Given a background color, how to get a foreground color that makes it readable on that background color?

Question

Given a background color, how to get a foreground color that makes it readable on that background color?

I mean computing that foreground color automatically in a pr

Answer 1

In case this could still be useful for someone, this is the Dart implementation based on the answers above

Color getInverseBW(Color color) {
    double luminance = (0.2126 * color.red + 0.7152 * color.green + 0.0722 * color.blue);
    return (luminance < 140) ? Color(0xffffffff) : Color(0xff000000);
}