/** * 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 );