Python使用.kv文件在Kivy中切换小部件

Kivy是Python中与平台无关的GUI工具。由于它可以在Android, IOS, Linux和Windows等操作系统上运行。它基本上是用于开发Android应用程序, 但这并不意味着它不能在桌面应用程序上使用。

??Kivy教程–通过示例学习Kivy。

Switch小部件：

Switch小部件是活动的或不活动的, 作为机械灯开关。用户可以向左/向右滑动以激活/停用它。

Switch表示的值为True或False。也就是说, Switch可以处于”开”位置或”关”位置。

要使用Switch, 你必须导入：

from kivy.uix.switch import Switch

将回调附加到交换机：

• Switch可以附加有回调, 以检索Switch的值。
• 开关的状态转换是从ON到OFF或从OFF到ON。
• 当switch进行任何转换时, 将触发回调, 并且可以检索新状态(即传来新状态), 并且可以基于状态采取任何其他操作。
• 默认情况下, 小部件的表示形式是静态的。所需的最小尺寸为83 * 32像素。
• 整个窗口小部件都处于活动状态, 而不仅仅是带有图形的部分。只要你在小部件的边界框上滑动, 它就会起作用。

Basic Approach:

1) import kivy
2) import kivyApp
3) import Switch
4) import Gridlayout
5) import Label
6) Set minimum version(optional)
7) create Layout class(In this you create a switch):
        --> define the callback of the switch in this
8) create App class
9) create .kv file (name same as the app class):
        1) create boxLayout
        2) Give Lable
        3) Create Switch
        4) Bind a callback if needed
10) return Layout/widget/Class(according to requirement)
11) Run an instance of the class

下面是实现：

我们已经解释了如何创建按钮, 为其添加回调以及如何在使按钮处于活动/非活动状态后禁用按钮。

main.py文件：

# Program to explain how switch works
  
# import kivy module   
import kivy 
    
# base Class of your App inherits from the App class.   
# app:always refers to the instance of your application  
from kivy.app import App
  
# this restrict the kivy version i.e 
# below this kivy version you cannot 
# use the app or software 
kivy.require( '1.9.0' )
  
# The Switch widget is active or inactive
# The state transition of a switch is from
# either on to off or off to on.
from kivy.uix.switch import Switch
  
# The GridLayout arranges children in a matrix.
# It takes the available space and
# divides it into columns and rows, # then adds widgets to the resulting "cells".
from kivy.uix.gridlayout import GridLayout
  
# The Label widget is for rendering text. 
from kivy.uix.label import Label
  
# A Gridlayout with a label a switch
# A class which contains all stuff about the switch 
class SimpleSwitch(GridLayout):
      
     # number of rows 
     rows = 4
  
     # Callback for the switch state transition
     # Defining a Callback function
     # Contains Two parameter switchObject, switchValue
     def switch_callback( self , switchObject, switchValue):
          
         # Switch value are True and False
         if (switchValue):
             print ( 'Switch is ON:):):)' )
         else :
             print ( 'Switch is OFF:(:(:(' )
            
  
# Defining the App Class
class SwitchApp(App):
      # define build function
      def build( self ):
           # retuen the switch class
           return SimpleSwitch()
  
   
# Run the kivy app
if __name__ = = '__main__' :
      SwitchApp().run()

.kv文件

：在此我们完成了回调并还禁用了按钮。

# .kv file in which the whole functions of a switch
# Along with labels are present
  
<SimpleSwitch>:
  
     # creating box layout for better view
     BoxLayout:
         size_hint_y: None
         height: '48dp'
  
         # Adding label to switch
         Label:
             text: 'Switch normal'
  
         # creating the switch
         Switch:
  
             # False means OFF and True means ON
             active: False
              
             # Arranging a callback to the switch
             on_active: root.switch_callback( self , self .active)
  
     # Another for another switch
      
     BoxLayout:
         size_hint_y: None
         height: '48dp'
  
         Label:
             text: 'Switch active'
         Switch:
             active: True
             on_active: root.switch_callback( self , self .active)
  
  
     BoxLayout:
         size_hint_y: None
         height: '48dp'
  
         Label:
             text: 'Switch off & disabled'
              
         Switch:
             # disabled True means After making switch False
             # it is disabled now you cannot change its state
             disabled: True
             active: False
  
     BoxLayout:
         size_hint_y: None
         height: '48dp'
  
         Label:
             text: 'Switch on & disabled'
         Switch:
             disabled: True
             active: True

输出如下：

图片1

图片2：

显示回调的图像：

首先, 你的面试准备可通过以下方式增强你的数据结构概念：Python DS课程。