contrastRatio method
Returns the WCAG contrast ratio between this color and other (1–21).
Colors.black.contrastRatio(Colors.white) // 21.0
Implementation
double contrastRatio(Color other) {
final l1 = luminance + 0.05;
final l2 = other.luminance + 0.05;
return l1 > l2 ? l1 / l2 : l2 / l1;
}