import { Buffer } from "buffer/index.js";
/**
 * Helper to create subsets of fonts
 * Large parts of this are a modified version of papandreou/subset-font
 */
export declare class SubsetManager {
    /**
     * Harfbuzz subset sets name id
     */
    private static readonly HB_SUBSET_SETS_NAME_ID;
    /**
     * Harfbuzz subset sets layout feature tag
     */
    private static readonly HB_SUBSET_SETS_LAYOUT_FEATURE_TAG;
    /**
     * Harfbuzz writable memory mode
     */
    private static readonly HB_MEMORY_MODE_WRITABLE;
    /**
     * OpenType name table ID for the COPYRIGHT notice.
     */
    private static readonly NAME_ID_COPYRIGHT;
    /**
     * OpenType name table ID for the TRADEMARK notice.
     */
    private static readonly NAME_ID_TRADEMARK;
    /**
     * OpenType name table ID for the LICENSE notice.
     */
    private static readonly NAME_ID_LICENSE;
    /**
     * OpenType name table ID for the LICENSE URL.
     */
    private static readonly NAME_ID_LICENSE_URL;
    /**
     * The cached harfbuzzjs instance
     */
    private harfbuzzJs?;
    /**
     * Used to limit the number of concurrent subsetFontInternal calls to 1
     */
    private readonly limiter;
    /**
     * Subsets a font
     * Modified version of papandreou/subset-font
     * Always includes the following name table entries: COPYRIGHT, TRADEMARK, LICENSE, LICENSE_URL
     *
     * @param originalFont the original font to subset
     * @param characters text including all characters that should be included in the subset, all characters are included if undefined
     * @param variationAxes optional object with variation axes to pin to specific values
     * @returns the subset font
     */
    subsetFont(originalFont: Buffer, characters: string | undefined, variationAxes: Record<string, number> | undefined): Promise<Buffer>;
    /**
     * Gets the harfbuzzjs instance
     * Result is cached
     * Must NOT be called concurrently / interleaved
     *
     * @returns the harfbuzzjs instance
     */
    private getHarfbuzzJs;
    /**
     * Creates a 32-bit integer from a string.
     *
     * @param str The string to convert, should be 4 characters long.
     * @returns The 32-bit integer.
     */
    private HB_TAG;
    /**
     * Subsets a font
     * Always includes the following name table entries: COPYRIGHT, TRADEMARK, LICENSE, LICENSE_URL
     * Must NOT be called concurrently / interleaved
     *
     * @param font the font to subset
     * @param characters text including all characters that should be included in the subset, all characters are included if undefined
     * @param variationAxes optional object with variation axes to pin to specific values
     * @returns the subset font
     */
    private subsetFontInternal;
    /**
     * Computes the subset
     *
     * @param harfbuzzJsWasm the harfbuzzjs instance
     * @param heapu8 the harfbuzz instance heap to use
     * @param face the harfbuzz face pointer
     * @param input the harfbuzz input pointer
     * @param fontBuffer the font buffer
     * @returns the subset font
     */
    private computeSubset;
    /**
     * Imports a font into harfbuzz
     *
     * @param harfbuzzJsWasm the harfbuzzjs instance
     * @param convertedFont the converted font
     * @param heapu8 the harfbuzz instance heap to use
     * @returns the input, face and font buffer
     */
    private importFontIntoHarfbuzz;
    /**
     * Sets the input unicodes for the subset
     *
     * @param harfbuzzJsWasm the harfbuzzjs instance
     * @param input the harfbuzz input pointer
     * @param characters the characters to include in the subset, all characters are included if undefined
     */
    private setInputUnicodesForSubset;
    /**
     * Sets the layout features for the subset
     * Removes all layout features
     *
     * @param harfbuzzJsWasm the harfbuzzjs instance
     * @param input the harfbuzz input pointer
     */
    private setLayoutFeaturesForSubset;
    /**
     * Sets the variation axes for the subset
     * Removes all variation axes, uses the default value for non-provided axes
     *
     * @param harfbuzzJsWasm the harfbuzzjs instance
     * @param variationAxes the variation axes
     * @param input the harfbuzz input pointer
     * @param face the harfbuzz face pointer
     */
    private setVariationAxesForSubset;
    /**
     * Sets the name table for the subset
     * Removes all name table entries except COPYRIGHT, TRADEMARK, LICENSE, LICENSE_URL
     *
     * @param harfbuzzJsWasm the harfbuzzjs instance
     * @param input the harfbuzz input pointer
     */
    private setNameTableForSubset;
    /**
     * Cleans up resources
     *
     * @param harfbuzzJsWasm the harfbuzzjs instance
     * @param result the harfbuzz result pointer
     * @param subset the harfbuzz subset pointer
     * @param face the harfbuzz face pointer
     * @param fontBuffer the font buffer
     */
    private cleanupResources;
}
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