/**
 * The ligatures of a tracked text, as the measurer sees them (#663, #770).
 *
 * A tracked word is measured at its natural width, the ligatures of the
 * face counted, plus the tracking times its letters. A browser sets no
 * optional ligature under a letter-spacing, on the canvas or in a box, so
 * the word painted with the spacing alone is wider than its place: Chrome
 * 154 at 40 px, `first` 4.56 px in Newsreader and 2.76 px in Source Serif
 * 4, `office` 7 px in EB Garamond. The canvas paints such a word in
 * pieces (`canvas-backend/trackedText.ts`): each ligature alone under no
 * letter-spacing, the letters between them tracked, every piece where the
 * natural shaping puts it and the tracking of every letter before it
 * further on. This module finds the same pieces with the engine's own
 * measurer, for an output that has no painting context to ask (the HTML).
 *
 * Which letters: two neighbours whose width under a letter-spacing, the
 * spacing taken off, is not their natural width are a ligature, and a
 * third joins them the same way (f + f + i). A face whose ligature is as
 * wide as its letters (Geist's `fi`) shows nothing here, and needs
 * nothing: set apart under the letter-spacing its letters stand where the
 * layout counted them.
 *
 * A form by the neighbours is no ligature. Under a letter-spacing the
 * browser takes the contextual alternates of a face away with its
 * ligatures, and two neighbours with such forms read as a ligature to the
 * probe above (Playpen Sans: `FO`, `OR`, most pairs). A zero width
 * non-joiner between the two tells: it dissolves a ligature and leaves a
 * form by the neighbours (`canvas-backend/trackedText.ts` has the widths
 * measured). Two neighbours as wide across a non-joiner as without one
 * are left in the letters around them: the HTML sets a word with such
 * forms whole, at the letter-spacing that ends it where it was measured,
 * as the canvas paints it in a document shaped in its own language. Only
 * such a document asks here.
 *
 * In the language measured in (`getMeasureLanguage`): a face ligates
 * otherwise under a language (no `fi` in Turkish).
 */
/** One piece of a tracked text set apart from the rest. */
export interface LigaturePiece {
    text: string;
    /** Where the piece starts in the text's natural shaping, px from its
     *  start, the kerning before it counted. */
    offset: number;
    /** Its natural width, px: alone, under no letter-spacing. */
    width: number;
    /** Its letters (graphemes): each takes the tracking once. */
    letters: number;
    /** A ligature: set under no letter-spacing. */
    ligature: boolean;
}
/**
 * The pieces a tracked `text` (a word, or any text set as one run) is set
 * in, in `font` and the language measured in, or null when it is set
 * whole: the browser shapes it the same under a letter-spacing, the
 * canvas measures none, or the text holds a joining letter or a
 * right-to-left one.
 */
export declare function trackedLigaturePieces(text: string, font: string): readonly LigaturePiece[] | null;
//# sourceMappingURL=trackedLigatures.d.ts.map