"

From 2011.igem.org

/**

* jquery.scrollFollow.js
* Copyright (c) 2008 Net Perspective (http://kitchen.net-perspective.com/)
* Licensed under the MIT License (http://www.opensource.org/licenses/mit-license.php)
* 
* @author R.A. Ray
*
* @projectDescription	jQuery plugin for allowing an element to animate down as the user scrolls the page.
* 
* @version 0.4.0
* 
* @requires jquery.js (tested with 1.2.6)
* @requires ui.core.js (tested with 1.5.2)
* 
* @optional jquery.cookie.js (http://www.stilbuero.de/2006/09/17/cookie-plugin-for-jquery/)
* @optional jquery.easing.js (http://gsgd.co.uk/sandbox/jquery/easing/ - tested with 1.3)
* 
* @param speed		int - Duration of animation (in milliseconds)
* 								default: 500
* @param offset			int - Number of pixels box should remain from top of viewport
* 								default: 0
* @param easing		string - Any one of the easing options from the easing plugin - Requires jQuery Easing Plugin < http://gsgd.co.uk/sandbox/jquery/easing/ >
* 								default: 'linear'
* @param container	string - ID of the containing div
* 								default: box's immediate parent
* @param killSwitch	string - ID of the On/Off toggle element
* 								default: 'killSwitch'
* @param onText		string - killSwitch text to be displayed if sliding is enabled
* 								default: 'Turn Slide Off'
* @param offText		string - killSwitch text to be displayed if sliding is disabled
* 								default: 'Turn Slide On'
* @param relativeTo	string - Scroll animation can be relative to either the 'top' or 'bottom' of the viewport
* 								default: 'top'
* @param delay			int - Time between the end of the scroll and the beginning of the animation in milliseconds
* 								default: 0
*/

( function( $ ) {

$.scrollFollow = function ( box, options ) { // Convert box into a jQuery object box = $( box );

// 'box' is the object to be animated var position = box.css( 'position' );

function ani() { // The script runs on every scroll which really means many times during a scroll. // We don't want multiple slides to queue up. box.queue( [ ] );

// A bunch of values we need to determine where to animate to var viewportHeight = parseInt( $( window ).height() ); var pageScroll = parseInt( $( document ).scrollTop() ); var parentTop = parseInt( box.cont.offset().top ); var parentHeight = parseInt( box.cont.attr( 'offsetHeight' ) ); var boxHeight = parseInt( box.attr( 'offsetHeight' ) + ( parseInt( box.css( 'marginTop' ) ) || 0 ) + ( parseInt( box.css( 'marginBottom' ) ) || 0 ) ); var aniTop;

// Make sure the user wants the animation to happen if ( isActive ) { // If the box should animate relative to the top of the window if ( options.relativeTo == 'top' ) { // Don't animate until the top of the window is close enough to the top of the box if ( box.initialOffsetTop >= ( pageScroll + options.offset ) ) { aniTop = box.initialTop; } else { aniTop = Math.min( ( Math.max( ( -parentTop ), ( pageScroll - box.initialOffsetTop + box.initialTop ) ) + options.offset ), ( parentHeight - boxHeight - box.paddingAdjustment ) ); } } // If the box should animate relative to the bottom of the window else if ( options.relativeTo == 'bottom' ) { // Don't animate until the bottom of the window is close enough to the bottom of the box if ( ( box.initialOffsetTop + boxHeight ) >= ( pageScroll + options.offset + viewportHeight ) ) { aniTop = box.initialTop; } else { aniTop = Math.min( ( pageScroll + viewportHeight - boxHeight - options.offset ), ( parentHeight - boxHeight ) ); } }

// Checks to see if the relevant scroll was the last one // "-20" is to account for inaccuracy in the timeout if ( ( new Date().getTime() - box.lastScroll ) >= ( options.delay - 20 ) ) { box.animate( { top: aniTop }, options.speed, options.easing ); } } };

// For user-initiated stopping of the slide var isActive = true;

if ( $.cookie != undefined ) { if( $.cookie( 'scrollFollowSetting' + box.attr( 'id' ) ) == 'false' ) { var isActive = false;

$( '#' + options.killSwitch ).text( options.offText ) .toggle( function () { isActive = true;

$( this ).text( options.onText );

$.cookie( 'scrollFollowSetting' + box.attr( 'id' ), true, { expires: 365, path: '/'} );

ani(); }, function () { isActive = false;

$( this ).text( options.offText );

box.animate( { top: box.initialTop }, options.speed, options.easing );

$.cookie( 'scrollFollowSetting' + box.attr( 'id' ), false, { expires: 365, path: '/'} ); } ); } else { $( '#' + options.killSwitch ).text( options.onText ) .toggle( function () { isActive = false;

$( this ).text( options.offText );

box.animate( { top: box.initialTop }, 0 );

$.cookie( 'scrollFollowSetting' + box.attr( 'id' ), false, { expires: 365, path: '/'} ); }, function () { isActive = true;

$( this ).text( options.onText );

$.cookie( 'scrollFollowSetting' + box.attr( 'id' ), true, { expires: 365, path: '/'} );

ani(); } ); } }

// If no parent ID was specified, and the immediate parent does not have an ID // options.container will be undefined. So we need to figure out the parent element. if ( options.container == ) { box.cont = box.parent(); } else { box.cont = $( '#' + options.container ); }

// Finds the default positioning of the box. box.initialOffsetTop = parseInt( box.offset().top ); box.initialTop = parseInt( box.css( 'top' ) ) || 0;

// Hack to fix different treatment of boxes positioned 'absolute' and 'relative' if ( box.css( 'position' ) == 'relative' ) { box.paddingAdjustment = parseInt( box.cont.css( 'paddingTop' ) ) + parseInt( box.cont.css( 'paddingBottom' ) ); } else { box.paddingAdjustment = 0; }

// Animate the box when the page is scrolled $( window ).scroll( function () { // Sets up the delay of the animation $.fn.scrollFollow.interval = setTimeout( function(){ ani();} , options.delay );

// To check against right before setting the animation box.lastScroll = new Date().getTime(); } );

// Animate the box when the page is resized $( window ).resize( function () { // Sets up the delay of the animation $.fn.scrollFollow.interval = setTimeout( function(){ ani();} , options.delay );

// To check against right before setting the animation box.lastScroll = new Date().getTime(); } );

// Run an initial animation on page load box.lastScroll = 0;

ani(); };

$.fn.scrollFollow = function ( options ) { options = options || {}; options.relativeTo = options.relativeTo || 'top'; options.speed = options.speed || 500; options.offset = options.offset || 0; options.easing = options.easing || 'swing'; options.container = options.container || this.parent().attr( 'id' ); options.killSwitch = options.killSwitch || 'killSwitch'; options.onText = options.onText || 'Turn Slide Off'; options.offText = options.offText || 'Turn Slide On'; options.delay = options.delay || 0;

this.each( function() { new $.scrollFollow( this, options ); } );

return this; }; })( jQuery );