kivy：我的屏幕管理器代码不适用于scrollview

Question

试图让我与屏幕管理器和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仅将其保留为简单的框和按钮（如代码中的屏幕2），则效果很好。 当我尝试添加带有按钮的滚动视图时，我得到的只是一个空白屏幕。

有人可以帮我指出我的错误吗？ 我是新手。

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

您至少需要将您的root添加到ScreenOne

class ScreenOne(Screen):

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