Display text in pygame with a "typewriter" effect

Question

I'm trying to make an RPG game using PyGame and I've done some searching and can't find a simple way to display text on the screen with a "typewriter" effect (each letter appearing letter by letter as if it was being typed). I've been trying to use other modules, and looking at other answers on StackOverflow, but none of it has worked for me so far. Any help would be appreciated. I'm trying to do this with as little code as I can, as currently it's very messy. The code so far can be found on my Github. https://github.com/LucasGlennieOC/classroom I tried to work out how to use Typewriter Effect Pygame in my game, but it didn't work.

Answer 1

A simple way to implement this is to use a clock to periodically re-render the bitmap of the text to include more and more letters.

#! /usr/bin/python3
import pygame
import sys

WIDTH = 600
HEIGHT= 300

WHITE = (255,255,255)
BLACK = (  0, 0, 0)

pygame.init()
window = pygame.display.set_mode( ( WIDTH, HEIGHT ) )
pygame.display.set_caption( "Typewriter Effect" )

font = pygame.font.Font( None, 30 )
text = 'The Owl and the Pussy-cat went to sea'
text_cursor  = 0   # what length of text is shown
text_image   = font.render( '*', True, BLACK )  # starting image
typing_speed = 50  # milliseconds, smaller is faster
next_update  = 0   # time (in future) next letter is added


while True:
    clock = pygame.time.get_ticks()   # time now

    # Handle events
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            exit()

    # paint the window
    window.fill( (0,0,0 ) )  # paint it black
    window.blit( text_image, ( 0,0 ) )

    # Is it time to type another letter
    if ( clock > next_update ):
        # Set the time for the *next* letter-add
        next_update = clock + typing_speed  # in the future
        if ( text_cursor < len( text ) ):
        # Update the text
        text_cursor += 1
        # Re-make the text-bitmap with another letter
        text_image = font.render( text[0:text_cursor], True, WHITE )

    pygame.display.flip()

The above demonstrates the algorithm, but it is not very efficient.