/**
 * A STRIP THAT SCROLLS SIDEWAYS — the two questions it has to answer, as
 * arithmetic, because neither can be answered from a rendered box in a unit
 * test and both are wrong in ways nothing on screen shows.
 *
 * `stripEdges` — which end still has content behind it, so the strip can SAY it
 * scrolls. A scroller whose last visible item ends flush with its edge is the
 * same picture as a strip holding everything there is, and a swipe nobody has a
 * reason to try hides whatever is past the fold.
 *
 * `scrollToShow` — where the strip has to stand for one item to be wholly
 * inside it. A reader arrives at a record already at its fourth stage, and a
 * strip that opens at the first stage has hidden the one thing the reader came
 * to see.
 */
/** A box's own edges, in any one coordinate system — viewport, page, it does
 *  not matter, as long as both boxes are read in the same one. */
export interface StripEdge {
    left: number;
    right: number;
}
/**
 * Is there content behind either end?
 *
 * A sub-pixel remainder is not a hidden item: a rounded box reports a
 * `scrollWidth` a fraction over its `clientWidth` at plenty of widths that fit.
 * `scrollLeft` is negative in a right-to-left strip, so the distance travelled
 * is read as a magnitude and the answer holds in both directions.
 */
export declare function stripEdges(scrollLeft: number, scrollWidth: number, clientWidth: number): {
    behind: boolean;
    ahead: boolean;
};
/**
 * The `scrollLeft` that brings `item` wholly inside `box`, or `null` when it is
 * already there — null rather than the current position, so a caller never
 * writes a scroll that would move nothing and the "already in view" case is one
 * the type states.
 *
 * It scrolls the SHORTER way: an item past the trailing edge comes to that edge
 * and no further, which keeps the stages before it on screen — a strip that
 * centred the current stage would scroll the run's beginning out of sight to
 * put the reader in the middle of a box with room for both.
 *
 * `pad` is what is left showing of whatever is behind the item, so the strip
 * reads as continuing rather than as starting there.
 */
export declare function scrollToShow(box: StripEdge, item: StripEdge, scrollLeft: number, pad?: number): number | null;