var slideNames = new Array("../pictures/slideshow/01.First_Parish_Church.jpg", "../pictures/slideshow/02.Christmas_Eve_Nativity_in_a_box.jpg", "../pictures/slideshow/03.Flower_communion_service.jpg", "../pictures/slideshow/04.Congregational_musicians.jpg", "../pictures/slideshow/05.Christmas_candlelight_service.jpg", "../pictures/slideshow/06.FPC_in_Spring.jpg", "../pictures/slideshow/07.Christmas_Eve_"Angel&quot_choir.jpg", "../pictures/slideshow/08.Congregational_musician.jpg", "../pictures/slideshow/09.Flower_communion.jpg", "../pictures/slideshow/10.Outside_service.jpg", "../pictures/slideshow/11.Mummers_Play.jpg", "../pictures/slideshow/12.Flower_communion.jpg", "../pictures/slideshow/13.Joyous_choir.jpg", "../pictures/slideshow/14.Child_dedication.jpg", "../pictures/slideshow/15.Christmas_Eve.jpg", "../pictures/slideshow/16.Remembrance.jpg");

/* ----------------------------------------------
 Cross fade slide slow
 Author: Keith Lundberg
 For First Parish Church of Acton & Stow
 Preloads slide one-at-a-time
 Delays fades until images have loaded
 ----------------------------------------------*/
// ----------------------------------------------
// Set these variables to control the slideshow
var slideHoldMilliseconds = 1900.0;
var slideFadeMilliseconds = 1500.0;
var slideFadeSteps        = 30.0;
var slideInitialDelay     = 20.0;
// var slideNames = new Array(
//    "pictures/slideshow/web01.jpg",
//    "pictures/slideshow/web02.jpg", 
//    ...
//    );
// ----------------------------------------------

// ----------------------------------------------
// These variables take care of themselves
var fadeOpVal = 0.99; // start with the top slide
var fadeOpInc = 0;
var fadeDelay = slideHoldMilliseconds;
var slideNumber = 0; // displayed slide Number
var loadNumber = 0; // loading slide number
var slideImg = new Array();
var slideIsLoading = false;
var slideIsHolding = false;
var frozen = false;
var slideCaption = "First Parish Church";
// ----------------------------------------------

// ---------------------------------------------------------------------------
// ------------------ Displaying Slides --------------------------------------
function setOpacity(obj, val) 
{
    // CSS3/mozilla/safari: style.opacity
    // Gecko before CSS3: style.MozOpacity
    // Konquerer and Safari: KhtmlOpacity
    // IE5.5+ : style.filter alpha(opacity=x)
    obj.style.opacity = val;
    obj.style.MozOpacity = val;
    obj.style.KhtmlOpacity = val;
    obj.style.filter = "alpha(opacity=" + (val*100) + ")";
}
function displayNewSlide(obj)
{
    slideNumber = (slideNumber + 1) % slideNames.length;
    obj.src = slideImg[slideNumber].src;
    //alert ("loading " + obj.id + " with " + obj.src);
}
function switchSlides(fromObj, toObj, topDirection)
{
    if (fromObj && toObj)
    {
        if (false == slideIsLoading)
        {
            // begin transition by changing the display of the hidden slide
            displayNewSlide(toObj);
            slideIsLoading = true;
        }
        else if (true == toObj.complete)
        {
          if (false == slideIsHolding)
          {
              fadeDelay = slideHoldMilliseconds;
              slideIsHolding = true;
          }
          else if (false == frozen)
          {
            // the hidden slide is ready, continue transition with the fade
            //alert("Begining fade from " + fromObj.id + " to " + toObj.id + "  (" + topDirection + ")" );
            fadeOpInc = topDirection / slideFadeSteps;
            slideIsLoading = false;
            slideIsHolding = false;
            var name1 = toObj.src.replace(/_/g, ' ');
            var name2 = name1.match(/[0-9]\..*\.jpg/);
            var name3 = name2[0].slice(2,-4);
            slideCaption = name3;
          }
          else
          {
            fadeDelay = 100; // continue checking for non frozen
          }
        }
        else
        {
            // continue checking for completed loading of hidden slide (10 times a second)
            fadeDelay = 100;
        }
    }
}
function onSlideOver()
{
    frozen = true;
}
function onSlideOut()
{
    frozen = false;
}

// ---------------------------------------------------------------------------
// ------------------ Setup / preloading slide images  -----------------------
function onSlideLoad(num)
{
    // Load the next slide
    loadNumber = loadNumber + 1;
    if (loadNumber < slideNames.length)
    {
        preloadSlide();
    }
}
function preloadSlide()
{
    slideImg[loadNumber] = new Image();
    slideImg[loadNumber].src = slideNames[loadNumber];
    slideImg[loadNumber].onLoad = onSlideLoad(loadNumber);
}
function setupSlides()
{
    setOpacity(document.images["slidetop"], fadeOpVal);
    //setTimeout(doSlides, slideInitialDelay);
    slideInitialDelay = 0;
    preloadSlide();
}


// ---------------------------------------------------------------------------
// ---------------------- Top level contoller --------------------------------
function doSlides()
{
    if (0 != slideInitialDelay)
    {
        setupSlides();
        //return;
    }
    
    var topImage = document.images["slidetop"];
    var bottomImage = document.images["slidebottom"];
    if (topImage && bottomImage)
    {
        fadeOpVal = fadeOpVal + fadeOpInc;

        if (fadeOpVal >= 0.99)
        {
            fadeOpVal = 0.99;
            switchSlides(topImage, bottomImage, -1.0);
        }
        else if (fadeOpVal <= 0)
        {
            fadeOpVal = 0;
            switchSlides(bottomImage, topImage, 1.0);
        }
        else
        {
            fadeDelay = slideFadeMilliseconds / slideFadeSteps;
        }
        setOpacity(topImage, fadeOpVal);
        setTimeout(doSlides, fadeDelay);
    }   
}