PDF/A-3 TCPDF-Support

[andreas-p]

In my current project, I create invoices using FPDI with TCPDF to import template PDFs and add the data to it.
With advancing legal requirements, the invoice needs to be signed and formatted PDF/A-3 (ZugFerd).

Apparently, the only PHP libraries supporting signatures are TCPDF and tc-lib-pdf. While TCPDF doesn't know PDF/A-3, tc-lib-pdf is work-in-progress, not working with FPDI and not having pdf import (#117). So I'm stuck.

I'm not the only one missing PDF/A-3 support, see tecnickcom/TCPDF#684. tc-lib-pdf is huge, so it will probably take quite some time until it's ready to replace TCPDF, but A-3 is needed NOW. Please consider porting that back to TCPDF. I know it hurts to code on a project that isn't the future...