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），我能够在屏幕之间切换。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并且难以维护。

这一次我尝试在单独的 .kv 文件中定义屏幕，但我无法在屏幕之间切换工作。到目前为止，每次尝试都会导致错误（语法无效，未定义屏幕名称......）。

是否有一种方法（或多种方法）在不同的 .kv 文件中定义的屏幕之间切换？ 以下是我正在使用的文件：

ma​​in.py

from kivy.app import App


class MainApp(App):
    pass


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

ma​​in.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，例如分别为<Screen1@Screen>: 和<Screen2@Screen>:。
2. 在main.kv 中实例化屏幕Screen1: 和Screen2:

示例

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"

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