Struct CrossTileSymbolIndex 

pub struct CrossTileSymbolIndex { /* private fields */ }

Cross-tile symbol index that deduplicates labels across tile boundaries.

This is the top-level entry point, keyed by style-layer id. Each style layer has an independent [LayerCrossTileIndex] so that labels from different layers do not interfere with each other.

Usage

let mut index = CrossTileSymbolIndex::new();

// For each tile's symbol candidates:
let changed = index.assign("poi-labels", tile_id, instance_id, &mut entries);

// After placement, prune tiles no longer visible:
index.prune_stale("poi-labels", &active_instance_ids);

// When a tile is evicted from the cache:
index.remove_tile(&tile_id);

Implementations

impl CrossTileSymbolIndex

pub fn new() -> Self

Create an empty cross-tile symbol index.

pub fn next_instance_id(&mut self) -> u64

Allocate a unique instance ID for a tile registration.

Each call to assign should use a fresh instance ID so the index can detect when a tile’s data has been replaced (e.g. after a style change or data update).

pub fn assign( &mut self, layer_id: &str, tile_id: TileId, instance_id: u64, candidates: &mut [SymbolCandidateEntry], ) -> bool

Register a tile’s symbol candidates and assign cross-tile IDs.

After this call, each entry in candidates will have a non-zero assigned_cross_tile_id that is stable across zoom transitions and tile reloads.

Returns true if any IDs changed (caller should re-run placement).

pub fn prune_stale( &mut self, layer_id: &str, current_instance_ids: &HashSet<u64>, ) -> bool

Remove grids for tiles whose instance IDs are no longer active.

Call this after each placement frame with the set of instance IDs that are still in use. Returns true if any stale grids were removed.

pub fn remove_tile(&mut self, tile_id: &TileId)

Remove all index entries for a specific tile across all layers.

Call this when a tile is evicted from the tile cache to release the associated cross-tile IDs.

pub fn prune_layers(&mut self, active_layers: &HashSet<String>)

Remove index state for layers that are no longer active.

active_layers is the set of style-layer IDs currently in use. Any layer not in this set has its index state dropped.

pub fn tile_count(&self) -> usize

Total number of indexed tiles across all layers and zoom levels.

pub fn entry_count(&self) -> usize

Total number of indexed symbol entries across all tiles and layers.

Trait Implementations

impl Clone for CrossTileSymbolIndex

fn clone(&self) -> CrossTileSymbolIndex

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CrossTileSymbolIndex

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

Formats the value using the given formatter.

impl Default for CrossTileSymbolIndex

fn default() -> CrossTileSymbolIndex

Returns the “default value” for a type.