Struct FocusRing 

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

Which id currently holds keyboard focus, plus Tab/Shift+Tab cycling through the ids registered as focusable.

Like HitTester, registrations are per-frame and draw-ordered, but advance/retreat always walk last frame’s finalized order: this frame’s registrations aren’t complete until the draw pass finishes. current itself, unlike the order, persists across frames like any other piece of app state, until focus moves or is cleared.

If the currently focused id isn’t in the order being cycled (e.g. it scrolled out of a list, or its widget wasn’t drawn this frame), the next advance/retreat treats that the same as nothing being focused, landing on the first/last registered id rather than getting stuck.

Implementations

impl<Id> FocusRing<Id>

pub const fn new() -> Self

Nothing focused, nothing registered.

pub fn begin_frame(&mut self)

Finalize this frame’s register calls into the order advance/retreat will walk during the frame that’s about to start, and clear the registration list for fresh calls. Call once per frame, before drawing.

pub fn clear(&mut self)

Drop focus entirely.

impl<Id: Copy + PartialEq> FocusRing<Id>

pub fn register(&mut self, id: Id)

Register id as focusable this frame.

pub const fn focused(&self) -> Option<Id>

The currently focused id, if any.

pub fn is_focused(&self, id: Id) -> bool

true if id currently holds focus.

pub const fn request(&mut self, id: Id)

Explicitly focus id, e.g. in response to a click.

pub fn advance(&mut self)

Move focus to the next id in last frame’s registration order, wrapping past the end. Focuses the first registered id if nothing was focused; a no-op if nothing was registered.

pub fn retreat(&mut self)

Move focus to the previous id in last frame’s registration order, wrapping past the start. Focuses the last registered id if nothing was focused; a no-op if nothing was registered.

pub fn handle_event(&mut self, event: &Event)

Default Tab/Shift+Tab handling: advance on Tab, retreat on BackTab (shift+tab). Called automatically by Interaction::handle_event; call it yourself if you’re using FocusRing standalone, or skip it entirely and drive advance/retreat from something else (a gamepad shoulder button, say) if Tab needs to mean something different in your app (inserting a literal tab into a text field, for instance).

Trait Implementations

impl<Id: Clone> Clone for FocusRing<Id>

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<Id: Debug> Debug for FocusRing<Id>

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

Formats the value using the given formatter.

impl<Id> Default for FocusRing<Id>

fn default() -> Self

Returns the “default value” for a type.