Struct NavMap 

pub struct NavMap { /* private fields */ }

The controls the kit composed this frame, with their laid-out rectangles.

Clone the map into every control: it is one shared registry behind an Rc. The game calls NavMap::begin_frame once per frame before composing, which retires controls that were not recomposed: a panel stays navigable through the frame after its last composition, so traversal made before composing still finds the layout the player was looking at, and leaves the map at the begin_frame after that.

A control registers itself while composing (NavMap::register) and reports its rectangle from the layout callback (NavMap::place). Traversal resolves against whatever is registered.

Implementations

impl NavMap

pub fn new() -> Self

pub fn begin_frame(&self)

Start a frame: every control must be marked or placed again to stay in the map. Call before composing the panel.

pub fn clear(&self)

Forget every control, including the ones marked this frame.

pub fn register( &self, requester: &FocusRequester, group: Option<GroupId>, ) -> bool

Register a control for this frame, deriving its view id from its focus requester.

This is what a kit control calls while composing. It returns false on the control’s first frame, before the first layout pass has assigned the id; the rectangle that layout reported is kept until the control registers with an id, so a control becomes navigable as soon as its id arrives, whether or not the panel composed in the frames between.

pub fn mark(&self, id: u64, group: Option<GroupId>, requester: FocusRequester)

Mark a control whose view id the caller already has.

Kit controls go through register; this is for a game that composes its own control and reads the id from the layout.

pub fn place( &self, requester: &FocusRequester, rect: Rect, group: Option<GroupId>, ) -> bool

Record a control’s laid-out rectangle, from Modifier::on_globally_positioned.

A rectangle that arrives before the control’s view id is known is held for it until the control registers with that id; after that, the callback only fires when the rectangle changes, so this is a cheap update. A group of None leaves the group the control already has alone: a caller that only knows the rectangle must not clear a modal trap. Returns whether the rectangle was recorded against a control.

pub fn active(&self) -> Vec<NavEntry>

Controls composed and laid out this frame, in composition order.

pub fn first(&self) -> Option<u64>

The first control in composition order.

pub fn len(&self) -> usize

pub fn is_empty(&self) -> bool

pub fn contains(&self, id: u64) -> bool

Whether id is a control on screen this frame.

pub fn request(&self, id: u64) -> bool

Ask the platform to focus id. false when there is no such control or the request was refused (captured focus, not laid out yet).

pub fn capture(&self, id: u64) -> bool

Pin focus to id until release: what a modal panel does when it opens, so traversal cannot escape to what is underneath.

The requester is remembered with the capture, so the release does not depend on the control still being in the map.

pub fn release(&self, id: u64) -> bool

Release a capture taken by capture.

Focus is cleared, so the caller asks for the next panel’s focus with NavDriver::enter once the modal is gone. A capture the map took is freed even after its control left the map, because the platform’s lock would otherwise pin focus to an id nothing can request again.

pub fn resolve(&self, from: Option<u64>, dir: NavDir, wrap: Wrap) -> NavStep

Resolve one traversal request.

Trait Implementations

impl Clone for NavMap

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Default for NavMap

fn default() -> Self

Returns the “default value” for a type.