/* http://keith-wood.name/backgroundPos.html
Background position animation for jQuery v1.0.1.
Written by Keith Wood (kbwood{at}iinet.com.au) November 2010.
Dual licensed under the GPL (http://dev.jquery.com/browser/trunk/jquery/GPL-LICENSE.txt) and 
MIT (http://dev.jquery.com/browser/trunk/jquery/MIT-LICENSE.txt) licenses. 
Please attribute the author if you use it. */
(function ($) { var g = 'bgPos'; $.fx.step['backgroundPosition'] = $.fx.step['background-position'] = function (a) { if (!a.set) { var b = $(a.elem); var c = b.data(g); b.css('backgroundPosition', c); a.start = parseBackgroundPosition(c); a.end = parseBackgroundPosition($.fn.jquery >= '1.6' ? a.end : a.options.curAnim['backgroundPosition'] || a.options.curAnim['background-position']); for (var i = 0; i < a.end.length; i++) { if (a.end[i][0]) { a.end[i][1] = a.start[i][1] + (a.end[i][0] == '-=' ? -1 : +1) * a.end[i][1] } } a.set = true } $(a.elem).css('background-position', ((a.pos * (a.end[0][1] - a.start[0][1]) + a.start[0][1]) + a.end[0][2]) + ' ' + ((a.pos * (a.end[1][1] - a.start[1][1]) + a.start[1][1]) + a.end[1][2])) }; function parseBackgroundPosition(c) { var d = { center: '50%', left: '0%', right: '100%', top: '0%', bottom: '100%' }; var e = c.split(/ /); var f = function (a) { var b = (d[e[a]] || e[a] || '50%').match(/^([+-]=)?([+-]?\d+(\.\d*)?)(.*)$/); e[a] = [b[1], parseFloat(b[2]), b[4] || 'px'] }; if (e.length == 1 && $.inArray(e[0], ['top', 'bottom']) > -1) { e[1] = e[0]; e[0] = '50%' } f(0); f(1); return e } $.fn.animate = function (e) { return function (a, b, c, d) { if (a['backgroundPosition'] || a['background-position']) { this.data(g, this.css('backgroundPosition') || 'center') } return e.apply(this, [a, b, c, d]) } } ($.fn.animate) })(jQuery);