U+2044 FRACTION SLASH

[van-de-bugger]

I accidentally found that some (not all) fonts treat U+2044 FRACTION SLASH specially, see the samples below.

The samples render the following text:

123456789012345
123/567 9/x y/5
123456789012345

All the digits are regular digits from range U+0030...U+0039, no superscript or subscript digits are used. The only difference is the slash character: in the text above slash is U+002F SOLIDUS (regular ASCII slash; to avoid problems with font used by the browser) while in the samples below slash is U+2044 FRACTION SLASH.

Cascadia Code:

Cascadia Mono:

(It looks identically to Cascadia Code.)

Fira Code:

(Incorrect fractions 9/x and y/5 look bad.)

Fira Mono:

(It looks like a bug: an extra space after the slash.)

IBM Plex Mono:

Source Code Pro:

(Incorrect fractions 9/x and y/5 look bad.)

Ubuntu Mono:

(It looks like a bug: too small 3 and 5 in the first fraction.)

Following fonts do not treat fraction slash specially:

Cousine:

DejaVu Sans Mono:

Droid Sans Mono:

Iosevka:

I think it is completely ok to render fraction slash as an ordinary slash, so it is not a real request, the ticket is just for your information.

[be5invis]

It looks like that you turned on frac feature?

[van-de-bugger]

It looks like that you turned on frac feature?

Sorry, I didn't get it. Do you mean I have requested a new feature to be implemented in Iosevka? Err... I don't think so. I quite happy with the current state (btw, thanks for the great font!). But you may want to implement it.

[be5invis]

Resolve as fixed.
I added support for frac. You need to manually enable this OT feature, but when it is on it will look like this:

[AndydeCleyre]

Thanks @be5invis!

A few questions:

• Enabling this OT feature is only done outside of building a custom font, right? As in, on Linux, we ought to use fontconfig or an app's own OT config.
• The Wikipedia description of the feature says "Converts figures separated by slash with diagonal fraction" -- when enabled, will this only apply when using U+2044, or also when using U+002F?
• Are you open to a new issue for afrc support, for vertically stacked fractions? I do not know what the reasonable limits of support for that one are.

[van-de-bugger]

What the difference between SOLIDUS and FRACTION SLASH then? Other fonts mentioned above do not convert 1/3 into a fraction ¹/₃ if numbers are separated by SOLIDUS. Conversion works only for FRACTION SLASH.

SOLIDUS is a path component separator. Many directories in my photo collection will look ugly: photos/²°²¹/₁₀/₀₃ instead of expected photos/2012/10/03. SOLIDUS is also used as delimiter in widely used date formats: yyyy/mm/dd, yyyy/dd/mm, so dates will also be broken.

[be5invis]

@van-de-bugger Fractions only enable if you manually turn on frac feature.