/*
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* jQuery appear plugin
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*
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* Copyright (c) 2012 Andrey Sidorov
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* licensed under MIT license.
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*
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* https://github.com/morr/jquery.appear/
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*
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* Version: 0.4
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*/
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(function($) {
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var selectors = [];
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var check_binded = false;
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var check_lock = false;
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var defaults = {
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interval: 250,
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force_process: false
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};
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var $window = $(window);
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var $prior_appeared = [];
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function appeared(selector) {
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return $(selector).filter(function() {
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return $(this).is(':appeared');
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});
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}
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function process() {
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check_lock = false;
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for (var index = 0, selectorsLength = selectors.length; index < selectorsLength; index++) {
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var $appeared = appeared(selectors[index]);
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$appeared.trigger('appear', [$appeared]);
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if ($prior_appeared[index]) {
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var $disappeared = $prior_appeared[index].not($appeared);
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$disappeared.trigger('disappear', [$disappeared]);
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}
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$prior_appeared[index] = $appeared;
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}
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}
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function add_selector(selector) {
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selectors.push(selector);
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$prior_appeared.push();
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}
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// ":appeared" custom filter
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$.expr.pseudos.appeared = $.expr.createPseudo(function(arg) {
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return function(element) {
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var $element = $(element);
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if (!$element.is(':visible')) {
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return false;
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}
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var window_left = $window.scrollLeft();
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var window_top = $window.scrollTop();
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var offset = $element.offset();
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var left = offset.left;
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var top = offset.top;
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if (top + $element.height() >= window_top &&
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top - ($element.data('appear-top-offset') || 0) <= window_top + $window.height() &&
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left + $element.width() >= window_left &&
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left - ($element.data('appear-left-offset') || 0) <= window_left + $window.width()) {
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return true;
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} else {
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return false;
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}
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};
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});
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$.fn.extend({
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// watching for element's appearance in browser viewport
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appear: function(selector, options) {
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$.appear(this, options);
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return this;
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}
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});
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$.extend({
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appear: function(selector, options) {
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var opts = $.extend({}, defaults, options || {});
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if (!check_binded) {
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var on_check = function() {
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if (check_lock) {
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return;
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}
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check_lock = true;
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setTimeout(process, opts.interval);
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};
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$(window).scroll(on_check).resize(on_check);
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check_binded = true;
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}
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if (opts.force_process) {
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setTimeout(process, opts.interval);
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}
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add_selector(selector);
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},
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// force elements's appearance check
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force_appear: function() {
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if (check_binded) {
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process();
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return true;
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}
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return false;
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}
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});
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})(function() {
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if (typeof module !== 'undefined') {
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// Node
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return require('jquery');
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} else {
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return jQuery;
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}
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}());
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