/*****************************************************************************
 List the images that need to be prefetched
*****************************************************************************/
var bImgList = [
  './img/banner04.jpg',
  './img/banner01.jpg',
  './img/banner02.jpg',
  './img/banner03.jpg'
  ];

var bImgs = [];

// =======================================
//   preload all images initially needed
// =======================================
var bDownloadTimer = null;
var bDownloadInterval = 300;
var bImgTimer = null;
var bImgInterval = 3000;

function startBannerDownload(idx) {
  if (bDownloadTimer != null) {
    window.clearTimeout(bDownloadTimer);
  }
  if (idx < bImgList.length) {
    bImgs[idx] = new Image();
    bImgs[idx].src = bImgList[idx];
    bDownloadTimer = window.setTimeout("startBannerDownload("+(idx+1)+")", bDownloadInterval);
  }
  else {
    if (bImgTimer != null) {
      window.clearTimeout(bImgTimer);
    }
    // schedule image slideshow immediately
    bImgTimer = window.setTimeout("showBannerImg(2)", 10);
  }
}

function showBannerImg(idx) {
  if (bImgTimer != null) {
    window.clearTimeout(bImgTimer);
  }
  var obj = document.getElementById("BannerImg");
  if (obj) {
    obj.src = bImgs[idx].src;
    if (idx == bImgs.length - 1) {
      idx=0;
    }
    else {
      idx++;
    }
    bImgTimer = window.setTimeout("showBannerImg("+idx+")", bImgInterval);
  }
}