gpui-transitions.

This crate provides an API for interpolating between values in gpui.

Transitions can be constructed via window.use_transition or window.use_keyed_transition. It's very similar to the use_state API.

let mut my_transition = window
    .use_keyed_transition(
        "my_transition",
        cx,
        Duration::from_millis(400),
        |_window, _cx| rgb(0xFF0000)),
    );

They can also be constructed more granularly via Transition::new:

let mut my_transition = Transition::new(
    cx.new(|_cx| TransitionState::new(rgb(0xFF0000))),
    Duration::from_millis(400),
);

To get the value of a transition you can use evaluate:

let value = my_transition.evaluate(window, cx);

If the transition is not finished when evaluate is called then an animation frame will be requested.

More examples can be found here.