zbarcam.kv (and xcamera.kv) are loaded multiple times

[misl6]

Loading multiple times zbarcam.kv

zbarcam/src/kivy_garden/zbarcam/zbarcam.py

Line 31 in e0899af

Builder.load_file(os.path.join(MODULE_DIRECTORY, "zbarcam.kv"))

Leads to multiple issues:

The usage is pretty the same mentioned in the example,

zbarcam/src/main.py

Line 12 in e0899af

DEMO_APP_KV_LANG = """

but it's in a specific "page" of the app (in my case the pages are some FloatLayout managed via https://github.com/kivy-garden/garden.router).

• Android: First time works fine, also if it logs that the operation could lead to issues. Starting from the second time that the page is opened and xcamera is initialized n times equals to the times the user visited the page that hosts the ZBarcam widget.

• Ubuntu + OpenCV: First time works fine, also if it logs that the operation could lead to issues. At the second time that the page is visited, this error is thrown:

   File "/mnt/....../venv/lib/python3.8/site-packages/Kivy-2.0.0rc2-py3.8-linux-x86_64.egg/kivy/core/camera/camera_opencv.py", line 120, in init_camera
     self._resolution = (int(frame.shape[1]), int(frame.shape[0]))
 AttributeError: 'NoneType' object has no attribute 'shape'

[AndreMiras]

Thanks for the report. How about using a class attribute to known if it has been loaded already?
Also if we do so we should probably demo it with a unit test so we don't introduce a regression