jquery.parallax-1.1.3.js
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/*
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($) {
var $window = $(window);
var windowHeight = $window.height();
$window.resize(
function() {
windowHeight = $window.height();
}
);
$.fn.parallax = function(xpos, speedFactor, outerHeight) {
var $this = $(this);
var getHeight;
var firstTop;
var paddingTop = 0;
//get the starting position of each element to have parallax applied to it
$this.each(
function() {
firstTop = $this.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 = $window.scrollTop();
$this.each(
function() {
var $element = $(this);
var top = $element.offset().top;
var height = getHeight($element);
// Check if totally above or totally below viewport
if (top + height < pos || top > pos + windowHeight) {
return;
}
$this.css('backgroundPosition', xpos + " " + Math.round((firstTop - pos) * speedFactor) + "px");
}
);
}
$window.bind('scroll', update)
.resize(update);
update();
};
})(jQuery);