/**
 * Japanese ruby geometry (furigana, #422), after JIS X 4051 §12 and JLReq
 * §3.3: where a reading sits on its base, how far a longer one may run
 * past the base before the base is spread, and how the readings of a
 * jukugo ruby (熟語ルビ) share a word.
 *
 * Pure arithmetic along the line, in px of the flow frame: the composer
 * (`cjkCompose.ts`) gives each base's advance and its reading's
 * characters, and how far the reading may pass the base on each side
 * (`allow`: what the neighbour outside takes, 0 at a line edge, where
 * the reading is set flush with the edge and the base moves in); it gets
 * back each base's box (its advance on the line), where the base's first
 * glyph starts in the box (`inset`), the spacing after each base
 * character (`tracking`) and the reading's pieces, placed from the box's
 * start.
 *
 * - A reading no longer than its base (JLReq §3.3.6 a) leaves the box as
 *   the base: `center` centres it, `start` sets it from the base's start,
 *   `jis` spreads it 1:2:1 (half a unit before the first character and
 *   after the last, a unit between characters), or, when that half unit
 *   would be more than a ruby character, from one end of the base to the
 *   other (space-between). One character is centred by either.
 * - A longer reading (§3.3.6 b) runs past the base as far as each side
 *   allows, evenly while both sides can take it; what is left spreads the
 *   base: 1:2:1 under `jis` (half a unit before the first character and
 *   after the last, a unit between), centred in its box otherwise. The
 *   reading is set solid.
 * - A jukugo ruby (§3.3.7) is set as mono ruby while every reading fits
 *   its base. When one does not, each reading stays by its own base and
 *   may run onto the next or the previous base of the word by up to one
 *   ruby character, the readings never overlapping, the first and the
 *   last passing the word by what the neighbours outside allow. When even
 *   that does not hold them, the word takes its readings as one, a group
 *   ruby over the whole word.
 */
/** A ruby base and its reading. */
export interface JisRubyBase {
    /** The base's advance (its characters at their own spacing), px. */
    width: number;
    /** How many characters (graphemes) the base holds. */
    graphemes: number;
    /** The reading's characters as painted, with their advances (px). */
    reading: readonly {
        text: string;
        width: number;
    }[];
}
/** Where a reading sits (see `CjkRubyAlign`). */
export type JisRubyAlign = 'center' | 'jis' | 'start';
/** How far a reading may pass its base, or a jukugo word, on each side, px. */
export interface JisRubyAllow {
    start: number;
    end: number;
}
/** A piece of a reading: its text, its advance and where it starts, px
 *  from the start of its base's box (negative: before the box). */
export interface JisRubyPiece {
    text: string;
    dx: number;
    width: number;
}
/** How a ruby base is set (see the module comment). */
export interface JisRubyBox {
    /** The box's advance on the line, px. */
    width: number;
    /** Where the base's first glyph starts in the box, px. */
    inset: number;
    /** Space after each base character (a spread base of two or more), px;
     *  counted in `width`. */
    tracking: number;
    pieces: JisRubyPiece[];
}
/** How far a longer reading passes its base on each side: evenly while
 *  both sides take it, then the side that takes more (`start` alignment:
 *  only after the base). */
export declare function overhangs(need: number, allow: JisRubyAllow, align: JisRubyAlign): {
    start: number;
    end: number;
};
/**
 * One base and its reading: a mono ruby's character, or a group ruby's
 * base (see the module comment). `rubyEm` is the reading's em, for the
 * limit of the 1:2:1 spread.
 */
export declare function layoutJisRuby(base: JisRubyBase, align: JisRubyAlign, rubyEm: number, allow: JisRubyAllow): JisRubyBox;
/**
 * A jukugo ruby's characters (a word, or the part of it on a line): one
 * box per base (see the module comment). `allow` is what the word's
 * neighbours outside it take.
 */
export declare function layoutJukugo(bases: readonly JisRubyBase[], align: JisRubyAlign, rubyEm: number, allow: JisRubyAllow): JisRubyBox[];
/** The total advance of boxes. */
export declare function boxesWidth(boxes: readonly JisRubyBox[]): number;
/** A reading with its small kana full size (がっこう → がつこう). */
export declare function fullSizeKana(reading: string): string;
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