Question

我有一个双屏kivy应用程序，我想使用python将变量从一个屏幕传递到第二个屏幕。

python文件

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.properties import StringProperty,ObjectProperty
from kivy.uix.label import Label

class MenuScreen(Screen):
    label1=StringProperty()
    label2=StringProperty()
    def __init__(self,**kwargs):
        super(MenuScreen, self).__init__(**kwargs)  
        self.label1="hello"
        self.label2="world" 
    def change_text(self):          
        lbl1=self.label1+ " and "
        lbl2= "A beautiful "+self.label2
        chg=SettingsScreen()
        chg.UpdateSettings(lbl1,lbl2)

        # HERE: something like



class SettingsScreen(Screen):
    label3=StringProperty()
    label4=StringProperty()
    def __init__(self,**kwargs):
        super(SettingsScreen, self).__init__(**kwargs)  
        #some default texts
        self.label3="Nothing"
        self.label4="Nothing"
    def UpdateSettings(self,lbl1,lbl2):
        print(lbl1,lbl2)
        self.label3=lbl1
        self.label4=lbl2

class TestScreenManager(ScreenManager):
    menu_screen=ObjectProperty(None)
    settings_screen=ObjectProperty(None)

class TestApp(App):
    def build(self):            
        return  TestScreenManager()

TestApp().run()

kvfile

#: import ScreenManager kivy.uix.screenmanager.ScreenManager
#: import Screen kivy.uix.screenmanager.ScreenManager
#: import SettingsScreen screen


<TestScreenManager>:
    id: screen_manager
    menu_screen: menu_screen
    settings_screen: settings_screen

    MenuScreen:
        id: menu_screen
        name: 'menu'
        manager: screen_manager
    SettingsScreen:
        id: settings_screen
        name: 'settings_screen'
        manager: screen_manager


<MenuScreen>:
    name: 'MenuScreen'
    BoxLayout:
        Label:
            text:root.label1
        Label:
            text:root.label2
        Button:
            text: 'Goto nn'
            size_hint_y:0.2
            on_press: 
                root.manager.current = 'settings_screen'
                root.change_text()


<SettingsScreen>:
    #name: 'SettingsScreen'
    label_id: label_field
    BoxLayout:
        Label:
            text:root.label3
        Label:
            text:root.label4
        Label:
            id: label_field
            text: "some text"

它运行没有错误，但它没有改变第二个屏幕的变量。为了进行调试，我在print(lbl1,lbl2)函数中添加了UpdateSetting，它打印出传递的lbl1和lbl2变量但不更新标签。

Answer 1

执行chg=SettingsScreen()后，您正在创建SettingsScreen类的新实例，并修改该实例的标签。您需要访问ScreenManager使用的对象，而不是创建新对象。

您可以使用当前屏幕的manager属性来获取另一个屏幕的实例引用：

def change_text(self):          
    lbl1=self.label1 + " and "
    lbl2= "A beautiful "+ self.label2
    chg = self.manager.settings_screen   #<<<<<<<<<<<<<<
    chg.UpdateSettings(lbl1,lbl2)

在kivy中使用python将变量从一个屏幕更改为另一个屏幕

1 个答案: