I'm trying to implement a 2 screen app on kivy. I have followed their example and it works if "Builder.load_string" is called in main.py.
However, if I comment it out and create a .kv file, I just get a blank screen. What am I doing wrong?
from kivy.app import App from kivy.lang import Builder from kivy.uix.screenmanager import ScreenManager, Screen #Builder.load_string(""" #<MainScreen>: #BoxLayout: #Button: #text: 'Goto settings' #on_press: root.manager.current = 'settings' #Button: #text: 'Quit' #<SettingsScreen>: #BoxLayout: #Button: #text: 'My settings button' #Button: #text: 'Back to menu' #on_press: root.manager.current = 'main' #""") # Declare both screens class MainScreen(Screen): pass class SettingsScreen(Screen): pass # Create the screen manager sm = ScreenManager() sm.add_widget(MainScreen(name='main')) sm.add_widget(SettingsScreen(name='settings')) class TestApp(App): def build(self): return sm if __name__ == '__main__': TestApp().run() And here is testapp.kv
<MainScreen>: BoxLayout: Button: text: 'Goto settings' on_press: root.manager.current = 'settings' Button: text: 'Quit' <SettingsScreen>: BoxLayout: Button: text: 'My settings button' Button: text: 'Back to menu' on_press: root.manager.current = 'main' 1 Answer
The kv file is loaded by the App class when run is called, but before the build method. You instantiate your widgets before this (above the App class declaration), so the kv rules haven't yet been loaded and do not apply. To fix it, move the instantiation to the build method.
Edit: Change:
# Create the screen manager sm = ScreenManager() sm.add_widget(MainScreen(name='main')) sm.add_widget(SettingsScreen(name='settings')) class TestApp(App): def build(self): return sm to
class TestApp(App): def build(self): # Create the screen manager sm = ScreenManager() sm.add_widget(MainScreen(name='main')) sm.add_widget(SettingsScreen(name='settings')) return sm 
