qtplasma does not work on Wayland

[dwrobel]

qtplasma does not seem to work on the latest Gnome 41.2 / Wayland 1.19 environment available on Fedora 35 (tested on https://github.com/LinuxCNC/linuxcnc/commit/14a02d19b05caf06e6fccd0865df81440760bbac). Note, that axis works fine on the same environment.

Here is the screenshot on Wayland after an attempt to load metric_circles.ngs file:

Please note that the Select button has been pressed, but the screen hadn't been refreshed (there is still a file selector dialog visible). Shortly after that Gnome starts to complain that qtplasma is not responding:

For the reference the same metric_circles.ngs loaded correctly on the X11 session:

[dwrobel]

One more screenshot from Wayland, taken directly after launching qtplasma without pressing any buttons:

Please note that the white rectangle part of the screen does not seem to be refreshed at all and it looks that in qtplasma this part is completely transparent as the text dw@t630:~/Pictures comes from the Gnome terminal title bar window which was beneath qtplasma when I launched it.

Very likely this part of the screen is handled by some X11 specific code and as a result it doesn't work on Wayland.

[c-morley]

Could you try running gcode_graphics directly in a terminal: python3 gcode_graphics.py Also interesting if any gladevcp screen grahics display works with wayland. They use alot of common code.

[dwrobel]

Could you try running gcode_graphics directly in a terminal: python3 gcode_graphics.py

Please find attached a screen recording from running it on a Wayland session:

[dw@t630 linuxcnc]$ loginctl 
SESSION  UID USER SEAT  TTY 
     16 1000 dw   seat0 tty2

1 sessions listed.
[dw@t630 linuxcnc]$ loginctl show-session 16 -p Type
Type=wayland

https://user-images.githubusercontent.com/228873/147849733-4bc61b6e-e100-4903-9464-582d5a8069fd.mp4

The output of both console and graphics screens are pretty much fully consistent between Wayland and X11 sessions.

The code of gcodegraphics.py seems to be session agnostic (OpenGL based)_ however, grepping the qtvcp code showed other places which contains X11 specific code:

[dw@t630 linuxcnc]$ git grep -i -- x11 lib/python/qtvcp
lib/python/qtvcp/lib/xembed.py:# embed qt instance 'window' into X11 window 'parent'
lib/python/qtvcp/lib/xembed.py:def reparent_qt_to_x11(window, parent):
lib/python/qtvcp/lib/xembed.py:# forward events to an X11 window id
lib/python/qtvcp/lib/xembed.py:class X11ClientMessage():
lib/python/qtvcp/lib/xembed.py:        print('X11 message sent')
lib/python/qtvcp/widgets/xembed.py:            self.x11mess = xembed.X11ClientMessage(self.external_id)
lib/python/qtvcp/widgets/xembed.py:    def send_x11_message(self,):
lib/python/qtvcp/widgets/xembed.py:        self.x11mess.send_client_message()

[dw@t630 linuxcnc]$ git grep -i -- xembed lib/python/qtvcp
lib/python/qtvcp/lib/xembed.py:    # Honor XEmbed spec
lib/python/qtvcp/lib/xembed.py:    atom = d.get_atom('_XEMBED_INFO')
lib/python/qtvcp/lib/xembed.py:class XEmbedFowarding():
lib/python/qtvcp/plugins/simplewidgets_plugin.py:from qtvcp.widgets.xembed import XEmbed
lib/python/qtvcp/plugins/simplewidgets_plugin.py:# XEmbed
lib/python/qtvcp/plugins/simplewidgets_plugin.py:class XEmbedPlugin(QPyDesignerCustomWidgetPlugin):
lib/python/qtvcp/plugins/simplewidgets_plugin.py:        super(XEmbedPlugin, self).__init__(parent)
lib/python/qtvcp/plugins/simplewidgets_plugin.py:        return XEmbed(parent)
lib/python/qtvcp/plugins/simplewidgets_plugin.py:        return "XEmbed"
lib/python/qtvcp/plugins/simplewidgets_plugin.py:        return QtGui.QIcon(QtGui.QPixmap(ICON.get_path('xembed')))
lib/python/qtvcp/plugins/simplewidgets_plugin.py:        return '<widget class="XEmbed" name="xembed" />\n'
lib/python/qtvcp/plugins/simplewidgets_plugin.py:        return "qtvcp.widgets.xembed"
lib/python/qtvcp/qt_istat.py:        # XEmbed tabs
lib/python/qtvcp/qt_makegui.py:    # These can get class patched by xembed library to catch events
lib/python/qtvcp/widgets/screen_options.py:from qtvcp.widgets.xembed import XEmbeddable
lib/python/qtvcp/widgets/screen_options.py:        # add any XEmbed tabs
lib/python/qtvcp/widgets/screen_options.py:            self.add_xembed_tabs()
lib/python/qtvcp/widgets/screen_options.py:    # XEmbed program into tabs
lib/python/qtvcp/widgets/screen_options.py:    def add_xembed_tabs(self):
lib/python/qtvcp/widgets/screen_options.py:                temp = XEmbeddable()
lib/python/qtvcp/widgets/xembed.py:from qtvcp.lib import xembed
lib/python/qtvcp/widgets/xembed.py:class XEmbeddable(QWidget, _HalWidgetBase):
lib/python/qtvcp/widgets/xembed.py:        super(XEmbeddable, self).__init__(parent)
lib/python/qtvcp/widgets/xembed.py:class XEmbed(XEmbeddable, _HalWidgetBase):
lib/python/qtvcp/widgets/xembed.py:        super(XEmbed, self).__init__(parent)
lib/python/qtvcp/widgets/xembed.py:            self.x11mess = xembed.X11ClientMessage(self.external_id)
lib/python/qtvcp/widgets/xembed.py:    ex = XEmbed()

