5. Loading images

Loading images to pygame is rather straightforward. The following code loads image relative to current file from subdirectory called assets. See Paths for more information.

import os
import pygame

pygame.init()

BASE_PATH = os.path.dirname(os.path.abspath(__file__))
image_path = os.path.join(BASE_PATH, "assets/image.png")
surface = pygame.image.load(image_path)

fast_surface = surface.convert()
fast_surface_per_pixel_alpha = surface.convert_alpha()

When looking above code you can notice two special surfaces fast_surface and fast_surface_per_pixel_alpha.

fast_surface is created by using convert() method on surface to convert image to same pixel format as display. This guarantees fastest possible surface for blitting.

You can set one color as transparent. That is also called as blanket alpha. To do that you use surface.set_colorkey(COLOR_HERE). For example surface.set_colorkey((0, 255, 0)) would set bright green as transparent color.

fast_surface_per_pixel_alpha is created by using convert_alpha() method on surface. It works similar way as convert() but additionally sets per pixel alpha. Per pixel alpha means then when you saved image in your image editor tool and you saved the alpha channel with your image every pixel can have their independent transparency (alpha) value set. This could be useful in cases where your image has borders or holes that uses antialiasing on transparent background or you do have images that are semi-transparent.

Note

If image has alpha channel defined convert() will strip it.

If you loaded image with alpha channel or used .convert_alpha() setting blanket alpha won’t work.

5.1. Batch loading images

When you do have multiple images it might come tedious to load images one by one. To help that you can declare function that does loading for you.

The following code is just one way to do this. It’s purpose is to give you ideas how to implement your own.

from pathlib import Path
import pygame

def load_images():
    # Make path relative to current file
    p = Path(__file__).absolute().parent.appendpath("images")
    d = {f.stem: pygame.image.load(f).convert() for f in p.glob("*.png")}
    return d

So what above code actually does?

First directory is determined being relative to Python file where function is and appends “images” to a path and assignd it to variable p. You can change those values to come from the parameters.

Second is dict comprehension. Code generates a dictionary where image name without extension is key and value is loaded image surface.

So when you call images = load_images() images will be a dictionary and you can reference images like images["player"]

To help you to understand above the following code would have same result:

images = {}
images["player"] = pygame.image.load("images/player.png").convert()
images["enemy1"] = pygame.image.load("images/enemy1.png").convert()
images["enemy2"] = pygame.image.load("images/enemy2.png").convert()

Note

Above code is missing proper relative path code due demonstration purposes.