Allows the customized UI elements used by OBS Studio to more cleanly
be integrated into consumers of the same elements, mainly frontend
plugins in the main source tree.
find_qt was necessary during the transitional period between Qt5 and
Qt6. With Qt6 being the only supported Qt version (for open source) for
the time being, code complexity can be reduced for easier maintenance.
Creation of Info.plist files through Xcode is more canonical and
future-proof, as it will automatically pick up changes/updates
introduced by Apple. Non-standard keys can still be added via a
template file, which will then be extended by Xcode with the default
keys.
If QT_VERSION is not defined, it gets define with the AUTO value. And
its definition is moved to the helper file.
find_qt now:
- Check quietly for Qt5 and Qt6
- If QT_VERSION is set to AUTO. It checks firstly if Qt5 was found it
will use it. If not it do the same for Qt6
- If QT_VERSION is set to 5 or 6, it checks if the choice was found and
use it. And if not, it falls back to the other if found.
- If neither Qt5 or Qt6 are found, a fatal error is emitted.
- The macro saved the _QT_VERSION in the cache to replace QT_VERSION,
so the process is not repeated each time that find_qt is used.
- When Qt::Gui is in the Linux component list, Qt::GuiPrivate is added.
So using the versioned one is no longer required.
Due to how CMake and generated project files are structured, just using
AUTOUIC to pick up Qt `.ui` files will lead to a situation where
changing such a file doesn't trigger a regeneration of the associated
header files and thus a re-build of the target.
Upstream fix still requires `.ui` files to be added as target sources.
CMake issue: https://gitlab.kitware.com/cmake/cmake/-/issues/17959
