use crate::macros::impl_ops;
use crate::{AnimateState, FRAME_TIME, IS_ANIMATING, Lerp};
use std::sync::atomic::Ordering;
#[derive(Debug)]
pub struct Once<T, E, I>(pub(crate) AnimateState<T, E, I>)
where
T: Lerp + PartialEq,
E: Fn(f64) -> f64,
I: Fn(&T, &T, f64) -> T;
impl<T, E, I> Once<T, E, I>
where
T: Lerp + PartialEq + Default,
E: Fn(f64) -> f64,
I: Fn(&T, &T, f64) -> T,
{
pub fn new(initial: T, duration: f64, easing: E, interp: I) -> Self {
Self(AnimateState::new(initial, duration, easing, interp))
}
pub fn set(&mut self, target: T) {
let now = FRAME_TIME.load(Ordering::Relaxed);
let inner = self.0.inner.get_mut();
inner.start = std::mem::take(&mut inner.current);
inner.target = target;
inner.started_at = Some(now);
}
pub fn get(&self) -> &T {
let now = FRAME_TIME.load(Ordering::Relaxed);
unsafe {
let inner = &mut *self.0.inner.get();
if inner.last_update != now {
if let Some(start_t) = inner.started_at {
let elapsed = now.saturating_sub(start_t) as f64;
let t = (elapsed / self.0.duration).clamp(0.0, 1.0);
inner.current =
(self.0.interp)(&inner.start, &inner.target, (self.0.easing)(t));
inner.last_update = now;
if t >= 1.0 {
inner.started_at = None;
} else {
IS_ANIMATING.store(true, Ordering::Relaxed);
}
}
}
&inner.current
}
}
pub fn target(&self) -> &T {
unsafe {
let inner = &*self.0.inner.get();
if inner.started_at.is_none() {
&inner.current
} else {
&inner.target
}
}
}
}
impl_ops!(Once);