var COUNT_IMGPREFIX		= "/images/imagenav_";
var COUNT_IMGSUFFIX		= ".png";

var NEXTIMG_ENABLED		= new Image();
NEXTIMG_ENABLED.src		= "/images/imagenav_forward.png";
var NEXTIMG_DISABLED	= new Image();
NEXTIMG_DISABLED.src	= "/images/imagenav_forward_disabled.png";
var PREVIMG_ENABLED		= new Image();
PREVIMG_ENABLED.src		= "/images/imagenav_back.png";
var PREVIMG_DISABLED	= new Image();
PREVIMG_DISABLED.src	= "/images/imagenav_back_disabled.png";

var PHOTO_PREFIX		= "photo";
var PHOTO_SUFFIX		= ".jpg";

var PHOTO_ARRAY			= new Array();
var NUMBERIMG_ARRAY		= new Array();

function init() {
	for( var i=0; i<PHOTO_ORDER.length; i++ ) {
		PHOTO_ARRAY[i] = new Image();
		PHOTO_ARRAY[i].src	= PHOTO_PREFIX + PHOTO_ORDER[i] + PHOTO_SUFFIX;
		
		NUMBERIMG_ARRAY[i] = new Image();
		NUMBERIMG_ARRAY[i].src	= COUNT_IMGPREFIX + (i+1) + COUNT_IMGSUFFIX;
	}	
}

function changePhoto( direction ) {
	if( direction == "next" && CURRENT_IMAGE+1 < PHOTO_ORDER.length ) {
		CURRENT_IMAGE++;	
	} else if( direction == "previous" && CURRENT_IMAGE > 0 ) {
		CURRENT_IMAGE--;
	}
	
	var photoObj	= document.getElementById( "photoImg" );
	var currImgObj	= document.getElementById( "currentNumImg" );
	photoObj.src	= PHOTO_ARRAY[CURRENT_IMAGE].src;
	currImgObj.src	= NUMBERIMG_ARRAY[CURRENT_IMAGE].src;
	
	var nextImgObj	= document.getElementById( "nextImg" );
	if( CURRENT_IMAGE+1 == PHOTO_ORDER.length ) {
		nextImgObj.src	= NEXTIMG_DISABLED.src;
	} else {
		nextImgObj.src	= NEXTIMG_ENABLED.src;
	}
	
	var backImgObj	= document.getElementById( "backImg" );
	if( CURRENT_IMAGE-1 < 0 ) {
		backImgObj.src	= PREVIMG_DISABLED.src;
	} else {
		backImgObj.src	= PREVIMG_ENABLED.src;
	}
}