pub type ScrollHandler = Arc<dyn Fn(f32, f32) -> bool + Send + Sync>;Expand description
A nested-scroll chain link (D-NESTED-SCROLL, 2026-08-02) — takes a
(dx, dy) DELTA (not an absolute position, unlike HitHandler) and
returns whether it actually moved: true if it consumed some or all of
the delta, false if it’s already fully exhausted in that exact
direction (hard-clamped, or stretched to Bounce’s own overscroll
limit) and had NO effect. A gesture starting inside nested scrollable
regions (an inner ScrollView/carousel sitting inside an outer one, or
a plain-hit Button/ListTile sitting inside any ScrollView) tries
the innermost link first each move and only offers the SAME delta to
the next link outward once the current one declines — so scrolling
naturally “hands off” to an enclosing scrollable ancestor exactly when,
and only when, the inner one has nothing left to give.
Aliased Type§
pub struct ScrollHandler { /* private fields */ }