Python教程-Python Kivy库中的Spinner小部件

Kivy是Python中的图形用户界面工具，它是跨平台的。使用Kivy开发的应用程序可以在iOS、Windows、Linux和Android操作系统上使用。Kivy工具的基本用途是开发Android操作系统的应用程序，但也可以用于开发桌面应用程序。

Spinner小部件：

用户可以通过以下命令导入Kivy库的Spinner小部件：

from kivy.uix.spinner import Spinner

Spinner小部件用于从一组值中选择一个值。在默认状态下，Spinner显示其当前选择的值。当用户点击Spinner时，它会显示一个下拉菜单，显示用户可以选择的所有其他可用值。

与下拉框类似，Spinner小部件也用于为用户提供多个选择选项，以便从菜单中选择其中一个。用户还可以附加回调到Spinner小部件，以接收有关从小部件菜单中选择的值的通知。

实现步骤：

步骤 1： 导入Kivy库
步骤 2： 导入KivyApp
步骤 3： 导入Label
步骤 4： 导入Spinner
步骤 5： 导入FloatLayout
步骤 6： 设置最低Kivy版本（此步骤是可选的）
步骤 7： 创建一个App类：
- 首先，创建Spinner小部件
- 然后，将标签附加到Spinner小部件
- 然后，附加回调
步骤 8： 返回布局/小部件/类（根据需求）
步骤 9： 运行该类的实例。

示例：

from kivy.config import Config  
    
# In this code:  
# 0 means off   
# 1 means ON   
# Here, we can also use 0 or 1 && True or False  
Config.set('graphics', 'resizable', True)  
    
# Here, we are writing a program for Showing how to create a switch  
# first, we will import the kivy module     
import kivy   
       
# the, base Class of our Application is inherited from the App class.     
# app will refers to the instance of our application    
from kivy.app import App as app1  
     
# this will limit the kivy version that means   
# below this kivy version we cannot   
# use the application or software   
kivy.require('1.9.0')  
    
# The Label widget is for rendering text.   
from kivy.uix.label import Label as lab  
    
# Now, we will import the spinner widget  
from kivy.uix.spinner import Spinner as spin  
    
# This module consist the float layout   
# for working with FloatLayout   
# we have to import it first   
from kivy.uix.floatlayout import FloatLayout as fl  
    
    
# Now, we will create an Application by deriving from the App class  
class Spinner_example(app1):  
    
    # now we will define build   
    def build_1(self):  
    
        # here, we will create floatlayout  
        layout = fl()  
    
        # then, we will create the spinner  
        # first, we will configure spinner object and then add it to the layout  
        self.spinnerObject = spin(text = "Option 1",  
             values = ("Option 1", "Option 2", "Option 3", "Option 4", "Option 5", "Option 6"),  
             background_color =(0.784, 0.443, 0.216, 1))   
    
        self.spinnerObject.size_hint = (0.3, 0.2)  
    
        self.spinnerObject.pos_hint ={'x': .35, 'y':.75}  
    
        layout.add_widget(self.spinnerObject)  
    
        # return the layout  
        return layout;  
    
    
# for, Running the application  
if __name__ == '__main__':  
    Spinner_example().run()

输出：

图像 1：

图像 2：

现在，我们需要显示菜单列表中当前选择的选项。我们可以将标签显示在Spinner小部件旁边。

示例 2：

from kivy.config import Config  
    
# In this code:  
# 0 means off   
# 1 means ON   
# Here, we can also use 0 or 1 && True or False  
Config.set('graphics', 'resizable', True)  
    
# Here, we are writing a program for Showing how to create a switch  
# first, we will import the kivy module     
import kivy   
       
# the, base Class of our Application is inherited from the App class.     
# app will refers to the instance of our application    
from kivy.app import App as app1  
     
# this will limit the kivy version that means   
# below this kivy version we cannot   
# use the application or software   
kivy.require('1.9.0')  
    
# The Label widget is for rendering text.   
from kivy.uix.label import Label as lab  
    
# Now, we will import the spinner widget  
from kivy.uix.spinner import Spinner as spin  
    
# This module consist the float layout   
# for working with FloatLayout   
# we have to import it first   
from kivy.uix.floatlayout import FloatLayout as fl  
    
    
# Now, we will create an Application by deriving from the App class  
class Spinner_example(app1):  
    
    # now we will define build   
    def build_1(self):  
    
        # here, we will create floatlayout  
        layout = fl()  
    
        # then, we will create the spinner  
        # first, we will configure spinner object and then add it to the layout  
        self.spinObject = spin(text = "Option 1",  
             values = ("Option 1", "Option 2", "Option 3", "Option 4", "Option 5", "Option 6"),  
             background_color =(0.784, 0.443, 0.216, 1))   
    
        self.spinObject.size_hint = (0.3, 0.2)  
    
        self.spinObject.pos_hint ={'x': .35, 'y':.75}  
    
        layout.add_widget(self.spinObject)  
        self.spinObject.bind(text = self.on_spinner_select)  
    
        # It will change the label information as well  
        # It will add a label displaying the selection from the spinner  
        self.spinSelection = Label(text = "Selected value in spinner widegt is: %s"   
                                                     %self.spinObject.text)  
    
        layout.add_widget(self.spinSelection)  
        self.spinSelection.pos_hint ={'x': .1, 'y':.3}  
            
        return layout;  
    
    # call back for the selection in spinner object  
    def on_spinner_select(self, spin, text):  
        self.spinSelection.text = ("Selected value in spinner widget is: %s" %self.spinObject.text)  
    
        print('The spinner widget', spin, 'have text', text)  
        
    
# Run the app  
if __name__ == '__main__':  
    Spinner_example().run()