Now it's your turn to write the code in main.py!

Your job is to make your program listen for things that happen in Pygame. When something happens, you need to print it out so you can see what it is.

Here are some examples of how to loop through things and print them, but remember, these are just examples! You'll need to use pygame.event.get() to get the events.

import pygame

# Example 1: Looping through a list and printing
def print_items_example():
    my_list = ["apple", "banana", "cherry"]
    for item in my_list:
        print(item)

# Example 2: Getting Pygame events (without printing them directly)
def check_pygame_events_example():
    # This gets all the events that have happened
    events = pygame.event.get()
    for one_event in events:
        # You would do something with 'one_event' here
        pass

Pygame Basics: Blueprint 1 Reference

This document provides a quick reference for fundamental Pygame concepts covered in the initial setup of a game window and basic event handling.

1. Getting Started

Before using Pygame, the library must be imported and initialized.

Initialization and Shutdown

pygame.init(): Prepares all the Pygame modules for use. This function should be called once at the very beginning of a Pygame program.
pygame.quit(): Shuts down all the Pygame modules. This function should be called once at the very end, typically after the main game loop has finished.

A simple animation or diagram illustrating the init/quit process.

2. The Game Window

The visual output of a Pygame program appears in a window, referred to as the display surface.

Creating the Display Surface (Screen)

screen = pygame.display.set_mode((width, height)): Creates the main window with the specified dimensions (width and height in pixels). The function returns a Surface object representing the window, which is commonly stored in a variable named screen.

Setting the Window Title

pygame.display.set_caption("Your Title"): Sets the text that appears in the window's title bar.

An image of a blank Pygame window with a title bar.

3. The Game Loop

A game program typically runs continuously, checking for input, updating game elements, and drawing to the screen many times per second. This is managed by a main loop.

Purpose and Basic Structure

The game loop keeps the program running. A common structure uses a variable to control the loop's execution.

running = True
while running:
    # Code inside the loop runs repeatedly
    pass # Placeholder for game logic

# Code outside the loop runs after the loop finishes

When the condition controlling the while loop becomes False, the loop terminates, and the program can proceed to shut down.

A diagram showing the game loop cycle (Events -> Update -> Draw -> Flip).

4. Handling Events

Events are how Pygame detects user input (like key presses, mouse movement, window closing) and other occurrences.

Fetching Events

pygame.event.get(): This function retrieves all events that have occurred since the last time it was called. It returns a list of event objects. This should be called once per frame inside the game loop.

Processing Events

The standard approach is to loop through the list of events obtained from pygame.event.get() and check the type attribute of each event.

for event in pygame.event.get():
    # Check the type of the event
    if event.type == SOME_EVENT_TYPE:
        # Respond to this specific event
        pass

Checking Specific Event Types

Pygame defines constants for different event types:

pygame.QUIT: Triggered when the user clicks the window's close button (the 'X').
pygame.KEYDOWN: Triggered when a keyboard key is pressed down.
pygame.MOUSEMOTION: Triggered when the mouse cursor moves within the window.

for event in pygame.event.get():
    # Check if the user clicked the window's 'X' button
    if event.type == pygame.QUIT:
        # Handle quitting
        pass

    # Check if any key was pressed down
    if event.type == pygame.KEYDOWN:
        # Handle key press
        pass

    # Check if the mouse was moved
    if event.type == pygame.MOUSEMOTION:
        # Handle mouse movement
        pass

Inspecting Event Data

Event objects carry additional information as attributes.

Inspecting All Data: To see all data associated with an event, you can print its internal dictionary using the __dict__ attribute. This is useful for exploration and debugging.
```
if event.type == pygame.KEYDOWN:
    # Prints all data associated with the key press event
    print(event.__dict__)
```
Accessing Specific Attributes: Specific event types have specific attributes. For example, the MOUSEMOTION event has a pos attribute, which is a tuple (x, y) representing the mouse coordinates.
```
if event.type == pygame.MOUSEMOTION:
    # Prints the current (x, y) coordinates of the mouse
    print(event.pos)
```

A console showing event data being printed, possibly highlighting __dict__ or pos output.

5. Drawing

Drawing in Pygame involves preparing the visual content and then making it visible on the screen.

The Drawing Process

Drawing is typically a two-step process per frame:

Draw onto a hidden surface (the 'back buffer').
Swap the hidden surface with the currently visible surface (the 'front buffer') to show the completed drawing.

Filling the Background

surface.fill(COLOR): Fills the entire surface (like the main screen surface) with a single color. This is often used at the beginning of each frame to clear the screen and set the background color. COLOR is usually an RGB tuple like (255, 0, 0) for red.

Updating the Display

pygame.display.flip(): Updates the entire screen to show everything that has been drawn since the last update. This function should be called once per frame after all drawing operations are complete.

A diagram showing a hidden "back" surface being drawn on, and then the flip() operation swapping it with the visible "front" surface.

PY-1.2-BP1-MQ40

Our Goal: Listen to Pygame!

Check Your Work: See What's Broken

Time to Code: Listen to Events!

Check Your Work Again: Did It Listen?

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