Helpers for manipulating colors in javascript.

gistfile1.js

/* Helpers for manipulating colors in javascript. */

/* IE patch. :( */
if(typeof String.prototype.trim !== 'function') {
    String.prototype.trim = function() {
        return this.replace(/^\s+|\s+$/g, '');
    }
}
/***/

function assure_hash_prefix(s) {
    if(s[0] == '#' || !(/^[\dabcdef]{3,6}$/).test(s)) return s;
    return '#' + s;
}
function hex_to_rgb(hex) {
    /* "FFFFFF" -> [255,255,255] */
    if(hex[0] == '#') {
        hex = hex.substring(1,7);
    }
    return [parseInt(hex.substring (0, 2), 16), parseInt(hex.substring(2, 4), 16), parseInt(hex.substring(4, 6), 16)]
}

function rgb_to_hex(rgb) {
    /* [255,255,255] -> "FFFFFF" */
    var r = (rgb[2] | (rgb[1] << 8) | (rgb[0] << 16)).toString(16);

    // Pad 0's
    for(var i=0, stop=6-r.length; i<stop; i++) r += "0";

    return r;
}

function css_to_rgb(s) {
    /* "rgb(255, 255, 255)" or "#ffffff" -> [255,255,255] */
    if(s[0] == '#') return hex_to_rgb(s); // NOTE: IE8 does not always return rgb
    return $.map(s.substring(4,s.length-1).split(','), function(o) { return parseInt(o.trim()) });
}

function rgb_to_css(rgb) {
    /* [255,255,255] -> "rgb(255, 255, 255)" */
    return 'rgb(' + rgb[0] + ',' + rgb[1] +',' + rgb[2] + ')';
}

function rgb_to_hsv(rgb){
    /* [50,50,100] -> [170, 127.5, 100] */
    var r = rgb[0]/255, g = rgb[1]/255, b = rgb[2]/255;
    var max = Math.max(r,g,b), min = Math.min(r,g,b);
    if(max==min) return [0,0,max*255];

    var v = max, s = (max-min) / max;
    var rc = (max-r) / (max-min),
        gc = (max-g) / (max-min),
        bc = (max-b) / (max-min);

    if(r==max) h = bc-gc;
    else if(g==max) h = 2+rc-bc;
    else h = 4.0+gc-rc;

    h = (h/6.0) % 1.0;
    if(h<0) h += 1.0

    return [h*255,s*255,v*255];
}