Pygskin 0.5.0

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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))

Assets class

Provides attribute access to asset files and batch loading

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

Camera class

A camera class for scrolling and zooming a surface.

camera = Camera(screen.get_rect(), clamp=world_map.get_rect())
camera.view.fill("black")
sprite_group.draw(camera)
camera.zoom = 2.4
camera.draw(screen)

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 and make_color_gradient functions.

Component class

A minimal ECS implementation.

@system
def apply_velocity_system(pos: Vector2, velocity: Vector2) -> None:
    pos += velocity

class Mob(Entity):
    pos: Vector2 = lambda: Vector2(0, 0)
    velocity: Vector2 = lambda: Vector2(0, 0)

mob = Mob(velocity=Vector2(3, 1))

apply_velocity_system()

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, exit):
    screen.fill(random.choice(pygame.color.THECOLORS.values()))

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


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)

imgui module

Immediate mode GUI.

gui = imgui.IMGUI()

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

map_inputs_to_actions function

Map input events to actions. Enables user-defined key bindings.

keyboard_controls = {
    "jump": Event(pg.KEYDOWN, key=pg.K_UP),
    "duck": Event(pg.KEYDOWN, key=pg.K_DOWN),
    "quit": Event(pg.KEYDOWN, key=pg.K_ESCAPE),
}
for action in map_inputs_to_actions(
    keyboard_controls,
    pygame.event.get(),
):
    if action == "jump":
        player.jump()
    if action == "duck":
        player.duck()
    if action == "quit":
        exit()

lazy class

Lazy loading object proxy. Works like a partial function application for objects.

image = lazy(pygame.image.load, "foo.png"))
screen.blit(image)

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.

top, right, bottom, left = [100, 50, 10, 5]
padded, rect = add_padding(Rect(0, 0, 10, 10), [top, right, bottom, left])
assert padded.size == (120, 65)
assert rect.topleft == (5, 100)

grid function

Divide a Rect into a specified number of rows and columns, and return a function to access the cells by row/column index, or string aliases.

get_cell = grid(
    Rect(0, 0, 100, 100),
    rows=2,
    cols=2,
    names={"nw": (0, 0), "ne": (1, 0), "sw": (0, 1), "se": (1, 1)},
)
assert get_cell("ne") == get_cell(1, 0) == Rect(50, 0, 50, 50)

screen_manager function

Screen manager state machine.

def main():
    return screen_manager(
        show_main_menu,
        play_level,
    )

def show_main_menu(surface, events, exit_screen):
    surface.blit(assets.main_menu)
    for event in events:
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                exit_screen()
            if event.key == pygame.K_RETURN:
                exit_screen(to=play_level)

def play_level(surface, events, exit_screen):
    ...

shake function

Shake animation generator.

rect = Rect(100, 100, 100, 100)
timer = Timer(3000)
shake_fn = shake()

def main_loop(screen, events, exit):
    screen.fill("black")
    timer.tick()
    pygame.draw.rect(screen, "red", rect.move(shake_fn(timer.quotient())))

spritesheet function

Provides grid cell access to a spritesheet image.

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

draw_sprite_stack function

Draw a pseudo-3d sprite using sprite-stacking.

draw_sprite_stack(
    screen,
    spritesheet(assets.player, rows=1, cols=8),
    (100, 100),
    spacing=3,
)

statemachine function

State machine as generator.

get_styles function

Simple cascading style sheet engine. Filters styles by object type, class and id attributes. Can be used with imgui module.

# styles.yaml
"*":
  color: black
  background_color: grey

"#error":
  background_color: red

# cascading styles
stylesheet = partial(get_styles, assets.styles)
Foo = namedtuple("Foo", ["id"])
styles = stylesheet(Foo(id="error"))
assert styles["background_color"] == "red"

# use with imgui
with imgui.render(gui, surface, stylesheet) as render:
    render(imgui.button("Click me!"), center=(100, 100))

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 function

Convert CapWords to snake_case.

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.