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/**
* author Christopher Blum
* - based on the idea of Remy Sharp, http://remysharp.com/2009/01/26/element-in-view-event-plugin/
* - forked from http://github.com/zuk/jquery.inview/
*/
(function ($) {
var inviewObjects = {}, viewportSize, viewportOffset,
d = document, w = window, documentElement = d.documentElement, expando = $.expando;
$.event.special.inview = {
add: function(data) {
inviewObjects[data.guid + "-" + this[expando]] = { data: data, $element: $(this) };
},
remove: function(data) {
try { delete inviewObjects[data.guid + "-" + this[expando]]; } catch(e) {}
}
};
function getViewportSize() {
var mode, domObject, size = { height: w.innerHeight, width: w.innerWidth };
// if this is correct then return it. iPad has compat Mode, so will
// go into check clientHeight/clientWidth (which has the wrong value).
if (!size.height) {
mode = d.compatMode;
if (mode || !$.support.boxModel) { // IE, Gecko
domObject = mode === 'CSS1Compat' ?
documentElement : // Standards
d.body; // Quirks
size = {
height: domObject.clientHeight,
width: domObject.clientWidth
};
}
}
return size;
}
function getViewportOffset() {
return {
top: w.pageYOffset || documentElement.scrollTop || d.body.scrollTop,
left: w.pageXOffset || documentElement.scrollLeft || d.body.scrollLeft
};
}
function checkInView() {
var $elements = $(), elementsLength, i = 0;
$.each(inviewObjects, function(i, inviewObject) {
var selector = inviewObject.data.selector,
$element = inviewObject.$element;
$elements = $elements.add(selector ? $element.find(selector) : $element);
});
elementsLength = $elements.length;
if (elementsLength) {
viewportSize = viewportSize || getViewportSize();
viewportOffset = viewportOffset || getViewportOffset();
for (; i<elementsLength; i++) {
// Ignore elements that are not in the DOM tree
if (!$.contains(documentElement, $elements[i])) {
continue;
}
var $element = $($elements[i]),
elementSize = { height: $element.height(), width: $element.width() },
elementOffset = $element.offset(),
inView = $element.data('inview'),
visiblePartX,
visiblePartY,
visiblePartsMerged;
// Don't ask me why because I haven't figured out yet:
// viewportOffset and viewportSize are sometimes suddenly null in Firefox 5.
// Even though it sounds weird:
// It seems that the execution of this function is interferred by the onresize/onscroll event
// where viewportOffset and viewportSize are unset
if (!viewportOffset || !viewportSize) {
return;
}
if (elementOffset.top + elementSize.height > viewportOffset.top &&
elementOffset.top < viewportOffset.top + viewportSize.height &&
elementOffset.left + elementSize.width > viewportOffset.left &&
elementOffset.left < viewportOffset.left + viewportSize.width) {
visiblePartX = (viewportOffset.left > elementOffset.left ?
'right' : (viewportOffset.left + viewportSize.width) < (elementOffset.left + elementSize.width) ?
'left' : 'both');
visiblePartY = (viewportOffset.top > elementOffset.top ?
'bottom' : (viewportOffset.top + viewportSize.height) < (elementOffset.top + elementSize.height) ?
'top' : 'both');
visiblePartsMerged = visiblePartX + "-" + visiblePartY;
if (!inView || inView !== visiblePartsMerged) {
$element.data('inview', visiblePartsMerged).trigger('inview', [true, visiblePartX, visiblePartY]);
}
} else if (inView) {
$element.data('inview', false).trigger('inview', [false]);
}
}
}
}
$(w).bind("scroll resize", function() {
viewportSize = viewportOffset = null;
});
// Use setInterval in order to also make sure this captures elements within
// "overflow:scroll" elements or elements that appeared in the dom tree due to
// dom manipulation and reflow
// old: $(window).scroll(checkInView);
//
// By the way, iOS (iPad, iPhone, ...) seems to not execute, or at least delays
// intervals while the user scrolls. Therefore the inview event might fire a bit late there
setInterval(checkInView, 250);
})(jQuery);
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