codenothing/CSSCompressor

/**
 * 
 * HSL to Hex
 * 
 * @author: Corey Hart <http://www.codenothing.com>
 * @source: Michael Jackson's formula for HSL to RGB conversion <http://mjijackson.com/2008/02/rgb-to-hsl-and-rgb-to-hsv-color-model-conversion-algorithms-in-javascript>
 * @description: Converts HSL to Hex code
 * 
 * @before:
 *     .example {
 *         color: hsl(312,54%,68%);
 *     }
 * 
 * @after:
 *     .example {
 *         color: #d981c8;
 *     }
 * 
 */

var CSSCompressor = global.CSSCompressor,
    rhsl = /^hsl\(\s*(\d{1,3})\s*,\s*(\d{1,3})\%\s*,\s*(\d{1,3})\%\s*\)$/i,
    HEX = '0123456789abcdef',
    hslConversion = function( p, q, t ) {
        if ( t < 0 ) {
            t += 1;
        }

        if ( t > 1 ) {
            t -= 1;
        }

        if ( t < 1/6 ) {
            return p + ( q - p ) * 6 * t;
        }

        if ( t < 1/2 ) {
            return q;
        }

        if ( t < 2/3 ) {
            return p + ( q - p ) * ( 2/3 - t ) * 6;
        }

        return p;
    };

CSSCompressor.rule({

    name: 'HSL to Hex',
    type: CSSCompressor.RULE_TYPE_VALUE,
    group: 'Color',
    description: "Converts HSL to Hex code",

    callback: function( value, position, compressor ) {
        var m = rhsl.exec( value ),
            str = '#',
            h, s, l,
            p, q;

        if ( m ) {
            // Pull out hsl
            h = parseInt( m[ 1 ] || '0', 10 ) / 360;
            s = parseInt( m[ 2 ] || '0', 10 ) / 100;
            l = parseInt( m[ 3 ] || '0', 10 ) / 100;

            // Ensure range is correct
            if ( h > 1 || s > 1 || l > 1 || h < 0 || s < 0 || l < 0 ) {
                return;
            }

            // Convert to rgb
            q = l < 0.5 ? l * ( 1 + s ) : l + s - l * s;
            p = 2 * l - q;

            // Generate rgb format
            [

                Math.round( hslConversion( p, q, h + 1/3 ) * 255 ),
                Math.round( hslConversion( p, q, h ) * 255 ),
                Math.round( hslConversion( p, q, h - 1/3 ) * 255 )

            // Convert each rgb value to it's hex form
            ].forEach(function( v){
                // Enforce Max/Min
                if ( v > 255 ) {
                    v = 255;
                }
                else if ( v < 0 ) {
                    v = 0;
                }

                str += HEX[ ( v - ( v % 16 ) ) / 16 ];
                str += HEX[ v % 16 ];
            });


            // Final hex string
            compressor.log(
                "Converting HSL to Hex code '" + value + "' => '" + str + "'",
                position
            );
            return str;
        }
    }

});