1919890 - [Wayland] Firefox blurry on plasma 6 wayland with fractional scaling

Status: RESOLVED DUPLICATE of bug 1849092

(Core :: Widget: Gtk, defect, P3)

Description

[Artemiy]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:130.0) Gecko/20100101 Firefox/130.0

Steps to reproduce:

On a system with NixOS 24.05, kde plasma 6.1.5, using a 4k (3840x2160) fractional scaling was configured to a value of 150%. Firefox is running in wayland mode (confirmed using kwin debug console and info from about:support).

Actual results:

Everything is slightly blurry. Additionally upon further inspection a possible cause was found. In about:support Diagnostics->Display0 reports a value of "3840x2160@144Hz scales:2.000000|2.000000". This is incorrect.

When running firefox in X11 mode this value is "3840x2160@144Hz scales:1.500000|1.000000" as expected and is sharp.

Additionally chromium reports Display(s) Information->Info as "Display[60] bounds=[0,0 2560x1440], workarea=[0,0 2560x1440], scale=1.5, rotation=0, panel_rotation=0 external detected" correctly identifying scaling factor and is also sharp. And all other apps running in wayland mode are sharp too.

Moreover additional testing revealed that fractional scaling is set correctly only for whole values, otherwise it is always set to ceil(actual scale), e.g. 215% result in Diagnostics->Display0 of "3840x2160@144Hz scales:3.000000|3.000000"

Expected results:

No blur, correct identification of fractional scaling.

Comment 1

[Artemiy]

Attachment: blurry.png

Example of blurry content in firefox

Comment 2

[Artemiy]

Attachment: sharp.png

Same content as blurry.jpg, but when running with MOZ_ENABLE_WAYLAND=0 (in X11 mode). Sharp

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Widget: Gtk' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 4

[Tem PQD [:tempqd]]

Fixed in latest Nightly? (Bug 1849092)