面临在 kivy 中切换屏幕的问题

Question

我不太熟悉 screenmanager 类的用法，因此尽管我将当前屏幕设置为“Title 4”，但我无法切换到名为“Title 4”的屏幕。由于某些奇怪的原因（“Title 2”），当前屏幕保持不变。我正在尝试使用 AnotherScreen(Screen) 类中的方法 ok_button_hit() 切换屏幕。有人能指出我在这里犯的错误吗？

ABC.py 文件：

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import ObjectProperty
from kivy.uix.popup import Popup
from kivy.uix.textinput import TextInput
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
from kivy.uix.listview import ListItemButton

check_id=0
menu=''
class FoodListButton(ListItemButton):
    pass


class ScreenManagement(ScreenManager):
    pass


class LoginScreen(Screen):
    username_input = ObjectProperty()
    passwd_input = ObjectProperty()

    def __init__(self, **kwargs):
        super(LoginScreen, self).__init__(**kwargs)

        self.boxp = BoxLayout(orientation='vertical')
        self.labs = Label(text='')
        self.boxp.add_widget(self.labs)

        self.box = BoxLayout()
        self.box.orientation = 'horizontal'
        btn5 = Button(text="ok", size_hint=(0.5, 0.5))
        btn5.bind(on_release=self.success)
        self.box.add_widget(btn5)
        self.box.add_widget(Button(text='cancel', size_hint=(0.5, 0.5), on_release=self.cancel_button_hit))
        self.boxp.add_widget(self.box)
        self.popup1 = Popup(title="LOGIN SUCCESSFUL",
                            content=self.boxp,
                            size=(200, 200),
                            size_hint=(0.3, 0.3),
                            auto_dismiss=True)

    def checkin(self):
        if self.username_input.text == "root" and self.passwd_input.text == "root":
            self.labs.text = self.username_input.text
            self.popup1.open()
        else:
            self.popup1.title = 'Failed Login'
            self.labs.text = 'Failed'
            self.popup1.open()

    def cancel_button_hit(self, instance):
        self.popup1.dismiss()

    def success(self, instance):
        self.popup1.dismiss()
        self.manager.current = 'Title 2'


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

        self.boxp = BoxLayout(orientation='vertical')
        self.labs = TextInput(multiline=False)
        self.boxp.add_widget(self.labs)

        self.box = BoxLayout()
        self.box.orientation = 'horizontal'
        btn5 = Button(text="OK", size_hint=(0.5, 0.5), on_release=self.ok_button_hit)

        self.box.add_widget(btn5)
        self.box.add_widget(Button(text='cancel', size_hint=(0.5, 0.5), on_release=self.cancel_button_hit))
        self.boxp.add_widget(self.box)
        self.popup1 = Popup(title="Enter Customer ID",
                            content=self.boxp,
                            size=(400, 400),
                            size_hint=(0.3, 0.3),
                            auto_dismiss=False)
        self.popup2 = Popup(title="Failed",
                            content=Label(text='''You don't seem to have a customer id. 
                                          Please check in first'''),
                            size=(400, 400),
                            size_hint=(0.3, 0.3),
                            auto_dismiss=True)

    def check_cust_id(self):
        self.custid = self.labs.text
        #check with database
        if True:
            return True
        else:
            return False

    def cancel_button_hit(self, instance):
        self.popup1.dismiss()

    def ok_button_hit(self, instance):
        if self.check_cust_id():
            self.popup1.dismiss()
            global menu
            k='Title'+menu
            print(k)
            self.manager.current = k
        else:
            self.popup1.dismiss()
            self.popup2.open()
            self.popup1.dismiss()


    def res_clicked(self):

        global menu
        menu = ' 4'
        self.popup1.open()

    def lan_clicked(self):
        self.popup1.open()
        global menu
        menu = ' 5'

    def game_clicked(self):
        self.popup1.open()
        global menu
        menu += ' 6'

    def checkout_clicked(self):
        self.popup1.open()
        global menu
        menu += ' 7'
    def check_in(self):
        self.manager.current = 'Title 3'


class Res_Page(Screen):
    total_food_bill = 0
    food_input = ObjectProperty()
    food_list = ObjectProperty()

