CQ-editor
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CadQuery
Crashes under Wayland, because some parts are assuming X
I’m filing this here because I’m not certain where it should go and CQ-editor is where I observe it, but it could belong on OCP or OpenCascade or something.
Environment: Arch Linux, Sway window manager, and OCP, CadQuery and CQ-editor master, via these AUR packages:
- python-ocp-git 7.5.RC1.r13.ge1df346-1 (corresponding to https://github.com/CadQuery/OCP/commit/e1df346), also observed with python-ocp 7.5.RC1-2;
- python-cadquery-git 2.1.r138.g2b7f39b-1 (corresponding to https://github.com/CadQuery/cadquery/commit/2b7f39b);
- python-cq-editor-git 0.2.r22.gfbf8c8c-1 (corresponding to fbf8c8c).
Result of running CQ-editor:
With XWayland enabled, the CQ-editor window opens very briefly in a regular Wayland window, and then the process dies:
$ cq-editor
Namespace(filename=None)
X Error of failed request: BadWindow (invalid Window parameter)
Major opcode of failed request: 3 (X_GetWindowAttributes)
Resource id in failed request: 0x3
Serial number of failed request: 10
Current serial number in output stream: 11
$ [exit code 1]
Looks like something is calling an X function with a Wayland id.
With XWayland pseudo-disabled (it’s still running, but I unset DISPLAY), it doesn’t start:
$ DISPLAY= cq-editor
Traceback (most recent call last):
File "/usr/bin/cq-editor", line 33, in <module>
sys.exit(load_entry_point('CQ-editor==0.3.0.dev0', 'gui_scripts', 'cq-editor')())
File "/usr/lib/python3.9/site-packages/cq_editor/__main__.py", line 16, in main
win = MainWindow()
File "/usr/lib/python3.9/site-packages/cq_editor/main_window.py", line 35, in __init__
self.viewer = OCCViewer(self)
File "/usr/lib/python3.9/site-packages/cq_editor/widgets/viewer.py", line 54, in __init__
self.canvas = OCCTWidget()
File "/usr/lib/python3.9/site-packages/cq_editor/widgets/occt_widget.py", line 35, in __init__
self.display_connection = Aspect_DisplayConnection()
OCP.Aspect.Aspect_DisplayConnectionDefinitionError: Can not connect to the server ""
$ [exit code 1]
Diagnosis: Qt supports Wayland, and so CQ-editor defaults to rendering to Wayland, but it looks like OCP or something like it is using X APIs where it should be using Qt APIs which abstract over the platform.
Workaround: force CQ-editor to use X instead of Wayland by setting the environment variable QT_QPA_PLATFORM=xcb, or by passing the command line arguments --platform xcb.
Other remarks: I strongly desire proper Wayland support, because I’m using fractional scaling (1.5×), which Sway handles fine, but XWayland renders at 2× and scales down, which mangles it terribly.
I’m not sure where the error message comes from; I haven’t delved in a debugger to find out (because I’m not sure quite how to).
If this is out of CadQuery’s control for whatever reason, then until it can be fixed, CQ-editor should be adjusted to default to xcb instead of wayland. No idea how you do that, but Krita does it (because it’s mostly broken under Wayland).
@chris-morgan Can you grab the 0.2 release for Linux, extract it, then add the following line to the CQ-editor.sh script (before it launches the CQ-editor binary)?
export QT_QPA_PLATFORM=xcb
Then try to launch CQ-editor by executing the CQ-editor.sh script. If that works, we can consider adding it to the script for new releases until the core issue is fixed.
Huh, although what I built from source supports Wayland, that 0.2 release actually doesn’t support wayland at all, and thus just detects that it should use wayland, emits a warning because it can’t, and successfully falls back to xcb:
$ ./CQ-editor.sh
qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in ""
Namespace(filename=None)
TKOpenGl | Type: Other | ID: 0 | Severity: Medium | Message:
OpenGl_Window::CreateWindow: window Visual is incomplete: no depth buffer, no stencil buffer
$ QT_QPA_PLATFORM=xcb ./CQ-editor.sh
Namespace(filename=None)
TKOpenGl | Type: Other | ID: 0 | Severity: Medium | Message:
OpenGl_Window::CreateWindow: window Visual is incomplete: no depth buffer, no stencil buffer
That is because of occ can't support waylan. https://github.com/tpaviot/pythonocc-core/issues/1230
So to summarize, please submit patches to OCCT if you want Weyland support.
