var paddingTop = 0;
var scrollTop = 0;
var lastScrollTop = 0;
var delta = 0;
var delta2 = 0;
var timer;
var timeOut = 25;

function scroll() {
  scrollTop = document.documentElement.scrollTop;
  timeOut = 500;
  if (lastScrollTop == scrollTop) {
    delta = Math.round((scrollTop - paddingTop)*1.1/2);
    delta2 = Math.round((document.getElementById("all").offsetHeight - (parseInt(document.getElementById("navi").offsetHeight) + 60))/2);
    paddingTop = Math.max(0, paddingTop + Math.min(delta, delta2));
    (document.getElementById("navi")).style.paddingTop = paddingTop + "px";
    if (delta != 0) {
      timeOut = 25;
    }
  }
  timer = window.setTimeout("scroll()", timeOut);
  lastScrollTop = scrollTop;
}

function showImage(ImageID) {
  document.getElementById(ImageID).style.visibility = "visible";
}

function hideImage(ImageID) {
    document.getElementById(ImageID).style.visibility = "hidden";
}

function ShowText(x, y, text) {
  var hovertext = document.getElementById("hovertext")
  hovertext.innerHTML = text;
  hovertext.style.visibility = "visible";
  hovertext.style.left = x + "px";
  hovertext.style.top = y + "px";
}

function HideText() {
  document.getElementById("hovertext").style.visibility = "hidden";
}