sdl2 'Unable to get a Window, abort' Raspberry pi 4 CM4 - reTerminal from seeedstudio

[mjk...@gmail.com]

Hello,

I have had success with Kivy running from the console on Raspberry pi 3B, 3B+ and 4.  Most recently I had set up Raspberry Pi with the 64-bit Raspberry Pi OS and I found almost everything worked better -like a dream. The mouse finally works without the Python module and several data science libraries installed very easily after changing to 64-bit.

However, I ran into a snag when building a new Raspberry Pi reTerminal which uses a CM4.  This has worked on the 32-bit OS and also worked for Python 3.11 and Python 3.9.  I just have to be careful to install the prerequisites and set the environment variables accordingly.
likethis:
KIVY_RPI_VERSION=4
KIVY_SDL2_PATH=/usr/local/lib
KIVY_GL_BACKEND=sdl2
KIVY_NO_ARGS=1
KIVY_TEXT=sdl2
KIVY_WINDOW=sdl2


However, after Numerous tries with various install methods and different Python versions, including the built in 3.9.2, I cannot get past the loading of the Window and get errors like this:

[DEBUG  ] [Cache       ] register <kv.resourcefind> with limit=None, timeout=60
[DEBUG  ] [Cache       ] register <kv.lang> with limit=None, timeout=None
[DEBUG  ] [Cache       ] register <kv.image> with limit=None, timeout=60
[DEBUG  ] [Cache       ] register <kv.atlas> with limit=None, timeout=None
[INFO   ] [Image       ] Providers: img_tex, img_dds, img_sdl2, img_pil (img_ffpyplayer ignored)
[DEBUG  ] [Cache       ] register <kv.texture> with limit=1000, timeout=60
[DEBUG  ] [Cache       ] register <kv.shader> with limit=1000, timeout=3600
[DEBUG  ] [Cache       ] register <kv.graphics.texture> with limit=None, timeout=None
[INFO   ] [Text        ] Provider: sdl2
[DEBUG  ] [App         ] Loading kv </home/pi/archive_install/my.kv>
[DEBUG  ] [App         ] kv </home/pi/archive_install/my.kv> not found
[INFO   ] [Window      ] Provider: sdl2
[DEBUG  ] [Window      ] Provider <x11> ignored by config
[CRITICAL] [Window      ] Unable to find any valuable Window provider. Please enable debug logging (e.g. add -d if running from the command line, or change the log level in the config) and re-run your app to identify potential causes
sdl2 - UnboundLocalError: local variable 'dpi' referenced before assignment
  File "/home/pi/py39/lib/python3.9/site-packages/kivy/core/__init__.py", line 71, in core_select_lib
    cls = cls()
  File "/home/pi/py39/lib/python3.9/site-packages/kivy/core/window/window_sdl2.py", line 165, in __init__
    super(WindowSDL, self).__init__()
  File "/home/pi/py39/lib/python3.9/site-packages/kivy/core/window/__init__.py", line 1102, in __init__
    self.create_window()
  File "/home/pi/py39/lib/python3.9/site-packages/kivy/core/window/window_sdl2.py", line 322, in create_window
    self._update_density_and_dpi()
  File "/home/pi/py39/lib/python3.9/site-packages/kivy/core/window/window_sdl2.py", line 422, in _update_density_and_dpi    if self.dpi != dpi:

[CRITICAL] [App         ] Unable to get a Window, abort.

--------------------

in window_sdl2.py there is a statement that is detecting self._is_desktop and this seems to be evaluating to True from the windows Core but I am not running the code from the desktop.  It must be getting fooled by the 64-bit architecture or some related change.

On different tries, I have had different flavors of error but never get past the Window provider.

Any ideas for further troubleshooting?

thanks!

[mjk...@gmail.com]

I changed config.desktop to 0 and this stopped that crash and error from coming up.  I don't recall that I have done anything with that setting before.

now, the application loads and the touchscreen events work, I can see my debug lines run according to the places I touch on the screen.

However, no imaging is drawn on the screen.  This is a curious situation I've never seen before.  All that I see on the screen is the console text.

Any ideas how to troubleshoot this problem?

[mjk...@gmail.com]

I have now also tried to run this from the Desktop and the result is the same.  The program runs without a crash (as long as I set the config "desktop = 0" but absolutely nothing is drawn on the desktop or console - there is no window I just see either the original console text or the regular desktop background.  The touch events will fire and my program executes based on the touch events.

I have compiled sdl2 (4 different projects) on this device as instructed in the installation guides.  as I have done many times before on other variations of Raspberry pi OS on other Raspberry pi models.  The new thing here is that I loaded a 64-bit OS image.  However, the 64-bit OS has worked for classic Raspberry pi 3B+ units with HDMI monitors.   It is only this CM4 with a touchscreen, and then only on 64-bit that I get this issue.

I could download and compile a development version of Kivy but I don't know what I would do with it unless guided by some advice.

thanks,
Mark

[Elliot Garbus]

You may have better luck getting an answer on the kivy discord.  There are a few of the Kivy devs on discord.

https://chat.kivy.org

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