Struct HitTester 

pub struct HitTester<Id> { /* private fields */ }

A per-frame registry of (Rect, Id) pairs, queried by pointer position to find the topmost widget under a point.

Standalone and headless: no Backend dependency, so it’s usable (and unit-testable) without a Terminal or any drawing at all, e.g. for hand-rolled hit-testing outside of Interaction.

Registrations are draw-ordered: a later push means drawn (and therefore visually on top) later, so topmost_at scans back-to-front and returns the last match. This mirrors the painter’s algorithm every widget in this crate already draws with.

A push_barriered rect additionally stops that scan: a point inside a barrier’s rect never resolves to anything registered before the barrier, regardless of overlap (an overlay region claims everything under it, not just what it happens to draw over), while a point outside the barrier’s rect is unaffected by it and keeps scanning past it normally.

Implementations

impl<Id> HitTester<Id>

pub const fn new() -> Self

An empty registry.

pub fn push(&mut self, rect: Rect, id: Id)

Register id as occupying rect, on top of everything registered so far this pass.

pub fn push_barrier(&mut self, rect: Rect)

Register rect as a barrier, on top of everything registered so far this pass: see the HitTester docs for what that does to topmost_at.

pub fn clear(&mut self)

Discard all registrations, e.g. at the start of a new frame’s draw pass.

pub const fn len(&self) -> usize

Number of rects currently registered, hits and barriers combined.

pub const fn is_empty(&self) -> bool

true if nothing has been registered.

impl<Id: Copy> HitTester<Id>

pub fn topmost_at(&self, pos: Pos) -> Option<Id>

The id of the topmost (most recently pushed) registration whose rect contains pos, if any.

Stops at the first (most recently registered) push_barriered rect that also contains pos: nothing registered earlier than that barrier can win at a position the barrier covers.

Trait Implementations

impl<Id: Clone> Clone for HitTester<Id>

fn clone(&self) -> HitTester<Id>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<Id: Debug> Debug for HitTester<Id>

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

Formats the value using the given formatter.

impl<Id> Default for HitTester<Id>

fn default() -> Self

Returns the “default value” for a type.