// wrap as a jQuery plugin and pass jQuery in to our anoymous function
(function ($) {
	$.fn.cross = function (options) {
		return this.each(function (i) { 
			// cache the copy of jQuery(this) - the start image
			var $$ = $(this);
			
			// get the target from the backgroundImage + regexp
			var target = $$.css('backgroundImage').replace(/^url|[\(\)'"]/g, '');

			// nice long chain: wrap img element in span
			$$.wrap('<span style="position: relative;height:20px;"></span>')
				// change selector to parent - i.e. newly created span
				.parent()
				// prepend a new image inside the span
				.prepend('<img>')
				// change the selector to the newly created image
				.find(':first-child')
				// set the image to the target
				.attr('src', target);

			// the CSS styling of the start image needs to be handled
			// differently for different browsers
			if ($.browser.msie || $.browser.mozilla) {
				$$.css({
					'position' : 'absolute', 
					'left' : 0,
					'background' : '',
					'top' : this.offsetTop
				});
			} else if ($.browser.opera && $.browser.version < 9.5) {
				// Browser sniffing is bad - however opera < 9.5 has a render bug 
				// so this is required to get around it we can't apply the 'top' : 0 
				// separately because Mozilla strips the style set originally somehow...                    
				$$.css({
					'position' : 'absolute', 
					'left' : 0,
					'background' : '',
					'top' : "0"
				});
			} else { // Safari
				$$.css({
					'position' : 'absolute', 
					'left' : 0,
					'background' : ''
				});
			}

			// similar effect as single image technique, except using .animate 
			// which will handle the fading up from the right opacity for us
			$$.hover(function () {
				$$.stop().animate({
					opacity: 0
				}, 50);
			}, function () {
				$$.stop().animate({
					opacity: 1
				}, 500);
			});
		});
	};
	
})(jQuery);

// note that this uses the .bind('load') on the window object, rather than $(document).ready() 
// because .ready() fires before the images have loaded, but we need to fire *after* because
// our code relies on the dimensions of the images already in place.
$(window).bind('load', function () {
	$('img.fade').cross();
});