import { MaybeRefOrGetter } from 'vue';
import { BendConfig } from './engine/bend/config';
/**
 * Cursor-driven local deformation ("liquid dent") for a MetalFx root.
 *
 * Field
 * ─────
 * Two gaussian blobs centred at `c` (which lags the cursor by `follow`):
 *   • directional: `amp · g_bend(r)` — a 2-D spring chasing the cursor's
 *     smoothed velocity × gain, so motion toward the centre pushes the ring
 *     in and motion away drags it out; recoils on release.
 *   • liquid: `(p − c)/σ · g_liq(r) · la` — the gradient of a bump, i.e. a
 *     divergent push away from the contact point. This term *stretches*
 *     material rather than sliding it, so the stroke thins under the cursor
 *     and thickens either side. `la` is its own slower spring; pressure is 1
 *     with the cursor on the ring, fading over `liquidReach`.
 *
 * Two render paths, chosen by `applyTo`:
 *
 * `ring` — vector. The engine masks the ring with a rounded-rect outline it
 * traces every frame; we hand it a `DeformFn` that displaces those outline
 * points, plus the fill / rim / hairline that normally live on CSS boxes so
 * they bend along. Edges stay anti-aliased at any stretch. The instance is
 * redrawn from here at the pointer's frame rate, since the shared loop only
 * composites at 15 fps.
 *
 * `all` — SVG `feDisplacementMap` on the whole root. Bends the content too,
 * but the sampler duplicates source pixels where material is stretched, so
 * quality degrades with amplitude. Kept for comparison.
 *
 * @param target the MetalFx root (element, `Ref`, or getter). It is resolved
 * inside `onMounted` and re-resolved whenever the bound element changes, so
 * `ref="rootEl"` works without the caller guarding for null.
 * @param getCfg live config reader, evaluated once per frame (defaults to the
 * shared, mutable `BEND` singleton).
 */
export declare function useMetalBend(target: MaybeRefOrGetter<HTMLElement | null>, getCfg?: () => BendConfig): void;