当屏幕在主 .kv 文件中管理时，如何从 .py 文件切换屏幕？

Question

我有三个代码，我对如何从 login.py 导航到 Organize.kv 中的下一个屏幕感到困惑，我有保存所有屏幕的主 kv 文件以及登录 python 和 kv 文件管理登录屏幕，登录 kv 文件平衡两个不同的选项卡，到目前为止，我有一个创建选项卡，它将您发送到连接到 mysql 的登录 python 文件的创建类，我将如何将屏幕切换到主菜单是在登录 python 文件的主 Organize.kv 文件中吗？对不起，如果这没有意义，我非常警告不要试图解决这个问题。

有什么帮助，谢谢

拥有所有屏幕的主 Organize.kv

#:import organize organize
#:import navigation_screen_manager navigation_screen_manager
#:import anchorlayout_with_action_bar anchorlayout_with_action_bar
#:import sharpen_skills sharpen_skills
#:import login login
<MainMenu@BoxLayout>:
    orientation: "vertical"
    padding: "40dp"
    spacing: "20dp"
    size_hint: .7, .9
    pos_hint: {"center_x": .5}
    Button:
        text: "Organize"
        on_press: app.manager.push("screen2")
    Button:
        text: "Journal"
        on_press: app.manager.push("screen3")
    Button:
        text: "Sharpen Skills"
        on_press: app.manager.push("SkillsExamplesTabs")
    Button:
        text: "Exit"
        on_press: app.stop()

<MyScreenManager>:
    Screen:
        name: "Login"
        title: "login"
        LoginTabs:
    Screen:
        name: "MainMenu"
        MainMenu:
    Screen:
        name: "screen2"
        AnchorLayoutWithActionBar:
            title: "Organize"


    Screen:
        name: "screen3"
        AnchorLayoutWithActionBar:
            title: "Journal"

    Screen:
        name: "SkillsExamplesTabs"
        AnchorLayoutWithActionBar:
            title: "Sharpen Skills"
            SkillsExamplesTabs:

我的 login.kv 文件

<LoginTabs@TabbedPanel>:
    do_default_tab: False
    TabbedPanelItem:
        text: "Create Account"
        Create:
    TabbedPanelItem:
        text: "Login"
        Login:

最后是我的 login.py 文件

from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager
from kivy.uix.stacklayout import StackLayout
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.widget import Widget
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.textinput import TextInput
from kivy.uix.label import Label
from kivy.graphics import Color, Rectangle
import mysql.connector
import navigation_screen_manager
from kivy.uix.screenmanager import ScreenManager, Screen

from navigation_screen_manager import NavigationScreenManager

Builder.load_file("login.kv")
Builder.load_file("Organize.kv")

sm = ScreenManager()

class MyScreenManager(NavigationScreenManager):
    pass

class Create(BoxLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.orientation = "vertical"
        self.build()

    def build(self):
        self.warning = Label(text="", pos_hint={'center_x': .5, 'center_y': .5})
        user_label = Label(text="Username", size_hint=(.5, .5),
                           pos_hint={'center_x': .5, 'center_y': .5})
        self.user_textinput = TextInput(text='Enter Username')
        pas_label = Label(text="Password", size_hint=(.5, .5),
                          pos_hint={'center_x': .5, 'center_y': .5})
        self.pas_textinput = TextInput(text="enter Password")
        enter_button = Button(text="Create")
        with user_label.canvas:
            Color(0, .25, 1, .25)
        enter_button.bind(on_press=self.Add)
        self.add_widget(self.warning)
        self.add_widget(user_label)
        self.add_widget(self.user_textinput)
        self.add_widget(pas_label)
        self.add_widget(self.pas_textinput)
        self.add_widget(enter_button)

    def Add(self, btn):
        print("Working")
        t1 = self.user_textinput.text
        t2 = self.pas_textinput.text
        print(f"T1 = {t1} and {t2}")
        conn = mysql.connector.connect(
            user='root',
            password='*******',
            host='127.0.0.1',
            database='Usersdb')
        mycursor = conn.cursor()
        try:
            sql = "INSERT INTO user_info (user_name, user_pass) VALUES (%s, %s)"
            val = (t1,t2)
            mycursor.execute(sql,val)
            conn.commit()
        except:
            self.warning = "Username Already Taken"

class Login(StackLayout):
    pass

最后是我的 App 类

from kivy.app import App
from kivy.uix.label import Label
from kivy.metrics import dp
from kivy.properties import StringProperty, BooleanProperty, ObjectProperty
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.uix.gridlayout import GridLayout
from kivy.uix.popup import Popup
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.stacklayout import StackLayout
from kivy.uix.widget import Widget

from navigation_screen_manager import NavigationScreenManager

class MyScreenManager(NavigationScreenManager):
    pass

class Organizer(App):

    manager = ObjectProperty(None)

    def build(self):
        self.manager = MyScreenManager()
        return self.manager

Organizer().run()

还有我的导航屏幕管理器

from kivy.uix.screenmanager import ScreenManager


class NavigationScreenManager(ScreenManager):
    screen_stack = []

    def push(self, screen_name):
        self.screen_stack.append(self.current)
        self.transition.direction = "left"
        self.current = screen_name

    def pop(self):
        if len(self.screen_stack) > 0:
            screen_name = self.screen_stack[-1]
            del self.screen_stack[-1]
            self.transition.direction = "right"
            self.current = screen_name

Answer 1

美好的一天。您必须访问屏幕管理器才能将当前屏幕设置为活动屏幕。在App 类中，我建议通过on_start 函数将屏幕管理器保存为属性。

class MyApp(App):
    def on_start(self):
        screen_manager = self.root

从那里，您可以使用 kivy 或 python 中的回调方法设置当前屏幕。

#in kv
on_release: setattr(app.screen_manager, 'current', 'the next screen name')

#in python
def set_screen_callback(self, instance *args):
    app.screen_manager.current = "the next screen name"

Answer 2

您的帖子不包含您的App 课程，因此不可能给出具体答案。一旦加载了这些kv 文件，您拥有多个kv 文件的事实就无关紧要了。通常，您只需将ScreenManager 的current 属性设置为您要显示的Screen 的name。

同样，一旦加载了这些kv 文件，您拥有多个kv 文件的事实就无关紧要了。所以在任何kv文件中，我相信你应该可以使用：

app.manager.push("MainMenu")

或：

app.manager.current = "MainMenu"

去MainMenuScreen。