largeImgRoot = 'images/tractors/500x500/'
var photoIndex = 0;
///////////////////////////////////////////////////////////
obj = document.getElementById('btnZoom')

if (obj)
{
	obj.onclick = function()
	{
		hideAllSelects();
		
		var vscroll = window.pageYOffset || document.documentElement.scrollTop  || 0; 
		var pageHeight = document.body.offsetHeight;
		
		document.getElementById('fade').style.top = '0';
		document.getElementById('fade').style.height = pageHeight + 500 + 'px';
		document.getElementById('fade').style.display = 'block';

		photoIndex = 0;
		document.getElementById('enlargedPhoto').src = largeImgRoot + enlargedPhotoFilenames[photoIndex];
		document.getElementById('caption').innerHTML = enlargedPhotoCaptions[photoIndex] + enlargedPhotoDisclaimer[photoIndex];
		
		var frontLayer = document.getElementById('overlayLargeImage');
		frontLayer.style.top =  vscroll + 20 + 'px';
		displayNextPrevButtons();
		frontLayer.style.display='block';
	}
}
///////////////////////////////////////////////////////////
function displayNextPrevButtons()
{
	if (enlargedPhotoFilenames.length > 1)
	{
		document.getElementById('btnPrevious').style.visibility = 'visible';
		document.getElementById('btnNext').style.visibility = 'visible';
	}
	else
	{
		document.getElementById('btnPrevious').style.visibility = 'hidden';
		document.getElementById('btnNext').style.visibility = 'hidden';	
	}
}
///////////////////////////////////////////////////////////
document.getElementById('btnCloseWindow').onclick = function()
{
	document.getElementById('fade').style.display='none';
	document.getElementById('overlayLargeImage').style.display='none';	
	document.getElementById('enlargedPhoto').src = largeImgRoot + '/loadingImage.jpg';
	revealAllSelects();
}
///////////////////////////////////////////////////////////
function hideAllSelects()
{
	objPageArray = document.getElementsByTagName('body');
	objPage = objPageArray[0];
	A = objPage.getElementsByTagName('select');
	
	for (i=0; i<A.length; i++)
	{
		A[i].style.visibility = 'hidden';	// hide controls so IE doesn't show them over lightbox
	}	
}
///////////////////////////////////////////////////////////
function revealAllSelects()
{
	objPageArray = document.getElementsByTagName('body');
	objPage = objPageArray[0];
	A = objPage.getElementsByTagName('select');
	
	for (i=0; i<A.length; i++)
	{
		A[i].style.visibility = 'visible';	// show controls
	}	
}
///////////////////////////////////////////////////////////
function prevPhoto()
{
	obj = document.getElementById('enlargedPhoto');
	obj.src = largeImgRoot + '/loadingImage.jpg';
	
	photoIndex--;
	
	if (photoIndex < 0)
	{
		photoIndex = enlargedPhotoFilenames.length - 1;	
	}
	
	obj.src = largeImgRoot + '/' + enlargedPhotoFilenames[photoIndex];
	document.getElementById('caption').innerHTML = enlargedPhotoCaptions[photoIndex] + enlargedPhotoDisclaimer[photoIndex];
}
///////////////////////////////////////////////////////////
function nextPhoto()
{
	obj = document.getElementById('enlargedPhoto');
	obj.src = largeImgRoot + '/loadingImage.jpg';
	
	photoIndex++;
	
	if (photoIndex >= enlargedPhotoFilenames.length)
	{
		photoIndex = 0	
	}
	
	obj.src = largeImgRoot + '/' + enlargedPhotoFilenames[photoIndex];
	document.getElementById('caption').innerHTML = enlargedPhotoCaptions[photoIndex] + enlargedPhotoDisclaimer[photoIndex];
}