var defaultPic = "empty.png";
var lightboxPics = new Array ("pic1.jpg","pic2.jpg","pic3.jpg","pic4.jpg",
							  							"pic5.jpg","pic6.jpg","pic7.jpg","pic8.jpg",
															"pic9.jpg","pic10.jpg","pic11.jpg", "pic12.jpg");
var curPicId = -1;															

function switchPic(picName, file)
{
  document[picName].src = String("images/"+file);
}
//------------------------------------------------------------
function rolloverId (id, suffix, prefix) {
	if (suffix == null) suffix = "";
	if (prefix == null) prefix = "";
	
	switchPic("thumb"+id, prefix+"thumb"+id+"_"+suffix+".jpg");
	switchPic("preview", prefix+"preview"+id+".jpg");
}
//------------------------------------------------------------
function getNrOfLightboxPics(prefix){
	if (prefix == "fu_") return 10; // only 10 pictures for functional units
	else return lightboxPics.length;
}
//------------------------------------------------------------
function openLightbox(id, prefix){
	if (prefix == null) prefix = "";

	document.getElementById('light').style.display='block';
	document.getElementById('fade').style.display='block';
	
	curPicId = id - 1;
	switchPic('pic', prefix+lightboxPics[curPicId]);
	checkPrevNextBtns(getNrOfLightboxPics(prefix));	
}
//------------------------------------------------------------
function closeLightbox(){
	document.getElementById('light').style.display='none';
	document.getElementById('fade').style.display='none';

	curPicId = -1;
	switchPic('pic', defaultPic);
	checkPrevNextBtns(getNrOfLightboxPics(""));
}
//------------------------------------------------------------
function nextLightboxPic(prefix){
	if (prefix == null) prefix = "";
	nrPics = getNrOfLightboxPics(prefix);

	curPicId++;
	if (curPicId > (nrPics -1)) {
		curPicId = (nrPics - 1);
	}
	switchPic('pic', prefix+lightboxPics[curPicId]);
	checkPrevNextBtns(nrPics);
}
//------------------------------------------------------------
function prevLightboxPic(prefix){
	if (prefix == null) prefix = "";

	curPicId--;
	if (curPicId < 0) {
		curPicId = 0;
	}
	switchPic('pic', prefix+lightboxPics[curPicId]);
	checkPrevNextBtns(getNrOfLightboxPics(prefix));
}
//------------------------------------------------------------
function checkPrevNextBtns(nrPics){
	if (curPicId >= (nrPics - 1)) {
		document.getElementById('next').style.display='none';
  }
	else {
		document.getElementById('next').style.display='block';
	}
	
	if (curPicId <= 0) {
		document.getElementById('prev').style.display='none';
  }	
	else {
		document.getElementById('prev').style.display='block';
	}
}