[css-text-4] `text-spacing-trim` (and `font-feature-settings: "palt"`) is harmful for Yu Gothic UI (system-ui in Japanese Windows)

[tats-u]

#3658 (comment)

halt in Yu Gothic UI is broken. It causes broken disastrous rendering of brackets:

https://issues.chromium.org/issues/331123676?pli=1

https://twitter.com/search?q=https%3A%2F%2Ftawara-memo.hatenablog.com%2Fentry%2F2024%2F10%2F12%2F174432&src=typed_query
https://b.hatena.ne.jp/entry/s/tawara-memo.hatenablog.com/entry/2024/10/12/174432
https://twitter.com/shirouzu/status/1845400436678983704/quotes
https://twitter.com/tawara_san/status/1845023105288372415/quotes

Images from: https://zenn.dev/inaniwaudon/scraps/f224417d4c51ee (Japanese)

Image from: https://twitter.com/shirouzu/status/1845400436678983704 (Japanese)

Image from: https://tawara-memo.hatenablog.com/entry/2024/10/12/174432 (Japanese)

As to https://tawara-memo.hatenablog.com/entry/2024/10/12/174432 (Japanese), the width of such brackets in Yu Gothic UI is 0 when halt is enabled.

Image from: https://tawara-memo.hatenablog.com/entry/2024/10/12/174432 (Japanese)

Image from: https://tawara-memo.hatenablog.com/entry/2024/10/12/174432 (Japanese)

https://codepen.io/tats-u/pen/MWNEJRN

We should detect broken fonts like Yu Gothic UI by checking the width of halt glyphs. If its width is less than 1/4 or 1/8 of the original width, halt of that glyph should be treated as broken.

[nt1m]

@kojiishi @fantasai @vitorroriz

[kojiishi]

Thank you for reporting the issue and sorry to hear the trouble. It looks like the fix is on its way, please see https://crbug.com/331123676#comment7. /cc @alisonmaher

[tats-u]

t looks like the fix is on its way,

I strongly doubt it. I have never heard Yu Gothic's GPOS has been fixed in 24H2. There is no reply from her or other employees since April.

[tats-u]

Yu Gothic's palt is broken, too. How useless its GPOS is!
Shouldn't you think browsers should ignore the GPOS of such a low-quality font making fun of Japanese designers and users?

pwid had no effect so the GSUB has no problem. Only GPOS does.

[tats-u]

It can cause DoS on a browser or WebView.

https://b.hatena.ne.jp/entry/4760513438625758112/comment/takinou0

鉤括弧を千個重ねても1こにしか見えないので、「これが無下限術式だ！」とか言って遊んでたら、同僚のteamsを異常終了させちゃって申し訳ない気持ちになったやつだ。遊んでたサラリーマンが悪いような気もするが……

I told Claude to translate it:

This is about that glitch - when I stacked a thousand corner brackets that all overlapped due to the bug, I was playing around saying "Behold the Unlimited Void technique!" but ended up accidentally crashing my colleague's Teams client. While I do feel guilty about it, maybe I'm also at fault for messing around as a salaryman...

[alisonmaher]

I strongly doubt it. I have never heard Yu Gothic's GPOS has been fixed in 24H2. There is no reply from her or other employees since April.

Apologies for the delayed response on the bug. Ali from the Windows has an update that he is planning to post in the bug shortly.

[alib-ms]

Fixed! An update for the Yu Gothic font family has been checked in. This update addresses the issue where overlapping characters appeared with the UI components of the Yu Gothic font family in online environments.

Before:

After:

I’ll collaborate with the Windows Servicing team and the Office team to ensure these fonts are available across various endpoints. I’ll share the public availability date once we have a confirmed timeline.

[tats-u]

Fixed! An update for the Yu Gothic font family has been checked in

I'm glad to know it, but can outsiders of Microsoft try this via some Insider channels today? Or can only employees do (just dogfooding phase)?
Also, was palt for hiragana & katakana fixed, too?

https://codepen.io/tats-u/pen/PoMOPyO

[alib-ms]

We removed the 'halt' and 'palt' OpenType features from the UI components of the fonts.

No changes for the Yu Gothic, only Yu Gothic UI components were updated.

It's not in the insider build yet. I will be happy to share a private build of the font for testing purposes.

[tats-u]

We removed the 'halt' and 'palt' OpenType features from the UI components of the fonts.

It's not a bad decision and good as a hotfix.
We might be able to keep the halt and palt GPOS of some punctuation marks in the Halfwidth and Fullwidth Form block (e.g. ！？（）［］｛｝). They work great in the current release:
It might be because it is a pain in the neck to inspect the entire content of GPOS that you chose to remove it.

https://codepen.io/tats-u/pen/GRVOWwY

It's not in the insider build yet. I will be happy to share a private build of the font for testing purposes.

I look forward a release for Insiders outside of your company.