import type { GeoJsonBbox, GeoJsonGeometry, GeoJsonPosition } from "@trackunit/geo-json-utils";
/**
 * Find the best visible vertex for the `vertex-auto` anchor.
 *
 * Searches ALL parts of multi-geometry, filters to vertices inside the
 * viewport, and returns the one closest to the viewport center.
 * Returns null if no vertices are visible.
 *
 * For Point geometry, returns the single coordinate (regardless of viewport).
 *
 * When `previousPosition` is provided (hysteresis mode):
 * - If the previous position is still inside the viewport, it is returned
 *   unchanged — the label stays put during panning.
 * - If the previous position left the viewport, the nearest visible vertex
 *   to that position is chosen (not nearest to viewport center) so the
 *   label migrates to the closest alternative.
 */
export declare const findBestVisibleVertex: (geometry: GeoJsonGeometry, viewportBounds: Readonly<GeoJsonBbox>, previousPosition?: GeoJsonPosition) => GeoJsonPosition | null;