// ChangeDocBg.js  --- JavaScript Document

var noFlagsBg = 'Images/Background.jpg';
var flagsBg = 'Images/USflaganimation.gif';
	
function createCookie(name,value,days)
	{
	if (days)
		{
    	var date = new Date();
    	date.setTime(date.getTime()+(days*24*60*60*1000));
    	var expires = ";expires="+date.toGMTString();
  		}
	else
		expires = "";
	document.cookie = name+"="+value+expires+"; path=/";
	}

function readCookie(name)
	{
	var nameEQ = name + "=";
	var ca = document.cookie.split(';');

	for(var i=0;i < ca.length;i++)
		{
		var c = ca[i];
		while (c.charAt(0)==' ')
			c = c.substring(1,c.length);
		if (c.indexOf(nameEQ) == 0)
			{
			// alert( "readCookie= " + c.substring(nameEQ.length,c.length) );
			return( c.substring(nameEQ.length,c.length) );
			}
		}
	return( null );
	}

function toggleDocBg()
	{ // when page loads, get saved selection or use default
	var bgImage = readCookie("bgImage");
	// alert( "toggleDocBg: bgImage= " + bgImage );
	if (bgImage && (bgImage == flagsBg))
		{
		// alert("toggleDocBg to noFlagsBg");
		changeBgImage( noFlagsBg );
		}
	else
		{
		// alert("toggleDocBg to flagsBg");
		changeBgImage( flagsBg );
		}
	}

function changeBgImage(whichImage)
	{
	if (document.body)
		{
		document.body.background = whichImage;
		createCookie("bgImage", whichImage, 49);
		}
	}

function setFlagsBg()
	{
	changeBgImage( flagsBg );
	}
	
function setDocBg()
	{ // when page loads, get saved selection or use default
	var bgImage = readCookie("bgImage");
	// alert( "toggleDocBg: bgImage= " + bgImage );
	if ((bgImage && (bgImage == flagsBg)) || !bgImage)
		{
		// If there's no cookie, set the bg to flags...
		// alert("setDocBg to flagsBg");
		changeBgImage( flagsBg );
		}
	else
		{
		// alert("setDocBg to noFlagsBg");
		changeBgImage( noFlagsBg );
		}
	}