Hey there, I've adjusted your code to add screen switching using a Button in your MainScreen. This example uses Kivy's ScreenManager (the standard way to handle multiple screens) and keeps things clean with both KV language and Python logic.

Complete Working Code #

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder

# Define our screen classes
class MainScreen(Screen):
    def go_edit(self):
        # Method to switch to EditScreen from Python code
        self.manager.current = 'edit'

class EditScreen(Screen):
    def go_back(self):
        # Go back to MainScreen
        self.manager.current = 'main'

# KV language definition
KV = """
ScreenManager:
    MainScreen:
        name: 'main'
    EditScreen:
        name: 'edit'

<MainScreen>:
    BoxLayout:
        orientation: 'vertical'
        Button:
            text: 'Go to Edit Screen'
            # Option 1: Call a Python method to handle switching
            on_press: root.go_edit()
            # Option 2: Switch directly from KV (uncomment below to use)
            # on_press: root.manager.current = 'edit'
        Label:
            text: 'This is the Main Screen'

<EditScreen>:
    BoxLayout:
        orientation: 'vertical'
        Button:
            text: 'Go Back to Main'
            on_press: root.go_back()
        Label:
            text: 'This is the Edit Screen'
"""

class ScreenSwitchApp(App):
    def build(self):
        return Builder.load_string(KV)

if __name__ == '__main__':
    ScreenSwitchApp().run()

Key Points Explained #

• ScreenManager: This is the core component that manages all your screens. Each screen gets a unique name property so we can reference it when switching.
• Screen Classes: Each screen inherits from Screen instead of FloatLayout—this lets them connect to the ScreenManager automatically.
• Button Switch Logic: You have two flexible options:
  1. Call a Python method (like go_edit()) which sets self.manager.current to the target screen's name. This is perfect if you need to add extra logic before switching (like saving user input).
  2. Switch directly from the KV language with root.manager.current = 'edit'—this is a simpler approach for basic, straightforward screen changes.
• Two-Way Navigation: The EditScreen includes a button to return to MainScreen, demonstrating how to implement navigation in both directions.

How to Adapt This to Your Existing Code #

1. Replace your existing layout classes with Screen subclasses to integrate with the ScreenManager.
2. Wrap all your screens in a ScreenManager block in your KV code, assigning each screen a unique name.
3. Add your target Button to the starting screen and bind its on_press event to either a Python method or direct KV screen switch, based on your needs.

内容的提问来源于stack exchange，提问作者ShaunBach