Bug 491641 - App resolution scaling
Summary: App resolution scaling
Status: RESOLVED DUPLICATE of bug 474738
Alias: None
Product: kwin
Classification: Plasma
Component: wayland-generic (show other bugs)
Version: 6.1.4
Platform: Arch Linux Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords: multiscreen
Depends on:
Blocks:
 
Reported: 2024-08-12 19:21 UTC by Massou
Modified: 2024-08-13 22:10 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
Illustration of the wrong (scaled down) app scale (26.97 KB, image/png)
2024-08-12 19:21 UTC, Massou
Details
Screenshot of krita with the problem (58.57 KB, image/png)
2024-08-12 19:44 UTC, Massou
Details

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Description Massou 2024-08-12 19:21:54 UTC
Created attachment 172561 [details]
Illustration of the wrong (scaled down) app scale

Hello,

I have a laptop with an external screen.
The screen of the laptop has a resolution of 2560*1600 (150% scale) and an external screen at 3440*1440 (100% scale).
When I open an some apps (with the lid of the laptop open or closed) and then I close or open the lid, app resolution is wrong (either too big if I close the lid or too small if I open it), resizing the window does nothing, if I reopen/close the lid the resolution of the app is back to normal, if I close/reopen the app the resolution is correct.

STEPS TO REPRODUCE
1. laptop with the lid open
2. Open an app
3. Close the lid of the laptop

OBSERVED RESULT
The resolution if scaled up too much

STEPS TO REPRODUCE
1. laptop with the lid closed
2. Open an app
3. Open the lid of the laptop
4. the app is now badly scaled

OBSERVED RESULT
The resolution of the app is too much scaled down

EXPECTED RESULT
Correct scaling of the content of the app

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.1.4
KDE Frameworks Version: 6.4.0
Qt Version: 6.7.2
Kernel Version: 6.10.3-arch1-2 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 9 7940HS w/ Radeon 780M Graphics
Memory: 58.7 GiB of RAM
Graphics Processor: AMD Radeon 780M


ADDITIONAL INFORMATION
The problem was also present in previous versions of kde.
It seem like the wrong screen scaling is picked.
I've noticed this bug with krita (5.2.3), discord and vscode.
If both screens have the same scaling the problem does not appear.
If I close and reopen the app without moving the lid, the app resolution is correct.
Comment 1 Massou 2024-08-12 19:36:02 UTC
I also forgot to mention that in addition to the incorrect scaling, applications that have this bug when visible, don't get drawn correctly (black squares and/or incorrect positioning of the ui elements, it seem that the app ui isn't redrawn properly), but this disappears when I resize the window (unfortunately the scaling is still broken).
Comment 2 Massou 2024-08-12 19:44:56 UTC
Created attachment 172562 [details]
Screenshot of krita with the problem
Comment 3 Nate Graham 2024-08-13 17:16:05 UTC
Does this happen with all apps, or just some? For example does it also happen with Dolphin, Okular, Discover, or GNOME Text?

I ask because I'm suspecting this is an issue specific to apps using XWayland, which all the ones you mentioned are.
Comment 4 Massou 2024-08-13 17:30:08 UTC
(In reply to Nate Graham from comment #3)
> Does this happen with all apps, or just some? For example does it also
> happen with Dolphin, Okular, Discover, or GNOME Text?
> 
> I ask because I'm suspecting this is an issue specific to apps using
> XWayland, which all the ones you mentioned are.

Hmm, this appends only with some apps.
Discord, vscode and krita, vlc have this bug.
Firefox, okular, dolphin, systems settings, obstudio, easy effects (a gtk app I think)are ok.
At first I thought that it was specific for electron apps and then I noticed the bug with krita as well which is not.
I think that you may be right about Xwayland apps (How can I verify this to be sure?).
In case it helps in screen settings I also have the setting "Legacy applications: apply scaling themselves". I've just tested: "scaled by the system" and the problem don't appear.
Comment 5 Nate Graham 2024-08-13 22:10:49 UTC
Ok, so good news and bad news!

Good news: I know what this is: Bug 474738.

Bad news: it's currently intentional. Not because we like it and think it's not a bug, but because the only way we can think of to fix it involves a lot of technical changes that we don't have the resources to make right now, and that would also increase resource consumption if we implemented them.

We may end up doing it anyway, as there are clear benefits. But until then, for the moment I'm afraid it's just something you're going to have to live with unless you want to use that other scaling setting that you found.

*** This bug has been marked as a duplicate of bug 474738 ***