$ git grep -i -- xset lib/python/qtvcp
lib/python/qtvcp/qt_action.py:            subprocess.Popen('xset -r {}'.format(k), stdout = subprocess.PIPE, shell = True)
lib/python/qtvcp/qt_action.py:            subprocess.Popen('xset r {}'.format(k), stdout = subprocess.PIPE, shell = True)

All of those places (the list might not be exhaustive) will very likely not work on the Wayland session.

[c-morley]

Xset is to work around a keystroke problem on some systems. xembed is for embedding third party programs into qtvcp windows Both should be optional - I don't think QtPlasmac uses them unless requested.

I don't know pretty much anything about Wayland and if there are equivalent functionality.

[rodw-au]

Setting the environment variable proposed by Seb should fix this issue on Wayland. https://github.com/LinuxCNC/linuxcnc/issues/ #2264 It lets QTplasmac run on my Chromebook under Debian Bullseye which has been broken for over 12 months.

There is no doubt a recent change in Bookworm caused this and previously my workaround was to install XFCE and not the default desktop.

[dwrobel]

should fix this issue on Wayland.

I'm afraid it won't. Please don't mix two separate issues.

Switching to X11 session type workaround it and I confirmed that also on the initial report _(search for: "For the reference the same metriccircles.ngs loaded correctly on the X11 session:" above).

As long as LinuxCNC will use X11 specific code (please have a look at the 'grep' output - in one of my above posts) this won't work natively on Wayland session type.

[rodw-au]

I'm not so sure.. Sebs additional post from today isolates the issue and explains what is causing it. https://github.com/LinuxCNC/linuxcnc/issues/2264#issuecomment-1383523049

I have been using qtplasmac on Bookworm for a long time and it stopped working during November as discussed later in the above issue..

Wayland also includes a Xorg server for legacy applications Ref: https://docs.fedoraproject.org/en-US/fedora/latest/system-administrators-guide/Wayland/

On my chromebook, X11 does not exist. Running the commands on that page, confirms that we are running Wayland but that when QTplasmac is running, additional X11 sessions are opened.

rod@penguin:~$ echo $WAYLAND_DISPLAY
wayland-0
rod@penguin:~$ xlsclients (no output, no X11 clients running)
rod@penguin:~$ xlsclients (with qtplasmac running shows two X11 clients running)
penguin  python3.9
penguin  python3.9
rod@penguin:~$ 

I suspect the two sessions would be the main sim and the torch sim window.

So it would appear that running export PYOPENGL_PLATFORM=x11 forces the buggy python3-opengl 3.1.6 to use X11 that Wayland obligingly serves.

[phillc54]

FWIW I tried Sebs suggestion of _export PYOPENGLPLATFORM=x11 on my Bookworm VM. It does prevent the error messages and allows QtPlasmaC to load but it then has the same transparent preview that @dwrobel has in the second post.

[rodw-au]

FWIW I tried Sebs suggestion of _export PYOPENGLPLATFORM=x11 on my Bookworm VM. It does prevent the error messages and allows QtPlasmaC to load but it then has the same transparent preview that @dwrobel has in the second post.

Odd, I'm not seeing any issues at all. I'll try on some real hardware

[rodw-au]

Hmm, ran tasksel on my xfce box to get wayland installed and the QTplasmac screen became badly corrupt. Its a bit funny I think as it is still using the xfce login screen. Retreated to xfce and my mesa 7i76e config and it all works,,,

[phillc54]

This PR seems to workaround this issue.