//SEE: http://brainerror.net/scripts/javascript/blendtrans/

function opacity(id, opacStart, opacEnd, millisec) {
	//speed for each frame
	var speed = Math.round(millisec / 100);
	var timer = 0;

	//determine the direction for the blending, if start and end are the same nothing happens
	if(opacStart > opacEnd) {
		for(i = opacStart; i >= opacEnd; i--) {
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
		}
	} else if(opacStart < opacEnd) {
		for(i = opacStart; i <= opacEnd; i++)
			{
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
		}
	}
}

//change the opacity for different browsers
function changeOpac(opacity, id) {
	var object = document.getElementById(id).style; 
	object.opacity = (opacity / 101);
	object.MozOpacity = (opacity / 101);
	object.KhtmlOpacity = (opacity / 100);
	object.filter = "alpha(opacity=" + opacity + ")";
}

function shiftOpacity(id, millisec) {
	//if an element is invisible, make it visible, else make it ivisible
	if(document.getElementById(id).style.opacity == 0) {
		opacity(id, 0, 100, millisec);
	} else {
		opacity(id, 100, 0, millisec);
	}
}

function blendimage(divid, imageid, imagefile, millisec) {
	var speed = Math.round(millisec / 100);
	var timer = 0;
	
	//set the current image as background
	document.getElementById(divid).style.backgroundImage = "url(" + document.getElementById(imageid).src + ")";
	
	//make image transparent
	changeOpac(0, imageid);
	
	//make new image
	document.getElementById(imageid).src = imagefile;

	//fade in image
	for(i = 0; i <= 100; i++) {
		setTimeout("changeOpac(" + i + ",'" + imageid + "')",(timer * speed));
		timer++;
	}
}

function currentOpac(id, opacEnd, millisec) {
	//standard opacity is 100
	var currentOpac = 100;
	
	//if the element has an opacity set, get it
	if(document.getElementById(id).style.opacity < 100) {
		currentOpac = document.getElementById(id).style.opacity * 100;
	}

	//call for the function that changes the opacity
	opacity(id, currentOpac, opacEnd, millisec)
}

/////
// Extended by Adam Barclay 2008
/////

var imageCache = new Array()

// Provides the ability for a slideshow of images to occur. Each image will
// be shown in turn with a pause of 'pauseDelay' between each one and the
// transition taking transitionDelay between going from one picture
// to the next
//
// images = An array of images to scroll through and show
// transitionDelay = Milliseconds it takes to go from one image to the next
// pauseDelay = Milliseconds paused between the transition of each image
// divID = The ID of the div tag that contains the images to be changed
// imageID = The ID of the img tag that contains the actual image to change
function slideshow(images, transitionDelay, pauseDelay, divID, imageID) {
    var divTag = document.getElementById(divID);
    
    divTag.images = images;
    divTag.transitionDelay = transitionDelay;
    divTag.pauseDelay = pauseDelay;
    divTag.divID = divID;
    divTag.imageID = imageID;
    divTag.currentIndex = 0;  
    
    imageCache[divID] = new Array  
    
    nextLink(divID);
}


function nextLink(divTagID) {   
    var divTag = document.getElementById(divTagID);
    
    divTag.currentIndex = divTag.currentIndex + 1;
    if(divTag.currentIndex >= divTag.images.length) {
        divTag.currentIndex = 0;
    }
    
    setTimeout('nextLink(\'' + divTagID + '\');', divTag.pauseDelay);
    changeOpac(0, divTag.imageID);
    blendimage(divTagID, divTag.imageID, divTag.images[divTag.currentIndex], divTag.transitionDelay);
    
    if(imageCache[divTagID][divTag.currentIndex] == null) {
        imageCache[divTagID][divTag.currentIndex] = new Image
        imageCache[divTagID][divTag.currentIndex].src = divTag.images[divTag.currentIndex];
    }
}