var uppath = 'slideshow/';
var spics = [];  //This is filled by each page for their own slideshow

var curpic = 0;
var curcont = 0;
var curopac = 0;
var scont = ['slideshow', 'slideshow2'];
var opac = [100, 0];
var fto;
var step = 1;
var speed = 20; // for setInterval

function load_first() {
  var nextpic = (curpic+1)%(spics.length);
  var nextcont = (curcont+1)%(scont.length);
  var nextopac = (curopac+1)%(opac.length);
  var src = 'url(\"'+uppath+spics[curpic]+'\")';
  var ss = document.getElementById(scont[curcont]);
  var src2 = 'url(\"'+uppath+spics[nextpic]+'\")';
  var ss2 = document.getElementById(scont[nextcont]);

  if (ss) {
  ss.style.backgroundImage = src;
  ss.style.opacity = opac[curopac]/100;
  ss.style.filter = 'alpha(opacity='+opac[curopac]+')';
  }
  if (ss2) {
  ss2.style.backgroundImage = src2;
  ss2.style.opacity = opac[nextopac]/100;
  ss2.style.filter = 'alpha(opacity='+opac[nextopac]+')';
  }
  var tmp = opac[curopac];
  opac[curopac] = opac[nextopac];
  opac[nextopac] = tmp;
  curpic = nextpic;
  curcont = nextcont;
  if (spics.length > 1) { fade(); }
}

function fade() {
  var nextpic = (curpic+1)%(spics.length);
  var nextcont = (curcont+1)%(scont.length);
  var nextopac = (curopac+1)%(opac.length);
  var ss = document.getElementById(scont[curcont]);
  var ss2 = document.getElementById(scont[nextcont]);
  if (curopac == 0) {
    opac[curopac] -= step;
    if (opac[curopac] < 0) { opac[curopac] = 0; }
    opac[nextopac] += step;
    if (opac[nextopac] > 100) { opac[nextopac] = 100; }
  } else {
    opac[curopac] += step;
    if (opac[curopac] > 100) { opac[curopac] = 100; }
    opac[nextopac] -= step;
    if (opac[nextopac] < 0) { opac[nextopac] = 0; }
  }
  ss.style.opacity = opac[curopac]/100;
  ss.style.filter = 'alpha(opacity='+opac[curopac]+')';
  ss2.style.opacity = opac[nextopac]/100;
  ss2.style.filter = 'alpha(opacity='+opac[nextopac]+')';
  if (opac[curopac] == 0 || opac[curopac] == 100) {
    //swap opacity for next container
    var tmp = opac[curopac];
    opac[curopac] = opac[nextopac];
    opac[nextopac] = tmp;
    //set source of invisible container
    var src = 'url(\"'+uppath+spics[curpic]+'\")';
    var ss = document.getElementById(scont[curcont]);
    ss.style.backgroundImage = src;
    //move to next pic
    curpic = nextpic;
    curcont = nextcont;
    clearTimeout(fto);
  }
}

function run_slideshow() {
  if (spics.length > 0) {
    fto = setInterval('fade()', speed);
  }
}

function preload_ss() {
  for (var i=0; i<preload_ss.arguments.length; i++) {
    myImg[i] = new Image();
    var src = uppath+preload_ss.arguments[i];
    myImg[i].src = src;
    spics.push(preload_ss.arguments[i]);
  }
}