import type { PdfEngineStamp, PdfEngineWatermark } from './pdf-engine-watermark-stamp.types';
/**
 * Appends PDF-engine watermark and stamp multipart fields for Gotenberg post-processing.
 */
export declare class PdfEngineWatermarkStampUtils {
    private static appendFileForField;
    /**
     * Appends watermarkSource, watermarkExpression, watermarkPages, watermarkOptions, and optional watermark file.
     */
    private static appendWatermark;
    /**
     * Appends stampSource, stampExpression, stampPages, stampOptions, and optional stamp file.
     */
    private static appendStamp;
    /**
     * @param data - Target FormData
     * @param options - Optional PDF-engine watermark and/or stamp configuration
     */
    static appendPdfEngineWatermarkStamp(data: FormData, options: {
        watermark?: PdfEngineWatermark;
        stamp?: PdfEngineStamp;
    }): Promise<void>;
}