import { _XmlWriter } from '../import-export/xml-writer';
import { PdfXmpSchema } from './pdf-xmp-schema';
import { PdfXmpSchemaType } from '../enumerator';
import { PdfXmpMetadata } from './pdf-xmp-metadata';
/**
 * Represents a user-defined metadata schema with custom properties.
 * ```typescript
 * // Load an existing PDF document
 * let document: PdfDocument = new PdfDocument(data, password);
 * // Access the document properties
 * let documentProperties: PdfDocumentInformation = document.getDocumentInformation(false);
 * // Gets XMP metadata
 * let xmpMetadata: PdfXmpMetadata = documentProperties.xmpMetadata;
 * // Create a custom schema
 * let custom: PdfCustomSchema = new PdfCustomSchema(xmpMetadata, 'cust', 'http://custom.example.com/ns/');
 * custom.customData.set('appVersion', '1.0.0');
 * // Save the document
 * document.save('output.pdf');
 * // Destroy the document
 * document.destroy();
 * ```
 */
export declare class PdfCustomSchema extends PdfXmpSchema {
    private _namespace;
    _namespaceUri: string;
    private _customdata;
    /**
     * Initializes a new `PdfCustomSchema` instance.
     *
     * @param {PdfXmpMetadata} xmp Parent PdfXmpMetadata reference.
     * @param {string} namespacePrefix The XML namespace prefix.
     * @param {string} namespaceUri The namespace URI.
     */
    constructor(xmp: PdfXmpMetadata, namespacePrefix: string, namespaceUri: string);
    /**
     * Gets the schema type.
     *
     * @returns {PdfXmpSchemaType} The schema type.
     * ```typescript
     * // Load an existing PDF document
     * let document: PdfDocument = new PdfDocument(data);
     * // Access the document properties
     * let documentProperties: PdfDocumentInformation = document.getDocumentInformation(false);
     * // Create a custom schema
     * let custom: PdfCustomSchema = new PdfCustomSchema(documentProperties.xmpMetadata, 'cust', 'http://custom.example.com/ns/');
     * let schemaType: PdfXmpSchemaType = custom.schemaType;
     * // Save the document
     * document.save('output.pdf');
     * // Destroy the document
     * document.destroy();
     * ```
     */
    readonly schemaType: PdfXmpSchemaType;
    /**
     * Gets the custom data map.
     *
     * @returns {Map<string, string>} The custom data.
     *
     * ```typescript
     * // Load an existing PDF document
     * let document: PdfDocument = new PdfDocument(data, password);
     * // Access the document properties
     * let documentProperties: PdfDocumentInformation = document.getDocumentInformation(false);
     * // Gets XMP metadata
     * let xmpMetadata: PdfXmpMetadata = documentProperties.xmpMetadata;
     * // Create a custom schema
     * let custom: PdfCustomSchema = new PdfCustomSchema(documentProperties.xmpMetadata, 'cust', 'http://custom.example.com/ns/');
     * // Gets the customData values
     * let customData: Map<string, string> = customSchema.customData;
     * // Destroy the document
     * document.destroy();
     * ```
     */
    /**
    * Sets the custom data map.
    *
    * @param {Map<string, string>} value The custom data to set.
    *
    * ```typescript
    * // Load an existing PDF document
    * let document: PdfDocument = new PdfDocument(data, password);
    * // Access the document properties
    * let documentProperties: PdfDocumentInformation = document.getDocumentInformation(false);
    * // Gets XMP metadata
    * let xmpMetadata: PdfXmpMetadata = documentProperties.xmpMetadata;
    * // Create a custom schema
    * let custom: PdfCustomSchema = new PdfCustomSchema(documentProperties.xmpMetadata, 'cust', 'http://custom.example.com/ns/');
    * // Sets custom data map
    * let dataMap: Map<string, string> = new Map<string, string>();
    * dataMap.set('appVersion', '1.0.0');
    * dataMap.set('buildNumber', '12345');
    * custom.customData = dataMap;
    * // Save the document
    * document.save('output.pdf');
    * // Destroy the document
    * document.destroy();
    * ```
    */
    customData: Map<string, string>;
    /**
     * Serializes custom data entries to RDF/XML using the provided writer.
     * Skips serialization when customData is empty.
     *
     * @private
     * @param {_XmlWriter} writer The XML writer to serialize into.
     * @returns {void}
     */
    _writeXml(writer: _XmlWriter): void;
}