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silnrsi / font-gentium

Fonts for languages and writing systems that use Latin, Cyrillic, and Greek scripts
https://software.sil.org/gentium/
SIL Open Font License 1.1
74 stars 6 forks source link

bad `ss01` at 12pt, 13pt, 13.5pt #34

Open mirabilos opened 1 month ago

mirabilos commented 1 month ago

screenshot, dark theme to not blind the reader

<html><head><title>test</title></head>
<body bgcolor="#000000" text="#AAAAAA" style="font-family:Gentium Plus;">
<p style="font-size:12pt;">test @ 12pt: mam mgm <b>mam mgm</b>
 <span style="font-feature-settings:'ss01';">mam mgm <b>mam mgm</b></span>
</p>
<p style="font-size:12.5pt;">test @ 12.5pt: mam mgm <b>mam mgm</b>
 <span style="font-feature-settings:'ss01';">mam mgm <b>mam mgm</b></span>
</p>
<p style="font-size:12pt;">test @ 13pt: mam mgm <b>mam mgm</b>
 <span style="font-feature-settings:'ss01';">mam mgm <b>mam mgm</b></span>
</p>
<p style="font-size:13.5pt;">test @ 13.5pt: mam mgm <b>mam mgm</b>
 <span style="font-feature-settings:'ss01';">mam mgm <b>mam mgm</b></span>
</p>
<p style="font-size:14pt;">test @ 14pt: mam mgm <b>mam mgm</b>
 <span style="font-feature-settings:'ss01';">mam mgm <b>mam mgm</b></span>
</p>
</body></html>
jvgaultney commented 1 month ago

Could you tell us what problem you're seeing here? Is it the height of the single-story a and g? Please also tell us what OS, version, and app this is from. Is this the latest Gentium Plus (version 6.200)?

We use an autohinting tool - ttfautohint - to optimize the rendering of letters at small ppem (pixels per em) sizes. It generally does very well, and in each major release we work to improve the results, but we don't have the capacity to manually hint special cases. Once version 7 is released, please check this again in the same environment.

mirabilos commented 1 month ago

Sure. It is indeed the a and g height. This is Firefox 115.15.0esr on Debian, with 6.200 installed system-wide but also provided as TTF and WOFF2 from the website.

Incidentally, this is how I noticed, because Debian bullseye ships 5.000 by default, which lacks the stylistic sets, but also the boldface, so before I had it installed system-wide (as texlive dependency) I got the webfont of 6.200, then I got 5.000 until I upgraded the fonts-sil-gentiumplus package. I wish there was a way in webfonts to require a specific minimum version for local(…) fonts…

But good to know ttfautohint is good; I need to have a look at that for the fixed-width font I’ll be improving when I have the time.

Unfortunately, 12 pt is the standard size for webpages, so any webpage that uses Gentium Plus and enables those stylistic sets, or uses the type-tuned versions, will exhibit this… and 12½ pt as workaround introduces slight problems with other fonts…