export type MorphEasingFn = (t: number) => number;
/** Progress per unit of normalised time. Forward, so a knot reports the segment ahead. */
export declare function slopeAt(easing: MorphEasingFn, t: number): number;
/**
 * The author's curve, leaving at the speed the box is already travelling.
 *
 * A morph arriving mid-transition restarts the curve at t=0, so a fast run of them
 * only ever plays each curve's opening sliver — the box crawls while the value races
 * ahead. Adding `k · t(1-t)^m` fixes the start slope to the carried velocity without
 * moving either endpoint; `m` narrows as `k` grows, holding the peak inside
 * CARRY_OVERSHOOT. Momentum is only ever added, never subtracted: a curve that starts
 * faster than the box was moving is the author's business, and slowing it to match
 * would make a value that had settled start sluggishly.
 */
export declare function carry(base: MorphEasingFn, normalisedVelocity: number): {
    curve: MorphEasingFn;
    k: number;
};
/** Sampled fine enough that a segment is shorter than a frame at 120Hz. */
export declare function sampleEasing(curve: MorphEasingFn, duration: number): string;
export declare function abortContainerTransition(element: HTMLElement): void;
export declare function clearContainerTransition(element: HTMLElement): void;
export declare function transitionContainerSize(element: HTMLElement, oldWidth: number, oldHeight: number, duration: number, ease: string, onComplete?: () => void, onCancel?: () => void): void;
export declare function holdContainerSize(element: HTMLElement, width: number, height: number, duration: number, onComplete?: () => void, onCancel?: () => void): void;