Struct BackHandler 

pub struct BackHandler<State: 'static> { /* private fields */ }

Android back-press ⇄ navigator auto-wiring: attach_back_handler/BackHandler pop a NavigatorController on a platform back press and keep frust-reactive‘s handles_back flag in sync with the stack depth, so a shell knows whether a root-level back should fall through to the platform (activity finish). Mirrors RouterDeepLinks’s shape and, like it, is the ONLY place in the facade that sees both frust-widgets’ NavigatorController and frust-reactive’s back-press source together — see BackHandler’s doc for the consume/dedupe and timing contracts. Call BackHandler::track from every Component::build. Android back-press ⇄ navigator auto-wiring: attach_back_handler/BackHandler pop a NavigatorController on a platform back press and keep frust-reactive‘s handles_back flag in sync with the stack depth, so a shell knows whether a root-level back should fall through to the platform (activity finish). Mirrors RouterDeepLinks’s shape and, like it, is the ONLY place in the facade that sees both frust-widgets’ NavigatorController and frust-reactive’s back-press source together — see BackHandler’s doc for the consume/dedupe and timing contracts. Call BackHandler::track from every Component::build. Android back-press ⇄ navigator auto-wiring: attach_back_handler/BackHandler pop a NavigatorController on a platform back press and keep frust-reactive‘s handles_back flag in sync with the stack depth, so a shell knows whether a root-level back should fall through to the platform (activity finish). Mirrors RouterDeepLinks’s shape and, like it, is the ONLY place in the facade that sees both frust-widgets’ NavigatorController and frust-reactive’s back-press source together — see BackHandler’s doc for the consume/dedupe and timing contracts. Call BackHandler::track from every Component::build. A NavigatorController wired to the process-wide back-press source (see the module docs) — the explicit back-wiring surface predating the automatic navigator auto-wiring.

App code using frust::navigator no longer needs this: back handling is automatic. It stays fully supported for apps that want an explicit handle (Huddle constructs one), and now shares the same single consumption source and request_back/back_interest routing as the automatic path — so constructing a BackHandler and calling frust::navigator on the same controller still consumes each press exactly once.

Construct once with attach_back_handler (or BackHandler::new) — typically from Component::init, storing the result in Component::State — then call track from every Component::build.

Implementations

impl<State: 'static> BackHandler<State>

pub fn new(controller: NavigatorController<State>) -> Self

Wire controller to the back-press source. Seeds the shared consumption marker to the current back-press count (so a press delivered before this handler existed does not trigger a spurious back on the first track), publishes the initial handles_back fallback flag, and registers the live back_interest provider (see the module docs’ timing note).

Call this once per controller (e.g. from Component::init) — from the UI thread, since the provider slot is UI-thread-affine (it reads the Rc-backed controller). A Component::init always runs on the UI thread.

Registration position does not depend on when you construct this (see the module docs’ R44-back section): a handler built in Component::init wires before any view exists, and a root overlay_host still outranks the navigator it wraps — the host’s rank comes from its own entry point, not from wire order. Where you call track from is likewise free.

pub fn track(&self)

Consume a new back press (routing it through request_back) and refresh the framework’s handles_back interest from the current stack. Call from every Component::build.

Shares the single consumption source with the automatic navigator path (see the module docs): a rebuild re-run that observes the same already-consumed count neither re-fires nor double-counts, and a frust::navigator on the same controller in the same rebuild cannot double-pop.

pub fn controller(&self) -> &NavigatorController<State>

The wired controller — hand it to navigator, or drive it directly.