//limitation that we can not apply additional filters on the divs being displayed
var timerlen = 5;
var slideAniLen = 300;
var timeToRetract = 500; //make sure this is not under the slideAniLen
var maxHeight = 150;  //try to make this just larger than the largest menu item for best apperences
var maxOpacity = 100;

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





function start_retract(objname){
	clear_retract(objname);
	timerRetractID[objname] = setInterval('slideup(\'' + objname + '\');',timeToRetract);
}


function slidedown(objname){
	clear_retract(objname);

        if(moving[objname])
                return;

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

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


function slideup(objname){
	clear_retract(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 * maxHeight);
                var o = Math.round(elapsed / slideAniLen * maxOpacity);
                if(dir[objname] == "up")
                {
                    d = maxHeight - d;
                    o = maxOpacity - o;
                }

                obj[objname].style.height = d + "px";
                obj[objname].style.filter = ' alpha(opacity=' + o + ')';
                obj[objname].style.opacity = o/100;
        }

        return;
}


function clear_retract(objname){
	clearInterval(timerRetractID[objname]);
	delete(timerRetractID[objname]);
}


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

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

        obj[objname].style.height = endHeight[objname] + "%";
        obj[objname].style.filter = ' alpha(opacity=' + maxOpacity + ')';
        obj[objname].style.opacity = maxOpacity/100;

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

        return;
}