In this article, we will learn how to draw lines using the keyboard (arrow keys) in turtle graphics. Let’s first discuss some methods used in the implementation below:
- wn.listen(): Using this then we can give keyboard inputs
- wn.onkeypress(func, “key”): This function is used to bind fun to the key-release event of the key. In order to be able to register key-events, TurtleScreen must have focus.
- setx(position): This method is used to set the turtle’s second coordinate to x, leaving the first coordinate unchanged Here, whatever the position of the turtle is, it set the x coordinate to the given input keeping the y coordinate unchanged.
- sety(position): This method is used to set the turtle’s second coordinate to y, leaving the first coordinate unchanged Here, whatever the position of the turtle is, it set the y coordinate to the given input keeping the x coordinate unchanged.
- ycor(): This function is used to return the turtle’s y coordinate of the current position of the turtle. It doesn’t require any argument.
- xcor(): This function is used to return the turtle’s x coordinate of the current position of the turtle. It doesn’t require any argument
- head.penup: Picks the pen up so the turtle does not draw a line as it moves
- head.hideturtle: This method is used to make the turtle invisible. It’s a good idea to do this while you’re in the middle of a complicated drawing because hiding the turtle speeds up the drawing observably. This method does not require any argument.
- head.clear: This function is used to delete the turtle’s drawings from the screen
- head.write: This function is used to write text at the current turtle position.
Approach:
- Import the turtle modules.
- Get a screen to draw on
- Define two instances for the turtle one is a pen and another is the head.
- Head is for telling which key is currently pressed
- Define the functions for the up, down, left, right movement of the turtle.
- In the respective up, left, right and down functions set the arrow to move 100 units in up, left, right, and down directions respectively by changing the x and y coordinates.
- Use function listen() for giving keyboard inputs.
- Use onkeypress in order to register key-events.
Below is the Python implementation of the above approach:
Python3
# import for turtle moduleimport turtle# making a workScreenwn = turtle.Screen()# defining 2 turtle instancehead = turtle.Turtle()pen = turtle.Turtle()# head is for telling which key is pressedhead.penup()head.hideturtle()# head is at 0,260 coordinatehead.goto(0, 260)head.write("This is to tell which key is currently pressed", align="center", font=("courier", 14, "normal"))def f(): y = pen.ycor() pen.sety(y+100) head.clear() head.write("UP", align="center", font=("courier", 24, "normal"))def b(): y = pen.ycor() pen.sety(y-100) head.clear() head.write("Down", align="center", font=("courier", 24, "normal"))def l(): x = pen.xcor() pen.setx(x-100) head.clear() head.write("left", align="center", font=("courier", 24, "normal"))def r(): x = pen.xcor() pen.setx(x+100) head.clear() head.write("Right", align="center", font=("courier", 24, "normal"))wn.listen()wn.onkeypress(f, "Up") # when up is pressed pen will go upwn.onkeypress(b, "Down") # when down is pressed pen will go downwn.onkeypress(l, "Left") # when left is pressed pen will go leftwn.onkeypress(r, "Right") # when right is pressed pen will go right# this is to stop the turtle window from closing until the close button is clickedturtle.mainloop() |
Output:
