python - Kivy - 如何在不同的屏幕上更改 StringProperty 值？

Question

我的应用程序从数据库中获取数据并将其存储到 Python 变量中。下面的代码是一个简化版本，其中有两个屏幕。第一个屏幕有两个按钮，第二个屏幕有一个标签和一个后退按钮。第二个屏幕上的标签文本将根据按下的按钮而改变。

运行时，标签设置为 StringProperty 的值，即“Test”。单击其中一个按钮时，将运行 ChangeScreen 函数并计算出正确的新标签。第二个运行的 LabelUpdater 函数应该更改字符串属性但没有。我该如何解决这个问题？谢谢<3

python :

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

class DemoScreen1(Screen):
    def ChangeScreen(self, button_text):
        if button_text == "Button 1":
            new_label = "This is the new label when button 1 is pressed"
            DemoScreen2.LabelUpdater(new_label)
        else:
            new_label2 = "This is the new label when button 2 is pressed"
            DemoScreen2.LabelUpdater(new_label2)
        self.parent.current = "demoscreen2"

class DemoScreen2(Screen):
    screen2_label = StringProperty("Test")
    def LabelUpdater(NEW_LABEL):
        screen2_label = StringProperty(NEW_LABEL)

class AppScreenManager(ScreenManager):
    pass
class Tester(App): 
    pass
if __name__ == '__main__':
    Tester().run() 

基维:

AppScreenManager:
    DemoScreen1:
    DemoScreen2:

<DemoScreen1>:
    name: "demoscreen1"
    orientation: "vertical"
    GridLayout:
        rows: 2
        Button:
            id: Button1
            text: "Button 1"
            on_release: root.ChangeScreen(Button1.text)
        Button:
            id: Button2
            text: "Button 2"
            on_release: root.ChangeScreen(Button2.text)

<DemoScreen2>:
    name: "demoscreen2"
    orientation: "vertical"
    GridLayout:
        rows:2
        Label:
            text: root.screen2_label
        Button:
            text:"Back"
            on_release: app.root.current = "demoscreen1"

Answer 1

使用 ids 并通过 AppScreenManager 也就是 ScreenManager 进行引用。

self.parent.ids.screen2.screen2_label = new_label

请参阅下面的完整示例。

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

class DemoScreen1(Screen):
    def ChangeScreen(self, button_text):
        if button_text == "Button 1":
            new_label = "This is the new label when button 1 is pressed"
            print('Palim')
            #DemoScreen2.LabelUpdater(new_label)
            self.parent.ids.screen2.screen2_label = new_label
        else:
            new_label2 = "This is the new label when button 2 is pressed"
            self.parent.ids.screen2.screen2_label = new_label2
            #DemoScreen2.LabelUpdater(new_label2)
        self.parent.current = "demoscreen2"

class DemoScreen2(Screen):
    screen2_label = StringProperty("Test")
    def LabelUpdater(NEW_LABEL):
        screen2_label = StringProperty(NEW_LABEL)

class AppScreenManager(ScreenManager):
    pass
class Tester(App): 
    pass
if __name__ == '__main__':
    Tester().run() 

千伏

AppScreenManager:
    DemoScreen1:
        id: screen1
    DemoScreen2:
        id: screen2

<DemoScreen1>:
    name: "demoscreen1"
    orientation: "vertical"
    GridLayout:
        rows: 2
        Button:
            id: Button1
            text: "Button 1"
            on_release: root.ChangeScreen(Button1.text)
        Button:
            id: Button2
            text: "Button 2"
            on_release: root.ChangeScreen(Button2.text)

<DemoScreen2>:
    name: "demoscreen2"
    orientation: "vertical"
    GridLayout:
        rows:2
        Label:
            text: root.screen2_label
        Button:
            text:"Back"
            on_release: app.root.current = "demoscreen1"