/**
 * Service for generating PDF thumbnails using PDF.js
 * Caches generated thumbnails to avoid regeneration
 */
export declare class PdfThumbnailGenerator {
    private cache;
    /**
     * Generates a thumbnail for a PDF document
     * @param documentId - Unique identifier for caching
     * @param pdfData - ArrayBuffer containing the PDF data
     * @param size - Desired thumbnail dimensions
     * @returns Data URL of the generated thumbnail
     */
    generatePdfThumbnail(documentId: string, pdfData: ArrayBuffer, size: {
        width: number;
        height: number;
    }): Promise<string>;
    /**
     * Retrieves a cached thumbnail
     * @param documentId - Document identifier
     * @returns Cached data URL or null
     */
    getCached(documentId: string): string | null;
    /**
     * Clears all cached thumbnails
     */
    clearCache(): void;
    /**
     * Removes a specific thumbnail from cache
     * @param documentId - Document identifier
     */
    removeCached(documentId: string): void;
}