Bug 488028

Summary:	Screenshot taken at wrong scaling factor when using multi-monitor Wayland with fractional scaling (attachment expires on 11JUN24!)
Product:	[Applications] Spectacle	Reporter:	Andrea Ippolito <andrea.ippo>
Component:	General	Assignee:	Noah Davis <noahadvs>
Status:	RESOLVED DUPLICATE
Severity:	normal	CC:	kde
Priority:	NOR
Version:	24.05.0
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	At wrong scale (477x280px) At correct scale (228x124px)

Description Andrea Ippolito 2024-06-04 17:03:59 UTC

Since a video is worth a thousand words, please check the attachment (sorry, it exceeds the limits so I had to upload it elsewhere):

https://we.tl/t-zY9iOxprIj

It expires in one week

Don't focus on the weird compression, the output has been rescaled by OBS, but it's in a proportional way, so it doesn't change the gist of the problem.

There is also a weird graphical artifact that you can see during the screencast. Not sure if it's a Plasma issue.

My setup:
- external monitor @100% on the left
- laptop monitor @125% on the right and slightly lower on my desk (similar positioning you will see in the screencast, I have arranged them on the OBS canvas in a realistic way)

When I'm on the external monitor, spectacle consistently takes screenshots at the wrong scale (they are zoomed in).
When I capture some content on the laptop monitor, it's captured with the correct size.
When I switch to the external monitor only (as shown in the screencast), the problem disappears.

Operating System: openSUSE Tumbleweed 20240531
KDE Plasma Version: 6.0.5
KDE Frameworks Version: 6.2.0
Qt Version: 6.7.1
Kernel Version: 6.9.3-1-default (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 7840U w/ Radeon 780M Graphics
Memory: 30,7 GiB of RAM
Graphics Processor: AMD Radeon Graphics
Manufacturer: Framework
Product Name: Laptop 13 (AMD Ryzen 7040Series)
System Version: A7

Comment 1 Andrea Ippolito 2024-06-04 17:05:51 UTC

Created attachment 170138 [details]
At wrong scale (477x280px)

Comment 2 Andrea Ippolito 2024-06-04 17:06:12 UTC

Created attachment 170139 [details]
At correct scale (228x124px)

Comment 3 Andrea Ippolito 2024-06-04 17:06:57 UTC

I don't know if this is an app issue, or a kwin problem. Please apologize if it's for kwin.

Comment 4 Andrea Ippolito 2024-06-04 17:29:45 UTC

(In reply to Andrea Ippolito from comment #0)

> When I capture some content on the laptop monitor, it's captured with the
> correct size.

Correction, it's at the wrong size even on the laptop display. So basically as soon as I use both displays at the same time, the captured content is at the wrong size.

The problem goes away IF I give up fractional scaling, i.e. set also the laptop display to 100%.

Comment 5 Andrea Ippolito 2024-06-04 17:36:57 UTC

(In reply to Andrea Ippolito from comment #4)
> (In reply to Andrea Ippolito from comment #0)
> 
> > When I capture some content on the laptop monitor, it's captured with the
> > correct size.
> 
> Correction, it's at the wrong size even on the laptop display. So basically
> as soon as I use both displays at the same time, the captured content is at
> the wrong size.
> 
> The problem goes away IF I give up fractional scaling, i.e. set also the
> laptop display to 100%.

Further finding: the behavior is also OK when setting external 100% and laptop 200%.
But any fractional scaling factor on the laptop triggers it. I also tried at 150%, and indeed the captured size is not the expected one.

Comment 6 Noah Davis 2024-06-05 19:24:13 UTC

Seems like a duplicate of bug 487997.

*** This bug has been marked as a duplicate of bug 487997 ***