We want to make our Pygame window show a solid blue color. This blue color should fill the whole window and stay there as long as the program is running.
This is what a blank Pygame window looks like:
PY-1.2-BP1-MQ51
Our Goal: Paint the Screen Blue!
Check Your Work: See What's Broken
Before we start, let's run a special check to see what parts of our code are not working yet. This helps us know what to fix.
Run this command:
pytest module-1.2/blueprint-1/quest-51
Here's what we expect to see:
- ❌
test_game_loop_draws_blue_and_flips
Time to Code: Paint it Blue!
Now it's your turn to write the code in main.py!
Your job is to make the Pygame window turn blue. You need to tell Pygame to fill the screen with blue color, and then show that blue screen to the player.
Here are some examples of how to fill and update the screen, but remember, these are just examples! You'll need to use the correct color and make sure you update the display.
import pygame
# Example 1: Filling with red and showing it
def paint_red_example():
screen_example = pygame.display.set_mode((400, 300))
RED = (255, 0, 0)
screen_example.fill(RED) # Fill the screen with red
pygame.display.flip() # Show the red screen
# Example 2: Filling with green and showing it
def paint_green_example():
another_screen = pygame.display.set_mode((200, 200))
GREEN = (0, 255, 0)
another_screen.fill(GREEN) # Fill the screen with green
pygame.display.flip() # Show the green screen
Check Your Work Again: Is It Blue?
Now that you've written your code, let's check if it works!
Run this command again:
pytest module-1.2/blueprint-1/quest-51
Here's what we want to see:
- ✅
test_game_loop_draws_blue_and_flips
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.
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 aSurfaceobject representing the window, which is commonly stored in a variable namedscreen.
Setting the Window Title
pygame.display.set_caption("Your Title"): Sets the text that appears in the window's 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.
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
MOUSEMOTIONevent has aposattribute, 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)
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 mainscreensurface) with a single color. This is often used at the beginning of each frame to clear the screen and set the background color.COLORis 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.
