import { PreviewFile, PreviewFileInput, PreviewType } from '../types/preview.types';
export declare class PreviewUtils {
    static formatFileSize(bytes?: number): string;
    static getFileType(file: File): PreviewType;
    static getFileTypeFromUrl(url: string): PreviewType;
    static isBase64Url(url: string): boolean;
    private static getFileTypeFromExtension;
    /**
     * 转换为 PreviewFile 类型
     */
    static normalizeFiles(input: PreviewFileInput): PreviewFile[];
    static normalizeFile(input: PreviewFileInput): PreviewFile;
    static isPreviewFile(input: any): input is PreviewFile;
    static getFileNameFromUrl(url: string): string;
}