function opacity(id, opacStart, opacEnd, millisec, doCallback) {
	if(doCallback == null)
		doCallback = true;
	//speed for each frame
	var diff = Math.abs(opacStart - opacEnd);
	var speed = Math.round(millisec / diff);

	//determine the direction for the blending, if start and end are the same nothing happens
	var modifier = 1;
	if(opacEnd < opacStart)
		modifier = -1;

	setTimeout("changeOpacRecursive(" + opacStart + ",'" + id + "',"+opacStart+","+opacEnd+","+modifier+","+speed+","+doCallback+")",speed);
}

function changeOpacRecursive(opacity, id, opacStart, opacEnd, modifier, speed, doCallback)
{
	changeOpac(opacity, id);
	opacity += modifier;
	if(opacity == opacEnd + modifier)
		setTimeout("blendComplete(" + doCallback + ")",speed);
	else
		setTimeout("changeOpacRecursive("+opacity+",'"+id+"',"+opacStart+","+opacEnd+","+modifier+","+speed+","+doCallback+")",speed);
}

function blendComplete(doCallback)
{
	if(blendCompleted && doCallback)
		blendCompleted();
}

//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.border.width = opacity;
//	object.border = opacity + "px solid #D7D7D7";
	object.backgroundImage = "";
	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)
}