Kivy-屏幕管理器-访问其他类中的属性

Question

使用Kivy屏幕管理器，我创建了两个屏幕。在屏幕1中时，我想在屏幕2中更改标签。我在代码中突出显示了有问题的区域：

我的 test.ky：

#: import ScreenManager kivy.uix.screenmanager.ScreenManager
#: import Screen kivy.uix.screenmanager.ScreenManager
#: import SettingsScreen screen


ScreenManager:
    MenuScreen:
    SettingsScreen:


<MenuScreen>:
    name: 'MenuScreen'
    BoxLayout:
        Button:
            text: 'Goto nn'
            on_press: 
                root.manager.current = 'SettingsScreen'
                root.change_text()


<SettingsScreen>:
    name: 'SettingsScreen'
    label_id: label_field
    BoxLayout:
        Label:
            id: label_field
            text: "to_be_changed"

和我的 screen.py

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen


class MenuScreen(Screen):
    def change_text(self):
        pass
        # HERE: something like
        # root.SettingsScreen.label_field.text = 'new text'


class SettingsScreen(Screen):
    pass


class TestApp(App):
    pass

TestApp().run()

任何帮助是极大的赞赏！谢谢，尼科

Answer 1

这个怎么样：

当您按下MenuScreen上的按钮时，它会在其自身上设置一个属性，该属性包含要放入SettingsScreen标签中的文本。然后，在kv文件中为MenuScreen分配了一个ID值，该ID值用于引用此属性。例：

main.py

class MenuScreen(Screen):
    text = StringProperty('')
    def change_text(self):
        self.text = "The text you want to set"
        self.manager.current = "SettingsScreen"

class SettingsScreen(Screen):
    label_text = StringProperty('')

KV文件

ScreenManager:
    id: screen_manager
    MenuScreen:
        id: menu_screen
        name: 'MenuScreen'
        manager: screen_manager
    SettingsScreen:
        name: 'SettingsScreen'
        manager: screen_manager
        label_text: menu_screen.text

<MenuScreen>:
    BoxLayout:
        Button:
            text: 'Goto nn'
            on_press:
                root.change_text()

<SettingsScreen>:
    BoxLayout:
        Label:
            text: root.label_text

如您所见，我在kv文件中的ScreenManager本身下设置了屏幕的名称和ID，因为这通常是我要做的工作。