import type { Transform2D } from "./transform.mjs";
export type GestureEventType = "start" | "pan" | "pinch" | "end" | "tap" | "doubleTap";
export interface GestureSnapshot {
	type: GestureEventType;
	transform: Transform2D;
	delta?: {
		dx: number;
		dy: number;
	};
	swipe?: {
		direction: "up" | "down" | "left" | "right";
		velocity: number;
	};
}
export interface GestureEngineOptions {
	/** Clamp the output scale to this range. Default [1, 8]. */
	minScale?: number;
	maxScale?: number;
	/** Tap threshold in pixels. Default 8. */
	tapThreshold?: number;
	/** Tap timeout in ms. Default 250. */
	tapTimeout?: number;
	/** Double-tap window in ms. Default 300. */
	doubleTapWindow?: number;
	/** Emit callback with every gesture update. */
	onUpdate?: (snapshot: GestureSnapshot) => void;
}
/**
* A small Pointer Events-based gesture engine shared by the lightbox.
*
* Responsibilities:
* - unify mouse/touch/pen into a single pipeline via Pointer Events
* - pan with one pointer
* - pinch-zoom around the centroid with two pointers
* - tap / double-tap detection with configurable thresholds
*
* Swipe / drag-to-dismiss / momentum live in a higher-level controller
* (next commit) so this class stays focused and testable.
*/
export declare class GestureEngine {
	private readonly el;
	private readonly opts;
	private readonly pointers;
	private transform;
	private lastPinchDistance;
	private lastTap;
	/**
	* rAF throttle state (#34). pointermove fires at the device sample
	* rate — on modern iPads that can be 120 Hz while the display only
	* commits at 60 Hz, wasting ~half of the transform work. We coalesce
	* all moves received within one frame into a single emit.
	*/
	private rafId;
	private pendingEmit;
	private readonly onPointerDown;
	private readonly onPointerMove;
	private readonly onPointerUp;
	private readonly onPointerCancel;
	constructor(el: HTMLElement, opts?: GestureEngineOptions);
	private attached;
	private detachController;
	attach(): void;
	detach(): void;
	[Symbol.dispose](): void;
	reset(): void;
	/** Visible for tests: force-drain the rAF queue synchronously. */
	flushPendingEmit(): void;
	get current(): Transform2D;
	/**
	* Programmatically set the transform (used by wheel zoom, double-tap
	* zoom, and other non-pointer sources). Emits a synthetic pinch event
	* so the viewer can repaint.
	*/
	setTransform(t: Transform2D): void;
	/** Public for tests: inject synthetic pointer events. */
	handleDown(e: PointerEvent): void;
	handleMove(e: PointerEvent): void;
	/**
	* Schedule a single emit on the next animation frame. Subsequent
	* pointermove events that arrive inside the same frame overwrite
	* the pending snapshot (pinch) or accumulate the delta (pan), so
	* the caller always sees the freshest transform per display commit.
	*/
	private queueEmit;
	private cancelPendingEmit;
	handleUp(e: PointerEvent): void;
	private emit;
}