Add more easing functions

There are a number of ‘easing functions’ used by the animation system. At the top of _animator.py you will see the following:

EASING = {
    "none": lambda x: 1.0,
    "round": lambda x: 0.0 if x < 0.5 else 1.0,
    "linear": lambda x: x,
    "in_cubic": lambda x: x * x * x,
    "in_out_cubic": lambda x: 4 * x * x * x if x < 0.5 else 1 - pow(-2 * x + 2, 3) / 2,
    "out_cubic": lambda x: 1 - pow(1 - x, 3),
}

These function have been copied from https://easings.net/ and translated from Javascript to Python. I would like to add the remaining functions to the EASING dict above.

See the animation.py example as a way of testing the above functions.

[willmcgugan]

No need for a donation! 😉

[rodrigogiraoserrao]

I have a Buy Me a Coffee account (associated with my blog) where people can buy me a slice of pizza, maybe I’ll move it to ko-fi…

But I do not want Will’s coffee for this contribution, and I will refund it if needed 🤣