Programming Project 10 Solution

Assignment Overview

This assignment will give you the opportunity to make up some classes and use them in turtle graphics to do some drawing.


Background

We are going to make three: five-pointed stars, rectangles and flags that consist of various combinations of those stars and rectangles. We will read in, from text files, some specifications so that we may draw some flags

There are a lot of flags out there, many with similar elements. Take a look at:

http://commons.wikimedia.org/wiki/Flags_with_stars

Many of these flags can be drawn with our two constructs. Here are two we will draw:



Flag of Senegal
Flag of Panama



Requirements

You are going to create the following classes and their methods
    • Star class:
        o __init__ (self, x, y, arm_length, color)
        o draw(self, turtle)

        o __str__(self)

    • Rectangle class:

        o __init__ (self, x,y,width,height,color)

        o draw(self, turtle)
        o __str__(self)

    • Flag class:

        o __init__(self, file_object)
    o draw(self, turtle)
    o __str__(self)
Star Class

Here's the geometry.





































    • __init__ (self, x, y, arm_length, color)

    • draw(self, turtle). It draws the star centered at the given x,y coordinates using the provided turtle.

    • __str__(self) method returns string of the form: 'Star: x:int, y:int, arm:int, color:str' . For example:

o  s = Star(100, 200, 50, 'green')

o  str(s) à 'Star x:100, y:200, arm:50, color:green'

Rectangle Class

Shouldn't need any geometry for rectangles.

    • __init__ (self, x,y,width,height,color)

•    draw(self, turtle) draws the rectangle centered at the given x,y coordinates using the provided turtle

    • __str__(self) method returns string of the form: 'Rectangle: x:int, y:int, width:int, height:int,
color:str'. For example

o  r = Rectangle(100,200,300,300,'blue')

o    str(s) à 'Rectangle x:100, y:200, width:300, height:300, color:blue'

Flag Class

The flag class works based on a text file specification of a flag. The textfile has the following format:
single int, number of rectangle specifications that follow

each line is a rectangle specification of the form x,y,width,height,color using comma separated values single int, number of stars to follow
each line is a star specification of the form x,y,arm_length,color using comma separated values

Below is the specification for the flag of Senegal (included in the project). 3 rectangles, 1 star 3
-200, 0, 200, 400, green

0,0,200,400, yellow

200,0,200,400, red
1

0,0,50, green

    • __init__(self, f_obj). The f_obj is an open text file that specifies a flag (as described) o it makes an instance for each rectangle line and stores it

o  it makes an instance for each star and stores it

    • draw(self, turtle). Draw all the rectangles and stars read in from the file specification using the turtle parameter

    • __str__(self): Returns a multiline string. For example:

    o f = Flag(Senegal_file_obj) o str(f) à
"Rectangles

x:-200, y:0, w:200, h:400, c:green x:0, y:0, w:200, h:400, c:yellow x:200, y:0, w:200, h:400, c:red Stars

x:0, y:0, a:50, c:green"

Deliverables

You must use handin two things this time:
    • your proj10.py

    • a flag specification called myFlag.txt Hard to draw flags (complicated flags, not like the ones I provided) will have potential to garner extra points!!!!!

Other good information

    1. Two flag specification files are provided in the project directory. Take a look at them.
    2. I provided a main.py for you to work with. You may copy it into your solution.

    3. Pick a flag from the website provided above to make the specifications for your own flag

    4. The readline() method of an opened file_obj is very useful here. It reads exactly one line at a time from the file. Since you know what the first line will be (an integer describing the number of rectangle lines to follow), you know what every line in the file will be and can read them appropriately using readline().

    5. It gets irritating to have to watch the turtle slowly draw. The setting pen.speed('fastest') makes it draw very quickly but you need to delay between flags to see the result. In the time module is a method time.sleep(seconds) where you can specify a delay in seconds. The main.py uses this.

    6. If you get some weird errors with colors, ask yourself: did you strip the color specification when you read it in? 'green' != ' green ' (see the spaces, I tripped on that)

7.