import type * as React from "react";
export declare const DEFAULT_OPTIMIZED_IMAGE_FORMATS: readonly ["avif", "webp", "jpeg"];
/** Serialize a URL as a quoted CSS url() value without changing its identity. */
export declare function cssUrl(value: string): string;
export declare function getOptimizedPath(src: string, format: string, size: number, _quality?: number): string;
export declare function generateSrcSet(src: string, format: string, sizes: readonly number[], _quality: number): string;
/**
 * Resolve build-emitted widths at the public React boundary.
 * Invalid runtime props use the original asset; the strict shared resolver
 * remains authoritative for build configuration and internal callers.
 */
export declare function getOptimizedImageVariantWidths(sourceWidth: number | undefined, targetWidths?: readonly number[], src?: string): readonly number[];
/** Return a valid numeric img dimension attribute, or omit invalid runtime values. */
export declare function getImageDimensionAttribute(value: number | undefined): number | undefined;
/** Use the original asset unless a corresponding optimized variant is known. */
export declare function getOptimizedImageFallback(src: string, format: string, widths: readonly number[], quality: number, preferredWidth?: number): string;
/** Use an optimized fallback only when `format` is in the caller-requested formats. */
export declare function getOptimizedImageFormatFallback(src: string, format: string, requestedFormats: readonly string[] | undefined, widths: readonly number[], quality: number): string;
/**
 * Get image file extension, defaulting to "jpeg" if none found.
 *
 * "jpg" is normalized to "jpeg" because the build pipeline only emits
 * "jpeg" variants (see SUPPORTED_FORMATS in the image optimizer), so a
 * ".jpg" source would otherwise produce a fallback URL that never exists.
 */
export declare function getImageExtension(src: string): string;
/**
 * Keyboard activation for a clickable image, matching how a native button and
 * `ui/list.tsx` behave: Enter fires on keydown, Space is deferred to keyup so
 * moving focus away cancels the pending activation.
 */
export declare function handleImageActivationKeyDown(event: React.KeyboardEvent<HTMLImageElement>): void;
/** Companion to {@link handleImageActivationKeyDown}: fires the deferred Space. */
export declare function handleImageActivationKeyUp(event: React.KeyboardEvent<HTMLImageElement>): void;
/** Companion to {@link handleImageActivationKeyDown}: drops a pending Space. */
export declare function handleImageActivationBlur(event: React.FocusEvent<HTMLImageElement>): void;
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