Huh, the example I found is for QQuick/qml, but my applications is traditional QWidgets. It doesn't look like using QQuickItems inside a QWidget is supported. There is a QOpenGLFrameBufferObject but it doesn't look at all like the QQuickFramebufferObject. No createRenderer function.
The LLMs are good at known solutions. I don't think anyone has published an actual solution to this problem (that I can find). I don't have any LLM subscriptions right now, but I'm almost certain it will give me non-working trash or something that says "Insert your GL framebuffer implementation here." I could use one of the local models that runs on my 3080-Ti via Ollama (and IntelliJ plugins), but that answer would probably be worse than useless.
The examples I found do work on my i3/X11 box and my KDE/Wayland box. The trouble is, the example is for QQuick and my existing application is made for traditional QWidgets. I can't figure out how to get mpv to render with a QOpenGLWidget (as opposed to a QQuickFramebufferObject).
@djsumdog Don't forget to check if you install the new Wayland module for qt6. Had applications not launching because the qt5 equivalent doesn't work even with qt6-qt5compat (Or whatever that package is named) installed
The question says X11 and Wayland. My app works fine on X11. I do need it to work on Wayland so other people actually use it. Also, switching from X Window Handles to OpenGL or Vulkan will benefit it on X11 as well.
So I did find a solution to this. I didn't update the question with an answer because fuck Stack Overflow. Now I just have two remaining issues.
I can't send mouse clicks to the on-screen-controls in MPV. I'm not sure if this is even possible. I haven't gotten any responses in #mpv on IRC. I opened an SO question, but doubt anyone will look at it seriously:
Fullscreening the QOpenGLWidget that's rendering the mpv video gives me a black screen. I can use other Python/Qt OpenGL examples and they fullscreen fine, so something weird is going on with the GL rendering context for MPV. I have so little 3D background I don't know where to start with this. I might have to break down and start using Microsoft™ Github again, because that's the only place where OSS like mpv and python-mpv have any support forums.
Finally broke down and asked on the official forums after I couldn't get any help on IRC. I hate that no one has a fucking mailing list any more and we're all reduced to using Microsoft Github. The open source devs of the 1990s would be appalled.
Without that, you can move a Qt OpenGL widget between different windows/layouts. No A.I. or search could point that out. That required going through the documentation.