PyGame : ... antialiased filled circle !

The pygame python module does not implement an antialiased filled circle and this is the scope of this tutorial.

The pygame module for drawing shapes are:

• pygame.draw.rect - to draw a rectangle
• pygame.draw.polygon - to draw a polygon
• pygame.draw.circle - to draw a circle
• pygame.draw.ellipse - to draw an ellipse
• pygame.draw.arc - to draw an elliptical arc
• pygame.draw.line - to draw a straight line
• pygame.draw.lines - to draw multiple contiguous straight line segments
• pygame.draw.aaline - to draw a straight antialiased line
• pygame.draw.aalines - to draw multiple contiguous straight antialiased line segments.

Let's install pygame python module.

pip install pygame
Collecting pygame
  Downloading pygame-2.5.2-cp312-cp312-win_amd64.whl.metadata (13 kB)
...
Installing collected packages: pygame
Successfully installed pygame-2.5.2

Let's see the source code:

import pygame
import pygame.gfxdraw

TARGET_SIZE = 200
BG_ALPHA_COLOR = (0, 0, 0, 100)

class Target(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = pygame.Surface((TARGET_SIZE, TARGET_SIZE), pygame.SRCALPHA)
        self.rect = self.image.get_rect()
        self.color = (255, 0, 0)
        self.filled = False
        self.width = 1

    def DrawTarget(self):
        pygame.gfxdraw.aacircle(self.image, int(self.rect.width/2), int(self.rect.height/2),\
                int(self.rect.width/2 - 1), self.color)
        
        pygame.gfxdraw.filled_ellipse(self.image, int(self.rect.width/2), \
            int(self.rect.height/2), int(self.rect.width/2 - 1), int(self.rect.width/2 - 1), self.color)
        
        temp = pygame.Surface((TARGET_SIZE, TARGET_SIZE), pygame.SRCALPHA)
        
        if not self.filled:
            pygame.gfxdraw.filled_ellipse(temp, int(self.rect.width/2), int(self.rect.height/2), \
                int(self.rect.width/2 - self.width), int(self.rect.width/2 - self.width), BG_ALPHA_COLOR)
            pygame.gfxdraw.aacircle(temp, int(self.rect.width/2), int(self.rect.height/2), \
                int(self.rect.width/2 - self.width), BG_ALPHA_COLOR)
        
        self.image.blit(temp, (0, 0), None, pygame.BLEND_ADD)
pygame.init()
screen = pygame.display.set_mode((400, 400))

target = Target()
target.DrawTarget()

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    screen.fill((255, 255, 255))
    screen.blit(target.image, (100, 100))
    pygame.display.flip()

pygame.quit()