python - 如何使用 kivy screenmanager 引用其他屏幕中的对象

Question

我正在尝试更新另一个屏幕中存在的字段，但没有成功。当有人能告诉我我在这里做错了什么时，我会非常非常高兴。

myscreenskv.py:

style = r'''
# File: myscreenskv.py
#: import myscreens myscreens

<ScreenManagement>:
    MainScreen:
    Screen1:
    Screen2:

<MainScreen>:
    name: 'main'
    mainlog:mainlog
    id: scrmain
    BoxLayout:
        orientation: "vertical"
        Label:
            text: "Main"
        Label:
            id: mainlog
        Button:
            text: "go to screen 1"
            on_press:
                app.root.current = "screen1"
                root.action1()
        Button:
            text: "go to screen 2"
            on_press:
                app.root.current = "screen2"
                root.action2()

<Screen1>:
    name: 'screen1'
    sc1log:sc1log
    id: scr1
    BoxLayout:
        orientation: "vertical"
        Label:
            text: "Screen1"
        Label:
            id: sc1log
        Button:
            text: "go to main screen"
            on_press: app.root.current = "main"
        Button:
            text: "go to screen 2"
            on_press: app.root.current = "screen2"

<Screen2>:
    name: 'screen2'
    id: scr2
    sc2log:sc2log
    BoxLayout:
        orientation: "vertical"
        Label:
            text: "Screen2"
        Label:
            id: sc2log
        Button:
            text: "go to main screen"
            on_press: app.root.current = "main"
        Button:
            text: "go to screen 1"
            on_press: app.root.current = "screen1"

'''

.py:

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

class MainScreen(Screen):
    def __init__(self, **kwargs):
        super(MainScreen, self).__init__(**kwargs)

    def action1(self):
        self.ids.scr1.sc1log.text = 'Coming from main'

    def action2(self):
        self.ids.scr2.sc2log.text = 'Coming from main'

class Screen1(Screen):
    def __init__(self, **kwargs):
        super(Screen1, self).__init__(**kwargs)

    def action1(self):
        self.ids.main.mainlog.text = 'Coming from screen1'

    def action2(self):
        self.ids.scr2.sc2log.text = 'Coming from screen1'


class Screen2(Screen):
    def __init__(self, **kwargs):
        super(Screen2, self).__init__(**kwargs)

    def action1(self):
        self.ids.main.mainlog.text = 'Coming from screen2'

    def action2(self):
        self.ids.scr1.sc1log.text = 'Coming from screen2'

class MyscreensApp(App):
    def build(self):
        Builder.load_string(style)
        sm = ScreenManager()
        sm.add_widget(MainScreen())
        sm.add_widget(Screen1())
        sm.add_widget(Screen2())
        sm.current = 'main'
        return sm


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

Answer 1

您正在尝试访问 ids 字典，这很好，但在完全不同的实例中，这就是此错误的原因:

AttributeError: 'super' object has no attribute '__getattr__'

您需要访问正确的实例，才能访问其属性，在您的情况下，您需要访问 ScreenManager，才能访问其 screens 属性(实例列表)，您可以从中对示例文本进行所需的编辑:

MainScreen.action1():

self.manager.screens[1].sc1log.text = 'Coming from main'
# no ids, because you put it into a variable before

要了解它的工作原理，让我们看看小部件树:

<MainScreen>:
    id: scrmain
    BoxLayout:
        Label:
        Label:
            id: mainlog
        Button:
        Button:

这里的 ids 是 MainScreen 中的字典，可从 MainScreen().ids(实例)访问，这是输出:

{'mainlog': <WeakProxy to <kivy.uix.label.Label object at 0x12345678>>}

这意味着你不能真正将根小部件分配给它自己的字典 - 至少不是这样+无论如何都没有意义，因为你可以只调用 root ，它会给你实例根小部件。