import { ApiPropertyOptions } from '@nestjs/swagger';
/**
 * Represents a Thumbnail with image source, accessibility text, background styling,
 * cropping behavior, and optional max size constraints.
 */
export declare class Thumbnail {
    /** Source URL of the thumbnail image (HTTPS required). */
    src: string;
    /** Alternative text for accessibility describing the image. */
    alt: string;
    /** Background colors or gradients as HEX color codes. */
    background: string[];
    /** Whether the image should be contained (true) or cropped (false). */
    contain: boolean;
    /** Optional max height in pixels, minimum validated dynamically. */
    maxHeight?: number;
    /** Optional max width in pixels, minimum validated dynamically. */
    maxWidth?: number;
}
/**
 * Creates a nested image-like property (e.g., thumbnail, cover).
 * Auto-generates validation and documentation from class or title.
 *
 * @param {ApiPropertyOptions & { type?: Function }} options - Swagger API property options.
 * @returns {PropertyDecorator} Composite decorator applying nested validation and type transformation.
 */
export declare function PropertyThumbnail(options?: ApiPropertyOptions & {
    type?: Function;
}): PropertyDecorator;