bugGNU Octave - Bugs: bug #67253, Plot window scale is not correct

 
 

bug #67253: Plot window scale is not correct

Submitter:  Mihai Vasiliu <silvergreen93>
Submitted:  Fri 27 Jun 2025 08:34:05 PM UTC
   
 
Category:  Plotting Severity:  3 - Normal
Priority:  5 - Normal Item Group:  None
Status:  Need Info Assigned to:  None
Originator Name:  Open/Closed:  * Open
Release:  * 9.4.0 Release: 
Operating System:  * GNU/Linux Fixed Release:  None
Planned Release:  None
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Tue 01 Jul 2025 05:49:21 AM UTC, comment #6: 

Setting `QT_SCALE_FACTOR_ROUNDING_POLICY=round` seems to solve the problem for me.
See:
https://doc.qt.io/qt-6/highdpi.html

It is probably just a workaround at this moment. I do not see any `hiDPI` calls in octave sources,so we are not using Qt6 specific HiDPI handling APIs, so could be using Qt5 default behavior as well.

Dmitri.
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Dmitri A. Sergatskov <dasergatskov>
Tue 01 Jul 2025 04:31:53 AM UTC, comment #5: 

It is not clear. it is quite possible that Octave should be able to handle the situation better.

Dmitri.
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Dmitri A. Sergatskov <dasergatskov>
Tue 01 Jul 2025 02:25:34 AM UTC, comment #4: 

Is there anything that Octave needs to change, or is this an upstream issue with Wayland?

Rik <rik5>
Group administrator
Sat 28 Jun 2025 02:51:05 PM UTC, comment #3: 

It is somewhat interestin that it work with flatpak, but the bug is still there.

https://forum.qt.io/topic/160425/wayland-and-fractional-screen-scaling-reported-as-integer-by-wayland-info-and-q-screen/4

Dmitri.
--

Dmitri A. Sergatskov <dasergatskov>
Sat 28 Jun 2025 11:20:14 AM UTC, comment #2: 

I don't have any other app to have such behaviour with fractional scaling, and in general it works quite good.

Anyway, I realised that the Octave version installed from apt is outdated... So I installed the flatpak version 10.2.0.

It seems that the issue is no longer present in 10.2.0. I presume it was fixed meanwhile.

Thanks.

Mihai Vasiliu <silvergreen93>
Sat 28 Jun 2025 02:02:47 AM UTC, comment #1: 

Fractional scaling is buggy on Wayland (does it even available on X11?). I see the same problem on both Plasma (KWin) or Gnome (Mutter).
So this is one of those "do not do it" things.

Dmitri.
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Dmitri A. Sergatskov <dasergatskov>
Fri 27 Jun 2025 08:34:05 PM UTC, original submission:  

I am using Kubuntu 25.04, with a display resolution of 2560x1440p and 125% scaling on Wayland.

Whenever I need to plot a graphic, the plot is offset and cropped outside of the plot window.

If I set the desktop scaling to 100% the plot is correct. So this is definitely related to scaling issue.

To reproduce, enter the following in the Octave terminal:

>> x = -10:0.1:10;
>> plot (x, sin (x));


Notice the display plot window. See screenshot attached.

Mihai Vasiliu <silvergreen93>

 

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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2025-07-01 rik5 StatusNone Need Info
    2025-06-27 silvergreen93 Attached File- Added Screenshot_20250627_231421.png, #57338

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