Hi David,

Many thanks for the reply and the info on how to get the ID.

I have added a basic example with some debug output at: https://portal.beam.ltd.uk/public//test016-qt6-video-example.tar.gz

If there are any ideas of things I could look at/investigate I am all ears!

In a previous email I stated:
I have tried using "weston-debug scene-graph" and I am coming to the conclusion that qtwayland 6.5.0 is not really using native Wayland surfaces when Qt::WA_NativeWindow is used. From what I can see (and I could easily be wrong) the Wayland protocol shows wl_surfaces being created and two QWidget's QPlatformNativeInterface nativeResourceForWindow("surface", windowHandle()) function does return different wl_surface pointers but even at the QWidget level (ignoring gstreamer), a QPainter paint into each of these QWidgets actually uses Wayland to draw into just the one top level surface and "weston-debug scene-graph" shows only one application xdg_toplevel surface and no subsurfaces. I don't know how to determine the Wayland surface ID from a wl_surface pointer unfortunately to really check this.

If my Video QWidget(0) is a top level QWidget, then video is shown and "weston-debug scene-graph" shows the application xdg_toplevel and two wl_subsurfaces as children.

Unfortunately I think "weston-debug scene-graph" only shows surfaces that are actually "active" so I can't see all of the surfaces that Weston actually knows about (is there a method of doing this ?).

My feeling is that although Qtwayland is creating native surfaces, it actually only uses the one top level one and presumably doesn't "activate" (set a role, do something ?) with the other surfaces.

Does anyone know a good list/place where I can ask such detailed qtwayland questions ?

I guess I can work around this by manually creating a Wayland subsurface from the Qt top level surface and handing that to waylandsink and then manage this subsurface, like hiding, showing and resizing, when the QWidget is hidden/shown/resized.

Or could there be a way of "activating" the child QWidget's Wayland surface ?


Terry

On 23/02/2024 08:35, David Edmundson wrote:
On Fri, Feb 23, 2024 at 6:15 AM Terry Barnaby <ter...@beam.ltd.uk> wrote:
I don't know how to determine the Wayland surface ID from a
wl_surface pointer unfortunately to really check this.
wl_proxy_get_id(static_cast<wl_proxy*>(myWlSurface));


Possibly when QWidget is below in hierarcy to be a child of of a parent,
as described in
That's fine.

A QWidget with WA_NativeWindow will create a QWindow with a parent. A
QWindow with a parent will create a subsurface in wayland terms.
But it is a subsurface where Qt is managing it and you're also
committing on it, which can be a bit confusing and going through
widgets to create a subsurface isn't really needed.
There's a bunch of other options there.


---

Can you link your test app. You can send me a private email and I'll
take a look.  It doesn't seem like a core wayland problem more a
Qt/application setup issue so far. Then we can follow it up on Qt's
Jira if there is a Qt issue.

David Edmundson  - QtWayland Maintainer


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