Why is blitting images on the screen making my game very very slow?

user_16565396 0
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im blitting a health bar onto the screen and seems like blitting the images on screen is causing the problem, i removed the for loop and whenever im making the player jump it seems like the performance is very very bad and when i remove the entire function the player was moving fast and jumping fast rather than being very very slow. What could be causing this issue? /(pls forget about the screens[0].blit that has nothing to do with the problem)

code:

def lives(lives_image1, lives_image2, x,y,lives_amount,lives_amount2, draw_lives):
    if len(screens) >= 1:
        if draw_lives:
            for i in range(lives_amount2):
                screens[0].blit(pygame.image.load(lives_image2),(x + pygame.image.load(lives_image2).get_width() * i,y))
            for i in range(lives_amount):
                screens[0].blit(pygame.image.load(lives_image1), (x + pygame.image.load(lives_image1).get_width() * i,y))
    if lives_amount <= 0:
        lives_amount = 0
    return lives_amount
    pass
game-development pygame python
1 Answers

Your application is slow because you are loading the images from the file every frame. Load the images once before the application loop, but blit them every frame:

def load_lives(lives_image)
    return pygame.image.load(lives_image);

def lives(lives1_surf, lives2_surf, x, y, lives_amount, lives_amount2, draw_lives):
    if len(screens) >= 1:
        if draw_lives:
            for i in range(lives_amount2):
                screens[0].blit(lives2_surf,(x + lives2_surf.get_width() * i, y))
            for i in range(lives_amount):
                screens[0].blit(lives1_surf, (x + lives1_surf.get_width() * i, y))
    if lives_amount <= 0:
        lives_amount = 0
    return lives_amount

lives1_surf = load_lives(lives_image1);
lives2_surf = load_lives(lives_image2);

while run:
    # [...]

    lives(lives1_surf, lives2_surf, ......)

    # [...]

Note that pygame.image.load is a very expensive operation. This function needs to load the image file from disk and finally needs to the decode the image.

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