Follow up from Kivy class in .py and .kv interaction , but more complex.

Here is the full code of what I'm writing:

The data/screens/learnkanji_want.kv has how I want the code to be, but I don't fully understand how the class KanjiOriginScreen() plays it's role in screen management.

data/screens/learnkanji.kv works how I want it, but for this to work I have to put keyb_height in class KanjiOriginScreen() (main.py). However I want that code to be in the class LayoutFunction() (learnkanji.py).

Question

How can I put keyb_height in the function LayoutFunction() and access this in the .kv file in <LayoutFunction>?

Could you also explain why KanjiOriginScreen: can be put in learnkanji.kv without < > and the program still recognizes it should use this?

If anything is unclear, please ask :)

Edit

I found out that I didn't import the learnkanji.py in the learnkanji.kv file and that caused that it couldn't find the class 'LayoutFunction'.

#:import learnkanji data.screens.learnkanji

To answer your questions:

1. The way you are doing it should work. You should be able to access object attributes from kv. If your attribute is going to change, however, and you want the UI to update when it does, you should use Kivy Properties. If it is constant, a normal attribute works fine.

2. From the Kivy Docs, <Widget>: is a class rule that will be applied to every instance of that class. Widget: will create an actual instance of that class (in this case it is your root widget).

As for ScreenManager and Screens, you can think of them this way. Each Screen is it's own individual UI (it's own root widget). The screen manager is a container that holds your Screen and can swap between different Screens. This lets you create separate UIs that you can toggle between. Each UI is a separate widget tree with a Screen at its root. The docs are actually pretty good at describing ScreenManager.