Struct BouncingSimulation 

pub struct BouncingSimulation { /* private fields */ }

Flutter BouncingScrollSimulation — the iOS UIScrollView fling.

While the content is inside [min, max] it coasts on exponential decay. The moment the coast would cross a bound, the simulation hands off to a spring anchored at that side’s rest target, so the content overshoots and is pulled back. A release that starts outside the range skips the coast and springs immediately.

The two pairs of bounds

min/max and leading/trailing are different questions, and conflating them is the reason both are parameters:

• min / max — the scroll extent: the offsets past which the content is overscrolled. This is where the coast gives way to the spring.
• leading / trailing — the spring’s rest targets: where overscrolled content comes to rest. Normally leading == min and trailing == max, which is what within fills in. They differ when the resting place is not the crossing place — content that snaps to a sticky header, or to a paged boundary, past the edge it crossed.

use std::time::Duration;
use teksilo_core::kinetic::{BouncingSimulation, ScrollSimulation};

// Released mid-range with plenty of room: pure exponential decay.
let sim = BouncingSimulation::within(0.0, 1000.0, -1.0e6, 1.0e6);
// Flutter FrictionSimulation: x(1s) = v·(0.135 − 1)/ln(0.135).
assert!((sim.position(Duration::from_secs(1)) - 431.96).abs() < 0.5);

Implementations

impl BouncingSimulation

pub fn within(position: f32, velocity: f32, min: f32, max: f32) -> Self

The common case: the spring rests exactly at the bound it crossed.

pub fn new( position: f32, velocity: f32, min: f32, max: f32, leading: f32, trailing: f32, ) -> Self

A bouncing fling with explicit spring rest targets, using the shipped physics tokens. See the type docs for what the two pairs mean.

pub fn with_tokens( position: f32, velocity: f32, min: f32, max: f32, leading: f32, trailing: f32, tokens: &ScrollPhysicsTokens, ) -> Self

new against a theme’s own physics tokens.

pub fn spring_time(&self) -> f32

When the spring takes over, in seconds; INFINITY when it never does.

Trait Implementations

impl Clone for BouncingSimulation

fn clone(&self) -> BouncingSimulation

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for BouncingSimulation

impl Debug for BouncingSimulation

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

Formats the value using the given formatter.

impl ScrollSimulation for BouncingSimulation

fn position(&self, t: Duration) -> f32

Where the content is at t, in logical pixels.

fn velocity(&self, t: Duration) -> f32

How fast the content is moving at t, in logical pixels per second.

fn is_done(&self, t: Duration) -> bool

Whether the content has come to rest at or before t.