Kivy 中的屏幕管理器使用 .kv 文件（Python）

17 Mar 2025 | 5 分钟阅读

Kivy 是 Python 中的一个平台无关的图形用户界面工具。因为它兼容 Android、iOS、Linux 和 Windows。它通常用于 Android 应用程序的开发，但这并不妨碍它应用于桌面程序。

屏幕管理器控件

一个名为 ScreenManager 的控件用于管理程序中的多个屏幕。默认的 ScreenManager 只显示一个屏幕，并使用 TransitionBase 在屏幕之间切换。它支持多种转场效果。

导入了 ScreenManager 和 Screen 类。Root 将按以下方式使用 ScreenManager

注意：ScreenManager 默认使用的转场类型是 SlideTransition，它带有方向和持续时间的参数。

基本方法

1) import kivy
2) import kivyApp
3) Import Screen Manager, Screen, "Transitions you want to use" 
4) Set minimum version(optional)
5) Create Different Screen classes and pass them
6) Create features of Screen classes in the .kv file 
       :: Add features on different screens
7) Create an App class
8) return screen manager
9) Run an instance of the class

下面展示了使用 .kv 文件在 .py 文件中实现的示例代码。

# Program to Show how to create a switch
# import kivy module   
import kivy       
# Your app's basic class derives from the App class.   
# app: always refers to your application's instance.  
from kivy.app import App    
# This limits the kivy version, meaning that you cannot use the app or software below this kivy version. 
kivy.require('1.9.0') 
# When a .kv file is to be used in a .py file, a builder is used.
from kivy.lang import Builder 
# A widget devoted to handling numerous screens
# for your program is the screen manager.
from kivy. uix.screenmanager import ScreenManager, Screen  
# Your code can be created in the Python file.
Builder.load_string("""
<ScreenOne>:
    BoxLayout:
        Button:
            text: "Go to Screen 2"
            background_color : 0, 0, 1, 1
            on_press:
                # You can specify the slide's direction and the change's number and duration.
                root.manager.transition.direction = 'left'
                root.manager.transition.duration = 1
                root. manager.current = 'screen_two'  
<ScreenTwo>:
    BoxLayout:
        Button:
            text: "Go to Screen 3"
            background_color: 1, 1, 0, 1
            on_press:
                root.manager.transition.direction = 'left'
                root.manager.transition.duration = 1
                root. manager.current = 'screen_three'
<ScreenThree>:
    BoxLayout:
        Button:
            text: "Go to Screen 4"
            background_color: 1, 0, 1, 1
            on_press:
                root.manager.transition.direction = 'left'
                root.manager.transition.duration = 1
                root. manager.current = 'screen_four'
<ScreenFour>:
    BoxLayout:
        Button:
            text: "Go to Screen 5"
            background_color : 0, 1, 1, 1
            on_press:
                root.manager.transition.direction = 'left'
                root.manager.transition.duration = 1
                root. manager.current = 'screen_five'
<ScreenFive>:
    BoxLayout:
        Button:
            text: "Go to Screen 1"
            background_color: 1, 0, 0, 1
            on_press:
                root.manager.transition.direction = 'right'
                root. manager.current = 'screen_one' 
""")
# Make a class for every screen where you may add 
# helpful screen-specific functions.
class ScreenOne(Screen):
    pass  
class ScreenTwo(Screen):
    pass 
class ScreenThree(Screen):
    pass 
class ScreenFour(Screen):
    pass
class ScreenFive(Screen):
    pass
# Switching between screens is controlled by the ScreenManager.
screen_manager = ScreenManager()  
# Provide a name 
# to switch screens after adding the screens to the manager.
screen_manager.add_widget(ScreenOne(name ="screen_one"))
screen_manager.add_widget(ScreenTwo(name ="screen_two"))
screen_manager.add_widget(ScreenThree(name ="screen_three"))
screen_manager.add_widget(ScreenFour(name ="screen_four"))
screen_manager.add_widget(ScreenFive(name ="screen_five")) 
# Creating the App class
class ScreenApp(App):
    def build(self):
        return screen_manager 
# running the app
sample_app = ScreenApp()
sample_app.run()

