System Fallback for Cyrillic, Hiragana, Katakana, Han etc.

[tpreusse]

http://localhost:3007/2018/05/11/russlands-staatsfeind-nummer-eins.pdf (prd)

on local version (@react-pdf/core@0.7.7-24)

on prd version (@react-pdf/core@0.7.7-22)

on the web

Пенсионеры из "Отрядов Путина" сожгли фото Павла Дурова

Ultimately we do need font manager. As long as we're SSR-Rendering we should get the benefit of being able to access system fonts for such cases.

[diegomura]

Do we need font-manager or just being able to just pass many font-families on styles? such as the web?
The thing about font-manager is that I cannot add it to the react-pdf substitution engine because it’s not installable on the web. We can either follow a solution like the one above, or make a custom republik font-substitution engine

[tpreusse]

I think it should be an API like this:

import { Font } from '@react-pdf/core'

const substitutionCallback = (postscriptName, char) => {
  // get a font instance
}

Font.registerSubstitutionCallback(substitutionCallback);

This would follow internally to fontSubstitutionEngine via the LayoutEngine.

@react-pdf/node could then set a default substitutionCallback powered by font-manager. On the web someone could implement this callback to feed in a large fallback font, but most will not want to because of the associated size.

being able to just pass many font-families on styles?

Not sure how important that one is. Generally I wouldn't want to specify Helvetica everywhere because 0.1% of my documents may contain a odd Cyrillic or Han line.

I also realised that it makes sense to fallback to the system Helvetica after trying the asm Helvetica, since the asm file has a small subset of what probably most system Helvetica have. The original substitution engine probably had this strange loading from font-manager in many or most cases because of that.