ScreenManager 是否与 Kivy 中的 DropDown 兼容？

Question

我想在由 Kivys ScreenManager 管理的第二个屏幕中生成一个下拉列表。如果我这样做，我会得到这个回溯：

    ... 
File "C:/Users/ORANG/PycharmProjects/waldi/playground/cw.py", line 76, in on_text
         instance.drop_down.open(instance)
File "C:\Kivy-1.9.0-py2.7-win32-x64\kivy27\kivy\uix\dropdown.py", line 215, in open
         'Cannot open a dropdown list on a hidden widget')
     kivy.uix.dropdown.DropDownException: Cannot open a dropdown list on a hidden widget

这是代码，和这个基本一样 example，只是嵌入了一个简单的屏幕管理器场景：

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.dropdown import DropDown
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.textinput import TextInput
from kivy.properties import ListProperty, StringProperty
import re
from kivy.lang import Builder

Builder.load_string('''
<Lieferant>:
    ComboLayout:
        Label:
            text: 'Label'
        ComboEdit:
            size_hint: .5, .3
            pos_hint: {'center':(.5, .5)}
            # `args` is the keyword for arguments passed to `on_text` in kv language
            on_text: self.parent.on_text(self, args[1])
''')

class ComboEdit(TextInput):
    """
    This class defines a Editable Combo-Box in the traditional sense
    that shows it's options
    """
    options = ListProperty(('',))
    '''
    :data:`options` defines the list of options that will be displayed when
    touch is released from this widget.
    '''

    def __init__(self, **kw):
        ddn = self.drop_down = DropDown()
        ddn.bind(on_select=self.on_select)
        super(ComboEdit, self).__init__(**kw)

    def on_options(self, instance, value):
        ddn = self.drop_down
        # clear old options
        ddn.clear_widgets()
        for option in value:
            # create a button for each option
            but = Button(text=option,
                         size_hint_y=None,
                         height='36sp',
                         # and make sure the press of the button calls select
                         # will results in calling `self.on_select`
                         on_release=lambda btn: ddn.select(btn.text))
            ddn.add_widget(but)

    def on_select(self, instance, value):
        # on selection of Drop down Item... do what you want here
        # update text of selection to the edit box
        self.text = value

class ComboLayout(BoxLayout):
    rtsstr = StringProperty("".join(("Substrate1,,,Substrate1,,,Substrate1,,,",
                                     "Substrate1,,,Substrate1,,,Substrate_coating",
                                     ",,,silicon,,,silicon_Substrate,,,substrate_",
                                     "silicon,,,")))
    def on_text(self, instance, value):
        if value == '':
            instance.options = []
        else:
            match = re.findall("(?<=,{3})(?:(?!,{3}).)*?%s.*?(?=,{3})" % value, \
                               self.rtsstr, re.IGNORECASE)
            # using a set to remove duplicates, if any.
            instance.options = list(set(match))
        instance.drop_down.open(instance)
class Intro(Screen):
    pass
class Lieferant(Screen):
    pass

class CWApp(App):
    def build(self):
        sm = ScreenManager()
        sm.add_widget(Intro(name='Intro'))
        sm.add_widget(Lieferant(name='Lieferant'))
        return sm

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

可以合并吗？你会怎么做？这段代码是运行如果我只是注释掉这一行，它会在带有下拉菜单的屏幕之前添加一个屏幕：

sm.add_widget(Intro(name='Intro'))

Answer 1

好的 - 对于这个问题我得到了 "Tumbleweed Badget" - LOL
我承认这是一个非常特别的，并且很明显，我是这里的初学者。所以我根据同样的问题问了另一个问题，并花了一些精力使代码更容易理解和重现。这得到了回报！如果您曾经遇到过此类问题，请在此处寻找解决方案：

ScreenManager 是否与 Kivy 中的 DropDown 兼容？

Is ScreenManager compatible with DropDown in Kivy?

python

kivy