Bug 493490

Summary:	Opentype font feature override list is ineffective
Product:	[Applications] systemsettings	Reporter:	Andrea Ippolito <andrea.ippo>
Component:	kcm_fonts	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	akselmo, aoeui, christoph, nate
Priority:	NOR
Version First Reported In:	6.1.5
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Left: original Inter Display ttf font, Right: my variation with some OpenType features enabled my patched version of InterDisplay-Regular with calt, cv05, cv06, cv08, ss01, along with the unpatched font

Description Andrea Ippolito 2024-09-22 15:21:18 UTC

I was amazed to see, with a recent update, that the fonts System Settings module now allows to specify a comma separated list of OpenType features to enable for the chosen font.

Unfortunately, it's completely ineffective for me.

I have "frozen" some OpenType features for Inter Display and exported the resulting ttf, which is the one I now use as my Plasma variable-width font, and it's called `Inter Display calt, cv05, cv06, cv08, ss01`

One of the most visible changes is cv05 which brings `Lower-case L with tail`

So, I tried to replicate the same aspect by using KDE System Settings' font feature override feature, but nothing changes.

Is this a somewhat beta feature? Does it require some better integration on behalf of my distro?

System info:

Operating System: openSUSE Tumbleweed 20240920
KDE Plasma Version: 6.1.5
KDE Frameworks Version: 6.6.0
Qt Version: 6.7.2
Kernel Version: 6.10.9-1-default (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 7840U w/ Radeon 780M Graphics
Memory: 30.7 GiB of RAM
Graphics Processor: AMD Radeon 780M
Manufacturer: Framework
Product Name: Laptop 13 (AMD Ryzen 7040Series)
System Version: A7

Comment 1 Andrea Ippolito 2024-09-22 15:26:32 UTC

Created attachment 173965 [details]
Left: original Inter Display ttf font, Right: my variation with some OpenType features enabled

The one on the left comes straight from:
https://rsms.me/inter/download/

In the zip, it's under `extras/ttf/InterDisplay-Regular.ttf`

The one on the right is that ttf after having undergone some changes with opentype-feature-freezer: https://github.com/twardoch/fonttools-opentype-feature-freezer

`pyftfeatfreeze -rv -f calt,ss01,cv05,cv06,cv08 -S InterDisplay-Regular.ttf newName.ttf`

I will attach both TTFs for ease of investigation

Comment 2 Andrea Ippolito 2024-09-22 15:28:16 UTC

Created attachment 173966 [details]
my patched version of InterDisplay-Regular with calt, cv05, cv06, cv08, ss01, along with the unpatched font

Comment 3 Andrea Ippolito 2024-09-22 15:30:05 UTC

Also, when I open the font selection popup again, the overrides (comma separated list of features) I had provided are gone.

Comment 4 Akseli Lahtinen 2024-09-24 09:52:01 UTC

I agree this is a bit confusing, but it has not been yet implemented in other apps but Kate for now.

It should be hidden from applications that do not support it yet.

Comment 5 Andrea Ippolito 2024-09-24 09:58:45 UTC

(In reply to Akseli Lahtinen from comment #4)
> I agree this is a bit confusing, but it has not been yet implemented in
> other apps but Kate for now.
> 
> It should be hidden from applications that do not support it yet.

Indeed that seems to be the case. However, even in the Kate font settings, it seems that only the first feature of the list is taken into account

Comment 6 Christoph Cullmann 2025-11-08 19:07:50 UTC

If we fix that bug in KConfig it should work.

*** This bug has been marked as a duplicate of bug 499736 ***