var howOften = 5;
var imagefile = 'images/head_bg.jpg';
var imagefile2 = 'images/Spine-Products-Group.jpg';
var imagefile3 = 'images/Spine-Products-Group.jpg';
var _firstTime = true;

function blendimage() {
	if (_firstTime)
	{
		_firstTime = false;
		blendimage2();
		blendimage3();
	}
	var divid = 'blenddiv';
	var imageid = 'blendimage';
	var millisec = 4000;

    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++; 
    }
    if (imagefile == 'images/head_bg.jpg')
    	imagefile = 'images/head_bg2.jpg';
    else
    	imagefile = 'images/head_bg.jpg';
    setTimeout("blendimage()",howOften*1000);

}
function blendimage2() {
	var divid = 'blenddiv2';
	var imageid = 'blendimage2';
	var millisec = 4000;
if (document.getElementById(divid)!=null)
{
    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 = imagefile2; 

    //fade in image 
    for(i = 0; i <= 100; i++) { 
        setTimeout("changeOpac(" + i + ",'" + imageid + "')",(timer * speed)); 
        timer++; 
    }
    if (imagefile2 == 'images/Spine-Products-Group.jpg')
    	imagefile2 = 'images/Image-C-2009.jpg';
    else if (imagefile2 == 'images/collage1.jpg')
    	imagefile2 = 'images/Spine-Products-Group.jpg';
	else
		imagefile2 = 'images/collage1.jpg';
    setTimeout("blendimage2()",howOften*1000);
}
}

function blendimage3() {
	var divid = 'blenddiv3';
	var imageid = 'blendimage3';
	var millisec = 4000;
if (document.getElementById(divid)!=null)
{
    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 = imagefile3; 

    //fade in image 
    for(i = 0; i <= 100; i++) { 
        setTimeout("changeOpac(" + i + ",'" + imageid + "')",(timer * speed)); 
        timer++; 
    }
    if (imagefile3 == 'images/Spine-Products-Group.jpg')
    	imagefile3 = 'images/Image-C-2009.jpg';
    else if (imagefile3 == 'images/Image-A-B.jpg')
    	imagefile3 = 'images/Spine-Products-Group.jpg';
	else
		imagefile3 = 'images/Image-A-B.jpg';
    setTimeout("blendimage3()",howOften*1000);
}
}

window.onload=blendimage;

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 / 100);
	object.MozOpacity = (opacity / 100);
	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)
}