使用 Kivy 的时钟从 kivy 文件 (.kv) 访问不同类的 id/widget？

Question

我花了一天的时间处理来自How to access id/widget of different class from a kivy file (.kv)? 的代码，我已经将它与最简单的代码配对，因为我想做的是使用 Kivy 的时钟功能为我更改文本，而不是单击按钮。

尽我所能理解更改文本的代码应该在程序的第 38 行，但我尝试的所有代码都停止执行，因为它无法访问文本来更改它。时钟功能在提供的代码中工作。

我已将按钮按下处于活动状态，但我想更改文本的是时钟代码。我想知道是否有人知道解决方案。

提前致谢。

....布拉德....

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.clock import Clock
from kivy.properties import ObjectProperty

Builder.load_string("""
<SingleScreen>:
    id: single_screen
    orientation: 'vertical'
    Button:
        text: "You Can Change Me By Button Press Here But I Really Want To Be Changed By Kivy's Clock Function"
        on_release: root.rooted()
    Change_Label:
        id: gb
<Change_Label>:
    _python_access: ChangeLabel
    Label:
        id: ChangeLabel
        text: "I'm Gonna Change."
""")

class SingleScreen(BoxLayout):

    def rooted(self):
        self.ids.gb._python_access.text = "I Changed It By Clicking!. But That's Not What I Wanted To Program!"

class Change_Label(BoxLayout):
    _python_access = ObjectProperty(None)

class OnlyScreen(App):
    def build(self):
        Clock.schedule_interval(self.Callback_Clock, 3)
        return SingleScreen()

    def Callback_Clock(self, dt):
        print "Hello, world! I'm the clock working...."
        # What code goes here that will change the text via Kivy's clock instead of using the button?

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

Answer 1

请执行以下操作并参考我的示例了解详细信息：

片段

class OnlyScreenApp(App):

    def build(self):
        Clock.schedule_interval(self.Callback_Clock, 3)
        return SingleScreen()

    def Callback_Clock(self, dt):
        self.root.ids.gb._python_access.text = "I Changed It By Clock! dt=" + str(dt)

示例

main.py

​​>

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.clock import Clock
from kivy.properties import ObjectProperty


class SingleScreen(BoxLayout):
    pass


class Change_Label(BoxLayout):
    _python_access = ObjectProperty(None)


class TestApp(App):

    def build(self):
        Clock.schedule_interval(self.Callback_Clock, 3)
        return SingleScreen()

    def Callback_Clock(self, dt):
        self.root.ids.gb._python_access.text = "I Changed It By Clock! dt=" + str(dt)


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

test.kv

#:kivy 1.10.0

<SingleScreen>:
    id: single_screen
    orientation: 'vertical'
    Change_Label:
        id: gb

<Change_Label>:
    _python_access: ChangeLabel
    Label:
        id: ChangeLabel
        text: "I'm Gonna Change."

输出

Answer 2

根据上面 ikolim 的回答，我想将解决方案发布为一个完整的 python 程序，该程序与发布问题的格式相关。真的很感激这个解决方案。完整的工作（一个文件）代码如下；

import kivy
kivy.require('1.9.1')
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.clock import Clock
from kivy.properties import ObjectProperty

Builder.load_string("""
<SingleScreen>:
    id: single_screen
    orientation: 'vertical'
    Change_Label:
        id: gb

<Change_Label>:
    _python_access: ChangeLabel
    Label:
        id: ChangeLabel
        text: "I'm Gonna Change."
""")

class SingleScreen(BoxLayout):
    pass


class Change_Label(BoxLayout):
    _python_access = ObjectProperty(None)


class OneScreen(App):

    def build(self):
        Clock.schedule_interval(self.Callback_Clock, 3)
        return SingleScreen()

    def Callback_Clock(self, dt):
        self.root.ids.gb._python_access.text = "I Changed It By Clock! dt=" + str(dt)


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