GazeTK

// onScreen jQuery plugin v0.2.1

// (c) 2011-2013 Ben Pickles

//

// http://benpickles.github.io/onScreen

//

// Released under MIT license.

;(function($) {

  $.expr[":"].onScreen = function(elem) {

    var $window = $(window)

    var viewport_top = $window.scrollTop()

    var viewport_height = $window.height()

    var viewport_bottom = viewport_top + viewport_height

    var $elem = $(elem)

    var top = $elem.offset().top

    var height = $elem.height()

    var bottom = top + height

    return (top >= viewport_top && top < viewport_bottom) ||

           (bottom > viewport_top && bottom <= viewport_bottom) ||

           (height > viewport_height && top <= viewport_top && bottom >= viewport_bottom)

  }

})(jQuery);