var timerlen = 5;
var slideAniLen = 1500;

var timerID = new Array();
var startTime = new Array();
var obj = new Array();
var endHeight = new Array();
var moving = new Array();
var dir = new Array();

function slidedown(objname){
        if(moving[objname])
                return;

        if(document.getElementById(objname).style.display != "none")
                return; // cannot slide down something that is already visible

		if(document.getElementById('content_about').style.display == "block") {
			document.getElementById('content_about').style.display = 'none';
		}
		if(document.getElementById('content_clients').style.display == "block") {
			document.getElementById('content_clients').style.display = 'none';
		}
		if(document.getElementById('content_contact').style.display == "block") {
			document.getElementById('content_contact').style.display = 'none';
		}
		if(document.getElementById('content_login').style.display == "block") {
			document.getElementById('content_login').style.display = 'none';
		}
	
        moving[objname] = true;
        dir[objname] = "down";
        startslide(objname);
}

function slideup(objname){
        if(moving[objname])
                return;

        if(document.getElementById(objname).style.display == "none")
                return; // cannot slide up something that is already hidden

        moving[objname] = true;
        dir[objname] = "up";
        startslide(objname);
}

function startslide(objname){
        obj[objname] = document.getElementById(objname);

        endHeight[objname] = parseInt(obj[objname].style.height);
        startTime[objname] = (new Date()).getTime();

        if(dir[objname] == "down"){
                obj[objname].style.height = "1px";
        }

        obj[objname].style.display = "block";

        timerID[objname] = setInterval('slidetick(\'' + objname + '\');',timerlen);
}

function slidetick(objname){
        var elapsed = (new Date()).getTime() - startTime[objname];

        if (elapsed > slideAniLen)
                endSlide(objname)
        else {
                var d =Math.round(elapsed / slideAniLen * endHeight[objname]);
                if(dir[objname] == "up")
                        d = endHeight[objname] - d;

                obj[objname].style.height = d + "px";
        }

        return;
}

function endSlide(objname){
        clearInterval(timerID[objname]);

        if(dir[objname] == "up")
                obj[objname].style.display = "none";

        obj[objname].style.height = endHeight[objname] + "px";

        delete(moving[objname]);
        delete(timerID[objname]);
        delete(startTime[objname]);
        delete(endHeight[objname]);
        delete(obj[objname]);
        delete(dir[objname]);

        return;
}

function toggleSlide(objname){
  if(document.getElementById(objname).style.display == "none"){
    // div is hidden, so let's slide down
    slidedown(objname);
	switch(objname) {
		case 'content_about':
		  document.getElementById('nav_clients').src='/img/nav_clients.png';
		  document.getElementById('nav_contact').src='/img/nav_contact.png';
		  document.getElementById('nav_login').src='/img/nav_ftp.png';
		  document.getElementById('nav_about').src='/img/nav_about_on.png';
		  break;
		case 'content_clients':
		  document.getElementById('nav_about').src='/img/nav_about.png';
		  document.getElementById('nav_contact').src='/img/nav_contact.png';
		  document.getElementById('nav_login').src='/img/nav_ftp.png';
		  document.getElementById('nav_clients').src='/img/nav_clients_on.png';
		  break;
		case 'content_contact':
		  document.getElementById('nav_about').src='/img/nav_about.png';
		  document.getElementById('nav_clients').src='/img/nav_clients.png';
		  document.getElementById('nav_login').src='/img/nav_ftp.png';
		  document.getElementById('nav_contact').src='/img/nav_contact_on.png';
		  break;
		case 'content_login':
		  document.getElementById('nav_about').src='/img/nav_about.png';
		  document.getElementById('nav_clients').src='/img/nav_clients.png';
		  document.getElementById('nav_contact').src='/img/nav_contact.png';
		  document.getElementById('nav_login').src='/img/nav_ftp_on.png';
		  break;
	}
  } else {
    // div is not hidden, so slide up
    slideup(objname);
	switch(objname) {
		case 'content_about':
		  document.getElementById('nav_about').src='/img/nav_about.png';
		  break;
		case 'content_clients':
		  document.getElementById('nav_clients').src='/img/nav_clients.png';
		  break;
		case 'content_contact':
		  document.getElementById('nav_contact').src='/img/nav_contact.png';
		  break;
		case 'content_login':
		  document.getElementById('nav_login').src='/img/nav_ftp.png';
		  break;
	}
  }
}