Struct ScrollHandlingOptions 

pub struct ScrollHandlingOptions {
    pub line_height: f32,
    pub smooth: bool,
    pub smooth_duration: Duration,
    pub overscroll_behavior: OverscrollBehavior,
    pub overscroll_style: OverscrollStyle,
    pub axes: PanAxes,
    pub rubber_band: bool,
    pub pan_devices: PointerKindMask,
    pub reduced_motion: bool,
    pub physics: ScrollPhysicsTokens,
}

Everything handle_scroll_event needs to know that is not state.

Snapshot, not signals: a scrollable builds one of these in build(), where the theme and the reduced-motion preference are in scope, and the handler closure captures it. Both change through a rebuild, which is the level a density switch and a preference change already mark.

Fields

line_height: f32

Pixels one ScrollDelta::Lines unit is worth.

smooth: bool

Whether a wheel notch tweens to its target instead of jumping. Never consulted on the pan path — a finger is already the animation.

With this on, every ScrollableAxes offset that has a range must be Signal::new_animated — animate_to panics on a plain signal. The qualifier is load-bearing, not a caveat: an axis whose maximum is permanently zero is never written by either path, which is exactly why ScrollableAxes::vertical and ScrollableAxes::horizontal pin their unused axis with a plain Signal::new(0.0) and why ListView, TreeView and GridView each pair ScrollableAxes::vertical with a smooth_scrolling that defaults to true. The rule is stated once on ScrollableAxes itself; this is the same rule.

smooth_duration: Duration

How long that tween lasts.

overscroll_behavior: OverscrollBehavior

Whether a boundary scroll chains outward (OverscrollBehavior::Chain) or is absorbed (OverscrollBehavior::Contain).

overscroll_style: OverscrollStyle

Which overscroll feel this surface asks for when rubber_band is on.

axes: PanAxes

Which axes a finger may pan. An axis outside this set takes no movement from a pan (the wheel path is unaffected — a wheel has always reached every axis the range allows).

rubber_band: bool

Whether this surface follows the finger past its own end.

Off by default, and that is the load-bearing default. A band that engages absorbs the movement, so a nested list that rubber-banded at its end would never hand the gesture to the container around it. The band belongs to the outermost surface of a scroll chain; everything inside it clamps and chains, which is also what every desktop toolkit does.

pan_devices: PointerKindMask

Which pointer kinds may pan this surface. Defaults to PointerKindMask::DIRECT — a mouse scrolls with its wheel and must never be treated as a panning pointer.

reduced_motion: bool

prefers-reduced-motion, snapshotted at build. Hard-clamps the band.

physics: ScrollPhysicsTokens

The theme’s scroll-physics constants. Only the rubber-band friction factor is read here — the fling’s constants belong to the tree’s driver, which reads them from the same tokens.

Trait Implementations

impl Clone for ScrollHandlingOptions

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 ScrollHandlingOptions

impl Debug for ScrollHandlingOptions

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

Formats the value using the given formatter.

impl Default for ScrollHandlingOptions

fn default() -> Self

Returns the “default value” for a type.