/** This file contains methods to take a string and return a consistent color
    that corresponds to that string.  The string does not say anything about the
    color; the color is returned from a hash code of the string.  This is
    basically a lazy way to obtain "random" colors that remain consistent across
    runs of a program.

    To obtain a different color scheme, you can append another value
    consistently to each string.  For example, appending " 16" to each string
    can be found experimentally to give a good color scheme for your strings.
*/

/** This function turns a string into a repeatable color as a Frink color
    object. */
hashColor[str] :=
{
   [r,g,b] = hashColorToIntRGB[str]
   return new color[r/255, g/255, b/255]
}


/** This function turns a string ito a repeatable color from 0 to 255 as
    integers [r,g,b] */
hashColorToIntRGB[str] :=
{
   hash = right[messageDigest[str, "MD5"], 6]
   r = parseInt[substrLen[hash, 0, 2], 16]
   g = parseInt[substrLen[hash, 2, 2], 16]
   b = parseInt[substrLen[hash, 4, 2], 16]
   return [r,g,b]
}

/** This function turns a string into a repeatable color as a hexadecimal string
    like 'FF10CC".  You may want to preface this with a pound sign # to make
    this an HTML color.
*/
hashColorToHex[str] :=
{
   [r,g,b] = hashColorToIntRGB[str]
   return padLeft[hex[r], 2, "0"] + padLeft[hex[g], 2, "0"] + padLeft[hex[b], 2, "0"]
}

/** 
g = new graphics
g.backgroundColor[hashColor["mars"]]
g.show[]
*/