turtle.ondrag() function in Python

turtle.ondrag() function is used to bind a function to the mouse-drag event on a turtle object. This means when you click and drag the mouse over the turtle on the canvas, the specified function will be called with the current mouse coordinates.

Syntax:

turtle.ondrag(fun, btn=1, add=None)

Parameter:

• fun : function with two arguments (x, y) that receives the coordinates of the dragged mouse.
• btn : (optional) Integer specifying which mouse button triggers the drag. Default is 1 (left button)
• add: (optional) Boolean. If True, adds a new binding. If False, replaces the previous binding.

Returns: This function does not return anything.

Example :

import turtle

def fxn(x, y):
    turtle.ondrag(None)
    turtle.setheading(turtle.towards(x, y)) 
    turtle.goto(x, y)                   
    turtle.ondrag(fxn)                     

turtle.speed(10)         
sc = turtle.Screen()       
sc.setup(400, 300)         

turtle.ondrag(fxn)         
sc.mainloop()              

Output :

Explanation:

• def fxn(x, y): function that makes the turtle follow the mouse when dragged.
• turtle.ondrag(None) & turtle.ondrag(fxn): Temporarily disable and then re-enable drag to avoid recursion.
• turtle.setheading(turtle.towards(x, y)): Turn turtle toward the drag point.
• turtle.goto(x, y) : Move turtle to the dragged coordinates.
• turtle.Screen() & sc.mainloop() : Create screen and keep it open to listen for drag events.