// Angus Turbull
// H1 Fading Text Script
// http://www.twinhelix.com

function HeaderFader(tagName, colors) {
    this.tagName = tagName; // Pass "h1" or similar.
    this.colors = colors; // An array of colours in order.
    this.left = true; // false for right-aligned.
    this.frames = 10;
    this.elements = [];

    var obj = this;
    if (window.addEventListener) {
        window.addEventListener('load', function() {
            obj.setup();
        }, false);
    } else {
        var oldOnload = window.onload;
        window.onload = function() {
            if (oldOnload) oldOnload();
            obj.setup();
        }
    }
};

HeaderFader.prototype.setup = function() {
    this.elements = document.getElementsByTagName(this.tagName);
    for (var h = 0; h < this.elements.length; h++) {
        var h1 = this.elements[h],
			text = h1.firstChild.nodeValue;
        h1.removeChild(h1.firstChild);
        h1.animNodes = [];
        for (var i = 0; i < text.length; i++) {
            var span = document.createElement('span');
            span.appendChild(document.createTextNode(text.substring(i, i + 1)));
            h1.appendChild(span);
            h1.animNodes[h1.animNodes.length] = span;
        }
        h1.animCount = 0;
        var obj = this;
        h1.animTimer = setInterval((function(hh) {
            return function() {
                obj.animate(hh);
            }
        } (h)), 1); // adjustable timer
    }
};

HeaderFader.prototype.animate = function(h) {
    var h1 = this.elements[h], c = h1.animCount++, noAnim = 1;
    for (var i = 0; i < h1.animNodes.length; i++) {
        var s = h1.animNodes[i],
			pc = (this.left ? (c - i) : (c - (h1.animNodes.length + this.frames - i))),
			frac = Math.max(0, Math.min(1, pc / this.frames)),
			marg = document.all && !window.opera ? 'marginRight' : 'marginLeft';
        if (s.animDone) continue;
        noAnim = 0;
        s.style.color = this.colors[Math.floor(frac * 0.99999 * this.colors.length)];
        if (frac == 1) {
            s.style[marg] = '0';
            s.animDone = 1;
        } else {
            s.style[marg] = 0.6 * (1 - frac) + 'em';
        }
    }
    if (noAnim) {
        clearInterval(h1.animTimer);
    }
    h1.style.visibility = 'inherit';
};

// SCRIPT SETUP

if (document.documentElement) {
    // Hide H1 elements for animation and trigger show on load.
    document.write('<style type="text/css"> h1 { visibility: hidden } </style>');
    // Off we go!
    var h1Anim = new HeaderFader(
		'h1',
		['#FFFFFF', '#DDDDDD', '#BBBBBB', '#999999', '#777777', '#555555']
	);
    h1Anim.left = false;
    h1Anim.frames = 30; // adjustable frames
}