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python - 为什么即使列出了类名，kivy 也不处理我的 kv 文件中的规则？

问题描述

我是一个 kivy 新手，正在尝试编写一个供我个人使用的应用程序。我正在使用ScreenManager。第一个屏幕 ( ThoughtsClass) 的类规则从 kv 文件中正确读取并执行。但是当涉及到第二个屏幕 ( Distortion) 时，Kivy 没有阅读规则，我只看到一个空白屏幕。如果我手动调用add_widget小部件，则会出现该小部件。但是 kv 文件没有处理任何内容。

这是我的kv文件：

Root:
    ThoughtsClass:
    Distortion:


<ThoughtsClass>:
    cols: 1
    thought: thought
    id: thoughtclass

    TextInput:
        id: thought
        multiline: False

    BoxLayout:
        size_hint_y: 0.25
        orientation: 'horizontal'

        Button:
            text: 'Next Thought'
            on_press: thoughtclass.nextthought()

        Button:
            text: 'Done'
            on_press: thoughtclass.donethought()

<Distortion>:
    cols: 1
    disttext: disttext
    thoughtdisplay: thoughtdisplay

    Label:
        id:thoughtdisplay
        text: ''

    BoxLayout:
        orientation: 'horizontal'
        SelectDist:
            id: disttext

这是主要的 Python 代码：

#!/usr/bin/env python3

from kivy.app import App
from kivy.uix.gridlayout import GridLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.widget import Widget
from kivy.uix.label import Label
from kivy.uix.textinput import TextInput
from kivy.properties import StringProperty, ObjectProperty, DictProperty
from kivy.storage.dictstore import DictStore
from kivy.uix.dropdown import DropDown
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen

class Root(ScreenManager):

    def __init(self, **kwargs):
        super(Root, self).__init__(self,**kwargs)


class ThoughtsClass(Screen):
    thought = ObjectProperty()
    negstatements = DictProperty()
    distmeanings = DictProperty()

    def __init__(self, **kwargs):
       super(ThoughtsClass, self).__init__(**kwargs)
       self.distmeanings = distortions
       self.name = 'Thoughts'


    def nextthought(self):
        print ('Thought: ' + self.thought.text)
        if self.thought.text:
            self.negstatements[self.thought.text] = {'distortion':'', 'rational':''}
        self.thought.text = ''

    def donethought(self):
        print ('Done pressed')
        if self.thought.text not in self.negstatements:
            self.nextthought()
        root.current = 'Distortions'
        root.current_screen.thoughts = self.negstatements


class Distortion(Screen):
    disttext = ObjectProperty()
    thoughts = DictProperty()
    thoughtdisplay = ObjectProperty()

    def __init__(self, **kwargs):
        super(Distortion, self).__init__(**kwargs)
        self.name = 'Distortions'

    def display_thought(self):
        for thoughttext in self.thoughts:
            self.thoughtdisplay.text = thoughttext
        dist_dd = SelectDist()
        dist_dd.build_dd()
        distbutton = Button(text='Choose a distortion:')
        distbutton.bind(on_release=dist_dd.open)
        dist_dd.bind(on_select=self.choose_dist())

    def choose_dist(self, instance, value):
        print ("Chose " + value)

class SelectDist(DropDown):

    def __init__(self, **kwargs):
        super(SelectDist, self).__init__(**kwargs)

    def build_dd(self):
        for diststring in distortions:
            btn = Button(text = diststring)
            btn.bind(on_release=lambda btn: self.select(btn.text))
            self.add_widget(btn)


class ThreeColumnApp(App):

    def build(self):
        global root
        root = Root()
        root.add_widget(ThoughtsClass())
        root.add_widget(Distortion())
        return root

if __name__ == '__main__':
    distortions = {}
    cbtinstance = ThreeColumnApp()
    cbtinstance.run()

我无法弄清楚为什么会这样......

标签： pythonpython-3.xkivykivy-language

解决方案

显示为Distortion Screen空白，因为您的kv规则Screen没有定义任何在显示时显而易见的内容。尝试改变：

Label:
    id:thoughtdisplay
    text: ''

到：

Label:
    id:thoughtdisplay
    text: 'Nothing yet!!'

Label当显示 时，您应该会看到Distortion Screen。

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