已禁用 python：屏幕管理器

Question

这段代码有什么问题？（它显示一个空屏幕）我想有 2 个屏幕，每个屏幕上有 1 个按钮可以简单地添加一个小部件（来自 python 代码），还有 1 个按钮可以切换到另一个屏幕。当我运行代码时，我可以看到一个没有按钮和标签的空白屏幕。如何解决所有这些问题？

PS：当我执行以下操作时它完美地工作：

class MyScreenManager(ScreenManager):
    pass

# ... and

class MyAppli(App):
    def build(self):
        Window.clearcolor=(1,1,1,1)
        return MyScreenManager()

debug.py:

from kivy.app import App
from kivy.core.window import Window
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.label import Label
from kivy.lang import Builder

class MyScreenManager(ScreenManager):
    def initialize(self):   # I know this is not necessary, 
        # but in my real code, i have to proceed like this.

        # ... (some instructions)
        pass

class Menu1(Screen):

    def add_label(self):
        self.add_widget(Label(text="Hello", color=(1,0,0,1)))


class Menu2(Screen):

    def add_label(self):
        self.add_widget(Label(text="Hello", color=(1,0,0,1)))


Builder.load_file("debug.kv")

class MyAppli(App):

    def build(self):
        Window.clearcolor = (1,1,1,1)
        return MyScreenManager().initialize()

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

debug.kv:

#:kivy 1.9.1

<MyScreenManager>:
    Menu1:
        id: menu1
    Menu2:
        id: menu2

<Menu1>:
    name: "screen1"

    BoxLayout:

        Label:
            text:"Screen 1"
            color:(1,0,0,1)


        Button:
            text:"Add a label"
            size:(200,50)
            size_hint:(None,None)
            background_color:(1,0,0,1)
            on_press:
                root.manager.ids.menu1.add_label()

        Button:
            text:"Go to screen 2"
            size:(200,50)
            size_hint:(None,None)
            background_color:(1,0,0,1)
            on_press:
                root.manager.current = "screen2"


<Menu2>:
    name: "screen2"

    BoxLayout:

        Label:
            text:"Screen 2"
            color:(1,0,0,1)    

        Button:
            text:"Add a label"
            size:(200,50)
            size_hint:(None,None)
            background_color:(1,0,0,1)
            on_press:
                root.manager.ids.menu2.add_label()

        Button:
            text:"Go to screen 1"
            size:(200,50)
            size_hint:(None,None)
            background_color:(1,0,0,1)
            on_press:
                root.manager.current = "screen1"

Answer 1

请在 MyScreenManager class 中执行以下操作。具体请参考示例

片段

class MyScreenManager(ScreenManager):
    def __init__(self, **kwargs):
        super(MyScreenManager, self).__init__(**kwargs)
        self.initialize()

    def initialize(self):   # I know this is not necessary,
        # but in my real code, i have to proceed like this.

        # ... (some instructions)
        print("MyScreenManager.initialize called")
...
class MyAppli(App):

    def build(self):
        Window.clearcolor = (1, 1, 1, 1)
        return MyScreenManager()

例子

debug.py

from kivy.app import App
from kivy.core.window import Window
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.label import Label
from kivy.lang import Builder


class MyScreenManager(ScreenManager):
    def __init__(self, **kwargs):
        super(MyScreenManager, self).__init__(**kwargs)
        self.initialize()

    def initialize(self):   # I know this is not necessary,
        # but in my real code, i have to proceed like this.

        # ... (some instructions)
        print("MyScreenManager.initialize called")


class Menu1(Screen):

    def add_label(self):
        self.add_widget(Label(text="Hello", color=(1,0,0,1)))


class Menu2(Screen):

    def add_label(self):
        self.add_widget(Label(text="Hello", color=(1,0,0,1)))


Builder.load_file("debug.kv")


class MyAppli(App):

    def build(self):
        Window.clearcolor = (1, 1, 1, 1)
        return MyScreenManager()


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

debug.kv

#:kivy 1.10.0

<MyScreenManager>:
    Menu1:
        id: menu1
    Menu2:
        id: menu2

<Menu1>:
    name: "screen1"

    BoxLayout:

        Label:
            text:"Screen 1"
            color:(1,0,0,1)


        Button:
            text:"Add a label"
            size:(200,50)
            size_hint:(None,None)
            background_color:(1,0,0,1)
            on_press:
                root.manager.ids.menu1.add_label()

        Button:
            text:"Go to screen 2"
            size:(200,50)
            size_hint:(None,None)
            background_color:(1,0,0,1)
            on_press:
                root.manager.current = "screen2"


<Menu2>:
    name: "screen2"

    BoxLayout:

        Label:
            text:"Screen 2"
            color:(1,0,0,1)

        Button:
            text:"Add a label"
            size:(200,50)
            size_hint:(None,None)
            background_color:(1,0,0,1)
            on_press:
                root.manager.ids.menu2.add_label()

        Button:
            text:"Go to screen 1"
            size:(200,50)
            size_hint:(None,None)
            background_color:(1,0,0,1)
            on_press:
                root.manager.current = "screen1"

输出

Output Apps Running

已禁用 python：屏幕管理器

KIVY python: ScreenManager

screen

kivy

片段

例子

debug.py

debug.kv

输出