当我在 Kivy 的另一个屏幕中按下按钮时，如何更改屏幕中标签的文本

Question

我是 Kivy 的新手，所以我想在 Kivy 中开发两个屏幕，第一个是关于输入用户详细信息和密码（目前没有身份验证），然后第二个屏幕显示用户名（在上一个屏幕输入）并显示用户名以及其他小部件。 基本思想是获取用户表单用户登录屏幕的值并将其显示到另一个屏幕。 这是我的代码，

从 kivy.app 导入应用程序

from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.properties import StringProperty # @UnresolvedImport


class LoginScreen(Screen):
    text = StringProperty()
    def change_text(self): 
        self.text = ''
        self.manager.current = 'StocksGUIScreen'

class StocksGUIScreen(Screen):
    label_text = StringProperty('')
    #pass


class PortfolioUIApp(App):
    #user_name = StringProperty()
    pass

PortfolioUIApp().run()

这是我的 .kv 文件：

ScreenManager:
    id: screen_manager
    LoginScreen:
        id: login_screen
        name: 'LoginScreen'
        manager: screen_manager
    StocksGUIScreen:
        id: stocks_gui
        name: 'StocksGUIScreen'
        manager: screen_manager
        label_text: login_screen.text


<LoginScreen>:
    BoxLayout:
        orientation: 'vertical'
        BoxLayout:
            Label:
                text: "User Name"
                size_hint: 0.3,0.2
                #pos: root.x, root.top-self.height
                color: 0,1,0,1

            TextInput:
                id: user_name
                size_hint: 0.3,0.2
                #on_text: root.user_name

        BoxLayout:
            Label:
                text: "Password"
                size_hint: 0.3,0.2
            TextInput:
                id: pass_word
                password: True
                size_hint: 0.3,0.2
        BoxLayout:
            Button:
                text: 'Log In'
                size_hint: 0.3,0.2
                on_press: 
                    #root.manager.current = 'StocksGUIScreen'
                    root.label_text: user_name
                    root.change_text()
            Button:
                text: 'Cancel'
                size_hint: 0.3,0.2
                on_release: app.stop()

<StocksGUIScreen>:
    BoxLayout:
        orientation: 'vertical'
        BoxLayout:
            orientation: 'horizontal'
            TextInput:
                size_hint_x: 50
                id: ticker_search
            Button: 
                text: "Go"
                size_hint_x: 25
                on_press: root.search_stock()
                id: search_box
            Label:
                text: root.label_text
                size_hint_x: 25

        BoxLayout:
            height: "10dp"
            size_hint_y: 5
            Label:
                size_hint_x: .2
                size_hint_y: .1
                text: "Advice"
                color: [1,0,0,1]
                text_size: self.size
                halign: 'left'
                valign: 'top'
            ScrollView:
                size: self.size
                GridLayout:
                    id: layout_content
                    size_hint_y: None
                    cols: 1
                    row_default_height: '20dp'
                    row_force_default: True
                    spacing: 0, 0
                    padding: 0, 0
                    color: [1,0,0,1]
                    Label:
                        text: "Lorem ipsum dolor sit amet"*10
                        id: advice_message
                        text_size: self.size
                        halign: 'left'
                        valign: 'top'
        BoxLayout:
            height: "10dp"
            size_hint_y: 10 
            Label:
                size_hint_x: .2
                size_hint_y: .1
                text: "Graphical Stuff"
                id: graphical_stuff
                text_size: self.size
                halign: 'left'
                valign: 'top'
            AsyncImage:
                source: "abc.png"
                id: graphical_stuff
                allow_stretch: True
                keep_ratio: False
                pos: 200,300
                size: root.width*0.5,root.height*0.2
        BoxLayout:
            orientation: 'horizontal'
            Button:
                text: 'My settings button'
            Button:
                text: 'Back to Log in screen'
                on_press: root.manager.current = 'LoginScreen'                

此代码有什么问题，任何帮助/指导将不胜感激 plz

Answer 1

如果你想要这个设置，你可以在第一个屏幕上设置一个属性。在第二个屏幕中通过 id 访问它。

from kivy.app import App
from kivy.uix.screenmanager import Screen
from kivy.lang import Builder
from kivy.properties import StringProperty

class Screen1(Screen):
    username = StringProperty("")

class Screen2(Screen):
    username = StringProperty("")


root = Builder.load_string('''

<Screen1>:
    BoxLayout:
        orientation: "vertical"
        TextInput:
            id: username
        Button:
            text: "Login"
            on_release: root.username = username.text; root.manager.current = "screen2"


<Screen2>:
    name: "screen2"
    Label:
        text: root.username


ScreenManager:
    Screen1:
        id: loginscreen
    Screen2:
        username: loginscreen.username

''')



class MyApp(App):
    def build(self):
        return root