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）来使多屏幕程序运行。

通过使用 root.current（在 .kv 文件中）或 self.root.current（在 Python 文件中），我能够在屏幕之间切换。但是，.kv 文件会变得非常大并且一旦有多个带有许多小部件的屏幕就很难维护。

这次我尝试在单独的 .kv 文件中定义屏幕，但无法在屏幕之间切换。到目前为止，每次尝试都会导致错误（语法无效，屏幕名称未定义...）。

是否有一种方法（或多种方法）可以在单独的 .kv 文件中定义的屏幕之间切换？ 以下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

解决方案

1. 将dynamic class添加到screen_1.kv和screen_2.kv中，例如<Screen1@Screen>: 和 <Screen2@Screen>: 分别。
2. 在main.kv
中实例化屏幕，Screen1:和Screen2:

例子

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"

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"

    Screen1:

    Screen2:

输出