在单独的.kv（Kivy）文件中定义的屏幕之间切换

Question

我曾经设法通过在单个.kv文件中定义所有内容（包括屏幕）来使多屏幕程序正常工作。

通过使用root.current （在.kv文件中）或self.root.current （在Python文件中），我可以在屏幕之间切换。 但是，一旦有多个带有许多小部件的屏幕，.kv文件就会变得非常大且难以维护。

这次，我试图在单独的.kv文件中定义屏幕，但是我无法在屏幕之间切换来工作。 到目前为止，每次尝试都导致错误（语法无效，屏幕名称未定义...）。

有没有一种方法可以在不同的.kv文件中定义的屏幕之间进行切换？ 这是我正在使用的文件：

main.py

from kivy.app import App


class MainApp(App):
    pass


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

main.kv：

#:include screen_1.kv
#:include screen_2.kv

#:import NoTransition kivy.uix.screenmanager.NoTransition

ScreenManager:
    transition: NoTransition()


    Screen:
        name: "main_screen"

        BoxLayout:
            orientation: "vertical"

            Label:
                text: "main screen"
            Button:
                text: "to screen 1"
                on_press: app.root.current = "screen_1"
            Button:
                text: "to screen 2"
                on_press: app.root.current = "screen_2"

screen_1.kv：

Screen:
    name: 'screen_1'

    BoxLayout:
        orientation: "vertical"

        Label:
            text: "Screen 1"
        Button:
            text: "to main screen"
            on_press: app.root.current = "main_screen"
        Button:
            text: "to screen 2"
            on_press: app.root.current = "screen_2"

screen_2.kv：

Screen:
    name: 'screen_2'

    BoxLayout:
        orientation: "vertical"

        Label:
            text: "Screen 2"
        Button:
            text: "to main screen"
            on_press: app.root.current = "main_screen"
        Button:
            text: "to screen 1"
            on_press: app.root.current = "screen_1"

Answer 1

解

1. 将动态类添加到screen_1.kv和screen_2.kv ，例如分别为<Screen1@Screen>:和<Screen2@Screen>: screen_2.kv
2. 实例化main.kv屏幕Screen1:和Screen2:

例

screen_1.kv

<Screen1@Screen>:
    name: 'screen_1'

    BoxLayout:
        orientation: "vertical"

        Label:
            text: "Screen 1"
        Button:
            text: "to main screen"
            on_press: app.root.current = "main_screen"
        Button:
            text: "to screen 2"
            on_press: app.root.current = "screen_2"

screen_2.kv

<Screen2@Screen>:
    name: 'screen_2'

    BoxLayout:
        orientation: "vertical"

        Label:
            text: "Screen 2"
        Button:
            text: "to main screen"
            on_press: app.root.current = "main_screen"
        Button:
            text: "to screen 1"
            on_press: app.root.current = "screen_1"

主.kv

#:include screen_1.kv
#:include screen_2.kv

#:import NoTransition kivy.uix.screenmanager.NoTransition


ScreenManager:
    transition: NoTransition()


    Screen:
        name: "main_screen"

        BoxLayout:
            orientation: "vertical"

            Label:
                text: "main screen"
            Button:
                text: "to screen 1"
                on_press: app.root.current = "screen_1"
            Button:
                text: "to screen 2"
                on_press: app.root.current = "screen_2"

    Screen1:

    Screen2:

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