Python | ScreenManager in Kivy using .kv file (original) (raw)

Last Updated : 16 Jan, 2022

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.

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:

import kivy
import kivyApp
import Screen Manager, Screen, ""Transitions you want to use""
Set minimum version(optional)
Create Different Screen classes and pass them
Create features of Screen classes in .kv file :: Add features in different screens
Create App class
return screen manager
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

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(""" : 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'

: 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'

: 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'

: 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'

: 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

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

: 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

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 -

Python | ScreenManager in Kivy using .kv file (original) (raw)

ScreenManager widget :

Program to Show how to create a switch

import kivy module

base Class of your App inherits from the App class.

app:always refers to the instance of your application

this restrict the kivy version i.e

below this kivy version you cannot

use the app or software

Builder is used when .kv file is

to be used in .py file

The screen manager is a widget

dedicated to managing multiple screens for your application.

You can create your kv code in the Python file

Create a class for all screens in which you can include

helpful methods specific to that screen

The ScreenManager controls moving between screens

Add the screens to the manager and then supply a name

that is used to switch screens

Create the App class

run the app

Program to Show how to create a switch

import kivy module

base Class of your App inherits from the App class.

app:always refers to the instance of your application

this restrict the kivy version i.e

below this kivy version you cannot

use the app or software

Builder is used when .kv file is

to be used in .py file

The screen manager is a widget

dedicated to managing multiple screens for your application.

You can create your kv code in the Python file

Create a class for all screens in which you can include

helpful methods specific to that screen

The ScreenManager controls moving between screens

You can change the transitions accordingly

Add the screens to the manager and then supply a name

that is used to switch screens

Create the App class

run the app