Pygame: key.get_pressed() does not coincide with the event queue

For things like movement, you should not check for events (like KEYDOWN or KEYUP), but check every iteration of your mainloop if your movement keys are pressed (using get_pressed).

In your code, you check the pressed keys only if there’s also a KEYDOWN event.

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There are also some other things to consider:

• You should seperate the key-mapping and the speed of your player, so it will be easier later on to change either of this.

• You should determine a movement vector and normalize it first, since otherwise, if your vertical and horizontal movement speed is 10, your diagonal movement speed would be ~14.

Working example:

import pygame

pygame.init()

screen = pygame.display.set_mode((200, 200))
run = True
pos = pygame.Vector2(100, 100)
clock = pygame.time.Clock()

# speed of your player
speed = 2

# key bindings
move_map = {pygame.K_LEFT: pygame.Vector2(-1, 0),
            pygame.K_RIGHT: pygame.Vector2(1, 0),
            pygame.K_UP: pygame.Vector2(0, -1),
            pygame.K_DOWN: pygame.Vector2(0, 1)}

while run:
  for e in pygame.event.get():
    if e.type == pygame.QUIT: run = False

  screen.fill((30, 30, 30))
  # draw player, but convert position to integers first
  pygame.draw.circle(screen, pygame.Color('dodgerblue'), [int(x) for x in pos], 10)
  pygame.display.flip()

  # determine movement vector
  pressed = pygame.key.get_pressed()
  move_vector = pygame.Vector2(0, 0)
  for m in (move_map[key] for key in move_map if pressed[key]):
    move_vector += m

  # normalize movement vector if necessary
  if move_vector.length() > 0:
    move_vector.normalize_ip()

  # apply speed to movement vector
  move_vector *= speed

  # update position of player
  pos += move_vector

  clock.tick(60)