Function colorDiff

packages/utils/src/index.ts:220–236

(
  rgba1: RGBAColor | RGBColor,
  rgba2: RGBAColor | RGBColor
)

 * ```
 */
export function colorDiff(
  rgba1: RGBAColor | RGBColor,
  rgba2: RGBAColor | RGBColor
) {
  const sq = (n: number) => Math.pow(n, 2);
  const { max } = Math;
  const maxVal = 255 * 255 * 3;
  const rgba1A = "a" in rgba1 ? rgba1.a : 255;
  const rgba2A = "a" in rgba2 ? rgba2.a : 255;

  return (
    (max(sq(rgba1.r - rgba2.r), sq(rgba1.r - rgba2.r - rgba1A + rgba2A)) +
      max(sq(rgba1.g - rgba2.g), sq(rgba1.g - rgba2.g - rgba1A + rgba2A)) +
      max(sq(rgba1.b - rgba2.b), sq(rgba1.b - rgba2.b - rgba1A + rgba2A))) /
    maxVal
  );
}

/**
 * Limits a number to between 0 or 255