blade: Text is rendered either too thick or too thin

[apricotbucket28]

Check for existing issues

• Completed

Describe the bug / provide steps to reproduce it

Ever since a89dc8c, text rendering has either been to thick or too thin, depending on the theme.

Screenshots

(they're not mine, I just took them from the Discord channel)

Dark theme

Before

After

Light theme

Before

After

Environment

Zed: v0.142.0 (Zed Nightly eb91468)
OS: Linux Wayland fedora 40
Memory: 30.5 GiB
Architecture: x86_64

Since this is an issue with the Blade renderer, I can also reproduce on Windows.

If applicable, add mockups / screenshots to help explain present your vision of the feature

No response

If applicable, attach your ~/Library/Logs/Zed/Zed.log file to this issue.

Zed.log

[ajstarks]

Workaround:
setting "buffer_font_weight": 600 works for light mode themes.

[ciaran-matthew-dunne]

Following on from #14169, it appears Zed is having issues with font weights. Changing the buffer font weight is ineffective until 600, which also looks badly rendered.

Zed.log

[landersson]

Agreed. Font's are way to skinny by default on Linux... With "ui_font_weight": 600, the font is instead too thick and generally looks a bit off.

[donjan]

Still the case with Zed 0.163.3. I can't make it look as good as other editors (or almost any other application) on Linux.
Image shows VSCode | Zed | Geany:

Reportedly this might improve if we move to a different text system, as suggested in #13951

[lnicola]

I think this is a relatively well-known issue related to linear ("correct") blending of text. I couldn't find a better source, but https://freetype.org/freetype2/docs/hinting/text-rendering-general.html touches on this.