Python使用.kv文件在Kivy中切换小部件 _Kivy

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 switchBoxLayout: 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: FalseBoxLayout: size_hint_y: None height: '48dp'Label: text: 'Switch on & disabled' Switch: disabled: True active: True

输出如下：
图片1