import { PointerEvent as ReactPointerEvent } from 'react';
/**
 * Drag-to-resize a spacer's height.
 *
 * A spacer is the one item whose whole point is its size, and the only one that
 * paints nothing to judge that size by: the number in the sidebar says 24, and
 * whether 24 is the gap the form wanted is a question about the form, not about
 * the number. So it gets a grip on its bottom edge, and the answer is the gap
 * opening under the hand.
 *
 * Pointer events for the reasons {@link useDragSort} is built on them: the
 * editor ships inside a shadow root and the gesture has to survive a finger.
 */
/** Pixels the height snaps to. Fine enough to place a gap, coarse enough to hit. */
export declare const HEIGHT_STEP = 2;
/** A spacer may close entirely — a gap of nothing is a legitimate answer. */
export declare const HEIGHT_MIN = 0;
/**
 * Tallest a spacer may be dragged. Not a limit on the value itself: the sidebar
 * number takes anything, and a form loaded with more keeps it. It is the point
 * past which a drag has stopped being a way to judge a gap, since neither end
 * of it is on screen any more.
 */
export declare const HEIGHT_MAX = 400;
/**
 * The height a drag lands on, given where it started and how far the pointer
 * travelled. Pure so the arithmetic can be checked directly.
 *
 * One to one with the pointer, unlike the card and the submit button: a spacer
 * hangs in the flow from its top edge, so only the bottom one moves, and it
 * moves exactly as far as the height changes.
 */
export declare function heightFromDrag(startHeight: number, travel: number): number;
export interface SpacerResize {
    /** The spacer being resized, or null when no drag is running. */
    resizingId: string | null;
    /** The height it currently shows, in px. The model still holds the old one. */
    previewHeight: number | null;
    /**
     * Call from a handle's `onPointerDown` to arm a resize. The height it starts
     * from is measured off the spacer itself, so a press alone changes nothing —
     * and a spacer that never had a `height` starts from the one it renders at.
     */
    start: (id: string, e: ReactPointerEvent) => void;
}
export declare function useSpacerResize(onCommit: (id: string, height: number) => void): SpacerResize;