Kivy在.py文件中选择屏幕并在.kv文件中使用

Question

我正在尝试制作一个屏幕列表，并在此python文件中随机选择其中一个（此处不包含其他代码，如构建器等）：

class selectionScreen
    testScreen = StringProperty('Screen1')

    def screenSelector(self)
        screenList = ['Screen1', 'Screen2']
        testNumber = random.randint(0, 1)
        testScreen = screenList[testNumber]
        return testscreen

然后我想在我的.kv文件中选择这个屏幕，看起来有点像这样，但也包括屏幕1和2

ScreenManager:
    SelectionScreen:
        name: 'SelectionScreen'
    Screen0:
        name: 'Screen0'
    Screen1:
        name: 'Screen1'

<SelectionScreen>:
     BoxLayout:
        Button:
            text: "Click when ready"
            size_hint: .6, .5
            font_size: 10
            on_press: root.screenSelector()
            on_release: root.manager.current = 'Screen0'
<Screen0>:
    BoxLayout:
        orientation: 'vertical'
        Button:
            text: "Next"
            on_release: root.manager.current = str(root.testScreen)

SelectionScreen工作正常，但现在我无法访问screen0。删除行

on_press: root.screenSelector()

但是，我可以这样做。

提前感谢您的帮助！

Answer 1

问题

1. 您无法访问 screen0 ，因为它不在 screenList 中。
2. 方法 screenSelector 中定义的变量 testScreen 是一个局部变量，它不是同一个类在 selectionScreen 类中定义的变量 testScreen 。
3. 由于拼写错误，未定义的变量，返回 testscreen 。
4. 在 Screen0 ，代码 on_release：root.manager.current = str（root.testScreen）将导致 AttributeError：＆＃ 39;位于Screen0＆＃39;对象没有属性＆＃39; testScreen＆＃39;

解决方案

要访问Screen0，您必须执行以下操作：

Python脚本

1. 将 Screen0 添加到变量 screenList
2. 将 random.randint（0,1） 替换为 random.randint（0,2） < / LI>
3. 将 testScreen 替换为方法 screenSelector self.testScreen >

   kv文件

   1. 定义一个ID，例如 id：selection_screen
   2. 参考，例如的 root.manager.ids.selection_screen.testScreen
   3. 在其他屏幕中添加on_press调用 screenSelector ，例如 on_press：root.manager.ids.selection_screen.screenSelector（）

   实施例

   main.py

   from kivy.app import App
   from kivy.uix.screenmanager import Screen, ScreenManager
   from kivy.properties import StringProperty
   import random
   
   
   class ScreenManager(ScreenManager):
       pass
   
   
   class SelectionScreen(Screen):
       testScreen = StringProperty('Screen1')
   
       def screenSelector(self):
           screenList = ['Screen0', 'Screen1', 'Screen2']
           testNumber = random.randint(0, 2)
           self.testScreen = screenList[testNumber]
           return self.testScreen
   
   
   class Screen0(Screen):
       pass
   
   
   class Screen1(Screen):
       pass
   
   
   class Screen2(Screen):
       pass
   
   
   class Test(App):
   
       def build(self):
           return ScreenManager()
   
   
   if __name__ == "__main__":
       Test().run()
   

   test.kv

   #:kivy 1.10.0
   
   <ScreenManager>:
       SelectionScreen:
           id: selection_screen
           name: 'SelectionScreen'
       Screen0:
           name: 'Screen0'
       Screen1:
           name: 'Screen1'
       Screen2:
           name: 'Screen2'
   
   <SelectionScreen>:
       BoxLayout:
           Button:
               text: "Click when ready"
               size_hint: .6, .5
               font_size: 10
               on_press: root.screenSelector()
               on_release:
                   root.manager.current = str(root.manager.ids.selection_screen.testScreen)
   
   <Screen0>:
       BoxLayout:
           orientation: 'vertical'
           Button:
               text: "Screen 0"
               on_press: root.manager.ids.selection_screen.screenSelector()
               on_release:
                   root.manager.current = str(root.manager.ids.selection_screen.testScreen)
   
   <Screen1>:
       BoxLayout:
           orientation: 'vertical'
           Button:
               text: "Screen 1"
               on_press: root.manager.ids.selection_screen.screenSelector()
               on_release:
                   root.manager.current = str(root.manager.ids.selection_screen.testScreen)
   
   <Screen2>:
       BoxLayout:
           orientation: 'vertical'
           Button:
               text: "Screen 2"
               on_press: root.manager.ids.selection_screen.screenSelector()
               on_release:
                   root.manager.current = str(root.manager.ids.selection_screen.testScreen)
   

   输出