kivy：我的 screenmanager 代码不适用于 scrollview

Question

正在尝试让我的 kivy 与 screenmanager 和 scrollview 一起工作。我不明白为什么它不起作用。如果我删除滚动视图并将其保留为一个简单的框和按钮（如代码中的屏幕 2），它就可以正常工作。一旦我尝试添加带有按钮的滚动视图，我得到的只是一个空白屏幕。

谁能帮我指出错误。我是kivy的新手。

import kivy
kivy.require('1.8.0')

from kivy.app import App
from kivy.uix.screenmanager import Screen, ScreenManager 
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.properties import ObjectProperty
from kivy.uix.gridlayout import GridLayout
from kivy.uix.scrollview import ScrollView

from urllib import urlopen
from re import findall, MULTILINE, sub

heading = []
date = []
id_ref = []

URL_list = 'web_site_here.xml'

O_WL = urlopen(URL_list).read()


class ScreenOne(Screen):

    def __init__ (self,**kwargs):
        super (ScreenOne, self).__init__(**kwargs)
        Buttonlayout = GridLayout(orientation='vertical',cols=1, spacing=2, size_hint_y=None)
        Buttonlayout.bind(minimum_height=Buttonlayout.setter('height'))
        for i in range(len(id_ref)):
            btn = Button(text=heading[i], size_hint_y=None, height=80,text_size=(350,None),font_size='12sp')
            btn.bind(on_press=(lambda a:self.changer()))
            Buttonlayout.add_widget(btn)
        root = ScrollView()
        root.add_widget(Buttonlayout)

    def changer(self,*args):
        self.manager.current = 'story_screen'

class ScreenTwo(Screen):

    def __init__(self,**kwargs):
        super (ScreenTwo,self).__init__(**kwargs)
        story_box = BoxLayout(orientation='vertical')
        story_heading = Label(text="testing")
        back = Button(text="Back",size_hint_y=None, size_y=50)
        back.bind(on_press=self.changer)
        story_box.add_widget(story_heading)
        story_box.add_widget(back)
        self.add_widget(story_box)

    def changer(self,*args):
        self.manager.current = 'but_screen'

class TestApp(App):

    O_WL = urlopen(URL_list).read()

    id_ex = findall('<id>(.*)</id>',O_WL)
    for i in id_ex:
        id_ref.extend([i])  

    head_ex = findall('<headline>(.*)</headline>',O_WL)
    for i in head_ex:
        heading.extend([i])
    date_ex = findall('<modifiedDate>(.*)</modifiedDate>',O_WL)
    for i in date_ex:
        date.extend([i]) 

    def build(self):
        my_screenmanager = ScreenManager()
        screen1 = ScreenOne(name='but_screen')
        screen2 = ScreenTwo(name='story_screen')
        my_screenmanager.add_widget(but_screen)
        my_screenmanager.add_widget(story_screen)
        return my_screenmanager

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

提前致谢。

Answer 1

您至少需要在 ScreenOne

中添加您的 root

class ScreenOne(Screen):

    def __init__ (self,**kwargs):
        ...
        root = ScrollView()
        root.add_widget(Buttonlayout)
        self.add_widget(root)

kivy：我的 screenmanager 代码不适用于 scrollview

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