//! Operate on widgets that can be scrolled. use crate::widget::{Id, Operation}; /// The internal state of a widget that can be scrolled. pub trait Scrollable { /// Snaps the scroll of the widget to the given `percentage`. fn snap_to(&mut self, percentage: f32); } /// Produces an [`Operation`] that snaps the widget with the given [`Id`] to /// the provided `percentage`. pub fn snap_to(target: Id, percentage: f32) -> impl Operation { struct SnapTo { target: Id, percentage: f32, } impl Operation for SnapTo { fn scrollable(&mut self, state: &mut dyn Scrollable, id: Option<&Id>) { if Some(&self.target) == id { state.snap_to(self.percentage); } } fn container( &mut self, _id: Option<&Id>, operate_on_children: &mut dyn FnMut(&mut dyn Operation), ) { operate_on_children(self) } } SnapTo { target, percentage } }