├── intro_ball.gif
├── README.md
└── main.py


/intro_ball.gif:
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https://raw.githubusercontent.com/AlexElvers/pygame-with-asyncio/HEAD/intro_ball.gif


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/README.md:
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 1 | # pygame with asyncio
 2 | This is a simple example how to connect pygame with asyncio.
 3 | 
 4 | The example uses a queue for handling pygame events. It runs a loop (`pygame_event_loop`) that is requesting pygame events with blocking (`pygame.event.wait()`). Using `pygame.event.get()` would produce high CPU load because it is not blocking. This event loop is started with `run_in_executor` that uses a thread pool (you could set the size of the thread pool to 1). A direct call from the main thread would not work because asyncio expects that functions use `await` for blocking operations (or `yield from` in older Python versions). The asyncio queue is not thread safe, so you have to use `run_coroutine_threadsafe` for putting events on the queue.
 5 | 
 6 | Handling events now works by using `await event_queue.get()` in a coroutine.
 7 | 
 8 | ```python
 9 | def pygame_event_loop(loop, event_queue):
10 |     while True:
11 |         event = pygame.event.wait()
12 |         asyncio.run_coroutine_threadsafe(event_queue.put(event), loop=loop)
13 | ```
14 | 
15 | The image of the ball is copied from the pygame documentation.
16 | 


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/main.py:
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 1 | #!/usr/bin/env python
 2 | 
 3 | import asyncio
 4 | import time
 5 | 
 6 | import pygame
 7 | 
 8 | 
 9 | FPS = 100
10 | width, height = 700, 400
11 | 
12 | 
13 | class Ball:  # using a Sprite would be better
14 |     def __init__(self):
15 |         self.ball = pygame.image.load("intro_ball.gif")
16 |         self.rect = self.ball.get_rect()
17 |         self.speed = [2, 2]
18 | 
19 |     def move(self):
20 |         self.rect = self.rect.move(self.speed)
21 |         if self.rect.left < 0 or self.rect.right > width:
22 |             self.speed[0] = -self.speed[0]
23 |         if self.rect.top < 0 or self.rect.bottom > height:
24 |             self.speed[1] = -self.speed[1]
25 | 
26 |     def draw(self, screen):
27 |         screen.blit(self.ball, self.rect)
28 | 
29 | 
30 | def pygame_event_loop(loop, event_queue):
31 |     while True:
32 |         event = pygame.event.wait()
33 |         asyncio.run_coroutine_threadsafe(event_queue.put(event), loop=loop)
34 | 
35 | 
36 | async def animation(screen, ball):
37 |     black = 0, 0, 0
38 | 
39 |     current_time = 0
40 |     while True:
41 |         last_time, current_time = current_time, time.time()
42 |         # call usually takes  a bit longer than ideal for framerate, so subtract from next wait
43 |         # sleeptime = 1/FPS - delayed = 1/FPS - (now-last-1/FPS)
44 |         # also limit max delay to avoid issues with asyncio.sleep() returning immediately for negative values
45 |         await asyncio.sleep(min(1 / FPS - (current_time - last_time - 1 / FPS), 1 / FPS))  # tick
46 |         ball.move()
47 |         screen.fill(black)
48 |         ball.draw(screen)
49 |         pygame.display.flip()
50 | 
51 | 
52 | 
53 | async def handle_events(event_queue, ball):
54 |     while True:
55 |         event = await event_queue.get()
56 |         if event.type == pygame.QUIT:
57 |             break
58 |         elif event.type == pygame.KEYDOWN:
59 |             if event.key == pygame.K_SPACE:
60 |                 if ball.speed == [0, 0]:
61 |                     ball.speed = [2, 2]
62 |                 else:
63 |                     ball.speed = [0, 0]
64 |         else:
65 |             print("event", event)
66 |     asyncio.get_event_loop().stop()
67 | 
68 | 
69 | def main():
70 |     loop = asyncio.get_event_loop()
71 |     event_queue = asyncio.Queue()
72 | 
73 |     pygame.init()
74 | 
75 |     pygame.display.set_caption("pygame+asyncio")
76 |     screen = pygame.display.set_mode((width, height))
77 | 
78 |     ball = Ball()
79 | 
80 |     pygame_task = loop.run_in_executor(None, pygame_event_loop, loop, event_queue)
81 |     animation_task = asyncio.ensure_future(animation(screen, ball))
82 |     event_task = asyncio.ensure_future(handle_events(event_queue, ball))
83 |     try:
84 |         loop.run_forever()
85 |     except KeyboardInterrupt:
86 |         pass
87 |     finally:
88 |         pygame_task.cancel()
89 |         animation_task.cancel()
90 |         event_task.cancel()
91 | 
92 |     pygame.quit()
93 | 
94 | 
95 | if __name__ == "__main__":
96 |     main()
97 | 


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