Turtle Graphics in Python

Turtle Graphics is a fun and easy way to learn Python programming concepts, especially well-suited for beginners. It provides a visual interface where you control a little turtle on a screen to draw shapes and designs.

Here's a breakdown of Turtle Graphics in Python:

What it is:

• A pre-installed library in Python for creating drawings and animations.
• Provides a virtual canvas and a turtle object that acts like a pen moving around the canvas.

Python shell, import all the objects of the turtle.

from turtle import *

Basic drawing turtle 

turtle forward 200 steps:

forward(200)

 drawing a triangle turtle

forward(200)

left(120)

forward(200)

 draw the star shape at the top of this page line color.

color('green')

fillcolor('red')

down() and  up() determine lines will be drawn

begin_fill() 

create a loop turtle

while True:

    forward(300)

    left(120)

    if abs(pos()) < 1:

        break

 

   you give the end_fill() command

end_fill()

turtle graphics example-

 import turtle as turtle

from random import random

for i in range(200):

    steps = int(random() * 200)

    angle = int(random() * 260)

    turtle.right(angle)

    turtle.fd(steps)

turtle.mainloop()

 object-oriented turtle graphics

from turtle import Turtle

from random import random

turtle = Turtle()

for j in range(200):

    steps = int(random() * 300)

    angle = int(random() * 260)

    turtle.right(angle)

    turtle.fd(steps)

turtle.screen.mainloop()

Change the Turtle Screen Background Color and title

turtle.screen.title('RAHULTECHWEB')

turtle.screen.bgcolor("red")

Turtle methods

The Turtle library in Python provides a bunch of methods to control your turtle and create various effects while drawing. Here's a glimpse into some common methods:

Movement:

• forward(distance) or fd(distance): Move the turtle forward by the specified distance.
• backward(distance) or bk(distance): Move the turtle backward by the specified distance.
• right(angle) or rt(angle): Turn the turtle right by the given angle in degrees.
• left(angle) or lt(angle): Turn the turtle left by the given angle in degrees.
• goto(x, y) or setpos(x, y) or setposition(x, y): Move the turtle to a specific position (x, y) on the canvas.

Pen Control:

• pencolor(color): Change the color of the pen for drawing.
• penup(): Lift the pen up, so the turtle won't draw as it moves.
• pendown(): Put the pen down, so the turtle starts drawing again as it moves.
• pensize(width): Set the thickness of the line drawn by the turtle.

Other:

• home(): Move the turtle back to its starting position (center of the canvas) and set its direction to face upwards.
• clear(): Clear the entire drawing on the screen.
• dot(size, color): Draw a small circle (dot) at the turtle's current position.
• speed(speed): Set the animation speed of the turtle (1 being slowest, 10 being fastest).
• done(): Keep the drawing window open until you close it manually. This is typically used at the end of your program.

 

Turtle’s state

Turtle's state in Python's Turtle Graphics depends on the context:

1. Turtle's position and direction: This refers to the turtle's current location (x, y coordinates) on the canvas and the direction it's facing (angle in degrees).

   • Methods like position(), pos(), xcor(), and ycor() retrieve the current coordinates.
   • There's no direct method to get the facing direction, but you can keep track of it yourself based on the last-turn commands (left(angle), right(angle)) used.

2. Turtle's pen state: This refers to whether the pen is currently up (not drawing) or down (drawing as the turtle moves).

   • The penup() method lifts the pen and pendown() puts it down.

3. Turtle's visual state (less common):  This refers to the turtle's appearance on the screen, like its shape or color. While not directly related to the state that affects drawing, it can be part of the overall concept.

• Methods like shape(), pencolor(), and pensize() can modify these visual aspects.

• distance()
• towards()
• xcor()
• ycor()
• position() | pos()
• heading()

Setting and measuring turtle

Python's Turtle Graphics, "setting and measuring" the turtle refers to controlling its various aspects and getting information about its state. Here's a breakdown:

Setting the Turtle:

• Position:
  • goto(x, y) or setpos(x, y) or setposition(x, y): Move the turtle to a specific location (x, y) on the canvas.
• Direction:
  • right(angle) or rt(angle): Turn the turtle right by the given angle (in degrees).
  • left(angle) or lt(angle): Turn the turtle left by the given angle (in degrees).
• Pen:
  • pencolor(color): Change the color of the pen for drawing.
  • penup(): Lift the pen up, so the turtle won't draw as it moves.
  • pendown(): Put the pen down, so the turtle starts drawing again as it moves.
  • pensize(width): Set the thickness of the line drawn by the turtle.
• Other:
  • shape(shape_name): Change the shape of the turtle (default is "turtle").
  • speed(speed): Set the animation speed of the turtle (1 being slowest, 10 being fastest).

