An Introduction To Python - Graphics

An Introduction To Software

Development Using Python

Spring Semester, 2015

Class #4.5:

Graphics

How To Do Graphics In Python?You

Tkinter / Ttk

Tkinter is Python's

de-facto standard

GUI (Graphical User

Interface) package.

Turtle

PythonTurtle strives to provide

the lowest-threshold way to

learn (or teach) software

development in the Python

programming language.

What Is Turtle Graphics?

• Logo is an educational programming language, designed in 1967 by Daniel G. Bobrow, Wally Feurzeig, Seymour Papertand Cynthia Solomon.

• Today the language is remembered mainly for its use of "turtle graphics", in which commands for movement and drawing produced line graphics either on screen or with a small robot called a "turtle".

Image Credit: el.media.mit.edu

What Is Turtle In Python?

• Imagine a robotic turtle starting at (0, 0) in the x-y plane.

• Execute the import turtle Python command

• Now give it the command turtle.forward(15), and it moves (on-screen!) 15 pixels in the direction it is facing, drawing a line as it moves.

• Give it the command turtle.right(25), and it rotates in-place 25 degrees clockwise.

Image Credit: www.turtlemob.com

Tic-Tac-Toe: What It Is

X

O

Turtle Motion

• turtle.forward(distance)

• turtle.back(distance)

• turtle.right(angle)

• turtle.left(angle)

• turtle.goto(x, y=None)

• turtle.setx(x)

• turtle.sety(y)

• turtle.home()

Image Creditmegaicons.net

Turtle Heading

• turtle.setheading(to_angle)

Turtle Pen Control

• turtle.pendown()

• turtle.penup()

• turtle.pensize(width=None)

Image www.clipartpanda.com

Turtle Color Control

• turtle.pencolor(*args)

• turtle.fillcolor(*args)

Image www.clipartlord.com

Tic-Tac-Toe: What It Is

(0,0)

(-200,+200) (+200,+200)

(+200,-200)(-200,-200)

(-100,+200) (+100,+200)

(-100,-200) (+100,-200)

(-200,-75)

(-200,+75)

(+200,-75)

(+200,+75)

Drawing The First Vertical Line#

# Python program to use the Turtle library to draw a Tic-Tac-Toe board

#

# Spring Semester, 2015

#

#

# Get Turtle library

import turtle

# Configure Turtle to draw thick red lines

turtle.pensize(10)

turtle.color("red")

# Lift the pen and move to the top of the left vertical line

turtle.penup()

turtle.goto(-110, 200)

# Put the pen down, point South, and move to bottom of Tic-Tac-Toe grid

turtle.pendown()

turtle.setheading(270)

turtle.forward(400)

(-100,+200)

(-100,-200)

Drawing The Second Vertical Line# Draw the second vertical line

#

# Lift the pen up and move to the top of the second vertical line

turtle.penup()

turtle.goto(100, 200)

# Put the pen down, point South, and move to bottom of Tic-Tac-Toe grid

turtle.pendown()


turtle.forward(400)(+100,+200)

(+100,-200)

Draw The Top Horizontal Line# Draw the top horizontal line

#

# Lift the pen up and move to the leftmost start of the top horizontal line

turtle.penup()

turtle.goto(-200,100)

# Put the pen down, point East, and move to right hand side of Tic-Tac-Toe grid

turtle.pendown()


turtle.forward(400)

(-200,+75) (+200,+75)

Draw The Bottom Horizontal Line# Draw the bottom horizontal line

#

# Lift the pen up and move to the leftmost start of the bottom horizontal line

turtle.penup()

turtle.goto(-200,-100)

# Put the pen down, point East, and move to right hand side of Tic-Tac-Toe grid

turtle.pendown()


turtle.forward(400)

(-200,-75) (+200,-75)

Turtle Circles

• turtle.circle(radius, extent=None, steps=None)

• Draw a circle with given radius. The center is radius units left of the turtle; extent –an angle – determines which part of the circle is drawn. If extent is not given, draw the entire circle. If extent is not a full circle, one endpoint of the arc is the current pen position. Draw the arc in counterclockwise direction if radius is positive, otherwise in clockwise direction. Finally the direction of the turtle is changed by the amount of extent.

• As the circle is approximated by an inscribed regular polygon, steps determines the number of steps to use.

Adding An “O” To Tic-Tac-Toe

The “O” goes here!

“O” Code# Add an "O" to the tic-tac-toe grid

#

# Lift pen, move to center, put pen down, draw a circle

turtle.penup()

turtle.goto(0,-50)

turtle.pendown()

turtle.circle(50)

Adding An “X” To Tic-Tac-Toe

The “X” goes here!

“X” Code# Add an "X" to the tic-tac-toe grid

#

# Lift pen, move to bottom left of upper left square

turtle.penup()


turtle.pendown()

# Point pen in north east direction and draw a line



# Lift pen, move to upper left of upper left square

turtle.penup()


turtle.pendown()

# Point pen in north east direction and draw a line



Turtle Extras• turtle.dot(size=None, *color)

• turtle.stamp()

• turtle.clearstamp(stampid)

• turtle.clearstamps(n=None)

• turtle.undo()

• turtle.speed(speed=None)– If input is a number greater than 10 or smaller than 0.5, speed is set to 0. Speedstrings

are mapped to speedvalues as follows:

• “fastest”: 0

• “fast”: 10

• “normal”: 6

• “slow”: 3

• “slowest”: 1

Turtle Stamp

Image www.webweaver.nu

Turtle State

• turtle.position()

• turtle.towards(x, y=None)

• turtle.xcor()

• turtle.ycor()

• turtle.heading()

• turtle.distance(x, y=None)

Image www.clipartbest.com

Turtle Pen Control

• turtle.pendown()

• turtle.penup()

• turtle.pensize(width=None)

• turtle.isdown()

Image 4vector.com

Turtle Filling

• turtle.begin_fill()

• turtle.end_fill()

Image www.dreamstime.com

What We Covered Today

1. Turtle graphics

2. Drawing lines

3. Drawing circles

4. Filling shapes

Image Credit: http://www.tswdj.com/blog/2011/05/17/the-grooms-checklist/

What We’ll Be Covering Next Time

1. IF Statement

2. Relational Operators

Image Credit: http://merchantblog.thefind.com/2011/01/merchant-newsletter/resolve-to-take-advantage-of-these-5-e-commerce-trends/attachment/crystal-ball-fullsize/

Education

An Introduction To Python - Graphics