Create flatpak distributable, preferrably distribute via FlatHub

[scottAnselmo]

The flatpak on FlatHub for pegasus-frontend has been useful in working around Qt framework related issues. Having a flatpak for the editor would be nice to avoid similar Qt runtime/build issues in addition to making it generally easier to install on various Linux distros via a simple flatpak install [...]

[mmatyas]

Sounds good! Will try to set things up when I have a little time.

[TiZ-HugLife]

I actually forked the Pegasus repo on Flathub to try and add this to it and do a pull request so you could do flatpak run --command=pegasus-metadata-editor org.pegasus_frontend.Pegasus, but it fails to build.

/run/build/pegasus-metadata-editor/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp: In member function ‘virtual int qqsfpm::RoleSorter::compare(const QModelIndex&, const QModelIndex&, const qqsfpm::QQmlSortFilterProxyModel&) const’:
/run/build/pegasus-metadata-editor/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:61:19: error: no match for ‘operator<’ (operand types are ‘QVariant’ and ‘QVariant’)
   61 |     if (leftValue < rightValue)
      |         ~~~~~~~~~ ^ ~~~~~~~~~~
      |         |           |
      |         QVariant    QVariant

[mmatyas]

Yes, the SortFilterProxyModel dependency has some old style code, which will fail to build with the latest Qt if deprecated Qt features are disabled. Make sure you don't have any QT_DISABLE_DEPRECATED_BEFORE defines when you build, and make sure that Qt 5 is used.