python - 如何在 Kivy 中浏览屏幕？

Question

我正在尝试创建一个具有两个屏幕的应用程序，一个是登录屏幕，下一个是主页。我无法为我的第二个屏幕合并 Kivy 代码。如何添加代码以便切换到第二个屏幕？

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.image import Image
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
from kivy.uix.label import Label


class SigninWindow(BoxLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

    def validate_user(self):
        user = self.ids.username_field
        pwd = self.ids.pwd_field
        info = self.ids.info

        uname = user.text
        passw = pwd.text

        if uname == '' or passw == '':
            info.text = '[color=#FF0000]username and/ or password required[/color]'
        else:
            if uname == 'admin' and passw == 'admin':
                info.text = '[color=#00FF00]Logged In successfully![/color]'
            else:
                info.text = '[color=#FF0000]Invalid Username and/or Password[/color]'




class SigninApp(App):
    def build(self):
        return SigninWindow()

if __name__=="__main__":
    sa = SigninApp()
    sa.run()

kv文件：

<FlatButton@ButtonBehavior+Label>:
    font_size: 16

<SigninWindow>:
    id: main_win
    orientation: "vertical"
    spacing: 10
    space_x: self.size[0]/3
    canvas.before:
        Color:
            rgba: (1,1,1, 1)
        Rectangle:
            size: self.size
            pos: self.pos
        BorderImage:
            source: 'E:\pythonpics/blu2.png'
            pos: self.pos
            size: self.size
    BoxLayout:
        size_hint_y: None
        height: 50
        canvas.before:
            Color:
                rgba: (.06, .45, .45, 1)
            Rectangle:
                size: self.size
                pos: self.pos
        Label:
            text: "Hello! Dear User Please Sign In"
            bold: True
            size_hint_x: .9

    BoxLayout:
        orientation: 'vertical'
        padding: main_win.space_x, 10
        #spacing: 20
        BoxLayout:
            orientation: "vertical"
            spacing: 10
            size_hint_y: None
            height: 100

            Label:
                id: info
                text: ''
                markup: True
                size_hint_y: None
                height: 20
            TextInput:
                id: username_field
                hint_text: "Username"
                multiline: False
                focus: True
                on_text_validate: pwd_field.focus = True
            TextInput:
                id: pwd_field
                hint_text: "Password"
                multiline: False
                password: True
                on_text_validate: root.validate_user()
        Label:
            id: sp
            size_hint_y: None
            height: 40
        Button:
            text: "Sign In"
            size_hint_y: None
            height: 40
            background_color: (.06,.45,.45, 1)
            background_normal: ''
            on_release: root.validate_user()

        Label:
            id: sp2

标签： pythonkivy-language

Answer 1

欢迎来到 Stackoverflow！

你需要一个ScreenManager和Screens。您可以通过 切换到特定屏幕ScreenManager.current = "Name of Other Screen"。

您可能想要更改您的小部件，因此您可以省略类似App.get_running_app().root.current.

Your app python code:

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.image import Image
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.lang import Builder
from kivy.uix.label import Label


Builder.load_string("""

<Rootwidget>:
    Screen:
        name: "SignIn"
        SigninWindow:
    Screen:
        name: "SignedIn"
        Label:
            text: "You have signed in."

<FlatButton@ButtonBehavior+Label>:
    font_size: 16

<SigninWindow>:
    id: main_win
    orientation: "vertical"
    spacing: 10
    space_x: self.size[0]/3
    canvas.before:
        Color:
            rgba: (1,1,1, 1)
        Rectangle:
            size: self.size
            pos: self.pos
        BorderImage:
            source: 'E:\pythonpics/blu2.png'
            pos: self.pos
            size: self.size
    BoxLayout:
        size_hint_y: None
        height: 50
        canvas.before:
            Color:
                rgba: (.06, .45, .45, 1)
            Rectangle:
                size: self.size
                pos: self.pos
        Label:
            text: "Hello! Dear User Please Sign In"
            bold: True
            size_hint_x: .9

    BoxLayout:
        orientation: 'vertical'
        padding: main_win.space_x, 10
        #spacing: 20
        BoxLayout:
            orientation: "vertical"
            spacing: 10
            size_hint_y: None
            height: 100

            Label:
                id: info
                text: ''
                markup: True
                size_hint_y: None
                height: 20
            TextInput:
                id: username_field
                hint_text: "Username"
                multiline: False
                focus: True
                on_text_validate: pwd_field.focus = True
            TextInput:
                id: pwd_field
                hint_text: "Password"
                multiline: False
                password: True
                on_text_validate: root.validate_user() 
        Label:
            id: sp
            size_hint_y: None
            height: 40
        Button:
            text: "Sign In"
            size_hint_y: None
            height: 40
            background_color: (.06,.45,.45, 1)
            background_normal: ''
            on_release: root.validate_user() 

        Label:
            id: sp2
""")

class Rootwidget(ScreenManager):
    pass

class SigninWindow(BoxLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

    def validate_user(self):
        user = self.ids.username_field
        pwd = self.ids.pwd_field
        info = self.ids.info

        uname = user.text
        passw = pwd.text

        if uname == '' or passw == '':
            info.text = '[color=#FF0000]username and/ or password required[/color]'
        else:
            if uname == 'admin' and passw == 'admin':
                info.text = '[color=#00FF00]Logged In successfully![/color]'
                App.get_running_app().root.current = "SignedIn"
            else:
                info.text = '[color=#FF0000]Invalid Username and/or Password[/color]'





class SigninApp(App):
    def build(self):
        return Rootwidget()

if __name__=="__main__":
    sa = SigninApp()
    sa.run()