    def __init__(self, **kwargs):
        super(Res_Page, self).__init__(**kwargs)
        self.boxp = BoxLayout(orientation='vertical')
        self.labs = Label(text=" ")
        self.boxp.add_widget(self.labs)

        self.box = BoxLayout()
        self.box.orientation = 'horizontal'
        btn5 = Button(text="OK", size_hint=(0.5, 0.5), on_release=self.ok_button_hit)

        self.box.add_widget(btn5)
        self.popup1 = Popup(title="Food Bill",
                            content=self.boxp,
                            size=(200, 200),
                            size_hint=(0.3, 0.3),
                            auto_dismiss=False)
        self.popup2 = Popup(title="Error",
                            content=Label(text='''Sorry we don't make that'''),
                            size=(200, 200),
                            size_hint=(0.3, 0.3),
                            auto_dismiss=True)

    def ok_button_hit(self, instance):
        self.popup1.dismiss()
        self.manager.current = 'Title 2'

    def submit_food(self):
        food_name = self.food_input.text
        # Check if food is present
        if (True):
            self.food_list.adapter.data.extend([food_name])
            self.food_list._trigger_reset_populate()
            # Retreive price and subtract from total amount
        else:
            self.popup2.open()

    def delete_food(self, *args):

        if self.food_list.adapter.selection:
            selection = self.food_list.adapter.selection[0].text
            # Check if food is present
            if (True):
                self.food_list.adapter.data.remove(selection)
                self.student_list._trigger_reset_populate()
                # Retreive price and subtract from total amount
            else:
                self.popup2.open()

    def bill_food(self):
        self.labs.text = str(self.total_food_bill)
        self.popup1.open()


class checkinscrn(Screen):
    def checkin_nextscr(self):
        self.manager.current = 'Title 4'


class checkinadv(Screen):
   pass




class MainApp(App):
    def build(self):
        self.root = Builder.load_file('ABC.kv')
        my_screenmanager = ScreenManager()
        screen1 = LoginScreen(name='Title 1')
        screen2 = AnotherScreen(name='Title 2')
        screen3 = checkinscrn(name='Title 3')
        screen4 = AnotherScreen(name='Title 4')
        screen14 = checkinadv(name='Title 14')

        my_screenmanager.add_widget(screen1)
        my_screenmanager.add_widget(screen2)
        my_screenmanager.add_widget(screen3)
        my_screenmanager.add_widget(screen4)
        #my_screenmanager.add_widget(screen14)
        return my_screenmanager


MainApp().run()

ABC.kv 文件：

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#: import FadeTransition kivy.uix.screenmanager.FadeTransition
<ScreenManagement>:
    transition: FadeTransition()
    LoginScreen:
    AnotherScreen:
    Res_Page:
    checkinscrn:
    checkinadv:


<LoginScreen>:
    name: 'Title 1'
    orientation: "vertical"
    username_input: username
    passwd_input: passwd

    padding: 10
    spacing: 10
    BoxLayout:
        padding:[10,50]
        spacing: 40
        orientation: "vertical"
        Label:
            text: "Username"
            size_hint_x: 0.4
            size_hint_y: 0
            size: [200, 50]
            font_size: 20
            pos_hint: {'left_x': 1, 'center_y': 0.5}


        TextInput:
            id: username
            size_hint_x: 0.4
            size_hint_y: 0
            size: [400, 75]
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}


        Label:
            text: "Password"
            size_hint_x: 0.4
            size_hint_y: 0
            size: [200, 50]
            font_size: 20
            pos_hint: {'left_x': 0, 'center_y': 0.5}

        TextInput:
            id: passwd
            password: True
            size_hint_x: 0.4
            size_hint_y: 0
            size: [400, 75]
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        Button:
            on_release: root.checkin()
            text: 'Login'
            font_size: 50
            size_hint_x: 0.4
            size_hint_y: 0
            size: [400, 75]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}


<AnotherScreen>:
    name: 'Title 2'
    orientation: "vertical"
    padding: 10
    spacing: 10

