Kivy标签没有出现

Question

所以我是基维的初学者。我编写了一个程序，它从列表中读取句子，并以按钮的形式显示在from布局中。are布局在Floatlayout中，因此我可以控制句子的位置。如果我点击其中一个句子，它就会为每个单词分成几个按钮。到目前一切尚好。现在我想创建一个标签，显示在Now布局下面的某个地方。只要单击word按钮，它就会显示出来，并显示与按钮相同的文本。所以让我把这句话当作按钮：

你好世界，这是一个例句。|

如果我点击这个句子：

单词应该分裂成独立的按钮。例如，当我点击‘句子’按钮时，标签应该出现在文本‘句子’下面的某个地方。

.py：

import kivy

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Widget, Label
from kivy.config import Config

sentences = ['This is example sentence 1.', 'This is example sentence 2.', 'This is example sentence 3.', 'This is example sentence 4.', 'This is example sentence 5.', 'This is example sentence 6.']

words = [ ['This', 'is' , 'example' ,  'sentence' , '1' ], ['This', 'is' , 'example' ,  'sentence' , '2' ], ['This', 'is' , 'example' ,  'sentence' , '3' ], ['This', 'is' , 'example' ,  'sentence' , '4' ], ['This', 'is' , 'example' ,  'sentence' , '5' ], ['This', 'is' , 'example' ,  'sentence' , '6' ] ]



class AdaptiveButton(Button):
    """This button takes as much space as it needs to contain its text."""

    def __init__(self, **kwargs):
        super(AdaptiveButton, self).__init__(**kwargs)
        self.size_hint = (None, None)
        self.bind(texture_size = self.setter("size"))


class Boxlayout(BoxLayout):
    """This will arrange all the necessary widgets."""



    def __init__(self, **kwargs):
        super(Boxlayout, self).__init__(**kwargs)
        self.orientation = "vertical"
        self.spacing = "10dp"

        for i, line in enumerate(sentences):
            abtn = AdaptiveButton(text = line, font_size=30) 
            abtn.bind(on_press = lambda btn, j = i : self.destroy_then_create(btn, j))
            self.add_widget(abtn)
    def destroy_then_create(self, btn, index):
        self.remove_widget(btn)

        box = BoxLayout(size_hint = (None, None), spacing = "10dp")

        box.bind(minimum_size = box.setter("size"))
        sentence = words[index]
        i = len(sentences)-index-1
        for word in sentence:
            abtn = AdaptiveButton(text = word)
            abtn.bind(on_press=lambda btn, j=i: show(word)) # Here is the function for #the label being binded
            box.add_widget(abtn)

        self.add_widget(box, i)

class Meaningclass(Label): # Label class
    pass


def show(k): #function for the Label

    MeC = Meaningclass()
    Meaning = Label(text=k, font_size=30)
    MeC.add_widget(Meaning)






class MyApp(App):

    def build(self):
        self.icon = 'budspencer.png'
        # creating Floatlayout
        Fl = FloatLayout()

        Box = Boxlayout(pos_hint={'x': .23, 'y': .58}) 
        
        meaning = Meaningclass(pos_hint={'x': .9, 'y': .1}) 
        Fl.add_widget(Box)
        Fl.add_widget(meaning) #Here we add the Label to the FloatLayout


        # return the layout
        return Fl


# run the App
if __name__ == "__main__":
    MyApp().run()

Answer 1

问题是，您实际上正在向函数show中的另一个标签中添加一个标签，但是您从未访问过已经添加到应用程序子类中的标签。

解决办法如下，

1. 首先为该标签

创建一个引用

    def build(self):
        ...

        Box = Boxlayout(pos_hint={'x': .23, 'y': .58}) 
        # Create a reference of the label with 'self'.
        self.meaning = Meaningclass(pos_hint={'x': .2, 'y': .1}, font_size=30) # Reduce it so that it doesn't go out of the screen.
        Fl.add_widget(Box)
        Fl.add_widget(self.meaning) #Here we add the Label to the FloatLayout

1. 与使用kwarg.，

之前一样，在方法destroy_then_create中传递“word”。

        ...
        for word in sentence:
            abtn = AdaptiveButton(text = word)
            abtn.bind(on_press=lambda btn, w=word: show(w)) # Pass the word only as before using kwarg.
            box.add_widget(abtn)
        ...

1. 现在对函数show，

进行以下更改

def show(k): #function for the Label
    # Grab the running app instance.
    app = App.get_running_app()
    # Access the label you already added to the app's subclass and set the text.
    app.meaning.text = k

您可以在代码中的任何地方添加此函数show，但请记住以任何合适的方式访问应用程序实例。