In the settings dialogue | Miscellaneous, tab "System" there are two settings about high DPI, "Use high DPI scaling from the screen factor" and "Use pixmaps with high DPI resolution". The settings work as expected if the KDE session uses display :0. However, if digikam is started in a session using another display, it no longer works, i.e. fonts and images are too small on a high DPI screen. STEPS TO REPRODUCE 1. log in as first user, start digikam, set the two options named above and restart digikam 2. observe the splash screen on startup is bigger, i.e. the option works 3. start a new KDE session with the same user and start digikam OBSERVED RESULT high DPI scaling no longer works EXPECTED RESULT should be independent of the display SOFTWARE/OS VERSIONS Linux/KDE Plasma: openSUSE Tumbleweed 20201108 KDE Plasma Version: 5.20.2 KDE Frameworks Version: 5.75.0 Qt Version: 5.15.1 ADDITIONAL INFORMATION DPI set to 144, 144
Please post the output of: echo $QT_SCREEN_SCALE_FACTORS Maik
#> echo $QT_SCREEN_SCALE_FACTORS DisplayPort-0=1.5;DisplayPort-1=1.5;HDMI-A-0=1.5;HDMI-A-1=1.5; It's the same on both displays :0 and :1 /Gerhard
I don't think we can do anything here and the problem is with Qt or KWin. We have no further options to enforce HiDPI. Maik
Can the problem be reproduced with other programs, e.g. Gwenview or Krita? Maik
Good point, in fact, it's quite a lot of programs that suffer from this problem. I tried krita, k3b, kdenlive, showfoto, gwenview (best seen if they have a splash at startup). However, gimp works correctly on both screens. Maybe it only affects Qt applications? /Gerhard
Hi Gerhard, Please try with the Krita 5 AppImage just released. It use a LTS version of Qt. Perhaps the bug is fixed in this release, or perhaps krita as specific rules at startup for this kind of problem. See below... Maik, I recommend to take a quick look to the main.cc file from Krita. It's always a good inspiration as plenty of technical workaround are patched here. Perhaps there is something suitable for digiKam about HDPI support : https://invent.kde.org/graphics/krita/-/blob/master/krita/main.cc#L293 https://invent.kde.org/graphics/krita/-/blob/master/CMakeLists.txt#L414 Gilles
@Gilles, I have often looked in the main.cc file from Krita. ((:-)) Maik
Meanwhile, I'm on openSUSE Tumbleweed 20220112, usinf Plasma 5.23.5, KF 5.90, Qt 5.15.2, and digikam 7.4. The high DPI problem is gone now. digikam, showfoto and krita scale as desired on X displays > :0. :-)
Great, thanks for the feedback...