Enum A11yOffScreenMode 

pub enum A11yOffScreenMode {
    AllItems,
    ViewportPlusN {
        n: u32,
    },
    ViewportOnly,
}

Off-screen visibility policy for the AT walker. Decides which scene items get emitted as synthetic AT nodes per AT-rebuild.

ViewportPlusN { n: 1 } is the default: an item appears in the AT tree if its bounds_in_scene intersects viewport ∪ (1× viewport-grown-rect). That keeps the tree close to “what the user can interact with right now” while letting screen-reader users discover items just outside the visible region by jumping to the next/prev — at which point SceneView::ensure_visible pans the view to bring the focused item into view.

Variants

AllItems

Emit every item in the scene as a synthetic AT node. Heaviest mode — appropriate for small scenes (< ~500 items) where AT users want a complete table of contents.

ViewportPlusN

Emit items inside the viewport plus an n × viewport-grown margin around it. n = 0 collapses to “viewport only” with the same allocation pattern as ViewportOnly. n = 1 is the default — gives screen-reader users a one-screen “lookahead” to navigate without ensure_visible round-tripping through pan animation.

Fields

n: u32

ViewportOnly

Strict: only items intersecting the current viewport. Pairs with apps that have very large scenes where listing off-screen content would overwhelm AT clients.

Implementations

impl A11yOffScreenMode

pub fn at_visible_region(&self, visible_scene_region: Rect) -> Option<Rect>

Compute the scene-coord rectangle a given mode considers “AT-visible” given the current visible scene region. Used by SceneView::accessibility as the spatial-index query rect. AllItems returns None so the caller knows to bypass the query and emit every item.

Trait Implementations

impl Clone for A11yOffScreenMode

fn clone(&self) -> A11yOffScreenMode

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for A11yOffScreenMode

impl Debug for A11yOffScreenMode

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

Formats the value using the given formatter.

impl Default for A11yOffScreenMode

fn default() -> Self

Returns the “default value” for a type.