Text rendering is broken/blurry on Sway when using fractional scaling upon resizing

[tropicaaal]

Summary

This is a little strange. Below are two screenshots of the same text run when the window is resized to different heights:

The top one is noticably blurrier, while the bottom is sharper. This appears to only happen when using fractional scaling (I am running 125% scaling on GNOME, Fedora 41). My best guess as to what could be causing this would be that resizing the window relayouts the text to be on a subpixel, resulting in some subpar antialiasing results.

You can also observe the text slightly shifting when rendered to subpixel boundaries every few pixels of window height when I resize:

Screencast.From.2025-02-19.15-06-30.mp4

This does not occur on 100% scaling (video below)

Screencast.From.2025-02-19.15-08-46.mp4

This behavior also appears to be mostly GPUI-specific. I don't observe this behavior on electron apps (VSCode) for example.

Steps to trigger the problem:

1. Apply a fractional scaling factor (e.g. 125%)
2. Scale the window's height by slight amounts.
3. Observe slight shifts in text rendering as the height changes.

Actual Behavior:

Text clarity changes every few pixels of height, shifting between sharp and blurry rendering.

Expected Behavior:

Text should remain sharp at all window heights and scale factors.

Zed Version and System Specs

Zed: v0.173.11 (Zed)
OS: Linux Wayland fedora 41
Memory: 15 GiB
Architecture: x86_64
GPU: AMD Radeon Graphics (RADV RENOIR) || radv || Mesa 24.3.4

[smitbarmase]

Thank you for reporting this. I'm using KDE Wayland and can consistently reproduce the issue at fractional scales like 125% and 175%. The blur and jittering (~1px) are subtle but clearly noticeable.

[jansol]

Duplicate of #18113, but this does illustrate the issue better.

[suhaylmv]

has anyone found a workaround?