[Libreoffice-bugs] [Bug 137924] New: [KF5] UI not scaled correctly on HIDPI Wayland/KDE screens

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=137924

            Bug ID: 137924
           Summary: [KF5] UI not scaled correctly on HIDPI Wayland/KDE
                    screens
           Product: LibreOffice
           Version: 7.0.2.2 release
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: UNCONFIRMED
          Severity: normal
          Priority: medium
         Component: UI
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: david at ingeniumdigital.com

Description:
When running any LibreOffice application under a KDE Wayland session
(specifically, the "Plasma (Full Wayland)" session under OpenSUSE Tumbleweed),
on a HiDPI display, the UI elements (buttons, etc) are not scaled, appearing
tiny.

The layout of most windows (dialog boxes, etc), including the main windows of
the various applications (Writer, Impress, etc) only use the top-left quarter
of the window (when 2× scaling is enabled for the display in KDE), though
resizeable windows will usually correctly use the whole window area if it's
resized. Note that the mouse cursor still interacts correctly with these
controls, so it seems to be a layout problem rather than a rendering problem.

Note that the menu bar is scaled correctly — presumably it's handled
differently.

The "gtk3" VCL plugin seems to work fine. This issue seems to have only
appeared when Bug 127687 was fixed (beforehand, everything was blurry and
pixelated: I think KWin was scaling the window). I haven't actually tried to
bisect, though, so take that with a grain of salt.

Steps to Reproduce:
Start any LibreOffice application under a KDE Wayland session, (with
QT_QPA_PLATFORM=wayland and SAL_USE_VCLPLUGIN=kf5, both of which should be
defaults).

Actual Results:
The controls in windows are tiny, and may be squeezed into the top-left-hand
corner of the window.

See screenshots:
https://davidgow.net/stuff/lowriter-recovery-hidpi-scale.png
https://davidgow.net/stuff/lowriter-totd-hidpi-scale.png
https://davidgow.net/stuff/lowriter-mainwin-hidpi-scale.png


Expected Results:
The controls in the UI are twice the width and twice the height.

Basically, it should look like this, but not blurry (this is running under
XWayland, where a lower-resolution display is reported to the application, and
the window manager scales the input/output):
https://davidgow.net/stuff/lowriter-mainwin-x11-scale.png


Reproducible: Always


User Profile Reset: Yes


OpenGL enabled: Yes

Additional Info:
This seems to have been happening since LibreOffice 7.0.

I've tried it with and without a new UserProfile and OpenGL enabled/disabled.
The system in question is running OpenSUSE Tumbleweed (a rolling-release
distro), with an Intel Integrated Graphics chipset. (This is a Dell XPS 13 9360
laptop.)

The output of "$ env | grep QT" is below, but changing these (except
QT_QPA_PLATFORM) doesn't fix the issue:
QT_QPA_PLATFORM=wayland
PLASMA_USE_QT_SCALING=1
QT_WAYLAND_FORCE_DPI=96
QT_IM_MODULE=fcitx
QT_AUTO_SCREEN_SCALE_FACTOR=0

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