（蟒蛇）Kivy：不需要的黑屏

Question

我实际上正在使用kivy lib编写应用程序，我的官方代码出现问题所以我用一个简单的kivy文件（debug.kv）创建了一个小的调试代码（debug.py）。当我启动应用程序时，它会给我一个黑屏。为什么？感谢。

debug.py：

import kivy
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout

class App(App):

    def build(self):
        return Screen1()

class Screen1(BoxLayout):
    def __init__(self, **kwargs):
        super(Screen1, self).__init__(**kwargs)
    def change_screen(self):
        return Screen2()


class Screen2(BoxLayout):
    def __init__(self, **kwargs):
        super(Screen2, self).__init__(**kwargs)
    def change_screen(self):
        return Screen1()

if __name__ == '__main__':
    App().run()

debug.kv：

#:kivy 1.9.1

<Screen1>
    Label:
        text:"Screen 1"
    Button:
        text:"Go to screen 2"
        size:(100,300)
        size_hint:(None,None)

        on_press:root.change_screen()

<Screen2>
    Label:
        text:"Screen 2"
    Button:
        text:"Go to screen 1"
        size:(100,300)
        size_hint:(None,None)

        on_press:root.change_screen()

____编辑____

如何从python代码更改屏幕？ 因为在我的官方代码中，我希望有一个功能，只有在密码正确的情况下才能检查密码并更改屏幕。

示例（虽然不起作用，但您可以理解我的想法）：

的.py

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen

class MyScreenManager(ScreenManager):
    pass

class Screen1(Screen):

    def goto2(self):
        root.manager.current = "screen2"
    pass

class Screen2(Screen):
    def say_hello(self):
        print 'hello2'
    pass

class DebugApp(App):
    def build(self):
        return MyScreenManager()

if __name__ == '__main__':
    DebugApp().run()

.kv

#:kivy 1.9.1

<MyScreenManager>:
    Screen1:
    Screen2:

<Screen1>:
    name: "screen1"
    BoxLayout:
        Label:
            text:"Screen 1"
        Button:
            text: "Go to screen 2"
            size: (300,300)
            size_hint:(None,None)
            color:(1,0,0,1)

            on_press: root.goto2()

<Screen2>:
    name: "screen2"
    BoxLayout:
        Label:
            text: "Screen 2"
        Button:
            text: "Go to screen 1"
            size: (300,300)
            size_hint: (None,None)
            color:(1,0,0,1)

            on_press: root.manager.current = "screen1"

Answer 1

你得到一个黑屏，因为Kivy无法提交Kivy规则文件。请更改您的班级＆＃34;应用程序（应用程序）：＆＃34; to＆＃34; DebugApp（App）：＆＃34;

实施例

main.py

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen


class MyScreenManager(ScreenManager):
    pass


class LoginScreen(Screen):

    def check_password(self, instance, password):
        if password == "pwd":
            instance.current = "screen2"


class Screen2(Screen):
    pass


class TestApp(App):
    title = "Login Screen"

    def build(self):
        return MyScreenManager()


if __name__ == '__main__':
    TestApp().run()

test.kv

#:kivy 1.10.0

<MyScreenManager>:
    LoginScreen:
        id: login
    Screen2:

<LoginScreen>:
    name: "screen1"
    GridLayout:
        size_hint: (0.5, 0.5)
        pos_hint: {"center_x": 0.5, "center_y": 0.6}
        rows: 3
        padding: 20

        Label:
            size_hint: (0.2, 0.2)
            text:"Password:"
            font_size: 30
            halign: "center"
            valign: "middle"

        TextInput:
            id: password
            size_hint: (0.2, 0.06)
            cursor_blink: True
            font_size: 20
            multiline: False
            password: True

        Button:
            text: "Continue"
            size_hint: (0.2, 0.08)

            on_release:
                root.manager.ids.login.check_password(root.manager, password.text)

<Screen2>:
    name: "screen2"
    BoxLayout:
        Label:
            text: "Hello"
        Button:
            text: "Go to screen 1"
            size: (100,300)
            size_hint: (None,None)

            on_press: root.manager.current = "screen1"

输出