Compute hex color code for an arbitrary string

Question

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Is there a way to map an arbitrary string to a HEX COLOR code. I tried to compute the HEX number for string using string hashcode. Now I need to convert this hex number to six digits which are in HEX color code range. Any suggestions ?

String [] programs = {"XYZ", "TEST1", "TEST2", "TEST3", "SDFSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS"};

for(int i = 0; i < programs.length; i++) {
  System.out.println( programs[i] + " -- " + Integer.toHexString(programs[i].hashCode()));
}

Solution 1

If you don't really care about the "meaning" of the color you can just split up the bits of the int (remove the first for just RGB instead of ARGB)

String [] programs = {"XYZ", "TEST1", "TEST2", "TEST3", "SDFSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS"};

for(int i = 0; i < programs.length; i++) {
  System.out.println( programs[i] + " -- " + intToARGB(programs[i].hashCode()));
}
....
public static String intToARGB(int i){
    return Integer.toHexString(((i>>24)&0xFF))+
        Integer.toHexString(((i>>16)&0xFF))+
        Integer.toHexString(((i>>8)&0xFF))+
        Integer.toHexString((i&0xFF));
}

Solution 2

How about anding the hashcode with 0x00FFFFFF (or 0xFFFFFF if you want to default the alpha channel)? For example:

private String getColorCode(String inputString)
{
    String colorCode = String.format("#%06x", 0xFFFFFF & inputString.hashCode());
}

Solution 3

I ran into this question while looking for a Ruby solution, so I thought I would add an answer for Ruby in case someone follows the same path I did. I ended up using the following method, which creates the same six digit hex code from a string by using String.hash and the optional base-specifying parameter of Fixnum.to_s. It slices from 1 rather than 0 to skip negative signs.

def color_from_string(query)
  '#'+query.hash.to_s(16).slice(1,6)
end

Solution 4

In case anyone else is looking for a solution for Flutter/Dart:

    Color _fromInt(int i) {
      final a = (i >> 24) & 0xFF;
      final r = (i >> 16) & 0xFF;
      final g = (i >> 8) & 0xFF;
      final b = i & 0xFF;
      return Color.fromARGB(a, r, g, b);
    }

It's also worth noting that with certain background colours e.g. black, it may be difficult to differentiate the colours.

To this end, I set the alpha channel to the max value of 255:

    Color _fromInt(int i) {
      const a = 255;
      final r = (i >> 16) & 0xFF;
      final g = (i >> 8) & 0xFF;
      final b = i & 0xFF;
      return Color.fromARGB(a, r, g, b);
    }

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