// Customize your photo shuffle settings
// 
// * Surround the target <img /> with a <div>. specify id= in both
// * set background-repeat:no-repeat in CSS for the div
// * The first and final photo displayed is in the html <img> tag
// * The array contains paths to photos you want in the rotation. 
//   If you want the first photo in the rotation, then it's best to
//   put it as the final array image. All photos must be same dimension
// * The rotations variable specifies how many times to repeat array.
//   images. zero is a valid rotation value.

var gblPhotoShufflerDivId = "photodiv";
var gblPhotoShufflerImgId = "photoimg"; 
var gblImg = new Array(
  "images/index/rotation/board.jpg",
  "images/index/rotation/poster.jpg",
  "images/index/rotation/deck.jpg",
  "images/index/rotation/meeting.jpg",
  "images/index/rotation/path.jpg"
  );
var gblPauseSeconds = 4.0;
var gblFadeSeconds = 1.0;
var gblRotations = 0;

// End Customization section

var gblDeckSize = gblImg.length;
var gblOpacity = 100;
var gblOnDeck = 0;
var gblStartImg;
var gblImageRotations = gblDeckSize * (gblRotations+1);

window.onload = photoShufflerLaunch;
 
function photoShufflerLaunch()
{
  var theimg = document.getElementById(gblPhotoShufflerImgId);
  gblStartImg = theimg.src; // save away to show as final image

  document.getElementById(gblPhotoShufflerDivId).style.backgroundImage='url(' + gblImg[gblOnDeck] + ')';
  setTimeout("photoShufflerFade()",gblPauseSeconds*1000);
}

function photoShufflerFade()
{
  var theimg = document.getElementById(gblPhotoShufflerImgId);
	
  // determine delta based on number of fade seconds
  // the slower the fade the more increments needed
  var fadeDelta = 100 / (30 * gblFadeSeconds);

  // fade top out to reveal bottom image
  if (gblOpacity < 2*fadeDelta ) 
    {
      gblOpacity = 100;
	  // stop the rotation if we're done
	  if (gblImageRotations < 1) return;
	  photoShufflerShuffle();
	  // pause before next fade
          setTimeout("photoShufflerFade()",gblPauseSeconds*1000);
	}
  else
	{
	  gblOpacity -= fadeDelta;
	  setOpacity(theimg,gblOpacity);
	  setTimeout("photoShufflerFade()",30);  // 1/30th of a second
	}
}

function photoShufflerShuffle()
{
  var thediv = document.getElementById(gblPhotoShufflerDivId);
  var theimg = document.getElementById(gblPhotoShufflerImgId);
	
  // copy div background-image to img.src
  theimg.src = gblImg[gblOnDeck];
  // set img opacity to 100
  setOpacity(theimg,100);

  // shuffle the deck
  gblOnDeck = ++gblOnDeck % gblDeckSize;
  // decrement rotation counter
  if (--gblImageRotations < 1)
	{
	  // insert start/final image if we're done
	  gblImg[gblOnDeck] = gblStartImg;
	}

  // slide next image underneath
  thediv.style.backgroundImage='url(' + gblImg[gblOnDeck] + ')';
}

function setOpacity(obj, opacity)
{
  opacity = (opacity == 100)?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;
}