Python | ScreenManager in Kivy using .kv file

Kivy is a platform independent GUI tool in Python. As it can be run on Android, IOS, linux and Windows etc. It is basically used to develop the Android application, but it does not mean that it can not be used on Desktops applications.

ScreenManager widget :

The screen manager is a widget which is used to managing multiple screens for your application. The default ScreenManager displays only one Screen at a time and uses a TransitionBase to switch from one Screen to another. Multiple transitions are supported.
The ScreenManager and Screen class are imported. The ScreenManager will be used for the root like:

from kivy.uix.screenmanager import ScreenManager, Screen

Note:The default ScreenManager.transition is a SlideTransition with options direction and duration.

Basic Approach:
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 .kv file 
       :: Add features in different screens
7) Create App class
8) return screen manager
9) Run an instance of the class

Below is the implementation of the code with .kv file in .py file.

Python3

# Program to Show how to create a switch
# 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')

# Builder is used when .kv file is
# to be used in .py file
from kivy.lang import Builder

# The screen manager is a widget
# dedicated to managing multiple screens for your application.
from kivy.uix.screenmanager import ScreenManager, Screen

# You can create your kv code 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 define the duration of the change
                # and the direction of the slide
                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'


""")

# Create a class for all screens in which you can include
# helpful methods specific to that screen
class ScreenOne(Screen):
    pass

class ScreenTwo(Screen):
    pass

class ScreenThree(Screen):
    pass

class ScreenFour(Screen):
    pass

class ScreenFive(Screen):
    pass


# The ScreenManager controls moving between screens
screen_manager = ScreenManager()

# Add the screens to the manager and then supply a name
# that is used to switch 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"))

# Create the App class
class ScreenApp(App):
    def build(self):
        return screen_manager

# run the app
sample_app = ScreenApp()
sample_app.run()

Output:

Changing Transitions:

You have multiple transitions available by default, such as: 

• NoTransition – switches screens instantly with no animation
• SlideTransition – slide the screen in/out, from any direction
• CardTransition – new screen slides on the previous or the old one slides off the new one depending on the mode
• SwapTransition – implementation of the iOS swap transition
• FadeTransition – shader to fade the screen in/out
• WipeTransition – shader to wipe the screens from right to left
• FallOutTransition – shader where the old screen ‘falls’ and becomes transparent, revealing the new one behind it.
• RiseInTransition – shader where the new screen rises from the screen center while fading from transparent to opaque.

You can easily switch transitions by changing the ScreenManager.transition property: 

sm = ScreenManager(transition=FadeTransition())

Python3

# Program to Show how to create a switch
# 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')

# Builder is used when .kv file is
# to be used in .py file
from kivy.lang import Builder

# The screen manager is a widget
# dedicated to managing multiple screens for your application.
from kivy.uix.screenmanager import (ScreenManager, Screen, NoTransition,
SlideTransition, CardTransition, SwapTransition,
FadeTransition, WipeTransition, FallOutTransition, RiseInTransition)

# You can create your kv code 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 define the duration of the change
                # and the direction of the slide
                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'


""")

# Create a class for all screens in which you can include
# helpful methods specific to that screen
class ScreenOne(Screen):
    pass

class ScreenTwo(Screen):
    pass

class ScreenThree(Screen):
    pass

class ScreenFour(Screen):
    pass

class ScreenFive(Screen):
    pass


# The ScreenManager controls moving between screens
# You can change the transitions accordingly
screen_manager = ScreenManager(transition = RiseInTransition())

# Add the screens to the manager and then supply a name
# that is used to switch 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"))

# Create the App class
class ScreenApp(App):
    def build(self):
        return screen_manager

# run the app
sample_app = ScreenApp()
sample_app.run()

Note: Code is Same some points is added in code don’t confuse.
Output Video of Different transitions –