Related Articles

Related Articles

Python | Animation in Kivy using .kv file
  • Last Updated : 29 Jun, 2019

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.

Animation:

Animation and AnimationTransition are used to animate Widget properties. You must specify at least a property name and target value. To use Animation, follow these steps:

  • Setup an Animation object
  • Use the Animation object on a Widget

To use animation you must have to import:
from kivy.animation import Animation

Basic Approaches: 

1) import runTouchApp
2) import Builder
3) import Widget
4) import Animation
5) import Clock
6) import Window
7) import random
8) import listproperty
9) Build the .kv file
10) Create root class
11) Create the clock and anim react class used to animate the boxes
12) Run the App

In the below example we are creating the two boxes (red and green) in which we are giving animations to the red box i.e when the App starts the red box is in its animated view but to clear the concepts i am providing the green box which on click provide random animations i.e it goes anywhere at random.
The program consists of two main classes first is clock class which is for the red box as we are declaring it animated and the green box animation is in anim class.

To provide the motion you must have to play with velocity.



Implementation of the Approach:

filter_none

edit
close

play_arrow

link
brightness_4
code

# work same as kivy.App used to run the App
from kivy.base import runTouchApp
  
# to use .kv file as a string we have to import it
from kivy.lang import Builder
  
# A Widget is the base building block of GUI interfaces in Kivy
from kivy.uix.widget import Widget
  
# The Clock object allows you to schedule a
# function call in the future
from kivy.clock import Clock
  
# Animation and AnimationTransition are
# used to animate Widget properties
from kivy.animation import Animation
  
# The Properties classes are used when
# you create an EventDispatcher.
from kivy.properties import ListProperty
  
# Core class for creating the default Kivy window. 
from kivy.core.window import Window
  
# As name suggest used when random thiungs required
from random import random
  
  
# load the kv file as string 
Builder.load_string('''
<Root>:
  
# Setting the position (initial) of boxes
  
    ClockRect:
        pos: 300, 300
    AnimRect:
        pos: 500, 300
  
# creation and animation of red box
<ClockRect>:
    canvas:
        Color:
            rgba: 1, 0, 0, 1
        Rectangle:
            pos: self.pos
            size: self.size
  
# creation and animation of red box
<AnimRect>:
    canvas:
        Color:
            rgba: 0, 1, 0, 1
        Rectangle:
            pos: self.pos
            size: self.size
''')
  
  
# Create the root class
class Root(Widget):
    pass
  
  
# Create the clock class Then is when cliked
# how much time to animate
# the red colour block animation is created by it
class ClockRect(Widget):
    velocity = ListProperty([10, 15])
  
    def __init__(self, **kwargs):
        super(ClockRect, self).__init__(**kwargs)
        Clock.schedule_interval(self.update, 1 / 60.)
  
    def update(self, *args):
        self.x += self.velocity[0]
        self.y += self.velocity[1]
  
        if self.x < 0 or (self.x + self.width) > Window.width:
            self.velocity[0] *= -1
        if self.y < 0 or (self.y + self.height) > Window.height:
            self.velocity[1] *= -1
  
  
# Create the Animation class
# And add animaton
# green colour box is animated through this class
class AnimRect(Widget):
      
    def anim_to_random_pos(self):
        Animation.cancel_all(self)
        random_x = random() * (Window.width - self.width)
        random_y = random() * (Window.height - self.height)
  
        anim = Animation(x = random_x, y = random_y,
                         duration = 4,
                         t ='out_elastic')
        anim.start(self)
  
    def on_touch_down(self, touch):
        if self.collide_point(*touch.pos):
            self.anim_to_random_pos()
  
# run the App
runTouchApp(Root())

chevron_right


Output:

Animated Output vedio:

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course.




My Personal Notes arrow_drop_up
Recommended Articles
Page :