lighten method
Lightens the color with the given integer percentage amount. Defaults to 10%.
Implementation
Color lighten([final int amount = 10]) {
if (amount <= 0) return this;
if (amount > 100) return Colors.white;
// HSLColor returns saturation 1 for black, we want 0 instead to be able
// lighten black color up along the grey scale from black.
final HSLColor hsl = this == const Color(0xFF000000)
? HSLColor.fromColor(this).withSaturation(0)
: HSLColor.fromColor(this);
return hsl
.withLightness(math.min(1, math.max(0, hsl.lightness + amount / 100)))
.toColor();
}