Crash on Wayland, XGetImage failed

[Igetin]

NormCap crashes when trying to run it under Wayland:

20:29:41 - INFO - normcap.normcap - Starting NormCap v0.1.2 ...
Traceback (most recent call last):
  File "/home/ige/.local/bin/normcap", line 10, in <module>
    sys.exit(run())
  File "/home/ige/.local/lib/python3.7/site-packages/normcap/__main__.py", line 5, in run
    _ = main()
  File "/home/ige/.local/lib/python3.7/site-packages/normcap/normcap.py", line 153, in main
    normcap_data = client_code(capture, normcap_data)
  File "/home/ige/.local/lib/python3.7/site-packages/normcap/normcap.py", line 106, in client_code
    result = handler.handle(normcap_data)
  File "/home/ige/.local/lib/python3.7/site-packages/normcap/handlers/capture_handler.py", line 26, in handle
    request = self._take_screeshot(request)
  File "/home/ige/.local/lib/python3.7/site-packages/normcap/handlers/capture_handler.py", line 40, in _take_screeshot
    raw = sct.grab(position)
  File "/home/ige/.local/lib/python3.7/site-packages/mss/linux.py", line 403, in grab
    ZPIXMAP,
  File "/home/ige/.local/lib/python3.7/site-packages/mss/linux.py", line 175, in validate
    raise ScreenShotError(err, details=details)
mss.exception.ScreenShotError: XGetImage() failed

[dynobo]

Thanks for the report, @Igetin . I can reproduce the problem on Ubuntu 20.04 with Gnome under Wayland.

This is probably an issue in the python library mss, which I'm leveraging to get the screenshot on the multiple platform.

Just to be sure, can you please also run the following snippet, e.g. by typing it in python3 console, can you confirm that you experience the same behavior as described below?

If I run only the following lines...

import mss
fn = mss.mss().shot(mon=-1, output="screenshot.png")
print(fn)

...under X it works (filename is printed, screenshot saved), while under Wayland I get the following error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/holger/.local/lib/python3.8/site-packages/mss/factory.py", line 41, in mss
    return linux.MSS(**kwargs)
  File "/home/holger/.local/lib/python3.8/site-packages/mss/linux.py", line 226, in __init__
    self.root = self.xlib.XDefaultRootWindow(MSS.display)
  File "/home/holger/.local/lib/python3.8/site-packages/mss/linux.py", line 175, in validate
    raise ScreenShotError(err, details=details)
mss.exception.ScreenShotError: XDefaultRootWindow() failed

[dynobo]

I opened an issue for mss: BoboTiG/python-mss#155

Beside waiting to get it fixed in that dependency, I'll think about a (temporary) workaround, e.g. by falling back to pyscreenshot or an execution of gnome-screenshot. But I'll have to check, if the effort is worth the temporary benefit. Stay tuned! :-)

[dynobo]

I added a fallback for wayland. However, that workaround uses gnome-screenshot tool, which have to be installed (it is by default on Ubuntu). Please test and report back, if it worked.

[Igetin]

The gnome-screenshot workaround works, thank you.