import type { RowAlignment, RowSpan } from '@variance-authority/raster';
import type { DecodedImage } from './mask.js';
/**
 * Which row of the before image each row of the after image shows.
 *
 * A full-page capture is a column of rows, and the content of a document flows:
 * a paragraph inserted near the top pushes everything under it down. Compared
 * position by position, every row under the insertion sits against the row that
 * used to be there, and a 1,155-pixel insertion paints the whole tail of a
 * 45,000-pixel page as changed. A reviewer then sees one change as the entire
 * page, and the regions under it are attributed to every node it pushed.
 *
 * So the rows are diffed the way lines of text are. Each row is hashed, runs of
 * identical rows become one token, and Myers' algorithm finds the shortest edit
 * between the two token columns. The result is a pairing, not a verdict: the
 * caller still compares each after row with the before row it is paired with,
 * pixel by pixel, and every row that moved, came or went is itself a change, so
 * no pairing can make a page read as unchanged. A row with no partner is
 * reported, never paired with white. Where two paired runs meet, the before
 * rows on either side were not neighbours, and pixelmatch's anti-aliasing test,
 * which reads neighbours, may count a pixel on that seam differently.
 *
 * Myers is O((N+M)·D) in time and keeps O(D²) of trace, where N and M count runs
 * rather than rows and D is the size of the edit in runs. A page's runs are
 * about two thirds of its rows, and an insertion is one edit once the common
 * head and tail are trimmed, so an ordinary change costs one hashing pass. D
 * grows with every edit on the page, not only the largest: a rewritten section
 * and the lines it reflowed further down came to 3,031 runs on a 28,519-row
 * page. Past `limit` the search stops and the columns are split at runs each
 * side holds once ({@link edits}), so the rows an edit only moved still pair,
 * and a stretch that shares no such run, or that the split reaches after
 * spending its work bound, is compared by position within it.
 *
 * Only whole rows are matched. Content that moves in one column beside a column
 * that stays put does not move whole rows, and is compared where it sits.
 */
export interface AlignedRows extends RowAlignment {
    /** For each after row, the before row it is compared against, or `-1` for none. */
    readonly source: Int32Array;
    /**
     * The inserted rows that repeat the run of identical rows they grew: a gap or a
     * padding that got taller. They add no content; they move what follows.
     */
    readonly grown: readonly RowSpan[];
    /** The removed rows a run of identical rows lost, the other way round. */
    readonly shrunk: readonly (RowSpan & {
        readonly at: number;
    })[];
}
/** The rounds, in runs, one Myers search takes before the columns are split at runs each side holds once. */
export declare const ALIGNMENT_LIMIT = 2000;
/**
 * The pairing, or `undefined` when there is none to make: the widths differ, so
 * no row of one is a row of the other, or the pairing leaves no fewer pixels
 * differing than position does.
 */
export declare function alignRows(before: DecodedImage, after: DecodedImage, limit?: number): AlignedRows | undefined;
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