Kivy 中的下拉列表

2025年3月17日 | 阅读 3 分钟

下拉列表与自定义组件一起使用。用户使用下拉列表来显示在显示组件下的组件列表。组件列表用于存储任何类型的组件，例如图像、简单按钮等等。

用户可以重新排列下拉列表的位置，因为它是完全自动的。此外，开发人员可以以简单的方式放置此列表，以便用户可以轻松地从列表中选择项目。

开发下拉列表时要记住的要点

当用户添加组件时，用户应手动指定其高度，以便下拉列表可以轻松计算出所需的区域。
下拉列表中的所有按钮都应触发下拉 **"DropDown.select()"**。调用后，主按钮文本必须显示在下拉列表的选择中。

要使用此组件，开发人员应首先导入以下内容

下拉列表的基本方法

导入 Kivy
然后，导入 Kivy 应用程序
然后，我们将导入下拉列表
并且，导入按钮
我们还可以看到它的最低版本，这是可选的。
最后，我们将导入 runTouchApp
我们将创建下拉列表
然后，我们将创建 runTouchApp 函数，该函数将 widget 作为参数来运行应用程序。

示例

# Python Program for explaining how to create a drop-down in kivy 
# first we will import kivy module    
import kivy  
       
# the base Class of our Application is inherited from the App class.    
# app is alway used for refering to the instance of our application   
from kivy.app import App 
     
# this will restrict the kivy version that means we can not use 
# the application or software below this Version of Kivy   
kivy.require('1.9.0') 
     
# Now we will import the Drop-down from the module for using it in the program
from kivy.uix.dropdown import DropDown
  
# The Button will be a Label with associated actions which will be released when the button is clicked
from kivy.uix.button import Button
  
# the another way used for running the kivy application 
from kivy.base import runTouchApp
  
# now we will create the dropdown with 15 buttons
drop_down = DropDown()
for index in range(15):
  
    # now, Add the button in the drop down list
    btton = Button(text ='List % d' % index, size_hint_y = None, height = 30)
  
    # now we will bind the button for showing the text when it is selected
    btton.bind(on_release = lambda btton: drop_down.select(btton.text))
  
    # then we will add the button inside the drop_down list
    drop_down.add_widget(btton)
  
# now we will create the big main button
main_button = Button(text ='MAIN', size_hint =(None, None), pos =(350, 300))
  
# now, we will first show the drop_down menu when the main button will releases
# we should note that all of the bind() function calls will pass the instance of the caller 
# as the first argument of the callback (in this program, the main_button instance)
# now, dropdown.open.
main_button.bind(on_release = drop_down.open)
  
# now we have to do last thing, listen for the selection in the 
# dropdown list and assign the data to the button text.
drop_down.bind(on_select = lambda instance, x: setattr(main_button, 'text', x))
  
# runtouchApp:
# If we pass only the widget in runtouchApp(), the Window will be
# created and our widget will be added to that window as the root widget.
runTouchApp(main_button)

输出

运行上述代码后，用户将获得此输出