avia-snippet-sticky-header-bluepi

(function($)
{
    "use strict";

    $(document).ready(function()
    {
        // decreases header size when user scrolls down
        avia_header_size();
    });


    function av_change_class($element, change_method, class_name)
    {
        if($element[0].classList)
        {
            if(change_method == "add")
            {
                $element[0].classList.add(class_name);
            }
            else
            {
                $element[0].classList.remove(class_name);
            }
        }
        else
        {
            if(change_method == "add")
            {
                $element.addClass(class_name);
            }
            else
            {
                $element.removeClass(class_name);
            }
        }
    }


    function avia_header_size()
    {
        var win             = $(window),
            header          = $('.html_header_top.html_header_sticky #header'),
            unsticktop      = $('.av_header_unstick_top');

        if(!header.length && !unsticktop.length) return;

        var logo            = $('#header_main .container .logo img, #header_main .container .logo a'),
            elements        = $('#header_main .container:not(#header_main_alternate>.container), #header_main .main_menu ul:first-child > li > a:not(.avia_mega_div a, #header_main_alternate a), #header_main #menu-item-shop .cart_dropdown_link'),
            el_height       = $(elements).filter(':first').height(),
            isMobile        = $.avia_utilities.isMobile,
            scroll_top      = $('#scroll-top-link'),
            transparent     = header.is('.av_header_transparency'),
            shrinking       = header.is('.av_header_shrinking'),
            topbar_height   = header.find('#header_meta').outerHeight(),
            search_form     = $('#top #avia-menu #searchform > div'),
            set_height      = function()
            {
                var st = win.scrollTop(), newH = 0, st_real = st;

                if(unsticktop) st -= topbar_height;
                if(st < 0) st = 0;

                if(shrinking)
                {
                    if(st < el_height/2)
                    {
                        newH = el_height - st;
                        if(st <= 0){
                            newH = el_height;
                        }

                        av_change_class(header, 'remove', 'header-scrolled');
                        //header.removeClass('header-scrolled');
                    }
                    else
                    {
                        newH = el_height/2;
                        //header.addClass('header-scrolled');
                        av_change_class(header, 'add', 'header-scrolled');
                    }

                    if(st - 30 < el_height)
                    {
                        av_change_class(header, 'remove', 'header-scrolled-full');
                    }
                    else
                    {
                        av_change_class(header, 'add', 'header-scrolled-full');
                    }

                    elements.css({'height': newH + 'px', 'lineHeight': newH + 'px'});
                    logo.css({'maxHeight': newH + 'px'});
                    search_form.css({'top': (0.48*newH) - 20 + 'px'});
                }

                if(unsticktop.length)
                {
                    if( st <= 0)
                    {
                        if(st_real <= 0) st_real = 0;
                        unsticktop.css({"margin-top":"-"+st_real+"px"});
                    }
                    else
                    {
                        unsticktop.css({"margin-top":"-"+topbar_height+"px"});
                    }
                }

                if(transparent)
                {
                    if(st > 50)
                    {
                        //header.removeClass('av_header_transparency');
                        av_change_class(header, 'remove', 'av_header_transparency');
                    }
                    else
                    {
                        //header.addClass('av_header_transparency');
                        av_change_class(header, 'add', 'av_header_transparency');
                    }
                }


            };

            if($('body').is('.avia_deactivate_menu_resize')) shrinking = false;

            if(!transparent && !shrinking && !unsticktop.length) return;

            win.on( 'debouncedresize',  function(){ el_height = $(elements).attr('style',"").filter(':first').height(); set_height(); } );
            win.on( 'scroll',  function(){ window.requestAnimationFrame( set_height )} );
            set_height();
    }
})(jQuery);