Creating Dynamic Text Using the blit method

Question

I'm creating a basic game where a black square moves around the screen. There are two other squares, a green square and a red square. When the black square collides with the red square it quits the program, when it collides with the green square it adds to your points counter. I've got the red square part down but I'm having trouble creating dynamic text using sprites and classes. Someone from a previous question I asked told me I should blit the score to the screen and then re-blit it every time the square collided with the green square. I don't know how to properly do this however. Here is my code:

import os, sys
import pygame
from pygame.locals import *

pygame.init()
mainClock = pygame.time.Clock()

WINDOWWIDTH = 1000
WINDOWHEIGHT = 700
windowSurface = pygame.display.set_mode((WINDOWWIDTH, WINDOWHEIGHT), 0, 32)
pygame.display.set_caption("Avoid!")

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

player = pygame.Rect(500, 300, 40, 40)
playerImage = pygame.Surface((40, 40))

enemy = pygame.Rect(300, 400, 20, 20)
enemyImage = pygame.Surface((20, 20))
enemyImage.fill((RED))

food = pygame.Rect(300, 500 , 20, 20)
foodImage = pygame.Surface((20, 20))
foodImage.fill((GREEN))

class Score(pygame.sprite.Sprite):
    """A sprite for the score."""

    def __init__(self, xy):
        pygame.sprite.Sprite.__init__(self)
        self.xy = xy    # save xy -- will center our rect on it when we change the score
        self.font = pygame.font.Font(None, 50)  # load the default font, size 50
        self.color = (BLACK)         # our font color in rgb
        self.score = 0  # start at zero
        self.reRender() # generate the image

    def update(self):
        pass

    def add(self, points):
        """Adds the given number of points to the score."""
        if player.colliderect(food):
            my_score.score += points
        self.reRender()

    def reset(self):
        """Resets the scores to zero."""
        self.score = 0
        self.reRender()

    def reRender(self):
        """Updates the score. Renders a new image and re-centers at the initial coordinates."""
        self.image = self.font.render("%d"%(self.score), True, self.color)
        self.rect = self.image.get_rect()
        self.rect.center = self.xy

my_score = Score((75, 575))
print my_score.score

font = pygame.font.Font(None, 36)
text = font.render("%d" % (my_score.score), 1, (10, 10, 10))
textpos = text.get_rect(centerx=windowSurface.get_width()/2)

moveLeft = False
moveRight = False
moveUp = False
moveDown = False

MOVESPEED = 6

while True:
    for event in pygame.event.get():
        if event.type == QUIT:
            pygame.quit()
            sys.exit()
        if event.type == KEYDOWN:
            if event.key == K_LEFT:
                moveRight = False
                moveLeft = True
            if event.key == K_RIGHT:
                moveLeft = False
                moveRight = True
            if event.key == K_UP:
                moveDown = False
                moveUp = True
            if event.key == K_DOWN:
                moveUp = False
                moveDown = True
        if event.type == KEYUP:
            if event.key == K_ESCAPE:
                pygame.quit()
                sys.exit()
            if event.key == K_LEFT:
                moveRight = False
                moveLeft = True
            if event.key == K_RIGHT:
                moveLeft = False
                moveRight = True
            if event.key == K_UP:
                moveDown = False
                moveUp = True
            if event.key == K_DOWN:
                moveUp = False
                moveDown = True

    windowSurface.fill(WHITE)

    if moveDown and player.bottom < WINDOWHEIGHT:
        player.top += MOVESPEED
    if moveUp and player.top > 0:
        player.top -= MOVESPEED
    if moveLeft and player.left > 0:
        player.left -= MOVESPEED
    if moveRight and player.right < WINDOWWIDTH:
        player.right +=MOVESPEED

    if player.colliderect(enemy):
        pygame.quit()
        sys.exit()

    windowSurface.blit(playerImage, player)
    windowSurface.blit(enemyImage, enemy)
    windowSurface.blit(foodImage, food)
    windowSurface.blit(text, textpos)

    score = Score((75, 575))

    pygame.display.update()
    mainClock.tick(40)

Do I put windowSurface.blit(text, textpos) into the add function within the Score class? How do I increase the score once the big square touches the little green square?

Answer 1

Honestly, I don't think you really need a separate class for the score, you can just have an add score method which is called whenever the rects for the big and little squares collide:

def addScore():
     global score
     score += 1 #just increasing thescore
     if pygame.font: #checking if the font loading correctly, this section is taken directly from the Chimp Line by Line tutorial
          font = pygame.font.Font(None, 36)
          text = font.render("score: " + str(score), 1, (10, 10, 10))
          textpos = text.get_rect(centerx=background.get_width()/2)
          background.blit(text, textpos)

Note: I haven't tested this myself within python

Does this work for you?