What's the difference between 'optional'…

[jakearchibald]

…and swap 0s?

[KenjiBaheux]

Yeah, I don't think there is any difference. Optional is definitely easier to understand. Does this tell us something about swap <timeout>? itself? Is it not natural enough?

I think that mandatory <timeout>? is more straightforward.

Without knowing about the mandatory option, would someone think that "swap 0s" mean to swap immediately and "swap 1s" to swap after waiting for 1s after the font?

What if we had optional defined as follows:

optional <timeout>?

• user agent should not block text rendering
  • if the desired font is available then it should be used, but if the font is not available then the fallback should be used
  • once rendered, the text is only re-rendered if the desired font becomes available before the timeout is reached
  • if a timeout is not specified, the text is never re-rendered, i.e. the first-font wins.

[jakearchibald]

I think that makes more sense, although you've still got the <timeout> value meaning something very different between optional and mandatory

[KenjiBaheux]

See https://github.com/KenjiBaheux/css-font-rendering/issues/11 for the latest on this area.