Measuring the Turtle (indirectly):

There's no direct way to measure the physical dimensions of the turtle object itself in Turtle Graphics. However, you can indirectly measure the:

• Distance traveled: Keep track of the total distance moved by the turtle using the forward and backward commands.
• The path followed: Store the turtle's positions at different points in your code to reconstruct its path.\

• radians()
• degrees()

Pen control

Pen control is a fundamental aspect of Turtle Graphics in Python. It allows you to manipulate the turtle's pen to create various effects while drawing. Here's a detailed look at pen control methods:

Controlling the Pen State:

• penup(): Lifts the pen up, so the turtle won't draw anything as it moves. This is useful when you want to reposition the turtle without leaving a trail.
• pendown(): Puts the pen down, so the turtle starts drawing again as it moves.

• pendown() | pd() | down()
• penup() | pu() | up()
• pensize() | width()
• pen()
• isdown()

Color control

 color control is a crucial aspect of Turtle Graphics in Python. Here's a breakdown of the methods you can use to manage the turtle's pen color:

Setting Pen Color:

• Using color names: The simplest way is to use predefined color names like "red", "green", "blue", etc.

• color()
• pencolor()
• fillcolor()
• Filling
• filling()
• begin_fill()
• end_fill()

More drawing control

 Turtle Graphics offers various functionalities for more intricate drawing and design in Python. Here are some ways to achieve greater control:

1. Controlling the Turtle's Shape:

• shape(shape_name): Change the appearance of the turtle beyond the default "turtle" shape. Built-in options include "arrow", "circle", "square", and "triangle". You can even create custom shapes using polygons (explained later).

• reset()
• clear()
• write()

Turtle state

The Turtle's state in Python's Turtle Graphics refers to various aspects that define its current configuration and influence its drawing behavior. Here's a breakdown of the key elements of a Turtle's state:

1. Position:

• This represents the turtle's location on the canvas, specified by its X and Y coordinates.
• Methods like position(), pos(), xcor(), and ycor() retrieve these coordinates.

2. Direction (Heading):

• This indicates the direction the turtle is facing, typically measured in degrees (0 pointing right, 90 pointing up, 180 pointing left, and 270 pointing down).
• There's no direct method to get the current heading, but you can track it yourself based on the last turning commands (left(angle), right(angle)) used.

3. Pen State:

• This refers to whether the pen is currently up (not drawing) or down (drawing as the turtle moves).
• The penup() method lifts the pen, and pendown() puts it down.

• Visibility
• showturtle() | st()
• hideturtle() | ht()
• isvisible()

Appearance

Here's a detailed explanation of how to control the appearance of the turtle in Python's Turtle Graphics:

1. Changing the Turtle's Shape:

• shape(shape_name): This method allows you to modify the visual representation of the turtle beyond the default "turtle" shape. The Turtle library provides built-in shapes like "arrow", "circle", "square", and "triangle".

• shape()
• resizemode()
• shapesize() | turtlesize()
• shearfactor()
• settiltangle()
• tiltangle()
• tilt()
• shapetransform()
• get_shapepoly()

Using events

Event handling in Turtle Graphics adds a layer of interactivity to your Python programs. It allows your program to respond to user actions like mouse clicks, key presses, or even timer events. Here's a breakdown of the key event-handling methods:

1. Mouse Click Events:

• onclick(function): This function registers a function to be called whenever the user clicks the left mouse button on the turtle window.

• onclick()
• onrelease()
• ondrag()

Special Turtle methods

While the core Turtle functionality revolves around movement, drawing, and pen control, there are some "special" methods in the Turtle library that offer additional features and functionalities. Here's a glimpse into some noteworthy ones:

1. clone():

This method creates a copy of the current turtle object with all its properties (position, direction, pen state, etc.) However, the cloned turtle operates independently. Changes made to one turtle won't affect the other.

• begin_poly()
• end_poly()
• get_poly()
• clone()
• getturtle() | getpen()
• getscreen()
• setundobuffer()
• undobufferentries()

Methods of TurtleScreen/Screen

In Python's Turtle Graphics, the TurtleScreen class (often referred to as Screen) manages the drawing window where your turtles operate. Here's a detailed breakdown of key methods for controlling its appearance and behavior:

1. Setting Up the Screen:

• setup(width, height, startx, starty) (optional): This method customizes the size and initial position of the TurtleScreen window.
  • width and height: Specify dimensions in pixels (default: depends on system settings).
  • startx and starty: Define the initial screen position relative to the top-left corner of the display (default: centered). Values can be positive (pixels from the left/top) or negative (pixels from the right/bottom).

