RgbColor constructor
A color in the sRGB color space.
red, green, and blue must all be >= 0 and <= 255.
alpha must be >= 0 and <= 255.
Implementation
const RgbColor(
num red,
num green,
num blue, [
int alpha = 255,
]) : assert(red >= 0 && red <= 255),
assert(green >= 0 && green <= 255),
assert(blue >= 0 && green <= 255),
assert(alpha >= 0 && alpha <= 255),
super(red, green, blue, alpha);