addLoadEvent(prepareGallery);

var mainGalleryImageSrc  = false;
var mainGalleryImageCell = false;

function prepareGallery() {
	if (document.getElementById && document.getElementsByTagName) {
		var table = document.getElementById('frontpage-gallery');
		var cells = table.getElementsByTagName('TD');

		var cell = false;
		var images = new Array();
		for (var i = 0; i < cells.length; i++) {
			cell = cells[i];

			if (cell.className == 'main') {
				mainGalleryImage    = cell.getElementsByTagName('IMG')[0];
				mainGalleryImageSrc = mainGalleryImage.src;
			}
			else {
				// preload images by setting cell background as full image.
				images.push(getFullImagePath(cell));

				// add mouse functionality
				cell.onmouseover = function() {
					changeMainImage(this);
				}

				cell.onmouseout = function() {
					resetMainImage();
				}
			}
		}

		preLoadImages(images);
	}
}

function changeMainImage(cell) {
	mainGalleryImage.src = getFullImagePath(cell);
}

function resetMainImage() {
	mainGalleryImage.src = mainGalleryImageSrc;
}

function getFullImagePath(cell) {
	var crntCellImageSrc = cell.getElementsByTagName('IMG')[0].src;
	return crntCellImageSrc.replace('_t.jpg', '.jpg');
}

function preLoadImages(images) {
	if (document.images) {
		for (var i = 0; i < images.length; i++) {
			preload_image = new Image();
			preload_image.src = images[i];
		}
	}
}