https://bugs.kde.org/show_bug.cgi?id=477676
Bug ID: 477676
Summary: Fractional Scaling breaks chromium/electron apps
running in native wayland when scaling down below 100%
Classification: Plasma
Product: kwin
Version: git-stable-Plasma/5.27
Platform: Other
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: wayland-generic
Assignee: kwin-bugs-n...@kde.org
Reporter: ryu.ketsu...@outlook.com
Target Milestone: ---
Created attachment 163572
--> https://bugs.kde.org/attachment.cgi?id=163572&action=edit
Bug demonstrated using Chromium in native wayland
I'm marking this as a major bug because it may be considered as a wayland
showstopper. But it is also related to a previous bug I reported about
Spectacle, which has a similar effect.
I am running KDE Plasma 5.27 on a laptop with max resolution being 1366x768.
This is important to understand how to reproduce this bug. I scaled down to 70%
in order to have the whole UI and windows on a good size for this resolution,
or else everything looks too big. I am yet to see a Low DPI/Low Resolution
setting.
Previously I reported a bug about how this messes up Spectacle when in the
rectacle selection mode, making the static background shrink and stick to the
top left of the screen. At first I thought it was only a Spectacle issue but
after seeing a similar effect happening with chromium/electron windows also
running in native Wayland, such as Chromium, Visual Studio Code, Opera and
others, it appears the issue is not on Spectacle side but Wayland scaling side.
I could not test this with scaling up, like to 125%, only when scaling down to
70%. It may have a similar effect but I could not verify it. But I am attaching
a screenshot demonstrating the issue. There are apps that don't have this
issue, like Discord, likely because of the outdated electron version. But newer
electron versions all seem to have this issue.
So when these windows are running in native wayland mode, the scaling is wrong,
with them appearing much smaller than they should, and the window is also
cropped, even when maximized.
STEPS TO REPRODUCE
1. Set wayland fractional scaling below 100%, like to 75%
2. Open any chromium/electron application in native wayland with the flags
--enable-features=UseOzonePlatform --ozone-platform=wayland
OBSERVED RESULT
See attached screenshot for better understanding. Basically, the window is not
correctly rendered, even when maximized, messing up the scaling of hte window
and the cropping is also wrong.
EXPECTED RESULT
Scaling to be correct and no cropping.
SOFTWARE/OS VERSIONS
Operating System: openSUSE Tumbleweed 20231022
KDE Plasma Version: 5.27.9
KDE Frameworks Version: 5.111.0
Qt Version: 5.15.11
Kernel Version: 6.5.8-1-default (64-bit)
Graphics Platform: Wayland
Processors: 4 × Intel® Core™ i3-7020U CPU @ 2.30GHz
Memory: 11.5 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics 620
Manufacturer: LENOVO
Product Name: 81FE
System Version: Lenovo ideapad 330-15IKB
ADDITIONAL INFORMATION
I prefer to run applications in native wayland whenever I'm given the option
for the boost of speed. XWayland is often very sluggish with me.
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