Functions to check if items are in/out or centered in viewport.
function isCentreView($elem, buffer) {
var docViewMid = $(window).scrollTop() + ($(window).height()/2);
var elemTop = $elem.offset().top - (buffer * $(window).height());
var elemBottom = elemTop + $elem.height() + (buffer * $(window).height());
return ((docViewMid < elemBottom) && (docViewMid > elemTop));
};
function isScrolledIntoView($elem, bufferTop, bufferBottom) {
var docViewTop = $(window).scrollTop() + (bufferBottom * $(window).height());
var docViewBottom = $(window).scrollTop() + $(window).height() - (bufferTop * $(window).height());
var elemTop = $elem.offset().top;
var elemBottom = elemTop + $elem.height();
if ((docViewTop < elemBottom) && (docViewBottom > elemTop)) {
return 1;
} else if (docViewTop >= elemBottom) {
return 2;
} else {
return 0;
}
};