/* Plugin: jQuery Parallax Version 1.1.3 Author: Ian Lunn Twitter: @IanLunn Author URL: http://www.ianlunn.co.uk/ Plugin URL: http://www.ianlunn.co.uk/plugins/jquery-parallax/ Dual licensed under the MIT and GPL licenses: http://www.opensource.org/licenses/mit-license.php http://www.gnu.org/licenses/gpl.html */ (function( jQuery ){ var jQuerywindow = jQuery(window); var windowHeight = jQuerywindow.height(); jQuerywindow.resize(function () { windowHeight = jQuerywindow.height(); }); jQuery.fn.parallax = function(xpos, speedFactor, outerHeight) { var jQuerythis = jQuery(this); var getHeight; var firstTop; var paddingTop = 0; //get the starting position of each element to have parallax applied to it jQuerythis.each(function(){ firstTop = jQuerythis.offset().top; }); if (outerHeight) { getHeight = function(jqo) { return jqo.outerHeight(true); }; } else { getHeight = function(jqo) { return jqo.height(); }; } // setup defaults if arguments aren't specified if (arguments.length < 1 || xpos === null) xpos = "50%"; if (arguments.length < 2 || speedFactor === null) speedFactor = 0.1; if (arguments.length < 3 || outerHeight === null) outerHeight = true; // function to be called whenever the window is scrolled or resized function update(){ var pos = jQuerywindow.scrollTop(); jQuerythis.each(function(){ var jQueryelement = jQuery(this); var top = jQueryelement.offset().top; var height = getHeight(jQueryelement); // Check if totally above or totally below viewport if (top + height < pos || top > pos + windowHeight) { return; } jQuerythis.css('backgroundPosition', xpos + " " + Math.round((top - pos) * speedFactor) + "px"); }); } jQuerywindow.bind('scroll', update).resize(update); update(); }; })(jQuery);