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