/*********** EYES - Javascript Eyes That Follow ***********\
             Courtesy of http://oopstudios.com/
 Head over
\**********************************************************/

EYES = {};
EYES.stack = [];
//
// Stores the element
//
EYES.follow = function (eye) {
  // Get the "white"
  var el1 = document.getElementById (eye);
  // And the "pupil"
  var el2 = el1.getElementsByTagName ("IMG");
  el2 = el2[0];
  // Figure out the "centre" (for the top-left coords)
  el2.centre = (el1.offsetWidth - el2.offsetWidth) / 2;
  el2.style.margin = el2.centre + "px 0 0 " + el2.centre + "px";
  // The "max" distance is N x the width
  //  I used trial and error for this, do have a fiddle!
  el1.maxDist = 6 * el1.offsetWidth;
  // Add them to the list
  EYES.stack.push ([el1, el2]);
};
EYES.mousemove = function (e) {
  if (!EYES.stack.length) {
    return;
  }
  //
  // Cheers to quirksmode for mouse position lark!
  //  http://www.quirksmode.org/js/events_properties.html#position
  //
  var mouseX = mouseY = 0;
  if (!e) var e = window.event;
  if (e.pageX || e.pageY) 	{
    mouseX = e.pageX;
    mouseY = e.pageY;
  } else if (e.clientX || e.clientY) 	{
    mouseX = e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
    mouseY = e.clientY + document.body.scrollTop + document.documentElement.scrollTop;
  }
  //
  // Loop through all the defined eyes and calc them!
  //
  for (var e=0, l=EYES.stack.length; e<l; e++) {
    var el = EYES.stack[e];
    // Calculate it's position on the page
    //  (quirksmode based)
    var elX = elY = 0;
    if (el[0].offsetParent) {
      obj = el[0];
      do {
        elX += obj.offsetLeft;
        elY += obj.offsetTop;
      } while (obj = obj.offsetParent);
    }
    el[0].centreX = elX + Math.round (el[0].offsetWidth / 2);
    el[0].centreY = elY + Math.round (el[0].offsetHeight / 2);
    // Compare to the mouse position
    var difX = mouseX - el[0].centreX;
    var difY = mouseY - el[0].centreY;
    var dTan = Math.atan2 (difX, difY);
    var dist = Math.sqrt ((difX * difX) + (difY * difY));
    dist = Math.sin ((dist > el[0].maxDist ? 1 : dist / el[0].maxDist));
    // What's the pupil position?
    var newX = el[1].centre + Math.round (Math.sin (dTan) * el[1].centre * dist);
    var newY = el[1].centre + Math.round (Math.cos (dTan) * el[1].centre * dist);
    el[1].style.margin = newY + "px 0 0 " + newX + "px";
  }
};
//
// Automatically add the mouse event to the document
//
if (window.attachEvent) document.attachEvent ("onmousemove", EYES.mousemove);
else document.addEventListener ("mousemove", EYES.mousemove, false);