Pygskin 0.1.0

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Pygskin

A collection of useful functions and classes for Pygame

animate function

Animation generator function which takes a list of frames or mapping of quotients (0.0 - 1.0) to keyframes and a function that returns a quotient, and returns an generator that returns frames.

anim = animate([image1, image2], timer.quotient)
screen.blit(next(anim), (0, 0))

TODO

• Support duration and loop_count arguments
• send delta time to the generator?

Assets class

Provides attribute access to asset files and batch loading

assets = Assets()
screen.blit(assets.player, (0, 0))
assets.player_spawn_sfx.play()

TODO

• Wrap all assets with LazyObject to avoid loading assets at import time

Timer class

A countdown timer dataclass. Can be used with the animate function.

timer = Timer(3000)  # 3 seconds
timer.tick()
if timer.finished:
    timer.elapsed = 0  # loop

iter_dialogue function

Generator function for stepping through a dialogue script parsed from a JSON or YAML file.

context = {}
dialogue = iter_dialogue(
    assets.act1_scene1,
    context,
    speak=speak,
)

def main_loop(screen, events, quit):
    if action := next(dialogue, None):
        action()

Direction enum

Enum for up/down/left/right directions

direction = Direction.UP
if direction in Direction.VERTICAL:
    rect.move_ip(direction.vector)

easing module

A selection of easing functions for use with interpolation. Can be used with the animate function.

get_ecs_update_fn function

An extremely simple ECS implementation.

@filter_entities(has_velocity)
def apply_velocity(entity):
    entity.pos += entity.velocity

ecs_update = get_ecs_update_fn([apply_velocity])

@dataclass
class Entity:
    pos: Vector2
    velocity: Vector2

ecs_update([Entity(pos=Vector2(0, 0), velocity=Vector2(1, 1)])

bind function

Partial function application with one or more argument placeholders at arbitrary positions.

foos = filter(bind(isinstance, ..., Foo), items)

run_game function

Pygbag compatible game loop.

def main_loop(screen, events, quit):
    screen.fill(random.choice(pygame.color.THECOLORS.values()))

    for event in events:
        if event.type == pygame.KEYDOWN and event.key == pygame.K_ESCAPE:
            quit()


if __name__ == '__main__':
    run_game(Window("My Game", (WIDTH, HEIGHT)), main_loop)

make_color_gradient function

Generate a color gradient between two colors.

sky_image = make_color_gradient(screen.size, "white", "blue")
screen.blit(sky_image, (0, 0))

rhash/unrhash functions

Simple reversible hash function for generating unique IDs.

id = rhash("foo")
assert unrhash(id) == "foo"

imgui module

Immediate mode GUI.

gui = imgui.IMGUI()

def main_loop(screen, events, quit):
    with imgui.render(gui, screen) as render:
        if render(imgui.button("Quit"), center=(100, 200)):
            break

TODO

• More widgets
• Layouts

LazyObject class

Lazy loading object proxy.

image = LazyObject(lambda: pygame.image.load("foo.png"))
screen.blit(image, (0, 0))

scroll_parallax_layers function

Scroll parallax layers at different rates.

background = LayeredUpdates()
background.add(assets.sky, layer=0)
background.add(assets.mountains, layer=1)
background.add(assets.trees, layer=2)

scroll_parallax_layers(
    (vx, vy),
    background.layers,
    background.get_sprites_from_layer,
    {0: 0, 1: 1.5, 2: 2.0},
)

channel function

Simple pubsub implementation.

foo = channel()
foo.subscribe(lambda x: print(f"subscriber 1: {x}"))
foo("bar")

get_rect_attrs function

Filter rect attributes (eg top, center, size) from a dictionary. Useful for passing kwargs to pygame.Rect.move_to or pygame.Surface.get_rect.

def foo(image: Surface, **kwargs):
    image_rect = image.get_rect(**get_rect_attrs(kwargs))

add_padding function

Add padding of varying amounts to a Rect.

rect = add_padding(Rect(0, 0, 10, 10), [100, 50, 10, 5])
assert rect.size == (120, 65)

screen_manager function

Screen manager state machine.

def main():
    return screen_manager(
        {
            show_title: [start_level, enter_level_code],
            show_code_prompt: [start_level, return_to_titles],
            play_level: [end_level],
            show_game_over: [return_to_titles],
        }
    )

def show_main_menu(surface, events, screen_manager):
    surface.blit(assets.main_menu, (0, 0))
    for event in events:
        if event.type == pygame.KEYDOWN and event.key == pygame.K_RETURN:
            screen_manager.send("start_level")
        if event.type == pygame.KEYDOWN and event.key == pygame.K_c:
            screen_manager.send("enter_code")

def start_level(input):
    return play_level if input == "start_level" else None

def enter_level_code(input):
    return show_code_prompt if input == "enter_code" else None

TODO

• Transition animations (fade in/out, slide, wipe, etc)
• Less clunky transition functions

Spritesheet class

Provides item access to a spritesheet image where sprites are arranged in a grid.

spritesheet = Spritesheet("foo.png", rows=3, cols=4))
screen.blit(spritesheet[(2, 1], (0, 0))
walk_frames = [spritesheet[(0, i)] for i in range(4)]
walk_anim = animate(walk_frames, timer.quotient)

TODO

• Slice support for ranges

statemachine function

State machine as generator.

get_styles function

Simple cascading style sheet engine. Filters styles by object type, class and id attributes.

stylesheet = {
    "Button": {
        "color": "black",
        "background-color": "grey",
    },
    "Button#quit": {
        "background-color": "red",
    },
}
Button = namedtuple("Button", ["id"])
styles = get_styles(stylesheet, Button(id="quit"))
assert styles == {"color": "black", "background-color": "red"}

make_sprite function

Create a sprite from an image.

player = make_sprite(assets.player, center=player_pos)

rotate_surface function

Rotate a surface in place or around a specified point.

rotated_image = rotate_surface(image, angle, center=(0, 0))

to_snakecase and snakecase_to_capwords functions

Convert between snake_case and CapWords.

speech_duration function

Calculate rough speech duration in seconds.

tile function

Generate a blit sequence to tile an image across a surface.

screen.blits(tile(screen.get_rect(), assets.grass))

angle_between function

Calculate the angle between two points.

Other TODO

• Configurable controls
• Save / Load
• Network