Fonts passed to /forms/chromium/convert/html do not render if pdfa=PDF/A-2b

[Vovcharaa]

PDF/A-2 specifies that it can embed OpenType fonts.
But when I try to do src: url('futura-bold.otf') format('opentype'); in css and set pdfa=PDF/A-2b font is not used in pdf.
How to use custom fonts with PDF/A-2b/3b?

[gulien]

Hello @Vovcharaa 👋

That’s because the resulting PDF from Chromium is post-processed by LibreOffice, and it may remove custom fonts from it. A solution could be to install the font directly in the Docker image: https://gotenberg.dev/docs/configuration. Not sure it would work though.

[Vovcharaa]

Have you considered using Ghostscript for pdf to pdf/a conversion?

[gulien]

Not possible due to licenses incompatibility alas.

[gulien]

Someone did build a version with a Ghostscript module: https://github.com/Vrex123/gotenberg-ghostscript

[Vovcharaa]

I doubt that AGPL license allows me to use Ghostscript in commercial project.

[gulien]

It depends, if you pay for a license I guess it's ok 😄

[madduck]

Why is Libreoffice used to post-process the PDF with pdfa=PDF/A-2b, but not if I don't specify this configuration in the HTML POST?

My issue is that Libreoffice garbles ligatures. If I process an HTML file like this:

curl -v http://192.168.235.10:3000/forms/chromium/convert/html -F files=@/tmp/madduck/index.html -o /tmp/test.pdf

it generates a beautiful PDF. If I add -F pdfa=PDF/A-2b, then the result is ugly, with all ligatures simply dropped:

[gulien]

Hello @Vovcharaa

Because it’s the only tool with a correct license I’m aware of that can convert PDFs to PDF/A.

[madduck]

Because it’s the only tool with a correct license I’m aware of that can convert PDFs to PDF/A.

Okay, so I am trying to reproduce the issue with Libreoffice directly in order to chase down this bug. How does the pipeline work within Gotenberg? I am not too good with Go and cannot figure it out myself. Does Gotenberg use Chrome to make a PDF, and then pass that PDF to Libreoffice?

Because if I do that, i.e. create a PDF/not-A "normal" PDF with Gotenberg and then try to convert it, I get a silly error:

% libreoffice --headless --convert-to pdf --outdir /tmp /tmp/madduck/test.pdf
Warning: failed to launch javaldx - java may not function correctly
Error: source file could not be loaded

[madduck]

Note that I can reproduce the problem sending a PDF to the /forms/libreoffice/convert:

curl -v http://192.168.235.10:3000/forms/libreoffice/convert -F files=@/tmp/test.pdf -F pdfa=PDF/A-2b -o /tmp/broken.pdf

this results in broken ligatures.

Can you help me find out what Gotenberg actually does within, so that I can try to reproduce this with LO directly, and report a bug there?