Team:Tongji Shanghai/js/jquery.appear.js

/*

* jQuery.appear
* https://github.com/bas2k/jquery.appear/
* http://code.google.com/p/jquery-appear/
*
* Copyright (c) 2009 Michael Hixson
* Copyright (c) 2012 Alexander Brovikov
* Licensed under the MIT license (http://www.opensource.org/licenses/mit-license.php)
*/

(function($) { $.fn.appear = function(fn, options) {

var settings = $.extend({

//arbitrary data to pass to fn data: undefined,

//call fn only on the first appear? one: true,

// X & Y accuracy accX: 0, accY: 0

}, options);

return this.each(function() {

var t = $(this);

//whether the element is currently visible t.appeared = false;

if (!fn) {

//trigger the custom event t.trigger('appear', settings.data); return; }

var w = $(window);

//fires the appear event when appropriate var check = function() {

//is the element hidden? if (!t.is(':visible')) {

//it became hidden t.appeared = false; return; }

//is the element inside the visible window? var a = w.scrollLeft(); var b = w.scrollTop(); var o = t.offset(); var x = o.left; var y = o.top;

var ax = settings.accX; var ay = settings.accY; var th = t.height(); var wh = w.height(); var tw = t.width(); var ww = w.width();

if (y + th + ay >= b && y <= b + wh + ay && x + tw + ax >= a && x <= a + ww + ax) {

//trigger the custom event if (!t.appeared) t.trigger('appear', settings.data);

} else {

//it scrolled out of view t.appeared = false; } };

//create a modified fn with some additional logic var modifiedFn = function() {

//mark the element as visible t.appeared = true;

//is this supposed to happen only once? if (settings.one) {

//remove the check w.unbind('scroll', check); var i = $.inArray(check, $.fn.appear.checks); if (i >= 0) $.fn.appear.checks.splice(i, 1); }

//trigger the original fn fn.apply(this, arguments); };

//bind the modified fn to the element if (settings.one) t.one('appear', settings.data, modifiedFn); else t.bind('appear', settings.data, modifiedFn);

//check whenever the window scrolls w.scroll(check);

//check whenever the dom changes $.fn.appear.checks.push(check);

//check now (check)(); }); };

//keep a queue of appearance checks $.extend($.fn.appear, {

checks: [], timeout: null,

//process the queue checkAll: function() { var length = $.fn.appear.checks.length; if (length > 0) while (length--) ($.fn.appear.checks[length])(); },

//check the queue asynchronously run: function() { if ($.fn.appear.timeout) clearTimeout($.fn.appear.timeout); $.fn.appear.timeout = setTimeout($.fn.appear.checkAll, 20); } });

//run checks when these methods are called $.each(['append', 'prepend', 'after', 'before', 'attr', 'removeAttr', 'addClass', 'removeClass', 'toggleClass', 'remove', 'css', 'show', 'hide'], function(i, n) { var old = $.fn[n]; if (old) { $.fn[n] = function() { var r = old.apply(this, arguments); $.fn.appear.run(); return r; } } });

})(jQuery);