magnificPopup Retina lightbox add-on

    if (typeof $.fn.magnificPopup === 'function') {
        var lightboxgallerygroups = {};
        $('.portfolio-box [data-group], .gallery-box [data-group]').each(function () {
            var id = $(this).attr('data-group');
            if (!lightboxgallerygroups[id]) {
                lightboxgallerygroups[id] = [];
            }
            lightboxgallerygroups[id].push(this);
        });

        $.each(lightboxgallerygroups, function () {
            $(this).magnificPopup({
                type: 'image',
                closeOnContentClick: true,
                closeBtnInside: false,
                gallery: { enabled: true },
                image: {
                    src: function(item) {
                        var isRetina = window.devicePixelRatio > 1.5;
                        var retinaSrc = $(item.el).attr('data-retina');
                        return isRetina && retinaSrc ? retinaSrc : item.el.attr('href');
                    }
                }
            });
        });
    }