lightenColor function
Implementation
Color lightenColor(Color color, double tintFactor) {
return Color.fromRGBO(
(color.red + (255 - color.red) * tintFactor).round(),
(color.green + (255 - color.green) * tintFactor).round(),
(color.blue + (255 - color.blue) * tintFactor).round(),
color.opacity,
);
}