• bgcolor()
• bgpic()
• clearscreen()
• resetscreen()
• screensize()
• setworldcoordinates()

Animation control

Creating Frame-by-Frame Animations with Turtle Graphics and time.sleep()

While Turtle Graphics isn't a full-fledged animation library, it can be leveraged with time.sleep() from the time module to create simple frame-by-frame animations. 

• delay()
• tracer()
• update()

Using screen events

Here's a comprehensive explanation of using screen events in Turtle Graphics with Python:

Screen Events in Turtle Graphics

Turtle Graphics offers screen events that allow your program to respond to user interactions with the TurtleScreen window. This enables you to create interactive experiences where users can influence the drawing or animation.

• listen()
• onkey() | onkeyrelease()
• onkeypress()
• onclick() | onscreenclick()
• ontimer()
• mainloop() | done()

Settings and special methods

Turtle Graphics, settings and special methods offer functionalities beyond basic drawing and movement. Here's a breakdown of these valuable tools:

Settings:

These settings control various aspects of the turtle's appearance and behavior:

• pencolor(color): Sets the pen color. You can use color names ("red", "green", "blue") or RGB/HSV values as tuples (e.g., (255, 0, 0) for red).
• pensize(width): Sets the pen width (thickness) in pixels.
• penup()/pendown(): Control whether the pen leaves a trail (down) or not (up).
• speed(speed): Sets the animation speed of the turtle's movements. Values range from 1 (slowest) to 10 (fastest). You can also set speed(0) to turn off animation and have the turtle move instantly.
• hideturtle(): Hides the turtle shape on the screen, allowing you to draw lines without seeing the turtle itself.
• showturtle(): Makes the turtle visible again after hiding it.
• setheading(angle): Sets the turtle's heading (direction) in degrees (0 points to the right, 90 points up, etc.).

• mode()
• colormode()
• getcanvas()
• getshapes()
• register_shape() | addshape()
• turtles()
• window_height()
• window_width()

Input methods

While Turtle Graphics itself doesn't have built-in input methods like keyboard presses or mouse clicks, it offers two functions from the turtle module for user input:

1. textinput(title, prompt):

• This function displays a modal dialog box with a title and a prompt message.
• The user can enter text in a text field.
• The function returns the entered text as a string, or None if the user cancels the dialog.

• textinput()
• numinput()

Methods Specific to Screen

While the Turtle class in Python's Turtle Graphics offers various methods for drawing and manipulation, the Screen class (often referred to as turtle.Screen) provides functionalities specific to the drawing window itself. Here's a breakdown of key methods for controlling the TurtleScreen's appearance and behavior:

1. Setting Up the Screen:

• setup(width, height, startx, starty) (optional): This method customizes the size and initial position of the TurtleScreen window.
  • width and height: Specify dimensions in pixels (default: depends on system settings).
  • startx and starty: Define the initial screen position relative to the top-left corner of the display (default: centered). Values can be positive (pixels from the left/top) or negative (pixels from the right/bottom).

• bye()
• exitonclick()
• setup()
• title()

Turtle motion

Turtle Graphics, moving your turtle around the screen is a fundamental aspect of creating drawings and animations. Here's a comprehensive guide to the key methods for turtle motion:

• forward() | fd()
• backward() | bk() | back()
• right() | rt()
• left() | lt()
• goto() | setpos() | setposition()
• teleport()
• setx()
• sety()
• setheading() | seth()
• home()
• circle()
• dot()
• stamp()
• clearstamp()
• clearstamps()
• undo()
• speed()

1. Moving Forward and Backward:

• forward(distance): This method instructs the turtle to move forward a specified distance (in pixels) in the direction it's currently facing.

• backward(distance): This method moves the turtle backward the specified distance.

2. Turning the Turtle:

• right(angle): This method rotates the turtle clockwise by the specified angle (in degrees).

• left(angle): This method rotates the turtle counter-clockwise by the specified angle.

3. Absolute Positioning:

• goto(x, y): This method teleports the turtle to a specific position on the screen. x and y represent the coordinates (in pixels) relative to the origin (top-left corner being 0,0).

4. Setting the Heading:

• setheading(angle): This method sets the turtle's heading (direction) in degrees. 0 points to the right, 90 points up, 180 points to the left, and 270 points down.

5. Pen Control:

• penup(): This method lifts the turtle's pen, so it doesn't draw a line as it moves.

• pendown(): This method lowers the turtle's pen, so it draws a line as it moves.

Tips and Considerations:

• Combine these methods to create various shapes and patterns.
• Experiment with different distances, angles, and pen control to create visual interest.
• Remember that the turtle's direction determines in which direction it will move forward or backward.