如何从另一个 class/Screen 中的 TextInput 更改文本？

Question

我在这些文件中重现了我这里的情况。

我有两个屏幕，我正在使用 ScreenManager，我想要的是，当我单击“生成证据”按钮时，我没有在控制台上打印，而是将我作为参数传递的内容打印在其他屏幕（'Running'，其中只有一个 TextInput）。但这并没有改变另一个屏幕上的文本，我想知道这是否可能以及为什么它不能这样工作。提前致谢。

mainApp.py

from kivy.uix.screenmanager import ScreenManager, Screen
from kivymd.app import MDApp


class Manager(ScreenManager):
    def __init__(self):
        super(ScreenManager, self).__init__()


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

    # This is called when you click the button
    # Then the screen is changed
    # Then call this other function that is down there
    def change_text(self):
        self.manager.current = 'Running'
        print_whatever_is_happening()


# Second screen
class ScreenRunning(Screen):
    def __init__(self, **kwargs):
        super(ScreenRunning, self).__init__(**kwargs)

    def write_message_on_text_input(self, message):
        self.ids.data_log.text += message


class Example(MDApp):
    def build(self):
        sm = ScreenManager()
        self.running_screen = ScreenRunning(name='Running')
        self.main_screen = ScreenMain(name='ScreenMain')
        sm.add_widget(self.running_screen)
        sm.add_widget(self.main_screen)
        sm.current = 'ScreenMain'
        return sm


# This function is originally in a module, that's why it's outside the class
def print_whatever_is_happening():
    # Instead of this...
    print('Attaching 1')
    print('Attaching 2')
    print('Generating PDF file')
    print('Attaching file')

    # I would like to do this
    ScreenRunning().write_message_on_text_input('Attaching 1')
    ScreenRunning().write_message_on_text_input('Attaching 2')
    ScreenRunning().write_message_on_text_input('Generating PDF file')
    ScreenRunning().write_message_on_text_input('Attaching file')


Example().run()

example.kv

<Manager>:
    id: screen_manager

    screen_main: screen_main
    screen_running: screen_running

    ScreenMain:
        id: screen_main
        name: 'ScreenMain'
        manager: screen_manager

    ScreenRunning:
        id: screen_running
        name: 'Running'
        manager: screen_manager

<ScreenMain>:
    BoxLayout
        id: Screen_One
        orientation: 'vertical'
        padding: '15dp'
        canvas:
            Color:
                rgb: 0.878, 0.8, 0.984, 1
            Rectangle:
                size: self.size
                pos: self.pos
        MDRoundFlatIconButton:
            id: evidence_button
            text: 'Generate Evidence'
            font_size: '17dp'
            text_color: 1, 1, 1, 1
            md_bg_color: 0.4, 0, 0.922, 1
            on_press: root.manager.get_screen('ScreenMain').change_text()


<ScreenRunning>:
    BoxLayout:
        orientation: 'vertical'
        padding: '15dp'
        canvas:
            Color:
                rgb: 0.878, 0.8, 0.984, 1
            Rectangle:
                size: self.size
                pos: self.pos

        TextInput:
            id: data_log
            multiline: True
            text: ''

Answer 1

您可以使用 MDApp.get_running_app() 获取对 App 的引用，然后使用 root 获取 App 的 root（即ScreenManager。然后您可以使用 get_screen() 方法获取对 ScreenRunning 实例的引用。使用这种方法，您的 print_whatever_is_happening() 方法可以是：

def print_whatever_is_happening():
    # Instead of this...
    print('Attaching 1')
    print('Attaching 2')
    print('Generating PDF file')
    print('Attaching file')

    # I would like to do this
    screenRunning = MDApp.get_running_app().root.get_screen('Running')
    screenRunning.write_message_on_text_input('Attaching 1')
    screenRunning.write_message_on_text_input('Attaching 2')
    screenRunning.write_message_on_text_input('Generating PDF file')
    screenRunning.write_message_on_text_input('Attaching file')

如何从另一个 class/Screen 中的 TextInput 更改文本？

How to change text from TextInput that is in another class/Screen?

python

kivy

kivy-language

kivymd