Efficient way of adding one character at a time from one string to another in Python

Question

I'm currently making a function using pygame that draws a message on the screen, adding one character each frame (i.e. The Hunt for Red October). I know that I could simply copy (or pass) gradually bigger slices from the original string, but I know that it would be very resource-intensive. Is there a better way to do this?

Code, using gradually bigger slices:

def full_screen_dialog_tt(thesurface, thefont, theclock, message, thebeep):
 i = 0
 while(i < len(message)): # Initialize the string display
  theclock.tick(60)
  thesurface.fill((0, 0, 0))
  thesurface.blit(thefont.render(message[i]+"_"))
  pygame.display.flip()
  thebeep.play()
 while(1): # Whole string is here now
  theclock.tick(60)
  for event in pygame.events.get():
   if event.type == MOUSEBUTTONDOWN: return

relet · Accepted Answer · 2010-07-27 17:05:40Z

4

In a place where you are intentionally slowing down the game (for the text fade-in) - does it really matter? You could pass the whole string, and change the display routine to display one more letter in every frame.

answered Jul 27, 2010 at 17:05

relet

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1 Comment

mmirate Over a year ago

The frame-rate that I'm passing to pygame.clock.tick is the same 60 that I'm passing to it in the game's main loop. The text isn't "faded" in; it's supposed to look like it's being typed in (either by a keyboard or maybe a slow terminal). As a matter of fact, I may actually have to raise the frame-rate for this segment if I find that it takes forever for long messages to type out - though I'm not sure how many computers could handle it. I guess that if I assumed that there won't be any window manipulation, then I could just blank the surface once.

Noufal Ibrahim · Accepted Answer · 2010-07-27 17:12:09Z

1

Can't you just print the characters one at a time displaced without clearing the background? You can get the character using slicing.

answered Jul 27, 2010 at 17:12

Noufal Ibrahim

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2 Comments

mmirate Over a year ago

Well, I can't just distribute Courier along with the program, and without having a known font to work with, I don't know how many pixels wide or tall it is.

Noufal Ibrahim Over a year ago

The Font object can tell you that pygame.org/docs/ref/font.html#pygame.font.Font. Also, you can distribute a sheet of characters in a custom font along with your game. A Lot of them do that. Read it in as a sprite sheet and render them onto the screen rather than fonts.

Johannes Charra · Accepted Answer · 2010-07-27 17:19:55Z

1

Assuming you're having a screen object available, this might work:

import time
text = 'The Hunt for Red October'
myfont = pygame.font.SysFont("arial", 16)
for index, ch in enumerate(text): 
    letter = myfont.render(ch, True, (0, 0, 0), (255, 255, 255))
    screen.blit(letter, (index * 20, 20))
    time.sleep(1)

edited Jul 27, 2010 at 17:19

answered Jul 27, 2010 at 17:14

Johannes Charra

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1 Comment

mmirate Over a year ago

I'm already using pygame.clock for the timing (clock.tick(framespersecond) to be exact).

SilentGhost · Accepted Answer · 2010-07-27 17:06:23Z

-2

You can access a single character from a string using indexes:

>>> s = 'string'
>>> s[2]
'r'

answered Jul 27, 2010 at 17:06

SilentGhost

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