如何创建 kivy 下拉菜单？

Question

我想在 kivy 中创建一个DropDown菜单。 我的代码不起作用。 我没有收到错误，但我看不到DropDown菜单。 请帮忙。

tut10.py

from kivy.app import App
from kivy.uix.dropdown import DropDown
from kivy.uix.gridlayout import GridLayout
from kivy.lang import Builder

class drop_content(DropDown):
    pass

class Grid_5(GridLayout):
    drop = drop_content()

    def show_drop(self):
        self.drop.open

class Demo_9(App):   

    def build(self):
        return Builder.load_file("kv\Design8.kv")

if __name__ == "__main__":
    Demo_9().run()    

设计8.kv

<drop_content>:

    Label:
        text:"Drop1"
        size_hint_y: None
        height: 44

    Label:
        text:"Drop2"
        size_hint_y: None
        height: 44

Grid_5:    
    cols: 1

    Button:
        text: "Press me !!"
        size_hint: None, None
        on_press: root.show_drop()

Answer 1

代码中有几个问题。 在工作并尝试修复它们之后，我粘贴了我希望对你有用的代码。

tut10.py

from kivy.app import App
from kivy.uix.dropdown import DropDown
from kivy.uix.gridlayout import GridLayout
from kivy.lang import Builder

Builder.load_file("kv\Design8.kv")

class drop_content(DropDown):
    pass

class Grid_5(GridLayout):
    pass

class Demo_9(App):

    def build(self):

        return Grid_5()


if __name__ == "__main__":
    Demo_9().run()

kv\Design8.kv

<Grid_5>:

    Button:
        id: btn
        text: "Press me !!"
        size_hint: None, None
        on_parent: drop_content.dismiss()
        on_release: drop_content.open(self)

    DropDown:
        id: drop_content
        on_select: btn.text = '{}'.format(args[1])

        Button:
            id: btn1
            text: 'First Item'
            size_hint_y: None
            height: 35
            on_release: drop_content.select('First Item')

        Label:
            text:"Drop2"
            size_hint_y: None
            height: 44

        Button:
            id: btn3
            text: 'Third Item'
            size_hint_y: None
            height: 35
            on_release: drop_content.select('Third Item')