How to efficiently hold a key in Pygame?

Question

I\'ve found two related questions:

• Pygame hold key down causes an infinite loop
• pygame - on hold button down

But I want to be specific. H

Answer 1

I am not familiar with Pygame, but, as I see, the program in it should have an event-based architecture. Unless you get the incoming events and process them, nothing happens. That's why your simple loop becomes infinite: it just does not process events.

while keys[K_DOWN]: # Nobody updates the keys, no events are processed
    print "DOWN"

Then concerning the get_pressed() call. What it returns is a list of keys. So, you are trying to just loop until the key is released. That's a problem. According to this, pygame.event.get() returns immediately even if there are no events in the queue. The call to get() means: my code still has what to do, but I don't want to block the events, so please process the pending events before I continue. If your code is just waiting for an event, that means it has nothing to do.

The function to WAIT (without blocking the inner loop of Pygame) for an event is pygame.event.wait() (the logic is: I have nothing to do in my code until something happens). However, if you use it, you will have to get information about keys pressed or released from the event itself, not from get_pressed().

Here is an example from the comments to the doc page:

for event in pygame.event.get() :
  if event.type == pygame.KEYDOWN :
    if event.key == pygame.K_SPACE :
      print "Space bar pressed down." #Here you should put you program in the mode associated with the pressed SPACE key
    elif event.key == pygame.K_ESCAPE :
      print "Escape key pressed down."
  elif event.type == pygame.KEYUP :
    if event.key == pygame.K_SPACE :
      print "Space bar released."
    elif event.key == pygame.K_ESCAPE :
      print "Escape key released." #Time to change the mode again