PY-1.2-BP1-MQ60

Make a Pygame Window

We will make a Pygame window. We need to give it a name, 'My First Game', and make sure it closes when we click the 'X' button.

Here is what a blank window looks like:

See What's Not Working

Run this command to see what parts of your code are not working yet.

pytest module-1.2/blueprint-1/quest-60

Here's what we expect to see:

  • test_pygame_window_caption_and_loop

Write Your Code

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

Your program needs to set up a Pygame window, give it a title, and make sure it closes correctly.

Here are some examples of how Pygame works. These examples show different parts of a Pygame program. You will need to use these ideas to build your own complete program.

import pygame

def setup_and_teardown():
    pygame.init()
    print("Pygame is ready!")
    pygame.quit()

def create_a_window():
    pygame.init()
    game_display = pygame.display.set_mode((640, 480))
    pygame.display.set_caption("My Game")
    pygame.quit()

def game_loop():
    pygame.init()
    display_surface = pygame.display.set_mode((700, 500))
    is_running = True
    while is_running:
        for game_event in pygame.event.get():
            if game_event.type == pygame.QUIT:
                is_running = False
    pygame.quit()

See If It Works

Run this command again to see if your code works.

pytest module-1.2/blueprint-1/quest-60

Here's what we want to see:

  • test_pygame_window_caption_and_loop

Documentation

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:

  1. Draw onto a hidden surface (the 'back buffer').
  2. 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.