/**
 * Color-resolution helpers.
 *
 * Any user-supplied color field on Node / Region / Connector / Note /
 * NodeBadge is routed through these helpers. The contract:
 *
 *   Input                       Output
 *   -----                       ------
 *   undefined                   undefined
 *   'primary' etc.              theme[key]           (resolved theme color)
 *   'primary/20'                '#rrggbb20'          (hex + alpha byte)
 *   '#e8792f', 'red', etc.      passed through untouched
 *
 * `resolveColor()` returns a single string (or undefined) — suitable for
 * direct use in `fill` / `stroke`.
 *
 * `resolveRegionFill()` returns {fill, opacity?}. When the user writes a
 * BARE theme keyword on a region, the keyword resolves to the theme color
 * AND fill-opacity is set to DEFAULT_REGION_ALPHA so the region reads as a
 * subtle tint (matching the existing `#rrggbb12` hand-rolled convention).
 * Literals and keyword-with-alpha forms pass through unchanged — the user
 * is presumed to have chosen the opacity explicitly.
 */
import type { DiagramTheme, ThemeColorKey } from '../types.js';
export declare const KEYS: ThemeColorKey[];
/** Hex alpha byte used for node ring backgrounds (≈8%). */
export declare const NODE_RING_FILL_ALPHA: number;
/** Default fill-opacity for regions whose color is a bare theme keyword. */
export declare const DEFAULT_REGION_ALPHA: number;
/**
 * Resolve a color value. Supports theme keywords, keyword/AA alpha
 * syntax, and CSS literals. Returns a single string (or undefined).
 */
export declare function resolveColor(color: string | undefined, theme: DiagramTheme): string | undefined;
/** Returned fill pair — `opacity` is undefined when no auto-tint applies. */
export interface ResolvedFill {
    fill: string;
    opacity?: number;
}
/**
 * Resolve a region's color field into a (fill, fill-opacity) pair. Bare
 * theme keywords auto-tint with DEFAULT_REGION_ALPHA; everything else
 * passes through untouched (the user chose the exact color themselves).
 *
 * Returns { fill: 'none' } when color is undefined / empty.
 */
export declare function resolveRegionFill(color: string | undefined, theme: DiagramTheme): ResolvedFill;
/** True when a color value (literal or keyword) counts as transparent. */
export declare function isTransparent(color: string | undefined): boolean;
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