import type { ResolvedConfig } from '../vdt.js';
/**
 * The attribute {@link applySingleInkToSvg} writes on the root `<svg>` of
 * the markup it recolours, naming the ink (`data-postext-single-ink="#1f3a93"`).
 * Markup that carries it is never recoloured again — the mapping is not
 * idempotent, so a second pass would lighten every colour: black would come
 * out at `1 − luminance(ink)` of the ink.
 */
export declare const SINGLE_INK_MARK = "data-postext-single-ink";
/** Whether SVG markup was recoloured by {@link applySingleInkToSvg} already:
 *  its root element carries {@link SINGLE_INK_MARK}. */
export declare function isSingleInkSvg(svgText: string): boolean;
/**
 * Whether an image URL is an SVG data URI whose markup carries
 * {@link SINGLE_INK_MARK} — a picture recoloured by
 * {@link applySingleInkToSvg} before it was handed over as a URL. Only the
 * head of the payload is read. A blob or network URL cannot tell (false).
 */
export declare function isSingleInkSvgUrl(url: string): boolean;
/**
 * Recolour an SVG document to tints of a single ink.
 *
 * The result carries {@link SINGLE_INK_MARK} on its root element, and
 * markup that already carries it is returned as it is — whatever ink it
 * names — so a picture is never tinted twice, whichever of the host and
 * the backends recolours it first.
 *
 * @param svgText The SVG markup.
 * @param inkHex  The ink colour as a hex string (e.g. `'#295AA3'`).
 * @returns The recoloured markup; returns the input unchanged when `inkHex`
 *          cannot be parsed or the markup is marked as recoloured already.
 */
export declare function applySingleInkToSvg(svgText: string, inkHex: string): string;
/**
 * Recolour RGBA pixels in place to tints of a single ink — the mapping of
 * {@link applySingleInkToSvg}, applied to a rendered picture instead of its
 * markup (the canvas backend's path for SVG images it was handed decoded).
 * Alpha is kept; fully transparent pixels are skipped.
 *
 * @returns false (and leaves `data` as it was) when `inkHex` cannot be parsed.
 */
export declare function applySingleInkToPixels(data: Uint8ClampedArray, inkHex: string): boolean;
/**
 * The same mapping as the 4×5 matrix of an SVG `feColorMatrix` (values row
 * by row, on 0..1 gamma-encoded channels — use it with
 * `color-interpolation-filters="sRGB"`): each channel becomes
 * `ink + (1 − ink) · luminance`, alpha passes through. The HTML backend
 * filters SVG `<img>`s with it. Null when `inkHex` cannot be parsed.
 */
export declare function singleInkColorMatrix(inkHex: string): number[] | null;
/** The ink a document's SVG pictures are recoloured to — its resolved
 *  `diagramStyle.inkColor` — or null when `diagramStyle.singleInk` is off.
 *  Shared by the canvas, HTML and PDF backends. */
export declare function documentInkHex(config: Pick<ResolvedConfig, 'diagramStyle' | 'colorPalette'>): string | null;
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