// jquery for: titulka
// stridani obrazku na titulce
// (c) honzik

$(document).ready(function(){
    var switchTime = 6000;
    var appearTime = 900;
    var loadResolution = 100;

    var front = $('#imageBox');
    var back = $('#imageBoxSwap');
    var alternate = false;
    
    var cnt = 2;
    
    var prefetchImage = new Image();
    prefetchImage.src = PATH + "css/edu/blok-" + cnt + ".jpg";
    
    
    
    function moveDown() {
        var current;
        if(alternate) {
            current = front;
        } else {
            current = back;
        }
        
        if(!prefetchImage.complete) {
            setTimeout(moveDown, loadResolution);
            return;
        }
        
        $(current).find("img").attr("src", PATH + "css/edu/blok-" + cnt + ".jpg");
        $(current).css({'z-index' : '20', 'opacity' : '0.0' } );
         if(alternate) {
                $(back).css({'z-index': '1'});
            } else {                           
                $(front).css({'z-index': '1'});
            }       
        $(current).animate({'opacity': '1.0'}, appearTime, function(){
            // if finished
            cnt = cnt + 1;
            if(cnt == 4) {cnt = 1;}
            prefetchImage.src = PATH + "css/edu/blok-" + cnt + ".jpg";
            
            if(alternate) {
                alternate = false;
            } else {
                alternate = true;
            }
            
            setTimeout(moveDown, switchTime);            
        });       
    } 
    
    setTimeout(moveDown, switchTime);
});