jQuery numeric backgroundColor animation

I know you need the a 开发者_开发知识库jQuery Color Plugin or jQuery UI to animate between colors if you want to use the .animate() method.

Would it be possible to use jQuery to animate grey numbers... like #333 to #999 without this plugin?

If that sounds possible, would anyone like to venture what it would look like as code?

Here's the chunk of jquery-ui that handles the majority of color animation.

$.each(["backgroundColor", "borderBottomColor", "borderLeftColor",
    "borderRightColor", "borderTopColor", "borderColor", "color", "outlineColor"],
function(i, attr) {
    $.fx.step[attr] = function(fx) {
        if (!fx.colorInit) {
            fx.start = getColor(fx.elem, attr);
            fx.end = getRGB(fx.end);
            fx.colorInit = true;
        }

        fx.elem.style[attr] = "rgb(" +
            Math.max(Math.min(parseInt((fx.pos * (fx.end[0] - fx.start[0])) + fx.start[0], 10), 255), 0) + "," +
            Math.max(Math.min(parseInt((fx.pos * (fx.end[1] - fx.start[1])) + fx.start[1], 10), 255), 0) + "," +
            Math.max(Math.min(parseInt((fx.pos * (fx.end[2] - fx.start[2])) + fx.start[2], 10), 255), 0) + ")";
    };
});

Just parses the initial color values and then interpolates and steps through them. $.fx.step is part of the jQuery core. If you copy in the color parsing functions as well, I suspect this should work.

EDIT

Here's the color parsing for reference.

// Color Conversion functions from highlightFade
// By Blair Mitchelmore
// http://jquery.offput.ca/highlightFade/

// Parse strings looking for color tuples [255,255,255]
function getRGB(color) {
        var result;

        // Check if we're already dealing with an array of colors
        if ( color && color.constructor === Array && color.length === 3 )
                return color;

        // Look for rgb(num,num,num)
        if (result = /rgb\(\s*([0-9]{1,3})\s*,\s*([0-9]{1,3})\s*,\s*([0-9]{1,3})\s*\)/.exec(color))
                return [parseInt(result[1],10), parseInt(result[2],10), parseInt(result[3],10)];

        // Look for rgb(num%,num%,num%)
        if (result = /rgb\(\s*([0-9]+(?:\.[0-9]+)?)\%\s*,\s*([0-9]+(?:\.[0-9]+)?)\%\s*,\s*([0-9]+(?:\.[0-9]+)?)\%\s*\)/.exec(color))
                return [parseFloat(result[1])*2.55, parseFloat(result[2])*2.55, parseFloat(result[3])*2.55];

        // Look for #a0b1c2
        if (result = /#([a-fA-F0-9]{2})([a-fA-F0-9]{2})([a-fA-F0-9]{2})/.exec(color))
                return [parseInt(result[1],16), parseInt(result[2],16), parseInt(result[3],16)];

        // Look for #fff
        if (result = /#([a-fA-F0-9])([a-fA-F0-9])([a-fA-F0-9])/.exec(color))
                return [parseInt(result[1]+result[1],16), parseInt(result[2]+result[2],16), parseInt(result[3]+result[3],16)];

        // Look for rgba(0, 0, 0, 0) == transparent in Safari 3
        if (result = /rgba\(0, 0, 0, 0\)/.exec(color))
                return colors["transparent"];

        // Otherwise, we're most likely dealing with a named color
        return colors[$.trim(color).toLowerCase()];
}

function getColor(elem, attr) {
        var color;

        do {
                color = $.curCSS(elem, attr);

                // Keep going until we find an element that has color, or we hit the body
                if ( color != "" && color !== "transparent" || $.nodeName(elem, "body") )
                        break;

                attr = "backgroundColor";
        } while ( elem = elem.parentNode );

        return getRGB(color);
};

The only place these functions are used in jquery-ui is for color animation, so I would consider this a fairly minimal implementation.

EDIT 2

Just tested it out, and this works as long as you don't use named colors. (The reference to colors['transparent'] can be replaced with [255,255,255].) To used name colors, there's a bit more code I left out.

var colors = {
    aqua:[0,255,255],
    azure:[240,255,255],
    beige:[245,245,220],
    black:[0,0,0],
    blue:[0,0,255],
    brown:[165,42,42],
    cyan:[0,255,255],
    darkblue:[0,0,139],
    darkcyan:[0,139,139],
    darkgrey:[169,169,169],
    darkgreen:[0,100,0],
    darkkhaki:[189,183,107],
    darkmagenta:[139,0,139],
    darkolivegreen:[85,107,47],
    darkorange:[255,140,0],
    darkorchid:[153,50,204],
    darkred:[139,0,0],
    darksalmon:[233,150,122],
    darkviolet:[148,0,211],
    fuchsia:[255,0,255],
    gold:[255,215,0],
    green:[0,128,0],
    indigo:[75,0,130],
    khaki:[240,230,140],
    lightblue:[173,216,230],
    lightcyan:[224,255,255],
    lightgreen:[144,238,144],
    lightgrey:[211,211,211],
    lightpink:[255,182,193],
    lightyellow:[255,255,224],
    lime:[0,255,0],
    magenta:[255,0,255],
    maroon:[128,0,0],
    navy:[0,0,128],
    olive:[128,128,0],
    orange:[255,165,0],
    pink:[255,192,203],
    purple:[128,0,128],
    violet:[128,0,128],
    red:[255,0,0],
    silver:[192,192,192],
    white:[255,255,255],
    yellow:[255,255,0],
    transparent: [255,255,255]
};