Bug 500555

Summary: 'Rectangular Region' captures wrong monitor with fractional scaling
Product: [Applications] Spectacle Reporter: madness742
Component: GeneralAssignee: Noah Davis <noahadvs>
Status: RESOLVED DUPLICATE    
Severity: normal CC: john.kizer, kde, maik.schaefer, quarro
Priority: NOR    
Version First Reported In: 6.3.1   
Target Milestone: ---   
Platform: Fedora RPMs   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Showcase of the bug.

Description madness742 2025-02-21 22:56:00 UTC
Created attachment 178715 [details]
Showcase of the bug.

SUMMARY
When using per monitor fractional scaling, with a specific resolution and scaling value, the rectangular region feature captures the wrong screen.

STEPS TO REPRODUCE
1. Set primary monitor to 2560x1440, 125% scaling.
2. Set secondary monitor to 3840x2160, 185% scaling, placed left of the primary monitor.
3. Launch spectacles
4. Press on "Rectangular Region"
5. Select a region on the secondary monitor.

OBSERVED RESULT
The rectangular region captures the primary monitor.

EXPECTED RESULT
The rectangular region should capture the content on the secondary monitor.

SOFTWARE/OS VERSIONS
Linux: Fedora 41
KDE Plasma Version: 6.3.1
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2

ADDITIONAL INFORMATION
- This seems to be a regression, I cannot replicate it with a Fedora 41 Live USB.
- This bug does not appear when the secondary monitor is placed right of the primary monitor.
- Changing secondary monitor scaling to 175% fixes the issue.
- I was not able to replicate this bug on a different resolution.
Comment 1 Greeniac 2025-02-22 04:10:34 UTC
I have an AMD GPU and i cannot reproduce this bug.

Operating System: Arch Linux 
KDE Plasma Version: 6.3.1
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2
Kernel Version: 6.13.3-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 4 × Intel® Core™ i5-7600K CPU @ 3.80GHz
Memory: 23.4 GiB of RAM
Graphics Processor: AMD Radeon Pro 580X
Manufacturer: Apple Inc.
Product Name: iMac18,3
System Version: 1.0
Comment 2 maik.schaefer 2025-02-22 17:01:11 UTC
I have an AMD iGPU and I had exactly the same issue although using no scaling for my first screen (Laptop) and 115% the second (but set as primary) screen. Also the 2nd screen was on the left side.

While preparing this information, I completely removed the fractional scaling of my 2nd screen but to no prevail. However, just for testing, I've moved this screen to the right and suddenly it worked. Then I moved it back to the left side and surprise, it works as well. Even a logoff or reboot didn't change that. Looks like this moving have healed it.

Operating System: Arch Linux 
KDE Plasma Version: 6.3.1
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2
Kernel Version: 6.13.3-arch1-1 (64-bit)
Graphics Platform: Wayland
Comment 3 madness742 2025-02-24 17:03:10 UTC
(In reply to maik.schaefer from comment #2)
> While preparing this information, I completely removed the fractional
> scaling of my 2nd screen but to no prevail. However, just for testing, I've
> moved this screen to the right and suddenly it worked. Then I moved it back
> to the left side and surprise, it works as well. Even a logoff or reboot
> didn't change that. Looks like this moving have healed it.

This unfortunately does not work with my setup. I tried finding a more common resolution where I can reproduce this bug, but I wasn't able to. Lowering the scaling from 185% to 175% on my second monitor as a workaround for the time being.
Comment 4 John Kizer 2025-04-13 05:17:29 UTC
Hi - merging this in with another bug report for this issue. Thanks!

*** This bug has been marked as a duplicate of bug 502047 ***