How to Create custom Turtle shapes in Python?

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In Turtle, by default, we have an arrowhead-shaped cursor for drawing on the canvas. This can be changed to some other predefined shape or we can also create a custom shape and register it under a name. Not just that, we can even use gif format images to replace our cursor.

Changing cursor to predefined shapes

The shape() function is used to set the shape of the cursor. The pre-defined shapes include turtle, arrow, circle, square and triangle.

Python3

import turtle
 
# turtle object
c_turtle = turtle.Turtle()
   
# changing the cursor
# shape to circle
c_turtle.shape('circle')

Output :

Registering new shapes

The turtle module has register_shape() function for registering custom shapes.

Syntax : turtle.register_shape(name, shape)
Parameters :

name : a string- the name of the shape to be registered.

shape : a tuple of tuples containing the coordinates for the custom shape.

The n-tuple argument for the shape parameter, denotes the relative position of each corner of an n-sided polygon. Let us try to create a simple diamond shape to understand this.
Consider this diamond, having length of diagonal = 20, in a Cartesian plane :

To create this shape, we need to pass these coordinates in clockwise order.

Python3

import turtle
 
# turtle object
diamond_turtle = turtle.Turtle()
 
# the coordinates of each corner
shape = ((0, 0), (10, 10), (20, 0), (10, -10))
 
# registering the new shape
turtle.register_shape('diamond', shape)
 
# changing the shape to 'diamond'
diamond_turtle.shape('diamond')
 
# Keep the turtle window open
turtle.done()

Output:

Using images for Turtle cursor

To use an image as the cursor, we need to pass the image file path as parameter to register_shape(). Note that this image has to be in gif format.

Python3

import turtle
 
# turtle object
img_turtle = turtle.Turtle()
  
# registering the image
# as a new shape
turtle.register_shape('example.gif')
 
# setting the image as cursor
img_turtle.shape('example.gif')