FlightGear Qt launcher: Difference between revisions

Some code James has written in the 2014 will be obsolete, e.g. the native message box and menubar code.

For the time being, Qt is only needed for the launcher feature, which is automatically disabled if it is not found<ref>http://sourceforge.net/p/flightgear/mailman/message/33498614/</ref>.

If CMake does not find QT5 then it skips the QT launcher compilation<ref>http://sourceforge.net/p/flightgear/mailman/message/33498869/</ref>. Thus, Qt5 is an optional build dependency and people can continue to other other front-ends.

James isn't expecting many issues integrating Canvas layers with a Qt GUI, so there is no wasted development effort there (There is the possibility to make a [[Canvas]] backend based upon QPainter, which might be a great way to use spare CPU cycles to unload the GPU, however, as Canvas rendering becomes more intensive)<ref name="a">http://sourceforge.net/p/flightgear/mailman/message/33245028/</ref>. However, at least for the time being, the Qt5 GUI is not even available at run-time, but will be shut down after handing over control to the main FlightGear initialization routines.

In addition, the idea is to keep modernizing and [[Unifying_the_2D_rendering_backend_via_canvas|unifying the 2D rendering back-end]] in FlightGear by getting rid of legacy GL code to hopefully use modern OSG code in more and more places: <ref>http://forum.flightgear.org/viewtopic.php?p=229311#p229311</ref>. At least for now, it isn't even clear if/how and when Canvas-based MFDs may support HTML5/Qt5-based UI components or vice versa (e.g. a Qt5 based dialog showing Canvas-based features, such as a [[MapStructure]] layer or MFD instances like the [[NavDisplay]]). Unlike Canvas-based efforts like the [[Aircraft Center]], the Qt5 effort is also adding a rather significant build-time dependency for those wanting to use the new built-in launcher.

For now, the goal is to make an '''optional''' Qt dependency to replace PLIB PUI. Except of course PUI will have to remain for some awkward use cases in the short term (aircraft dialogs, potentially). When compiled without Qt support, you’ll get a fully functional FG (i.e., '''Qt will never be a requirement to build FG'''), but without the GUI functions – which is indeed what some people want anyway (e.g., in some home cockpit setups).

Related to Qt, up to now - only a simple replacement for the Mac Launcher has been introduced. This is not related to the internal user interface of FlightGear, at least for now. If, how and when the internal gui can leverage Qt is under investigation and in such an early state that those responsible preferred to not announce anything yet. If this ever happens, this will be discussed on the mailing list<ref>http://forum.flightgear.org/viewtopic.php?p=229563#p229563</ref>

The upcoming FlightGear 3.6 release is likely to contain an integrated, hard-coded, launcher based on Qt5 to work around the issue of the mac launcher no longer working on Yosemite<ref>http://forum.flightgear.org/viewtopic.php?p=228961#p228961</ref>, because James Turner is prototyping a Qt5 cross-platform GUI <ref>http://forum.flightgear.org/viewtopic.php?p=232593#p232593</ref>.