var MenuSpeed = 10;
var MenuTimer = 15;
var MenuOpacity = 0.9;

// main function to handle the mouse events //
function Menu(id,inside)
{
  var h = document.getElementById(id + '-ddheader');
  var c = document.getElementById(id + '-ddcontent');
  
  clearInterval(c.timer);
  
  if (inside)
  {
    clearTimeout(h.timer);
    if (c.maxh && c.maxh <= c.offsetHeight)
    {
      return
    }
    else if(!c.maxh)
    {
      c.style.display = 'block';
      c.style.height = 'auto';
      c.maxh = c.offsetHeight;
      c.style.height = '1px';
    }
    c.timer = setInterval(function(){MenuSlide(c,1)},MenuTimer);
  }
  else
  {
    h.timer = setTimeout(function(){MenuCollapse(c)},50);
  }
}

// collapse the menu //
function MenuCollapse(c)
{
  c.timer = setInterval(function(){MenuSlide(c,-1)},MenuTimer);
}

// cancel the collapse if a user rolls over the dropdown //
function MenuCancelHide(id)
{
  var h = document.getElementById(id + '-ddheader');
  var c = document.getElementById(id + '-ddcontent');
  clearTimeout(h.timer);
  clearInterval(c.timer);
  if(c.offsetHeight < c.maxh){
    c.timer = setInterval(function(){MenuSlide(c,1)},MenuTimer);
  }
}

// incrementally expand/contract the dropdown and change the opacity //
function MenuSlide(c,d)
{
  var currh = c.offsetHeight;
  var dist;
  if(d == 1){
    dist = (Math.round((c.maxh - currh) / MenuSpeed));
  }else{
    dist = (Math.round(currh / MenuSpeed));
  }
  if(dist <= 1 && d == 1){
    dist = 1;
  }
  c.style.height = currh + (dist * d) + 'px';
  MenuSetOpacity(c, MenuOpacity * currh / c.maxh);
  if((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1)){
    clearInterval(c.timer);
  }
}

function MenuSetOpacity(item,opacity)
{
  item.style.opacity = opacity;
  item.style.filter = 'alpha(opacity=' + opacity * 100 + ')';
}

function MenuItem(item, inside)
{
  if (inside)
  {
    item.style.background = 'url(Menu/Impressionism.jpg)';
  }
  else
  {
    item.style.background = 'none';
  }
}