/**
 * Zero-dependency text-to-PNG watermark image generator.
 *
 * Renders text into a semi-transparent PNG suitable for use as an Excel watermark.
 * Uses a built-in bitmap font for ASCII characters — no Canvas or external fonts required.
 * PNG data is deflate-compressed using the archive module's built-in compressor.
 *
 * @example
 * ```typescript
 * const png = createTextWatermarkImage("CONFIDENTIAL", {
 *   fontSize: 48,
 *   color: { r: 128, g: 128, b: 128 },
 *   opacity: 40,
 *   rotation: -45
 * });
 * const imgId = workbook.addImage({ buffer: png, extension: "png" });
 * worksheet.addWatermark({ imageId: imgId });
 * ```
 */
/**
 * Options for text watermark image generation.
 */
export interface TextWatermarkImageOptions {
    /**
     * Approximate font size in pixels (glyph height).
     * The built-in bitmap font is 8px tall; values larger than 8 are achieved by
     * integer scaling. e.g. fontSize 48 → 6x scale.
     * @default 48
     */
    fontSize?: number;
    /**
     * Text color as RGB (0-255 each).
     * @default { r: 128, g: 128, b: 128 }
     */
    color?: {
        r: number;
        g: number;
        b: number;
    };
    /**
     * Opacity as a percentage (0 = fully transparent, 100 = fully opaque).
     *
     * Note: this is a **0–100 percentage** used when rendering the PNG image pixels.
     * It is different from `WatermarkOptions.opacity` (which is 0–1) used by
     * `worksheet.addWatermark()` for DrawingML `alphaModFix`.
     *
     * @default 40
     */
    opacity?: number;
    /**
     * Rotation in degrees (positive = counter-clockwise).
     * @default -45
     */
    rotation?: number;
    /**
     * Padding in pixels around the text (before rotation).
     * @default 20
     */
    padding?: number;
}
/**
 * Generate a PNG image containing watermark text.
 *
 * The image has an alpha channel so the watermark is semi-transparent.
 * Works in both Node.js and browsers with zero dependencies.
 */
export declare function createTextWatermarkImage(text: string, options?: TextWatermarkImageOptions): Uint8Array;