WSL2 Ubuntu 22.04 and Qt Platform Plugins

[vismam]

My setup is Windows 11 with Ubuntu 22.04 run in WSL2. I would like to be able to run DLT Viewer in this Ubuntu instance.

I have downloaded DLT-Linux.zip of release 2.27.0, extracted the zip file and the contained tgz file. Upon executing the AppImage, I get the following error:

$ ./DLTViewer-2.27.0-STABLE-qt5.15.2-r1123_x86_64-linux-gnu_11.4.0.AppImage
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.

Installing x11-apps got rid of this issue, and the GUI can now be launched successfully. I haven't tracked down which of the dependencies of x11-apps are really relevant for Qt. Sadly, when executing the AppImage without GUI, I'm getting a different error:

$ ./DLTViewer-2.27.0-STABLE-qt5.15.2-r1123_x86_64-linux-gnu_11.4.0.AppImage --help
qt.qpa.plugin: Could not find the Qt platform plugin "offscreen" in ""

I have inspected the AppImage and found that libqoffscreen.so is missing inside usr/plugins/platforms. This can be worked around by installing libqt5gui5 and copying the contained libqoffscreen.so to the aforementioned path. Then, DLT Viewer can be executed from the extracted directory.

I haven't tried different DLT Viewer versions, but I have tried different Ubuntu versions and additionally Ubuntu 22.04 in VMware. I haven't found a configuration which works out of the box.

Is the need for x11-apps documented and I simply missed it? Should libqoffscreen be added to the AppImage?

[vifactor]

Hi, thanks for reporting! I can confirm that missing Qt offscreen plugin is a real issue (reproduced it on ubuntu 22.04 without WSL). I guess I fixed similar issue some time ago for Windows.

Regarding the xcb-plugin, it might be indeed undocumented dependency which is actually hard to track for various linux distros. Could you please run the appImage from terminal like this: QT_DEBUG_PLUGINS=1 ./DLTViewer-2.27.0-STABLE-qt5.15.2-r1123_x86_64-linux-gnu_11.4.0.AppImage? it should tell you which missing library xcb plugin depends on, from there we can figure out what package needs to be additionally installed

[vismam]

Hi @vifactor, thank you for processing my request and creating #624. I have had a look into the dependencies of the AppImage and it seems only the following is required (in Ubuntu 22.04):

• libfuse2 (required for AppImages to work, but Ubuntu 22.04 comes with fuse3)
• libsm6 (libSM.so.6 is required by libqxcb.so)

Please tell me if you need more info or maybe the entire output with QT_DEBUG_PLUGINS=1.