输出

转场效果

在转场效果方面，您有多种选择，包括：

NoTransition 无动画，即时切换屏幕。
使用滑动转场，屏幕可以向任何方向滑动。
CardTransition 根据模式，新屏幕会滑入旧屏幕，或者旧屏幕会滑出新屏幕。
iOS 交换转场效果的实现称为 SwapTransition。
屏幕淡入淡出着色器 FadeTransition
使用 WipeTransition 着色器，将屏幕从右向左清除。
在 FallOutTransition 着色器中，旧屏幕“落下”并变为透明，露出其下隐藏的新屏幕。
RiseInTransition 是一种着色器，它使屏幕从屏幕中心升起，同时从透明变为不透明。

通过修改 ScreenManager.transition 属性，您可以快速更改转场效果。

# Program to Demonstrate the Creation of a Switch
# Importing the kivy module   
import kivy       
# Your app's basic class derives from the App class.   
# app: always refers to your application's instance.  
from kivy.app import App
# This limits the kivy version, that is
# Below this Kivy version, the app or program is not usable. 
kivy.require('1.9.0') 
# When a .kv file is to be used in a .py file, a builder is used.
from kivy.lang import Builder 
# A widget  devoted to handling
# numerous screens for your programme is the screen manager.
from kivy. uix. screen manager import (ScreenManager, Screen, NoTransition,
SlideTransition, CardTransition, SwapTransition,
FadeTransition, WipeTransition, FallOutTransition, RiseInTransition)  
# Your kv code can be created in the Python file.
Builder.load_string("""
<ScreenOne>:
    BoxLayout:
        Button:
            text: "Go to Screen 2"
            background_color : 0, 0, 1, 1
            on_press:
                # You can specify the slide's direction and the change's number and duration.
                root.manager.transition.direction = 'left'
                root.manager.transition.duration = 1
                root. manager.current = 'screen_two'  
<ScreenTwo>:
    BoxLayout:
        Button:
            text: "Go to Screen 3"
            background_color: 1, 1, 0, 1
            on_press:
                root.manager.transition.direction = 'left'
                root.manager.transition.duration = 1
                root. manager.current = 'screen_three' 
<ScreenThree>:
    BoxLayout:
        Button:
            text: "Go to Screen 4"
            background_color: 1, 0, 1, 1
            on_press:
                root.manager.transition.direction = 'left'
                root.manager.transition.duration = 1
                root. manager.current = 'screen_four'
<ScreenFour>:
    BoxLayout:
        Button:
            text: "Go to Screen 5"
            background_color : 0, 1, 1, 1
            on_press:
                root.manager.transition.direction = 'left'
                root.manager.transition.duration = 1
                root. manager.current = 'screen_five'
<ScreenFive>:
    BoxLayout:
        Button:
            text: "Go to Screen 1"
            background_color: 1, 0, 0, 1
            on_press:
                root.manager.transition.direction = 'right'
                root. manager.current = 'screen_one'
""") 
# For each screen you can include, create a class.
# practical techniques particular to that screen
class ScreenOne(Screen):
    pass  
class ScreenTwo(Screen):
    pass 
class ScreenThree(Screen):
    pass 
class ScreenFour(Screen):
    pass 
class ScreenFive(Screen):
    pass  
# Switching between screens is controlled by the ScreenManager.
# The transitions can be adjusted accordingly.
screen_manager = ScreenManager(transition = RiseInTransition())  
# Give the manager the screens, then give it a name.
# that switches between screens
screen_manager.add_widget(ScreenOne(name ="screen_one"))
screen_manager.add_widget(ScreenTwo(name ="screen_two"))
screen_manager.add_widget(ScreenThree(name ="screen_three"))
screen_manager.add_widget(ScreenFour(name ="screen_four"))
screen_manager.add_widget(ScreenFive(name ="screen_five"))
 
# Creating the App class
class ScreenApp(App):
    def build(self):
        return screen_manager
# running the app
sample_app = ScreenApp()
sample_app.run()