Python 如何随机选择kivy按钮位置

我在kivy上有两个屏幕，当我在第二个屏幕上时，有两个按钮。我希望这些按钮在两个预定义位置之间有一个随机位置。例如，如果按钮“1”位于位置“2”，则按钮2的位置为“1”

我尝试了很多方法，但没有一种有效，而Listproperty方法在我看来是最好的。 尝试此方法时，出现以下错误：

BuilderException: Parser: File "<inline>", line 38:
...
     36:            id :1
     37:            text:' 1'
>>   38:            pos: root.manager.pos1
     39:            size_hint: .30, .10
     40:            background_color: 0,1,0,0.75
...
ValueError: Button.pos value length is immutable
  File "C:\src2\lib\site-packages\kivy\lang\builder.py", line 696, in _apply_rule
    setattr(widget_set, key, value)
  File "kivy\weakproxy.pyx", line 35, in kivy.weakproxy.WeakProxy.__setattr__
  File "kivy\properties.pyx", line 497, in kivy.properties.Property.__set__
  File "kivy\properties.pyx", line 1356, in kivy.properties.ReferenceListProperty.set
  File "kivy\properties.pyx", line 1345, in kivy.properties.ReferenceListProperty.check

感谢愿意花时间帮助我的人

对不起，我英语不好

这是我的代码：

import kivy
from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.label import Label
from kivy.core.window import Window
from kivy.clock import Clock
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
import random
from kivy.properties import ObjectProperty
from kivy.properties import ListProperty, StringProperty
kivy.uix.screenmanager.FadeTransition
from kivy.properties import StringProperty, BooleanProperty, NumericProperty
import csv
from collections import defaultdict

kv = """


MyScreenManager:
    MenuScreen:
        name: 'menu'
    Question1:
        name: "question1"

    


<MenuScreen>:
            
    FloatLayout:
        Button: 
            text:"Commencer"
            pos: 270, 300
            size_hint : .30, .10
            background_color: 0,1,0,0.75
            on_press: 
                root.manager.current: 'question1'
                root.update_pos()
    

<Question1>:
    
    FloatLayout:
        Button:
            id:2
            text: '2'
            pos: root.manager.pos2
            size_hint: .30, .10
            background_color: 0,1,0,0.75
        Button:
            id :1
            text:' 1'
            pos: root.manager.pos1
            size_hint: .30, .10
            background_color: 0,1,0,0.75

            

            
"""

ab= 180 #hauteur des boutons
ac= 240 #hauteur des boutons
ae= 270 #abcisse des boutons

class MyScreenManager(ScreenManager):
    pos1= ListProperty()
    pos2= ListProperty()

    


class MenuScreen(Screen): 
    
    def update_pos(self):
        d= [(ae,ab),(ae,ac)]
        random.shuffle(d)
        self.pos1= d[0]
        self.pos2= d[1]
        
    pass


class Question1(Screen):  
    pass 



class Quizz(App):
    def build(self):
        self.title = 'Quizz'
        Window.clearcolor = (0, 1, 1, 0.25)
        
        return Builder.load_string(kv)


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

---

错误消息是由于您使用了ListProperty。ListProperty的默认值为[]，在pos:root.manager.pos2中使用时，它试图将pos的长度更改为零。因此，您的代码只需进行一些小的更改即可工作。更改类定义：

class MyScreenManager(ScreenManager):
    pos1 = ListProperty([0,0])
    pos2 = ListProperty([0,0])


class MenuScreen(Screen):

    def update_pos(self):
        d = [(ae, ab), (ae, ac)]
        random.shuffle(d)
        self.manager.pos1 = d[0]
        self.manager.pos2 = d[1]

这将ListProperty的默认值更改为[0,0]，只是为了获得正确的长度。update_pos方法现在更改了ScreenManager中的pos1和pos2，ListProperties位于其中

然后在MenuScreen的kv中：

这里唯一的更改是使用=而不是：来分配当前屏幕名称

<MenuScreen>:

    FloatLayout:
        Button: 
            text:"Commencer"
            pos: 270, 300
            size_hint : .30, .10
            background_color: 0,1,0,0.75
            on_press: 
                root.manager.current = 'question1'
                root.update_pos()