Bug 505974

Summary:	With NVIDIA GPU, smooth lines in line charts look like dotted lines if the chart is wide
Product:	[Frameworks and Libraries] frameworks-kquickcharts	Reporter:	lojcsgit
Component:	general	Assignee:	Arjen Hiemstra <ahiemstra>
Status:	REPORTED ---
Severity:	normal	CC:	ahiemstra, kde, kdelibs-bugs-null, nate, plasma-bugs-null
Priority:	NOR
Version First Reported In:	6.15.0
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	nvidia_wide_window_no_dots

Description lojcsgit 2025-06-22 14:45:23 UTC

SUMMARY
Lines in system monitor line charts with 'smooth lines' ticked look dotted if the chart is above some width based on the line's incline.

STEPS TO REPRODUCE
1. Open the new history page in system monitor open as a small window.
2. Observe normal lines.
3. Slowly make the window wider
4. Observe portions of the line suddenly turn dotted at certain widths

OBSERVED RESULT
Dotted lines

EXPECTED RESULT
Smooth lines

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.4.0
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.1
Kernel Version: 6.15.3-arch1-1 (64-bit)

ADDITIONAL INFORMATION
Noticed this in 6.4 when I checked out the new history page, not sure since when it's like this

Comment 1 David Redondo 2025-06-24 07:45:39 UTC

Can you attach a screenshot? Which GPU do you have?

Comment 2 lojcsgit 2025-06-24 11:56:16 UTC

(In reply to David Redondo from comment #1)
> Can you attach a screenshot? Which GPU do you have?

I have an nvidia discrete gpu and an amd igpu
https://files.catbox.moe/6c85s4.png

Comment 3 Nate Graham 2025-06-24 19:35:47 UTC

I can't reproduce this issue with an AMD Radeon 780M iGPU.

Comment 4 lojcsgit 2025-06-27 11:53:31 UTC

It must be an nvidia issue then, I accidentally managed to run the desktop on the igpu and the issue was similiarly gone

Comment 5 David Redondo 2025-06-30 12:46:00 UTC

Created attachment 182799 [details]
nvidia_wide_window_no_dots

I cannot reproduce on my nvidia gpu