Switch to Harfbuzz

[shuding]

Satori currently relies on OpenType.js to parse font tables and generate the glyphs. I’m considering switching to Harfbuzz in the future because it supports a couple of more complex scripts and OpenType features. It can also improve the performance a bit as it’s a WASM port.

Pretty low priority at the moment as we need to improve the typography algorithm first.

[shuding]

Looks like the correct way to go in the future:

https://twitter.com/KhaledGhetas/status/1548752758282534913

[jlarmstrongiv]

@shuding how would you workaround the limitations of Harfbuzz, such as line breaking?

[devongovett]

You could also try fontkit, which is a pure JS implementation supporting complex scripts. It powers pdfkit.

There's also textkit for handling higher level text layout (eg line wrapping, font substitution, etc.). That's used by react-pdf.

I'd highly recommend looking into some of these libraries and how they do text layout, because it is extremely complicated (especially with non-English text). Back when react-pdf was investigating this, I wrote this comment explaining the whole text layout process - maybe it's helpful to you. foliojs/pdfkit#783 (comment)

[shuding]

Thanks again for the pointers @devongovett! I actually looked into fontkit before picking opentype.js (because it's smaller, seems like a wrong choice lol), and actually read a lot of your comments from everywhere (thank you again!), and I understand the complexibility of this. Hence the first phase of this project is to support only basic text layout and font features.

Anyways, this is definitely our top priority!

[LuciNyan]

@shuding how would you workaround the limitations of Harfbuzz, such as line breaking?

Thank you for sharing this!