Author here! Resolving one of the most-requested Typst features was definitely a big motivation for me, but I wouldn't say this was the only reason. I've done a lot of previous work on PDF (see e.g. the krilla library, although also mostly in the context of Typst), so I was already pretty familiar with how PDF works. In addition to that, I also just finished writing my master's thesis about 2D rendering (also in Rust), so I also gained a lot of knowledge in that area. Therefore, this project seemed like a good opportunity for me to create a bigger open source project myself that I could work on in my free time. :)

Would it be feasible, with hayro-interpret and krilla, to take an existing PDF and round-trip each of the pages while wrapping the contents in marked content spans and adding tags, to remediate the accessibility of an existing PDF? Round-tripping each of the page content streams through a full-featured PDF interpreter seems cleaner than trying to edit in-place. PDFium can round-trip the content streams and add the marked content spans, but can't do the tagging. What do you think?

Yeah, this is definitely a goal for the future. But there is still quite a bit of work needed in both libraries to make this possible.

Thanks for sharing the background. It's impressive work. Makes me curious about your thesis... Is it publicly available?

Not yet, but it should hopefully be graded in 1-2 weeks and then I can share it!

Impressive work, congrats!

And a job offer I hope!

Thanks for your contribution!

You are right that it's been on the roadmap for a while, however, it's definitely very high on their priority list. The recent update (v0.12) contained a lot of necessary internal refactorings of the layout engine, and they've mentioned on the Discord that after v0.12, they will start work on HTML output.

I really hope so, and I will start recommending typst when there is good accessible output.

However, it’s also been a “top priority” since basically the first release.

The issue is a bit more than a year old.

Feel free to step up and close it. Complaining about it isn't going to add velocity to a new project.

Adding accessibility to every open source project which neglected it would take a team of thousands.

I work on accessibility on the open source programs I already contribute to.

PDFs can be translated to EPUB using existing programs. I'm going to go out on a limb and guess that Typst emits "good" PDF (I worked on a PDF program for years and I know it when I see it) so that conversion should be fairly high fidelity.

Clearly this is not as good as offering a second backend, but the latter is also a huge amount of work. I'm sure if you showed Typst cases where their PDF output doesn't translate to EPUB cleanly using available converters, they would at least investigate and see if they can improve that.

But without demonstrating that translation isn't working, I'm not going to accept the claim that there's an accessibility problem here.

I downloaded the first typist pdf I could find:

https://github.com/Leedehai/typst-physics/blob/master/physic...

And fed it through the top pdf2epub on google:

https://cloudconvert.com/pdf-to-epub

Plain text is fine, but all maths is mangled, and tables and matrices are completely destroyed.