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Overview

The Game class is the core class of Serenity Valley, responsible for initializing Pygame, managing the game loop, handling events, and rendering the game world.

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Class Constants

The following constants are defined at the class level:
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BG_TILE_IMG
string
default:"'images/wood2.png'"
Path to the background tile image
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BUTTON_BGIMG
string
default:"'images/x.png'"
Path to the button background image
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SCREEN_WIDTH
int
default:"580"
Width of the game screen in pixels
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SCREEN_HEIGHT
int
default:"500"
Height of the game screen in pixels
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GRID_SIZE
int
default:"20"
Size of each grid cell in pixels
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FIELD_SIZE
tuple
default:"(400, 400)"
Dimensions of the game field (width, height)

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Constructor

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__init__()

Initializes the Game instance, setting up Pygame, the screen, background, widgets, buttons, and game objects. 
def __init__(self):
This method:
  • Initializes Pygame
  • Sets up the screen display
  • Loads the background tile image
  • Creates UI widgets (message boards, buttons, text entries)
  • Initializes the game clock and world objects
  • Sets up the grid configuration
  • Configures game options

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Methods

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xy2coord()

Converts a pixel coordinate (x, y) to a grid coordinate (row, column). 
def xy2coord(self, pos):
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pos
tuple
A tuple containing the (x, y) pixel position
Returns: A tuple (nrow, ncol) representing the grid coordinate

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coord2xy_mid()

Converts a grid coordinate (row, column) to a pixel position (x, y) at the center of that grid cell. 
def coord2xy_mid(self, coord):
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coord
tuple
A tuple containing the (nrow, ncol) grid coordinate
Returns: A tuple (x, y) representing the pixel position at the center of the grid cell

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get_field_rect()

Returns the internal field rectangle, excluding borders. 
def get_field_rect(self):
Returns: A pygame.Rect object representing the internal game field

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draw_background()

Draws the tiled background image across the entire screen. 
def draw_background(self):
This method calculates how many rows and columns of tiles are needed to cover the screen and blits them accordingly.

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draw_grid()

Draws the grid lines on the game field. 
def draw_grid(self):
Draws horizontal and vertical lines based on GRID_SIZE, grid_nrows, and grid_ncols.

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draw()

The main drawing method that renders the entire game state. 
def draw(self):
This method:
  • Draws the background
  • Draws the grid (if enabled in options)
  • Draws the message board
  • Draws all objects in the world

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run()

The main game loop that handles events, updates game state, and renders frames. 
def run(self):
This method:
  • Limits the frame rate to 30 FPS
  • Processes user input events (keyboard, mouse)
  • Handles pause/unpause functionality
  • Updates game entities
  • Calls the draw method
  • Flips the display buffer
Keyboard Controls:
  • SPACE: Toggle pause
  • G: Toggle grid visibility

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quit()

Exits the game application. 
def quit(self):
Calls sys.exit() to terminate the program.

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Usage Example

if __name__ == "__main__":
    game = Game()
    game.run()

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