/**
 * Grid3 Color Utilities
 *
 * Comprehensive color handling for Grid3 format, including:
 * - CSS color name lookup (147 named colors)
 * - Color format conversion (hex, RGB, RGBA, named colors)
 * - Color manipulation (darkening, normalization)
 * - Grid3-specific color formatting (8-digit ARGB hex)
 */
/**
 * Get RGB values for a CSS color name
 * @param name - CSS color name (case-insensitive)
 * @returns RGB tuple [r, g, b] or undefined if not found
 */
export declare function getNamedColor(name: string): [number, number, number] | undefined;
/**
 * Convert RGBA values to hex format
 * @param r - Red channel (0-255)
 * @param g - Green channel (0-255)
 * @param b - Blue channel (0-255)
 * @param a - Alpha channel (0-1)
 * @returns Hex color string in format #RRGGBBAA
 */
export declare function rgbaToHex(r: number, g: number, b: number, a: number): string;
/**
 * Convert a single color channel value to hex
 * @param value - Channel value (0-255)
 * @returns Two-digit hex string
 */
export declare function channelToHex(value: number): string;
/**
 * Clamp RGB channel value to valid range
 * @param value - Channel value
 * @returns Clamped value (0-255)
 */
export declare function clampColorChannel(value: number): number;
/**
 * Clamp alpha value to valid range
 * @param value - Alpha value
 * @returns Clamped value (0-1)
 */
export declare function clampAlpha(value: number): number;
/**
 * Convert any color format to hex
 * Supports: hex (#RGB, #RRGGBB, #RRGGBBAA), RGB/RGBA, and CSS color names
 * @param value - Color string in any supported format
 * @returns Hex color string (#RRGGBBAA) or undefined if invalid
 */
export declare function toHexColor(value: string): string | undefined;
/**
 * Darken a hex color by a specified amount
 * @param hex - Hex color string
 * @param amount - Amount to darken (0-255)
 * @returns Darkened hex color
 */
export declare function darkenColor(hex: string, amount: number): string;
/**
 * Lighten a hex color by a specified amount
 * @param hex - Hex color string
 * @param amount - Amount to lighten (0-255)
 * @returns Lightened hex color
 */
export declare function lightenColor(hex: string, amount: number): string;
/**
 * Convert hex color to RGBA object
 * @param hex - Hex color string (#RRGGBB or #RRGGBBAA)
 * @returns RGBA object with r, g, b, a properties (0-1 for alpha)
 */
export declare function hexToRgba(hex: string): {
    r: number;
    g: number;
    b: number;
    a: number;
};
/**
 * Normalize any color format to Grid3's 8-digit hex format
 * @param input - Color string in any supported format
 * @param fallback - Fallback color if input is invalid (default: white)
 * @returns Normalized color in format #AARRGGBBFF
 */
export declare function normalizeColor(input: string, fallback?: string): string;
/**
 * Ensure a color has an alpha channel (Grid3 format requires 8-digit ARGB)
 * @param color - Color string (hex format)
 * @returns Color with alpha channel in format #AARRGGBBFF
 */
export declare function ensureAlphaChannel(color: string | undefined): string;