Struct Transition 

pub struct Transition { /* private fields */ }

An interruptible open/close transition tracking a 0.0..=1.0 “openness” so a surface animates in and out, and a mid-flight reversal retargets from the current value instead of snapping to 0 first.

Implementations

impl Transition

pub fn closed() -> Transition

pub fn open() -> Transition

For surfaces that boot already shown.

pub fn value(&self, now: Instant) -> f32

Openness in 0.0..=1.0 at now.

pub fn modal_curve(&self, now: Instant, start_scale: f64) -> (f32, f64, f64)

(alpha, dy, scale) for a modal this transition drives, covering both the enter (openness 0→1) and the exit (openness 1→0). The panel starts 20 px low at start_scale and rises to rest on the enter; the exit plays the same curve in reverse instead of the panel vanishing.

pub fn is_visible(&self, now: Instant) -> bool

True while opening, open, or closing (openness > 0) — draw code gates on this, not the raw intent bool, so the exit curve paints instead of the panel vanishing.

pub fn is_open(&self) -> bool

The logical open/closed intent (the last set_open), independent of whether the animation has settled.

pub fn is_animating(&self, now: Instant) -> bool

True while the value is still moving — feeds needs_animation_frame.

pub fn set_open(&mut self, open: bool, duration: Duration, curve: Curve)

No-op when the intent is unchanged AND the animation has settled, so repeated calls each frame don’t restart the curve.

pub fn set_open_at( &mut self, open: bool, duration: Duration, curve: Curve, now: Instant, )

Self::set_open against a caller-supplied clock.

Every other reader here — Self::value, Self::is_visible, Self::is_animating — already takes now; set_open was the one that reached for the clock itself. That asymmetry is untestable: a test could start a transition and ask whether it was still running, but the two calls read the clock independently, so a scheduler stall longer than the animation between them let it finish and the assertion flip. Pinning both ends to one instant makes such a test a statement about the animation rather than about the machine’s load.

pub fn defer(&mut self, by: Duration)

Hold the curve for by. Wall time spent waiting on a full presenter is not progress.

Trait Implementations

impl Clone for Transition

fn clone(&self) -> Transition

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Transition

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Copy for Transition