Enum Curve 

pub enum Curve {
    Spring(Spring),
    Tween {
        duration: f32,
        easing: Easing,
    },
    Decay {
        k: f32,
    },
    Instant,
}

How a value moves to its target. Every curve starts from the value’s current position and velocity, so a retarget mid-flight never jumps or snaps its speed.

Variants

Spring(Spring)

A spring (the default for interface motion).

Tween

A timed curve: duration seconds along easing. A starting velocity fades out over the duration, so it is kept at the start and the value still lands at duration.

Fields

duration: f32

Seconds; 0 or less jumps, NaN is 0.3, capped at 60.

easing: Easing

The easing curve.

Decay

Momentum: the value coasts on its velocity and slows at k per second, resting at x + v / k. The target is ignored (see gesture::project for where it rests).

Fields

k: f32

Deceleration rate per second, clamped to 0.05..=1000 (NaN is 2, about a normal scroll).

Instant

Jump to the target.

Implementations

impl Curve

pub const DEFAULT: Curve

Spring::DEFAULT.

pub const fn tween(duration: f32, easing: Easing) -> Curve

A tween of duration seconds (sanitised like the field docs say).

pub fn decay(rate_per_ms: f32) -> Curve

Momentum with a per-millisecond deceleration rate (0.998 normal, 0.99 fast; see gesture::deceleration).

pub const fn sanitized(self) -> Curve

The same curve with its public fields in range: a zero-length tween or spring becomes Curve::Instant.

pub const fn is_instant(self) -> bool

Whether the value jumps.

pub fn rest(self, x0: f32, v0: f32, target: f32) -> f32

Where a motion from (x0, v0) toward target comes to rest: the target, or for Curve::Decay the projected point x0 + v0 / k.

pub fn sample(self, x0: f32, v0: f32, target: f32, t: f32) -> (f32, f32)

Position and velocity t seconds into a motion from (x0, v0) toward target. Always finite; t ≤ 0 (or NaN) is the start.

pub fn settle_time(self, x0: f32, v0: f32, target: f32, eps: Eps) -> f32

Seconds until a motion from (x0, v0) toward target stays within eps for good (the duration for a tween, 0 for instant, at most MAX_SETTLE).

pub fn settle_time_lanes( self, lanes: impl IntoIterator<Item = (f32, f32, f32)>, eps: Eps, ) -> f32

The settle time of several lanes (x0, v0, target) moving together along this curve: never earlier than any lane’s (see Spring::settle_time_lanes).

Trait Implementations

impl Clone for Curve

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Curve

impl Debug for Curve

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

Formats the value using the given formatter.

impl Default for Curve

fn default() -> Self

Returns the “default value” for a type.

impl From<Spring> for Curve

fn from(s: Spring) -> Self

Converts to this type from the input type.

impl PartialEq for Curve

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Curve