如何从 Kivy 中的 python 代码更改屏幕

Question

所以我正在为我的第一个正式的 kivy 应用程序制作一个功能齐全的登录屏幕，我希望能够在用户按下按钮时更改 windows/screens。我通常在 KV 文件中知道我只是在发布时使用，但我希望在发布时调用一种方法来验证用户凭据，如果这些凭据正确，则更改屏幕。那么在 python 中我如何能够调用屏幕管理器来更改屏幕？

from kivy.app import App
from kivy.lang.builder import Builder
from kivy.uix.screenmanager import Screen, ScreenManager




class LoginLayout(Screen):
    def login(self, **kwargs):
        print("Login function working")
        userEmail = self.ids.username.text
        userPassword = self.ids.password.text
        print(userEmail)
        print(userPassword)
        ScreenManager.current('emailWindow')


class EmailWindow(Screen):
    pass

class WindowManager(ScreenManager):
    pass

kv = Builder.load_file('loginScreen.kv')


class LoginScreen(App):

    def build(self):
        return kv


app = LoginScreen()
app.run()

KV

ScreenManager:
    LoginLayout:
    EmailWindow:

<LoginLayout>:
    name: 'loginWindow'

    canvas.before:
        Color:
            rgba: (28/255, 102/255, 137/255, 1)
        Rectangle:
            pos: self.pos
            size: self.size

    BoxLayout:
        orientation: 'vertical'
        size: root.width, root.height

        Label:
            text: 'Username'
            font_name: 'Framd.ttf'
            font_size: 20

        TextInput:
            id: username
            multiline: False
            size_hint: (.5, .3)
            pos_hint: {'center_x' : .5}


        Label:
            text: 'Password'
            font_name: 'Framd.ttf'
            font_size: 20

        TextInput:
            id: password
            multiline: False
            size_hint: (.5, .3)
            pos_hint: {'center_x' : .5}

        Button:
            text: 'Login'
            size_hint: (.2, .8)
            pos_hint: {'center_x' : 0.5}
            font_name: 'Framd.ttf'
            on_release: root.login()

        Button:
            text: 'Create Account'
            size_hint: (.2, .8)
            pos_hint: {'center_x' : 0.5}
            font_name: 'Framd.ttf'


        Button:
            text: 'Forgot login Info'
            size_hint: (.2, .8)
            pos_hint: {'center_x' : 0.5}
            font_name: 'Framd.ttf'

<EmailWindow>:
    name: 'emailWindow'

    canvas.before:
        Color:
            rgba:  (28/255, 102/255, 137/255, 1)
        Rectangle:
            pos: self.pos
            size: self.size

    BoxLayout:
        orientation: 'vertical'
        size: root.width, root.height

        Label:
            text: 'To:'
            font_name: 'Framd.ttf'

        TextInput:
            multiline: False
            pos_hint: {'center_x': 0.5}
            size_hint: (.5, .3)
            font_name: 'Framd.ttf'


        Label:
            text: 'Subject'

        TextInput:
            multiline: False
            pos_hint: {'center_x': 0.5}
            size_hint: (.5, .3)
            font_name: 'Framd.ttf'


        Label:
            text: 'Body'
            font_name: 'Framd.ttf'

        TextInput:
            size_hint: (.5, .7)
            pos_hint: {'center_x': 0.5}
            multiline: True


        Button:
            text: 'send'
            size_hint: (.2, .8)
            pos_hint: {'center_x' : 0.5}
            font_name: 'Framd.ttf'

Answer 1

当 Screen 添加到 ScreenManager 时，它会将 manager 属性设置为 ScreenManager。所以在你的 login() 方法中你可以这样做：

self.manager.current = 'emailWindow'

而不是：

ScreenManager.current('emailWindow')

请注意，如上所示，使用 ScreenManager 会引用 ScreenManager class，而不是应用程序中的 ScreenManager 实例。

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