仅使用KV文件在Kivy中创建DropDown

问题描述

我想使用DropDown类获得一个简单的组合框，如小部件.我可以使用python代码来做到这一点，但是仅使用kv语言就可以吗?

I wanted to get a simple combo box like widget using the DropDown class. I can do it using python code, but is it possible using just kv language?

我尝试了以下方法.这是我的python代码:

I tried the following. Here's my python code:

class CustomDropDown(DropDown):
   pass

class MainForm(BoxLayout):
    pass

class MainApp(App):
    def build(self):
        self.dropdown = CustomDropDown()
        self.mainForm = MainForm()
        return self.mainForm
    def do_something(self):
        self.dropdown.open(self.mainForm)

MainApp().run()

这是kv文件:

<MainForm>:
    Button:
        text: 'Press'
        size_hint: [None,None]
        height: '40dp'
        on_release: app.do_something()
<CustomDropDown>:
    Button:
        text: 'First Item'
    Label:
        text: 'Disabled item'
    Button:
        text: 'Second Item'

但是这不起作用.你能建议点什么吗?感谢您的帮助.

But this is not working. Can you please suggest something? Any help is appreciated.

推荐答案

是的，可以使用kivy语言.

Yes, it's possible using kivy language.

您可以阅读有关 DropDownList 或旋转器.另外，如果您想进一步了解他们的工作原理，则可能需要查看 kivy-showcase的链接

You can read about DropDownList or Spinner through these links. And also if you want to know more on their working, you might want to check this link for kivy-showcase

我认为代码是不言自明的.(on_select方法)

I think the code is self explanatory.(on_select method)

这是main.py文件

This is the main.py file

from kivy.app import App
from kivy.uix.dropdown import DropDown
from kivy.uix.boxlayout import BoxLayout

class CustomDropDown(BoxLayout):
    pass

class MainApp(App):
    def build(self):
        return CustomDropDown()
if __name__=='__main__':
    MainApp().run()

这是main.kv文件

This is the main.kv file

<CustomDropDown>:

    Button:
        id: btn
        text: 'Press'
        on_release: dropdown.open(self)
        size_hint_y: None
        height: '48dp'

    DropDown:

        id: dropdown
        on_parent: self.dismiss()
        on_select: btn.text = '{}'.format(args[1])

        Button:
            text: 'First Item'
            size_hint_y: None
            height: '48dp'
            on_release: dropdown.select('First Item')

        Label:
            text: 'Second Item'
            size_hint_y: None
            height: '48dp'

        Button:
            text: 'Third Item'
            size_hint_y: None
            height: '48dp'
            on_release: dropdown.select('Third Item')

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