/**
 * Shared crop constants for inventory PNG + tape-line overlay (#99).
 * Aspect is fixed 3:4; crop_fill only moves the long-axis end insets.
 * Non-retro: changing fill affects future encodes only, not stored PNGs.
 */

export const DEFAULT_CROP_FILL = 0.9;
export const ASPECT_W = 3;
export const ASPECT_H = 4;
export const FLOOR_PX = 800;

/** Fraction of the long axis inset from each end: (1 - fill) / 2. */
export function cropMarginFraction(fill: number = DEFAULT_CROP_FILL): number {
  const f = clampFill(fill);
  return (1 - f) / 2;
}

export function clampFill(fill: number): number {
  if (!Number.isFinite(fill)) return DEFAULT_CROP_FILL;
  return Math.min(1, Math.max(0.01, fill));
}