function preload(urls)
{
	var img = new Array();
	for ( var i=0; i<urls.length; i++ )
	{
		img[img.length] = new Image();
		img[img.length - 1].src = urls[i];
	}
}

function prev_photo()
{
	var photo_placeholder = document.getElementById('photo_placeholder');
	if (current_photo > 1)
	{
		current_photo--;
	}
	else
	{
		current_photo = max_photo;
	}
	set_photo_title();
	photo_placeholder.src = '';
	photo_placeholder.src = photos[current_photo-1];
}

function next_photo()
{
	var photo_placeholder = document.getElementById('photo_placeholder');
	if (current_photo < max_photo)
	{
		current_photo++;		
	}
	else
	{
		current_photo = 1;
	}
	set_photo_title()
	photo_placeholder.src = '';
	photo_placeholder.src = photos[current_photo-1];
}

function set_photo_title()
{
	if ( titles.length > 0 )
	{
		var photo_title = document.getElementById('title_placeholder');
		photo_title.innerHTML = titles[current_photo - 1];
		
		var title_prefix = document.getElementById('title_prefix');
		title_prefix.innerHTML = '';
		if ( titles[current_photo - 1] != '' )
		{
			title_prefix.innerHTML = 'на фото:';
		}
	
		if ( titles.length > 1 )
		{
			var photo_number = document.getElementById('number_placeholder');
			photo_number.innerHTML = '' + current_photo + '/' + max_photo + '';
		}
		
		var photo_placeholder = document.getElementById('photo_placeholder');
		photo_placeholder.alt = titles[current_photo - 1];
		photo_placeholder.title = titles[current_photo - 1];
	}
}