/**
 * @author Brendan Barr
 * code.brendanbarr.com
 */

	//change gallery
	function changeGallery(category){
		if(!document.getElementById||!document.getElementsByTagName||!document.createElement||!document.appendChild) return false;	
		
		//check progress (stop script if the old image is hasn't been removed yet)
		if(ready()==false) return false;
		
		//update gallery navigation
		var galNav = document.getElementById('gal_nav').getElementsByTagName('a');
		for(var i=0;i<galNav.length;i++){
			galNav[i].removeAttribute('id');
			galNav[0].setAttribute('id', 'activeGalLink');
			galNav[i].href='images/'+category+'_'+(i+1)+'.jpg';
			
			// preload images
			var preloader = document.getElementById('preload');
			newImg = document.createElement('img');
			newImg.src = galNav[i].href;
			preloader.appendChild(newImg);
			
			galNav[i].onclick=function(){
				
				//check progress (stop script if the old image is hasn't been removed yet)
				if(ready()==false) return false;
				
				updateGalleryLinks(this);
				return false;
			}
		}
		document.getElementById('next').onclick=function(){
			
			//check progress (stop script if the old image is hasn't been removed yet)
			if(ready()==false) return false;
			
			var index=parseInt(document.getElementById('galleryImage').getElementsByTagName('img')[0].src.split('_')[1].split('.jpg')[0]);
			if(index==10) index=0;
			updateGalleryLinks(document.getElementById('gal_nav').getElementsByTagName('a')[index]);
			return false;
		}
		document.getElementById('previous').onclick=function(){
			
			//check progress (stop script if the old image is hasn't been removed yet)
			if(ready()==false) return false;
			
			var index=parseInt(document.getElementById('galleryImage').getElementsByTagName('img')[0].src.split('_')[1].split('.jpg')[0]);
			if(index==1) index=11;
			updateGalleryLinks(document.getElementById('gal_nav').getElementsByTagName('a')[index-2]);
			return false;
		}

		updateGalleryImage('images/'+category+'_1.jpg');
	};
	
	//progress checker
	function ready(){ if(document.getElementById('galleryImage').getElementsByTagName('img')[1]) return false }
	
	//update gallery links
	function updateGalleryLinks(link){
		document.getElementById('activeGalLink').removeAttribute('id');
		link.setAttribute('id', 'activeGalLink');
		updateGalleryImage(link.href)
	}
	
	//update main gallery image
	function updateGalleryImage(href) {
		var newGalleryImage = document.createElement('img');
		newGalleryImage.className = 'newGalleryImage';
		newGalleryImage.src = href;
		document.getElementById('galleryImage').appendChild(newGalleryImage);
		xfade(0, newGalleryImage, document.getElementById('galleryImage').getElementsByTagName('img')[0])
		newGalleryImage = null;
	}
	
	//cross fade images
	function xfade(i, newImage, oldImage){
		if(typeof xfade.newImage == 'undefined' || xfade.oldImage == 'undefined' ) {
	        xfade.newImage = newImage;
	        xfade.oldImage = oldImage;
	    }
		if(i<105) {
			xfade.oldImage.style.filter='alpha(opacity='+(100-i)+')';
			xfade.oldImage.style.opacity=1-(i/100);
			xfade.newImage.style.filter='alpha(opacity='+i+')';
			xfade.newImage.style.opacity=i/100;
			i=i+5;
			setTimeout("xfade("+i+",'','')",10);
		}
		else {
			document.getElementById('galleryImage').removeChild(xfade.oldImage);
			xfade.oldImage = undefined;
			xfade.newImage = undefined;
		}};