easing.py

"""Easing functions from https://github.com/semitable/easing-functions"""


class EasingBase:
    limit = (0, 1)

    def __init__(self, start: float = 0, end: float = 1, duration: float = 1):
        self.start = start
        self.end = end
        self.duration = duration

    def func(self, t: float) -> float:
        raise NotImplementedError

    def ease(self, alpha: float) -> float:
        t = self.limit[0] * (1 - alpha) + self.limit[1] * alpha
        t /= self.duration
        a = self.func(t)
        return self.end * a + self.start * (1 - a)

    def __call__(self, alpha: float) -> float:
        return self.ease(alpha)


class LinearInOut(EasingBase):
    def func(self, t: float) -> float:
        return t


class QuadEaseInOut(EasingBase):
    def func(self, t: float) -> float:
        if t < 0.5:
            return 2 * t * t
        return (-2 * t * t) + (4 * t) - 1


class CubicEaseInOut(EasingBase):
    def func(self, t: float) -> float:
        if t < 0.5:
            return 4 * t * t * t
        p = 2 * t - 2
        return 0.5 * p * p * p + 1