/**
 * Form field appearance stream generation.
 *
 * Generates visual appearance streams for PDF form fields so that field
 * values are visible in all PDF viewers — even those that do not honor
 * the `/NeedAppearances` flag.
 *
 * @see PDF Reference 1.7, §12.5.5 — Appearance Streams
 * @see PDF Reference 1.7, §12.7.4 — Field Appearance
 */
/** Options for generating a text field appearance stream. */
export interface TextFieldAppearanceOptions {
    /** The text value to display. */
    value: string;
    /** Widget annotation rectangle [x1, y1, x2, y2]. */
    rect: number[];
    /** Font size in points. 0 or omitted = auto-size to fit the field height. */
    fontSize?: number;
    /** Font resource name to reference (e.g. "Helv"). */
    fontName?: string;
    /** Text alignment within the field. */
    alignment?: "left" | "center" | "right";
}
/**
 * Generate an appearance stream for a text form field.
 *
 * Builds a minimal content stream that clips to the widget rect and
 * draws the field value using the specified (or default) font.
 *
 * @returns The raw stream bytes and a resources dictionary string.
 */
export declare function generateTextFieldAppearance(options: TextFieldAppearanceOptions): {
    stream: Uint8Array;
    resources: string;
};
/**
 * Generate appearance streams for a checkbox form field.
 *
 * Returns two streams:
 * - `streamOn`:  draws a checkmark (✓-like shape) inside the rect
 * - `streamOff`: empty appearance (blank field)
 *
 * @param checked - Whether to generate the checked or unchecked variant
 *                  (both are always returned; `checked` is ignored — both
 *                  on and off streams are produced).
 * @param rect - Widget annotation rectangle [x1, y1, x2, y2].
 */
export declare function generateCheckboxAppearance(_checked: boolean, rect: number[]): {
    streamOn: Uint8Array;
    streamOff: Uint8Array;
};
/**
 * Build the BBox array string for a form XObject appearance stream.
 * The bounding box is in the widget's coordinate space: [0 0 width height].
 */
export declare function buildAppearanceBBox(rect: number[]): string;