我想要实现的是：当屏幕从 ScreenOne 切换到 ScreenTwo 时，运行“while 循环”功能，直到按下 ScreenTwo 上的按钮并中断循环。

此函数应该运行并接收来自连接到我的计算机的条形码扫描仪的输入（意思是，输入是条形码）并使用扫描的条形码数量更新 ScreenTwo 上的标签。

然后一旦我没有更多的条形码要扫描，按 ScreenTwo 上的“完成”按钮 - 这应该发送输入“999”以打破循环功能。

我如何在屏幕切换时尝试运行函数：使用“on_enter”

class ScreenTwo(Screen):
    def on_enter(self):
        getStatus()
        updatePoints()

我面临的问题：

1. 屏幕从 ScreenOne 切换到 ScreenTwo，该功能运行（我看到它发生在 Mac 终端上）但无法按下 ScreenTwo 上的按钮（Mac 色轮旋转）。
2. 而且我还没有弄清楚如何让“完成”按钮向函数发送输入“999”以打破循环。

我如何解决1？

我如何实现 2？

下面分别是 ScreenOne 和 ScreenTwo 的截图：

这是 returnStation2.py 文件

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


def getStatus():
    while True:
        answer = input('What is the box ID? ')
        if answer == 999: #LOOPS BREAK WHEN INPUT IS 999
            break
        elif type(answer) == int:
            do something
        else:
            print('Sorry I did not get that')

def updatePoints():
    do something

class ScreenManagement(ScreenManager):
    screen_one = ObjectProperty(None)
    screen_two = ObjectProperty(None)

class ScreenOne(Screen):
    member_status = ObjectProperty(None)

    def backspace(self, textString):
        newTextString = textString[0:-1]
        self.display.text = newTextString

    def getPoints(self, phoneNumber):
        self.manager.screen_two.member_status.text = phoneNumber

class ScreenTwo(Screen):
    input_text = ObjectProperty(None)

    def on_enter(self):
        getStatus()
        updatePoints()

    def clearField(self):
        self.manager.screen_one.input_text.text = ""

class ReturnStationLayout2App(App):

    def build(self):
        return ScreenManagement()


if __name__ == '__main__':
    ReturnStationLayout2App().run()

这是 returnStationLayout2.kv

“完成”按钮（在 ScreenTwo 中）位于脚本的底部。

屏幕切换到 ScreenTwo 时无法按下。我希望按下时，它可以输入'999'来中断正在运行的循环函数。

<ScreenManagement>:
    screen_one: screen_one
    screen_two: screen_two

    ScreenOne:
        id: screen_one
        name: 'menu'
    ScreenTwo:
        id: screen_two
        name: 'settings'

<CustButton@Button>:
    font_size: 32

<ScreenOne>:
    input_text : entry
    GridLayout:
        id: numberPad
        rows: 5
        padding: [300,200]
        spacing: 10

        # Where input is displayed
        BoxLayout:
            Label:
                text: "+65"
                font_size: 50
                size_hint: 0.2, 1
            TextInput:
                id: entry
                font_size: 50
                multiline: False
                padding: [20, ( self.height - self.line_height ) / 2]


        BoxLayout:
            spacing: 10
            CustButton:
                text: "1"
                on_press: entry.text += self.text
            CustButton:
                text: "2"
                on_press: entry.text += self.text
            CustButton:
                text: "3"
                on_press: entry.text += self.text
            CustButton:
                text: "DEL"
                on_press: root.backspace(entry.text)

        BoxLayout:
            spacing: 10
            CustButton:
                text: "4"
                on_press: entry.text += self.text
            CustButton:
                text: "5"
                on_press: entry.text += self.text
            CustButton:
                text: "6"
                on_press: entry.text += self.text
            CustButton:
                text: "AC"
                on_press: entry.text = ""

        BoxLayout:
            spacing: 10
            CustButton:
                text: "7"
                on_press: entry.text += self.text
            CustButton:
                text: "8"
                on_press: entry.text += self.text
            CustButton:
                text: "9"
                on_press: entry.text += self.text
            CustButton:
                text: "Enter" #HERE IS THE ENTER BUTTON
                on_press:
                    root.manager.transition.direction = 'left'
                    root.manager.transition.duration = 1
                    root.manager.current = 'settings'
                    root.getPoints(entry.text)

        BoxLayout:
            spacing: 10
            Label:
                text: ""
            CustButton:
                text: "0"
                on_press: entry.text += self.text
            Label:
                text: ""
            Label:
                text: ""

<ScreenTwo>:
    member_status: memberStatus
    BoxLayout:
        Label:
            id: memberStatus
            text: ''  
        GridLayout:
            rows: 3
            padding: [100,500]
            spacing: 10
            BoxLayout:
                Label:
                    text: "You have scanned:"
            BoxLayout:
                CustButton:
                    text: "Done" #THIS IS THE BUTTON I HOPE TO BE ABLE TO BREAK THE LOOP FUNCTION
                    on_press:
                        root.manager.transition.direction = "right"
                        root.manager.current = 'menu'
                        root.clearField()