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Python | Line (Canvas) in kivy

  • Last Updated : 06 Feb, 2020

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.

👉🏽 Kivy Tutorial – Learn Kivy with Examples.

Line canvas:

Line is a vertex canvas instruction. It allows drawing of lines through points. This code shows how to use/draw the extended line drawing such as circles, ellipses, rectangles and Bezier and so on.

Basic Approach:

1) import kivy
2) import kivy App
3) import Gridlayout
4) import widget
5) set minimum version(optional)
6) Create as much as widget class as needed
7) create the App class
8) return the widget/layout etc class
9) Run an instance of the class

Implementation of Approach:

# Main.py






# kivy Lines Demo
  
# 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  
      
  
# The GridLayout arranges children in a matrix. 
# It takes the available space and 
# divides it into columns and rows, 
# then adds widgets to the resulting “cells”. 
from kivy.uix.gridlayout import GridLayout 
  
# Widgets are elements of
# a graphical user interface that
# form part of the User Experience.
from kivy.uix.widget import Widget
  
  
##############################################
# Classes form Different types of line as  widgets
  
class LineEllipse1(Widget):
    pass
  
class LineEllipse2(Widget):
    pass
  
class LineEllipse3(Widget):
    pass
  
class LineCircle1(Widget):
    pass
  
class LineCircle2(Widget):
    pass
  
class LineCircle3(Widget):
    pass
  
class LineCircle4(Widget):
    pass
  
class LineRectangle(Widget):
    pass
  
class LineBezier(Widget):
    pass
  
  
# Create the App class
class LineApp(App):
    def build(self):
  
        # Assign the number of coloumn, spacing and padding 
        root = GridLayout(cols = 3, padding = 50, spacing = 100)
  
        # Adding the widgets
        root.add_widget(LineEllipse1())
        root.add_widget(LineEllipse2())
        root.add_widget(LineEllipse3())
        root.add_widget(LineCircle1())
        root.add_widget(LineCircle2())
        root.add_widget(LineCircle3())
        root.add_widget(LineCircle4())
        root.add_widget(LineRectangle())
        root.add_widget(LineBezier())
        return root
  
# Run the App class
if __name__ == '__main__':
    LineApp().run()

Line.kv file:




# Line.kv file of the code
  
# Creating Different types of Lines(or shapes through line)
  
###########################################
  
# Row 1:
  
# Ellipse(1st row 1st element)
  
<LineEllipse1>:
  
    # Creating Canvas
    canvas:
        Color:
            rgba: 1, .1, .1, .9
        # Ellipse Creation
        Line:
            width: 2.
            ellipse: (self.x, self.y, self.width, self.height)
  
    # Label the figure 
    Label:
        center: root.center
        text: 'Ellipse'
  
  
############################################
  
# Ellipse from 90 to 180((1st row 2nd element))
  
<LineEllipse2>:
    canvas:
        Color:
            rgba: 1, .1, .1, .9
        Line:
            width: 2.
            ellipse: (self.x, self.y, self.width, self.height, 90, 180)
    Label:
        center: root.center
        text: 'Ellipse from 90 to 180'
  
  
############################################
  
  
# Ellipse from 90 to 720, 10 segments(1st row 3rd element)
  
<LineEllipse3>:
    canvas:
        Color:
            rgba: 1, .1, .1, .9
        Line:
            width: 2.
            ellipse: (self.x, self.y, self.width, self.height, 90, 720, 10)
    Label:
        center: root.center
        text: 'Ellipse from 90 to 720, 10 segments'
        halign: 'center'
  
############################################
  
# Circle(2nd row 1st element)
<LineCircle1>:
    canvas:
        Color:
            rgba: .1, 1, .1, .9
        Line:
            width: 2.
            circle:
                (self.center_x, self.center_y, min(self.width, self.height)
                / 2)
    Label:
        center: root.center
        text: 'Circle'
  
############################################
  
# Circle from 90 to 180(2nd row 2nd element)
<LineCircle2>:
    canvas:
        Color:
            rgba: .1, 1, .1, .9
        Line:
            width: 2.
            circle:
                (self.center_x, self.center_y, min(self.width, self.height)
                / 2, 90, 180)
    Label:
        center: root.center
        text: 'Circle from 90 to 180'
  
############################################
# Circle from 90 to 180, 10 segments(1st row 3rd element)
<LineCircle3>:
    canvas:
        Color:
            rgba: .1, 1, .1, .9
        Line:
            width: 2.
            circle:
                (self.center_x, self.center_y, min(self.width, self.height)
                / 2, 90, 180, 10)
    Label:
        center: root.center
        text: 'Circle from 90 to 180, 10 segments'
        halign: 'center'
  
############################################
  
# Circle from 0 to 360 (3rd row 1st element)
<LineCircle4>:
    canvas:
        Color:
            rgba: .1, 1, .1, .9
        Line:
            width: 2.
            circle:
                (self.center_x, self.center_y, min(self.width, self.height)
                / 2, 0, 360)
    Label:
        center: root.center
        text: 'Circle from 0 to 360'
        halign: 'center'
  
############################################
  
# Rectangle (3rd row 2nd element)
<LineRectangle>:
    canvas:
        Color:
            rgba: .1, .1, 1, .9
        Line:
            width: 2.
            rectangle: (self.x, self.y, self.width, self.height)
    Label:
        center: root.center
        text: 'Rectangle'
  
############################################
  
# Bezier (3rd row 3rd element)
<LineBezier>:
    canvas:
        Color:
            rgba: .1, .1, 1, .9
        Line:
            width: 2.
            bezier:
                (self.x, self.y, self.center_x - 40, self.y + 100,
                self.center_x + 40, self.y - 100, self.right, self.y)
    Label:
        center: root.center
        text: 'Bezier'

Output:

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