First Dialogue Box - python-3.x

Question

I'm in my early days of pygame coding, but here is the piece I am trying to figure out right now, which is to draw the dialogue box, then the text on top of it. When ran, I see the displayed dialogue box, but no text.
import pygame
from pygame.locals import *
import os
pygame.init()
SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
screen = pygame.display.set_mode([SCREEN_WIDTH, SCREEN_HEIGHT])
class Text(pygame.sprite.Sprite):
def __init__(self, text):
# Call the parent class (Sprite) constructor
pygame.sprite.Sprite.__init__(self)
os.chdir(r"<my directory to the dialogue box>.png")
self.surf = pygame.image.load("spikey_box.png").convert()
os.chdir(r"<my directory to my font>")
self.font = pygame.font.Font("final_fantasy_36_font.ttf", 12)
# set up dialogue box sprite
self.rect = self.surf.get_rect()
self.rect.center = (400, 500)
screen.blit(self.surf, self.rect)
# for text
self.textSurf = self.font.render(text, True, (255, 255, 255))
self.textRect = self.textSurf.get_rect()
self.textRect.center = (400, 500)
screen.blit(self.textSurf, self.textRect)
test_message = Text("Hello, world!")
running = True
clock = pygame.time.Clock()
while running:
for event in pygame.event.get():
if event.type == KEYDOWN:
if event.key == K_ESCAPE:
running = False
elif event.type == QUIT:
running = False
pressed_keys = pygame.key.get_pressed()
screen.fill((255, 255, 255))
screen.blit(test_message.surf, test_message.rect)
pygame.display.flip()
clock.tick(30)
pygame.quit()
I have some sample code that I was able to adapt a little and make work for another piece I'm working on that I tried to use for inspiration to build the class:
def text_objects(text, font):
textSurface = font.render(text, True, (0, 0, 0))
return textSurface, textSurface.get_rect()
def message_display(text):
largeText = pygame.font.Font('freesansbold.ttf', 20)
TextSurf, TextRect = text_objects(text, largeText)
TextRect.center = ((SCREEN_WIDTH//2), (SCREEN_HEIGHT//2))
screen.blit(TextSurf, TextRect)
The set of two functions were defined outside of the game loop, and worked fine when called from within the game loop as {message_display(f-string)}. I respectfully request guidance to learn how to ask the right question to figure out how to make the class implementation work. I want to build on it to the point that I can call the dialogue window and allow the player to scroll back over dialogue already given in that instanced conversation.
Thank you in advance!

Answer 1

When you make a PyGame Sprite based on pygame.sprite.Sprite, you must define two variables as a minimum:
sprite.image - used to hold the sprite bitmap
sprite.rect - defines the location and size of the .image
Your Text Sprite does not appear to be creating the .image so it wont work as a normal sprite. But since you directly blit() the Text.surf to the display, you've dodged this issue for now.
The code is not writing the text image on top of the background dialogue. It's writing it directly to the screen in the sprite __init__(). Once the sprite is constructed, this screen update is lost.
Probably you need something like:
class Text(pygame.sprite.Sprite):
def __init__(self, text):
# Call the parent class (Sprite) constructor
pygame.sprite.Sprite.__init__(self)
os.chdir(r"<my directory to the dialogue box>.png")
self.image = pygame.image.load("spikey_box.png").convert()
os.chdir(r"<my directory to my font>")
# Draw the text, centred on the background
self.font = pygame.font.Font("final_fantasy_36_font.ttf", 12)
text = self.font.render(text, True, (255, 255, 255))
centre_x = ( self.rect.width - text.get_width() ) // 2
centre_y = ( self.rect.height - text.get_height() ) // 2
self.image.blit( text, ( centre_x, centre_y ) )
# Set the rect
self.rect = self.image.get_rect()
self.rect.center = (400, 500)
Which loads the dialogue background image, and then rendered the text centred into that box so there is just a single image.
Since surf has been renamed to image, the main loop needs a tweak:
...
screen.fill((255, 255, 255))
screen.blit(test_message.image, test_message.rect)
pygame.display.flip()
clock.tick(30)
pygame.quit()
But really the code should use the PyGame Sprite functions for drawing, rather than accessing the internal Surface directly.

Answer 2

Thank you #Kingsley for your input, and you're definitely right, and helped point me in the right direction. I found that the issue was how I was instantiating the class object, and performing an odd call in the game loop that didn't really make sense. I was trying to blit a blit. I restructured my class object, and it now works perfectly!
class Text(pygame.sprite.Sprite):
def __init__(self):
# Call the parent class (Sprite) constructor
pygame.sprite.Sprite.__init__(self)
os.chdir(r"C:\Users\mcbri\Documents\Python\master\Resources\pv1\pv1_objects")
self.surf = pygame.image.load("spikey_box.png").convert() #for box
os.chdir(r"C:\Users\mcbri\Documents\Python\master\Resources\fonts")
self.font = pygame.font.Font("final_fantasy_36_font.ttf", 12)
self.rect = self.surf.get_rect()
self.rect.center = (400, 500)
def pop_message(self, text):
screen.blit(self.surf, self.rect)
self.textSurf = self.font.render(text, True, (255, 255, 255))
self.textRect = self.textSurf.get_rect()
self.textRect.center = (400, 500)
screen.blit(self.textSurf, self.textRect)
...in loop:
elif event.type == QUIT:
running = False
pressed_keys = pygame.key.get_pressed()
screen.fill((255, 255, 255))
test_message.pop_message("Hello, world!")
pygame.display.flip()
clock.tick(30)
Thank you so much for the fast input!