Problem 1: Tracing Cars

class Car:
    def __init__(self, color, year):
        self.color = color
        self.year = year
        self.make = 'Toyota'

A = Car('blue', 2008)
A.make = 'Honda'
B = Car('red', 2006)
A.year = B.year
print(A.make, A.color, A.year)

Problem 2a: A Classy Song

• This is a coding problem. Work in pairs or trios on a single computer, and discuss your algorithm BEFORE YOU WRITE ANY CODE.
• Your task:
  • You want to define a class to hold information about a single song
  • You desire to store several attributes: title, artist, and duration_sec
  • Define the class and write the necessary constructor

Problem 2b: Genres

• Swap who is typing!
• Suppose you realized you also want to track genres in your class, and so add as an attribute
• What data-type will the value be that is assigned to the genres attribute? You get to choose, but have a reason for why you chose what you did!
• Implement this new attribute into your class

Problem 2b: Personal Taste

• Swap who is typing!
• For each member in your group, get at least two of their favorite songs
• Create a song object for each song (look up values online as needed) and add them to a list called playlist

Problem 2d: Play Time

• Swap who is typing!
• Write a function that loops through each song in the playlist, and then prints the total playlist duration to the screen.
• Bonus: Also print out all the different genres covered within the playlist

Starting

• ImageShop initially has only two buttons
  • “Load” will bring up a file selection box where you can choose what image to display
    • Internally, this is handled by a function that returns the chosen file path
  • “Flip Vertical” is the example feature button that flips an image vertically

Big Picture

• Each milestone in ImageShop boils down to:
  • Adding a button to the window to handle a new feature
  • Writing a simple callback function that sets the new image to be equal to the output of a new function you’ll write
  • Writing that function, which will generally return a GImage type object
• You are always free to write whatever other helper functions you might like!

So Many Files!

• ImageShop is the first project to start leveraging multi-file layouts:
  • Some functions will already be provided in GrayscaleImage.py that you can import into your main program
  • You are encouraged to write the necessary functions for Milestone 4 in their own file and import them in accordingly
  • I’ve seen you all scrolling madly around trying to find the code you want. This helps with that!
• Just make sure you save a file after editing!
  • See a circle in the tab for a file in VSCode? That file has not been saved!

GButtons

• To help facilitate working with buttons, ImageShop introduces a new type called GButton
• There is nothing magical about these! They are just pre-bundling PGL concepts that you already know like labels and mouse click events
• Each GButton gets a label and a callback function name that determines what function is called when that button is clicked
• ImageShop will come with a pre-defined add_button function which will take care of adding a new button to the correct part of the screen.
  • You’ll just need to provide it a label and function name to callback to

The Current Image

• ImageShop holds the GImage currently displayed on the window in a variable (really an attribute) called gw.current_image
• The variable is specifically added as an attribute to gw so that you will have access to it in any callback function you write
• This will generally be the input to your various image manipulation functions, since most of those functions work with whatever image was currently displayed on the screen
• Your callback function should run set_image on the output of your manipulation function, which will take care of updating the value of gw.current_image and displaying the new image in the window

Milestone 0

• Milestone 0 has you adding a “Flip Horizontal” button
  • Add the button
  • Add the action callback function
  • Write a function to manipulate the pixels to flip the image horizontally
• Slightly more complicated than the example function, but not much

Milestone 1

Milestone 2

• Here you’ll add a button to convert an image to grayscale
• If you understand the other library files that have been given to you as part of the project, this milestone should be the simplest!
• Don’t copy. Import!

Milestone 3

• Here you get to enable a green screen effect!
• Unlike other buttons, when this one is clicked, you should use the file chooser library to prompt the user to select another image
  • This is the image that will be overlaid on whatever image is currently shown on the screen
• You will want to start with an “empty” pixel array with the same dimensions as the background
• This will closely mimic our in-class example from Friday, where depending on how “green” a pixel is, you will choose between different choices
  • If green enough, you will copy the pixel from the background image to your new pixel array
  • If not green enough, you will copy the pixel from the foreground image to your new pixel array

Milestone 4

• Here you’ll implement one algorithm for increasing dynamic contrast across an image!
• Doing so requires several steps and different functions. It can be convenient to place these in their own file and import them into ImageShop.py as needed.
  • Compute all the pixel luminosities
  • Construct a histogram of these luminosity counts
    • Your histogram should have 256 elements, one for each possible luminosity
  • Construct a cumulative histogram using your histogram
  • Use the cumulative histogram to adjust the luminosity of each pixel in the pixel array
• You don’t need to display the visual histograms! But they can be a great way to check that you are doing the other parts correctly.
  • Related to Problem 1 on PSet 5

Extensions

• Give yourself time for extensions on this project!
• They are easy! Just come up with interesting or cool graphical effects and add a button for them!
• You’ll look at several this week in your section meetings
  • Adding these in your project is encouraged and will be regarded as “sub-extensions”, but come up with your own as well!
• Accidentally make a mistake but think it looks cool? Save it! Make it a feature!!