Build a Debug mode on linux

Laëtitia

Hello,

I am now stuck with the launching of SAMSON-Debug. the launchind fails and says:
This application failed to start because it could not find or load the Qt platform plugin "xcb"in "".
Reinstalling the application may fix this problem.

I tried to reinstall, not changing anything...

Best

DmitriyMarin

Dear @Laëtitia

Do you try to launch with SAMSON Element Samples from github? If so, then in the root CMakeLists.txt you need to disable PyBindTutorial (just comment ADD_SUBDIRECTORY( PyBindTutorial )).

Laëtitia

euh no, I just tried to launch SAMSON-Core.sh in NANO-D/SDK/0.7.0/SAMSON-Debug/Binaries to have a look at the "new" element I created (the empty one I had problem displaying and compiling before with Qt)

DmitriyMarin

@Laëtitia

Have you provided a path to your Qt installation in the SAMSON-Core.sh script for SAMSON-Debug?

It should be smth like this: export LD_LIBRARY_PATH=/home/YourUser/Qt/Qt5.9.3/5.9.3/gcc_64/lib:$script_dir:$LD_LIBRARY_PATH

Laëtitia

yes, I did
export LD_LIBRARY_PATH=$script_dir:/home/bomble/Qt5.9.3/5.9.3/gcc_64/lib/:$LD_LIBRARY_PATH

DmitriyMarin

Does SAMSON launch in Release mode?

Could you, please, try adding into the SAMSON-Core.sh script for SAMSON-Debug the a path to Qt platforms (/home/bomble/Qt5.9.3/5.9.3/gcc_64/plugins/platforms) to the LD_LIBRARY_PATH environment variable:
LD_LIBRARY_PATH=$script_dir:/home/bomble/Qt5.9.3/5.9.3/gcc_64/lib/:/home/bomble/Qt5.9.3/5.9.3/gcc_64/plugins/platforms:$LD_LIBRARY_PATH
which should provide a path to platforms ("xcb" including).

Do you have any Python installed with PyQt5 and their paths set into PATH or LD_LIBRARY_PATH ? The platforms and Qt libs from Python installation may interfere.

Laëtitia

Hello,

Yes Samson launch in Release mode.
Adding /home/bomble/Qt5.9.3/5.9.3/gcc_64/plugins/platforms path does not change anything (even if libqxcb.so is indeed there!).
export LD_LIBRARY_PATH=$script_dir:/home/bomble/Qt5.9.3/5.9.3/gcc_64/lib/:/home/bomble/Qt5.9.3/5.9.3/gcc_64/plugins/platforms/:$LD_LIBRARY_PATH

I don't have PyQt5 installed at all.

Laëtitia

if after setting the path I ldd the exe, I have only one lib with xcb in it called:
libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f820fc81000)
it's not calling for qxcb.
Maybe I should installe another version of libxcb.so.1?

DmitriyMarin

@Laëtitia

Could you, please, try making the following symbolic links in the SAMSON-Debug/Binaries folder :

cd ~/NANO-D/SDK/0.7.0/SAMSON-Debug/Binaries
ln -s ~/Qt5.9.3/5.9.3/gcc_64/plugins/platforms/ ./platforms
ln -s ~/Qt5.9.3/5.9.3/gcc_64/plugins/xcbglintegrations/ ./xcbglintegrations

If the symbolic links won't make it work, could you, please, try copying these folders from the Qt installation into the SAMSON-Debug/Binaries folder.

Laëtitia

the symbolic links stuff worked! thanks a lot, but I don't understand why it works now, could you explain me?

DmitriyMarin

@Laëtitia

Great! Sorry for this issue!

It is due to Qt debug libraries not being shipped together with SAMSON-Debug because they are too heavy. That's why you need to install Qt and apart from providing a path to Qt libraries themselves it is sometimes necessary to provide a path to the plugins folder (Qt5.9.3/5.9.3/gcc_64/plugins, subfolders platforms and xcbglintegrations in particular).

What can also be done instead of creating symbolic links is to provide these paths in your ~/.bashrc file (this works for me on Ubuntu)

QT_VERSION=Qt5.9.3/5.9.3
export QT_PATH=$HOME/$QT_VERSION
export QT5_CMAKE_INCLUDE_DIR=$QT_PATH/gcc_64/lib/cmake/
export QT5_PLATFORM_LIBRARY_PATH=$QT_PATH/gcc_64/plugins/platforms/
export LD_LIBRARY_PATH=$QT5_PLATFORM_LIBRARY_PATH:$LD_LIBRARY_PATH

Laëtitia

ok I see.
Now I can start playing!

Thanks for help and patience.

DmitriyMarin

Good luck @Laëtitia !
You can check https://github.com/1A-OneAngstrom/SAMSON-Developer-Tutorials/tree/develop for some SAMSON Elements Samples. We will be adding more soon.

Feel free to ask questions!