What sorts of things does QT do on SFOS?

As I understand it, SFOS is using wayland as display server. Wayland is managing the screen. Lipstick is the compositor on top which contains the launcher and manages how applications are displayed.

is Qt used then only responsible for all sorts of display related stuff and some interfaces, or is there more to it? Would some other widget library and e.g. using pulseaudio directly do the same thing?

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Swap “QT” for “QML” in your question title and you have largely answered your own question.

Display stuff: Item, Rectangle, Page, Label, Image, ListView, Flickable, Flipable, … to name a few modules.

I’m not sure about your final part of your question regarding widget library, I’ll leave that for someone more knowledgeable to chime in.

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Widget libraries use various wayland protocols to communicate with the compositior/display server. In theory it shouldn’t matter for your client application what toolkit is used in the server. Unfortunately SFOS uses a quite dated qt-based wayland compositor which only implements few (and dated) protocols. So in practice most toolkits beside Qt/Qml will lack some functionality when run on SFOS. Think of keyboard not popping up or dialogs in the wrong place or stuff like that.

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You can build ‘pure’ SDL 2 apps. @sashikknox ported quake, for instance. no QT there. @Levone1 has also done some pretty crazy builds with some obvious limitations.

I’m hoping to finally get going and follow @sashikknox lead an port some godot games. Also nix da QT.

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Exactly - “quite dated” for sure. No one in any QT forum even gives you the time of day when you tell them your using 5.6. It’s about equivalent to Jellybean on Android…

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Thus the compositor (lipstick) does provide the “desktop enviroment” for sailfish apps? Keyboard, notifications, launcher etc…

Is it kind of coincidence, that lipstick uses qt and the apps do as well (asides from styling etc)? (and e.g. That they use the same qt version?)

what are the limitations, implications of building a non-qt apps? What are the implications of having a compositor with qt5.6? Does that also require apps with qt 5.6?

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Not true at all and more to the point, how many QT forums are there?

I’ve had more help on the original qt.forum with problems than I have here, because here on FSO, there aren’t any real experts with broad general knowledge of QT/QML and then we have a few who think they know it all but don’t when it comes down to the crunch, so https://forum.qt.io/ is my go to when I’m stuck.

I’ve not been asked ONCE which version of QT I am using with regard to SFOS but I do agree it is all dated.

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Admitted - my experience is not extensive enough to have made such a strong statement. I was really just being light… Actually I have no bad feelings. I created an account just to post questions about the things I’ve asked here, and no one replied, but one mod-type was very positive, and appreciated my questions, which they felt were valid and properly posed, but suggested that maybe the lack of response had to do with such an old QT version. Maybe if I didn’t post the version, it would have helped…

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