Converting Color to ConsoleColor?

Question

What is the best way to convert a System.Drawing.Color to a similar System.ConsoleColor?

Answer 1

public static System.ConsoleColor FromColor(System.Drawing.Color c) {
    int index = (c.R > 128 | c.G > 128 | c.B > 128) ? 8 : 0; // Bright bit
    index |= (c.R > 64) ? 4 : 0; // Red bit
    index |= (c.G > 64) ? 2 : 0; // Green bit
    index |= (c.B > 64) ? 1 : 0; // Blue bit
    return (System.ConsoleColor)index;
}

The ConsoleColors enumeration seems to use the EGA style palette ordering, which is:

index Brgb
  0   0000  dark black
  1   0001  dark blue
  2   0010  dark green
  3   0011  dark cyan
  4   0100  dark red
  5   0101  dark purple
  6   0110  dark yellow (brown)
  7   0111  dark white (light grey)
  8   1000  bright black (dark grey)
  9   1001  bright blue
 10   1010  bright green
 11   1011  bright cyan    
 12   1100  bright red
 13   1101  bright purple
 14   1110  bright yellow
 15   1111  bright white

You can roughly map a 24-bit colour (or 32-bit colour, by ignoring the alpha channel) to what is essentially 3-bit colour with a brightness component. In this case, the 'brightness' bit is set if any of the System.Drawing.Color's red, green or blue bytes are greater than 128, and the red, green, blue bits are set if the equivalent source bytes are higher than 64.