    BoxLayout:
        padding:[10,50]
        spacing: 40
        orientation: "vertical"
        Button:
            on_release: root.check_in()
            text: 'Check In'
            font_size: 50
            size_hint_x: 0.4
            size_hint_y: 0
            size: [400, 45]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}


        Button:
            on_release: root.res_clicked()
            text: 'Restaurant'
            font_size: 50
            size_hint_x: 0.4
            size_hint_y: 0
            size: [400, 45]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}


        Button:
            on_release: root.lan_clicked()
            text: 'Laundry'
            font_size: 50
            size_hint_x: 0.4
            size_hint_y: 0
            size: [400, 45]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        Button:
            on_release: root.game_clicked()
            text: 'Gaming'
            font_size: 50
            size_hint_x: 0.4
            size_hint_y: 0
            size: [400, 45]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        Button:
            on_release: root.checkout_clicked()
            text: 'Check Out'
            font_size: 50
            size_hint_x: 0.4
            size_hint_y: 0
            size: [400, 45]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}


        Button:
            on_release: app.root.current = 'Title 1'
            text: 'Log Out'
            font_size: 50
            size_hint_x: 0.4
            size_hint_y: 0
            size: [400, 45]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}


<Res_Page>:
    name: 'Title 4'
    orientation: "vertical"
    food_input: food_name
    food_list: food_list_view
    padding: 10
    spacing: 10

    BoxLayout:
        size_hint_y: None
        height: "40dp"

        Label:
            text: "Dish"
        TextInput:
            id: food_name


    BoxLayout:
        size_hint_y: None
        height: "40dp"
        Button:
            text: "Submit"
            size_hint_x: 15
            on_press: root.submit_food()
        Button:
            text: "Delete"
            size_hint_x: 15
            on_press: root.delete_food()
        Button:
            text: "Generate Bill"
            size_hint_x: 15
            on_press: root.bill_food()

    ListView:
        id: students_list_view
        adapter:
            ListAdapter(data=[], cls=main.FoodListButton)






<checkinscrn>:
    name: 'Title 3'
    orientation: "vertical"
    padding: 10
    spacing: 10
    name_input: name
    address_input: addr
    checkin_input: cin
    checkout_input: cout
    BoxLayout:
        padding:[10,50]
        spacing: 40
        orientation: "vertical"
        Label:
            text: 'ENTER NAME'
            size_hint_x: 0.4
            size_hint_y: 0
            size: [50, 25]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        TextInput:
            id: name
            size_hint_x: 0.5
            size_hint_y: 0
            size: [50, 25]
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        Label:
            text: 'ENTER ADDRESS'
            size_hint_x: 0.5
            size_hint_y: 0
            size: [50, 25]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        TextInput:
            id: addr
            size_hint_x: 0.5
            size_hint_y: 0
            size: [50, 25]
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}
        Label:
            text: 'ENTER CHECK IN DATE'
            size_hint_x: 0.5
            size_hint_y: 0
            size: [50, 25]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        TextInput:
            id: cin
            size_hint_x: 0.5
            size_hint_y: 0
            size: [50, 25]
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        Label:
            text: 'ENTER CHECK OUT DATE'
            size_hint_x: 0.5
            size_hint_y: 0
            size: [50, 25]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        TextInput:
            id: cout
            size_hint_x: 0.5
            size_hint_y: 0
            size: [50, 25]
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

        Button:
            on_release: root.checkin_nextscr()
            text: 'CHECK IN'
            font_size: 50
            size_hint_x: 0.4
            size_hint_y: 0
            size: [50, 25]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

<checkinadv>:
    name: 'Title 14'
    orientation: "vertical"
    padding: 10
    spacing: 10
    BoxLayout:
        padding:[10,50]
        spacing: 40
        orientation: "vertical"
        Label:
            text: 'your check in id is'
            size_hint_x: 0.4
            size_hint_y: 0
            size: [50, 25]
            font_size: 20
            pos_hint: {'center_x': 0.5, 'center_y': 0.5}

Answer 1

在您的MainApp.build() 方法中，您创建了一个名为Title 4 的屏幕，但您正在创建另一个AnotherScreen，而不是Res_Page。所以切换到Title 4 就是切换到另一个AnotherScreen