Kivy从弹出窗口获取值并在屏幕上使用

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.popup import Popup
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Label

class MyPopup(Popup):
    def __init__(self, callback, **kwargs):
        super(MyPopup, self).__init__(**kwargs)
        self.callback = callback

        layout = BoxLayout(orientation='vertical')
        self.text_input = TextInput()
        button = Button(text='OK', on_release=self.get_value)

        layout.add_widget(Label(text='Enter a value:'))
        layout.add_widget(self.text_input)
        layout.add_widget(button)

        self.content = layout

    def get_value(self, instance):
        value = self.text_input.text
        self.callback(value)
        self.dismiss()

class MyApp(App):
    def __init__(self, **kwargs):
        super(MyApp, self).__init__(**kwargs)
        self.value = ''

    def show_popup(self, instance):
        popup = MyPopup(callback=self.set_value)
        popup.open()

    def set_value(self, value):
        self.value = value

    def build(self):
        layout = BoxLayout(orientation='vertical')
        button = Button(text='Open Popup', on_release=self.show_popup)
        label = Label(text='Value: {}'.format(self.value))

        layout.add_widget(button)
        layout.add_widget(label)

        return layout

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