The last required change was to include all embedded files in the catalog under /AF to pass PDF/A-3b validation.

The pdf generated via example_068.php will pass the online validator for FacturX found here
https://services.fnfe-mpe.org/

as well as https://www.portinvoice.com/ to validate it as Zugferd 2.3 compatible pdf

[williamdes]

Very nice!

[williamdes]

Maybe add a Fixes #578 to the PR description

[williamdes]

For reference on Dompdf Factur-x support is near to work. Could you help me with the last VeraPDF error?
dompdf/dompdf#3443

[fooman]

Thanks @williamdes - updated the description.

In regards to dompdf I am unfortunately not sure either what the error entails. One thing which tcpdf does when in pdfa mode is the forced embedding of fonts even for core fonts like https://github.com/tecnickcom/TCPDF/blob/main/fonts/pdfacourier.php and it also suppresses font subsetting.

[nicolaasuni]

Please trey to add this instead on the tc-lib-pdf project.

[williamdes]

Please trey to add this instead on the tc-lib-pdf project.

Could you re-consider for this one?
this feature is very critical for all the tcpdf current users that want to get Factur-X compliance done

[thomasDG897]

Please trey to add this instead on the tc-lib-pdf project.

Could you re-consider for this one? this feature is very critical for all the tcpdf current users that want to get Factur-X compliance done

Yes, could you please re-consider?
I can confirm that I check this PR two/three times a week, because we need the ability to embed xml files complaint for ZUGFeRD...

[AdrienWeber]

Please trey to add this instead on the tc-lib-pdf project.

Could you re-consider for this one? this feature is very critical for all the tcpdf current users that want to get Factur-X compliance done

Yes, could you please re-consider? I can confirm that I check this PR two/three times a week, because we need the ability to embed xml files complaint for ZUGFeRD...

Yes please, this would help a lot.