python - Kivy 更改标签文本

Question

这个问题已经有答案了:

What is the purpose of the `self` parameter? Why is it needed? (26 个回答)

已关闭 3 年前。

我想在检测到滑动事件后更改 Python/Kivy 中的标签文本。更改文本基本上通过以下行进行

    self.Translation.text = "test"

但在检测到来自另一个类的滑动事件后，我必须更改文本，在该类中我调用一个函数来更改标签文本:

    MyWidget.ThisDoesntWork("self_dummy")

在此函数中，与上面完全相同的行给了我一个错误。

如何更改类“Swiping_class”调用函数“MyWidget.ThisDoesntWork(“self_dummy”)”中的标签文本？

    from kivy.app import App
    from kivy.uix.boxlayout import BoxLayout
    from kivy.uix.anchorlayout import AnchorLayout
    from kivy.uix.button import Button
    from kivy.uix.label import Label
    from kivy.uix.textinput import TextInput
    from kivy.base import EventLoop
    from kivy.clock import Clock
    from kivy.factory import Factory
    from kivy.uix.stacklayout import StackLayout
    from kivy.uix.image import Image
    from kivy.uix.floatlayout import FloatLayout
    from kivy.graphics import *
    from kivy.properties import ListProperty
    from kivy.lang import Builder
    from kivy.core.window import Window
    from kivy.uix.screenmanager import ScreenManager, Screen
    from random import random
    import pickle
    import random


    kv = '''
    <ColoredLabel>:
        size: (self.size_x,self.size_y)
        pos: (0,0) # no effect
        background_color:
        canvas.before:
            Color:
                rgba: self.background_color
            Rectangle:
                pos: self.pos
                size: (self.size_x,self.size_y)
        '''

    Builder.load_string(kv)

    class ColoredLabel(Label):
        background_color = ListProperty((0,0,0,1))
        s_global = Window.size
        size_x = s_global[0]
        size_y = s_global[1]/3

    class MyWidget(BoxLayout):
        #init
        def __init__(self, **kwargs):
            super().__init__(**kwargs)
            s_global = Window.size
            size_x = s_global[0]
            size_y = s_global[1]/3
            self.ForeignLanguage = ColoredLabel(text="str_fl", size_hint=(None, None),size = (size_x,size_y), background_color=(0/255,171/255,169/255, 1))
            self.Translation = ColoredLabel(text="str_tr", size_hint=(None, None),size = (size_x,size_y), background_color=(45/255,137/255,239/255, 1))
            self.Example = ColoredLabel(text="str_ex", size_hint=(None, None),size = (size_x,size_y), background_color=(43/255,87/255,151/255, 1))

            self.verticalBox     = BoxLayout(orientation='vertical')
            self.verticalBox.add_widget(self.ForeignLanguage)
            self.verticalBox.add_widget(self.Translation)
            self.verticalBox.add_widget(self.Example)

            self.Translation.text = "test"

            s=Swiping_class()
            s.add_widget(self.verticalBox)
            self.add_widget(s)

        def ThisDoesntWork(self):
            print("this is printed")
            self.Translation.text = "I wanna change this via fucntion"
            print("this is not printed anymore")

    class Swiping_class(Screen):
        def __init__(self, **kwargs):
            super().__init__(**kwargs)
            self.initial = 0
        def on_touch_down(self, touch):
            self.initial = touch.x

        def on_touch_up(self, touch):
            if touch.x < self.initial:
                print("swiped left")
                MyWidget.ThisDoesntWork("self_dummy")
            else:
                print("swiped right")

    class BoxLayoutDemo(App):
        def build(self):
            return MyWidget()

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

Answer 1

我想我找到了解决方案。在您的 Swiping_class 中，替换此行:

MyWidget.ThisDoesntWork("self_dummy")

用这一行:

MyWidget.ThisDoesntWork(self.parent)

这样，您就不必将字符串传递给您的方法，而是传递标签对象，其中包含您尝试修改的文本属性。