import { ParsedTtf } from './ttf-parser.js';
/** A font style slot: regular, bold, italic or bold-italic. */
export type FontVariant = 'regular' | 'bold' | 'italic' | 'boldItalic';
/**
 * The single owner of face fallback (oop-design §8, A4): the candidate cascade a
 * missing variant degrades through (`boldItalic → bold → italic → regular`),
 * shared by the registry and every font provider.
 *
 * @param has    Predicate — does a given variant exist?
 * @param bold   Whether bold was requested.
 * @param italic Whether italic was requested.
 * @returns The best available variant, or `undefined` when even `regular` is missing.
 */
export declare function pickVariant(has: (variant: FontVariant) => boolean, bold: boolean, italic: boolean): FontVariant | undefined;
/** Raw TTF/OTF bytes per style variant; only `regular` is required. */
export interface FontBytesByVariant {
    /** The regular (upright, normal-weight) face — required. */
    readonly regular: Uint8Array;
    /** The bold face, if available. */
    readonly bold?: Uint8Array;
    /** The italic face, if available. */
    readonly italic?: Uint8Array;
    /** The bold-italic face, if available. */
    readonly boldItalic?: Uint8Array;
}
/**
 * A registry of parsed font variants. The renderer resolves a `(bold, italic)`
 * request to the closest available face via {@link pickVariant}, degrading
 * through `bold → italic → regular` when an exact match is missing.
 */
export declare class FontRegistry {
    private readonly fonts;
    private constructor();
    /**
     * Parse a set of font bytes into a registry.
     *
     * @param input The bytes per variant (`regular` required).
     * @returns A registry holding the parsed faces.
     */
    static fromBytes(input: FontBytesByVariant): FontRegistry;
    /**
     * Resolve a style request to the closest available face.
     *
     * @param bold   Whether bold was requested.
     * @param italic Whether italic was requested.
     * @returns The chosen variant and its parsed font.
     * @throws Error when the registry has no usable (regular) font.
     */
    resolveByStyle(bold: boolean, italic: boolean): {
        variant: FontVariant;
        parsed: ParsedTtf;
    };
    /** Iterate the `[variant, parsed font]` pairs the registry holds. */
    entries(): IterableIterator<[FontVariant, ParsedTtf]>;
    /** Whether a given variant is present. */
    hasVariant(v: FontVariant): boolean;
}