如何在 kivy 中使用 Stringproperty() 更改标签的文本

Question

我只是试图通过更改定义文本的变量来更改标签的文本，但它不起作用。然而我使用了 Stringproperty((。如果可能的话，我希望一旦我们按下按钮，文本就会直接更改，通过变量 theText

请问如何解决这个问题？

这是我的代码作为示例：

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

class MenuScreen(Screen):
pass

class SettingsScreen(Screen):
def change_text(self):
self.root.theText = '1'
class MyScreenManager(ScreenManager):
# This is the text that both Labels may display
theText = StringProperty('0')

kv = """
MyScreenManager:
MenuScreen:
name: 'menu'
SettingsScreen:
name: 'settings'
<MenuScreen>:
label_wid : ratio
FloatLayout:         
Button:
text: "options"
pos: 270, 240
size_hint: .30, .10
background_color: 0,1,0,0.75
on_press: root.manager.current = 'settings'
Label:
id:ratio
# Use theText Property from MyScreenManager
text: root.manager.theText
pos: 0,90
font_size:30
color:1,0,0,1
<SettingsScreen>:
FloatLayout:
Label:
id:ratio
# Use theText Property from MyScreenManager
text: root.manager.theText
pos: 0,90
font_size:30
color:1,0,0,1
Button:
text: "options"
pos: 270, 240
size_hint: .30, .10
background_color: 0,1,0,0.75
on_press: root.change_text
"""

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()

Answer 1

两个问题。首先，在kv中将方法调用分配给Button时，必须包含()。是的，与python中的其他任何地方都相反。所以on_press应该是：

on_press: root.change_text()

其次，change_text()方法需要引用MyScreenManager实例，这在SettingsScreen中只是self.manager。所以change_text()应该是：

def change_text(self):
self.manager.theText = '1'