Created
September 30, 2013 21:21
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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); |
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