// Scrolling bar - version 1.4

// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>
// 	

// --------------------------------------------------------------------
// Set values to adjust effects for your layout
// --------------------------------------------------------------------

// The ID of div to move 
myObjectToMove = "simuove";

// Stickyness of the movement (in pixels)
myStickyPixels = 300;

// Scrolling bar may contain a button to stop the sliding effect:
// <a href="#" onclick="javascript:switchRecursion()">Stop/Restart</a>
//
// User choice will be stored in a cookie, and will be remembered by the script
// while that user browses your website
//
// Moreover you can set a Javascript variable to make the menu fade in
//
// <script type="text/javascript">
//   isFront = true;
// </script>
//
// <style type="text/css">
//   #scrollingmenu { visibility:hidden }
// </style>

// --------------------------------------------------------------------
// YOU DO NOT NEED  TO MODIFY ANYTHING  BELOW THIS LINE UNLESS YOU KNOW 
// WHAT YOU ARE DOING. IF YOU NEED MORE INFORMATIONS, SEND ME A MESSAGE
// --------------------------------------------------------------------

// Initialization for scrolling menu
var myCurrentScrollTop = 0;
var myDeltaScrollTop = 0;
var myDx = 0;
var myDy = 0;
myInterval = 50;

// Function: createCookie
// Input parameters: name of the cookie, value to store, expiration days
// Output parameters: none
// Side effects: create a new cookie for storing values
//
function createCookie(name, value, days) {
  if (days) {
    var date = new Date();
    date.setTime(date.getTime()+(days*24*60*60*1000));
    var expires = "; expires="+date.toGMTString();
  }
  else expires = "";
  document.cookie = name+"="+value+expires+"; path=/";
}

// Function: readCookie
// Input parameters: name of the cookie to read
// Output parameters: value stored
// Side effects: none
//
function readCookie(name) {
  var nameEQ = name + "=";
  var cookieValues = document.cookie.split(';');
  for(var i=0; i < cookieValues.length; i++) {
    var aValue = cookieValues[i];
    while (aValue.charAt(0)==' ') aValue = aValue.substring(1, aValue.length);
    if (aValue.indexOf(nameEQ) == 0) return aValue.substring(nameEQ.length, aValue.length);
  }
  return null;
}

// Function: setOpacity
// Input parameters: object, opacity to set
// Output parameters: none
// Side effects: changes visibility property of the object
//
function setOpacity(obj, opacity) {
  opacity = (opacity >= 99)?99.999:opacity;
 
  // IE/Win
  obj.style.filter = "alpha(opacity:"+opacity+")";

  // Safari<1.2, Konqueror
  obj.style.KHTMLOpacity = opacity/100;
	
  // Older Mozilla and Firefox
  obj.style.MozOpacity = opacity/100;
	
  // Safari 1.2, newer Firefox and Mozilla, CSS3
  obj.style.opacity = opacity/100;
}

// Function: fadeIn
// Input parameters: object to show, name of variable, opacity to set, increasing opacity step, opacity upper limit
// Output parameters: none
// Side effects: changes visibility property of the object
//
function fadeIn(objectToFade, objectName, opacity, step, limit) {
  if (opacity < limit) {
	setOpacity(objectToFade, opacity);
	opacity += step * ( 1 - (opacity/100.0));
	window.setTimeout("fadeIn("+objectName+", '"+objectName+"', "+opacity+", "+step+", "+limit+")", 200);
  }
}

// Function checkLocation
// Input parameters: object to move, previous position
// Output parameters: none
// Side effects: updates position of given object on scrolling up/down the page
//
function checkLocation(obj,offs) {
  if (navigator.appName.indexOf("Netscape")!= -1) {
    myCurrentYPos = window.pageYOffset;
  }
  else {
    if (document.documentElement && document.documentElement.scrollTop) {
      myCurrentYPos = document.documentElement.scrollTop;
    }
    else {
      myCurrentYPos = document.body.scrollTop;
    }
  }
  
  // Menu will start moving after a scrolling of at least myStickyPixels pixels
  if ( myCurrentYPos > myStickyPixels || myCurrentYPos < myPreviousYPos ) {
   
    myDeltaY = Math.max(myCurrentYPos - myStickyPixels, 0) - myYPos ;

    // Check if is too close to its target
    if ( (myDeltaY >= 6) || (myDeltaY <= -6) ) {
    
	  // If abs(delta) < 6, round = 0, so it is useless to execute the following code
      myStepY = Math.round( myDeltaY / 12);
	  
	  // The new position needs to be positive or zero
	  if ( myYPos >= -myStepY ) {
        myYPos += myStepY;
        obj.style.top = myYPos + "px";
      }
    }
  }

  // We want to check if user has scrolled current page or not  
  if (offs != myCurrentYPos) myPreviousYPos = offs;
  
  // If the slider hasn't been blocked, reschedule all the checks
  if (isRecursive == "true") {
    setTimeout("checkLocation(obj,"+myCurrentYPos+")", myInterval);
  }
}


// Function switchRecursion
// Input parameters: none
// Output parameters: none
// Side effects: set to true/false isRecursive variable, to start/stop checkLocation execution, 
//               and writes new value into the cookie
//
function switchRecursion() {

  if (isRecursive == "false") {
    isRecursive = "true";
	createCookie("isRecursive", isRecursive, 365);
	checkLocation(obj,myYPos);
  }
  else {
    isRecursive = "false";
	createCookie("isRecursive", isRecursive, 365);
  }
}

window.onload = function(e) {
  
  // Get the objects with given ID
  if (document.getElementById(myObjectToMove)) {
    obj = document.getElementById(myObjectToMove);
  }
  else if (eval("document."+myObjectToMove)) {
    obj = eval("document."+myObjectToMove);
  }
  else {
    obj = eval(myObjectToMove);
  }

  // Another cookie tells us if the menu is sticky or not
  isCookieRecursive = readCookie("isRecursive");
  isRecursive = (isCookieRecursive != null && isCookieRecursive != undefined && isCookieRecursive != "") ? isCookieRecursive : "true";
  isFrontPage = (isFront != null && isFront != undefined && isFront != "") ? isFront : false; 
  
  // Netscape and compatible browsers use the WINDOW object for
  // storing window's properties
  //
  if (navigator.appName.indexOf("Netscape")!= -1) {
    myYPos = window.pageYOffset;
  }
  else {
    // Internet Explorer 6 changed implementation of its DOM, renaming
    // document.body into document.documentElement
    //
    if (document.documentElement && document.documentElement.scrollTop) {
      myYPos = document.documentElement.scrollTop;
    }
    else {
      // This applies to older IE browsers
      myYPos = document.body.scrollTop;
    }
  }
  myPreviousYPos = myYPos;
  
  // Let the menu fade in (only in front page)
  if (isFrontPage) {
    setOpacity(obj, 0);
    obj.style.visibility = "visible";
    fadeIn(obj, "obj", 0, 25, 99);
  }
  else {
	obj.style.visibility = "visible";
  }
  
  // And now move it up and down, depending on cookie value
  if (isRecursive == "true") {
    checkLocation(obj, myYPos);
  }
}