Stylesheet switcher

/***********************************************************************************************
                             Script to swap between stylesheets
                Using document.styleSheets - I recommend you use my other version
   Written by Mark Wilton-Jones, 05/12/2002; v1.1 updated 29/04/2004 for Konqeror XHTML fix
************************************************************************************************

Please see http://www.howtocreate.co.uk/jslibs/ for details of this script
Please see http://www.howtocreate.co.uk/jslibs/termsOfUse.html for terms of use

To set up the page in the first place:

	Inbetween the <head> tags, put:

		<script src="PATH TO SCRIPT/swapstyle.js" type="text/javascript" language="javascript1.2"></script>

	Also between the head tags, put your stylesheets, best done as external links, but you can use
	<style ...> tags as well.

		Stylesheets cannot be switched if they have no title attribute and will be used at all times:

			<link rel="stylesheet" type="text/css" href="all.css">

		Stylesheets will be on by default if they have a title attribute and their rel attribute is set to 'stylesheet'.
		Most browsers will only allow one of these to be defined (or several sharing the same title):

			<link rel="stylesheet" type="text/css" href="default.css" title="Default">

		Stylesheets will be off by default if they have a title attribute and their rel attribute is set to 'alternate stylesheet':

			<link rel="alternate stylesheet" type="text/css" href="contrast.css" title="High Contrast">
			<link rel="alternate stylesheet" type="text/css" href="bigFont.css" title="Big Font">

To swap between stylesheets:

	changeStyle();                           //switches off all stylesheets that have title attributes
	changeStyle('Default');                  //switches off all stylesheets that have title attributes that do not match 'Default'
	changeStyle('High Contrast');            //switches off all stylesheets that have title attributes that do not match 'High Contrast'
	changeStyle('Big Font');                 //switches off all stylesheets that have title attributes that do not match 'Big Font'
	changeStyle('High Contrast','Big Font'); //switches off all stylesheets that have title attributes that do not match 'High Contrast' or 'Big Font'

	Opera 7+ and Mozilla also allow users to switch between stylesheets using the view menu (only one at a time though ...)

To make the script remember the user's choice of stylesheets, for example to use on more than one page or if they reload
 - includes stylesheets chosen using the view menu:

	In these examples, I call the cookie used to store the choice 'styleTestStore'. You could use any name you like.

	To remember only until the browser window is closed:

		<body onload="useStyleAgain('styleTestStore');" onunload="rememberStyle('styleTestStore');">

	To remember for 10 days (for example):

		<body onload="useStyleAgain('styleTestStore');" onunload="rememberStyle('styleTestStore',10);">

If you are going to provide users with a mechanism to change stylesheets, you may want to check
if the browser will allow you to change stylesheets first. Use:

	if( document.styleSheets || ( window.opera && document.childNodes ) ) {
		document.write('Something that allows them to choose stylesheets');
	}

It's not perfect, because it will also appear in ICEbrowser, which makes a mess when it tries to
change to an alternate stylesheet. If you want, you can use
	if( ( document.styleSheets || ( window.opera && document.childNodes ) ) && !navigator.__ice_version ) {
but you should then update that if ICE is updated to make it work properly.
________________________________________________________________________________________________*/

function getSSTitle(ss) { if( ss.title ) { return ss.title; } else if( ss.owningElement ) { return ss.owningElement.title; } return ''; }
function getAllSheets() {
	if( document.styleSheets && ( window.ScriptEngine || navigator.taintEnabled ) ) { return document.styleSheets; }
	if( !document.getElementsByTagName ) { return []; }
	for( var x = 0, Lt = document.getElementsByTagName('link'), os = []; Lt[x]; x++ ) {
		var rel = Lt[x].rel ? Lt[x].rel : Lt[x].getAttribute ? Lt[x].getAttribute('rel') : '';
		if( typeof( rel ) == 'string' && rel.toLowerCase().indexOf('style') + 1 ) { os[os.length] = Lt[x]; }
	} for( var x = 0, St = document.getElementsByTagName('style'); St[x]; x++ ) { os[os.length] = St[x]; } return os;
}
function changeStyle() {
	window.userHasChosen = true;
	for( var x = 0, ss = getAllSheets(); x < ss.length; x++ ) {
		if( getSSTitle( ss[x] ) ) { ss[x].disabled = true; }
		for( var y = 0; y < arguments.length; y++ ) {
			if( getSSTitle( ss[x] ) == arguments[y] ) { ss[x].disabled = false; }
		}
	}
}
function rememberStyle( cookieName, cookieLife ) {
	if( !window.userHasChosen && !window.ScriptEngine && !navigator.taintEnabled ) { return; }
	for( var x = 0, ss = getAllSheets(), outLine = ''; x < ss.length; x++ ) {
		if( getSSTitle( ss[x] ) && ss[x].disabled == false ) { outLine += ( outLine ? ' MWJ ' : '' ) + escape( getSSTitle( ss[x] ) ); } }
	if( ss.length ) { document.cookie = escape( cookieName ) + '=' + escape( outLine ) + ( cookieLife ? ';expires=' + new Date( ( new Date() ).getTime() + ( cookieLife * 86400000 ) ).toGMTString() : '' ) + ';path=/'; }
}
function useStyleAgain( cookieName ) {
	for( var x = 0; x < document.cookie.split( "; " ).length; x++ ) {
		var oneCookie = document.cookie.split( "; " )[x].split( "=" );
		if( oneCookie[0] == escape( cookieName ) ) {
			var styleStrings = unescape( oneCookie[1] ).split( " MWJ " );
			for( var y = 0, funcStr = ''; styleStrings[y]; y++ ) { funcStr += ( y ? ',' : '' ) + 'unescape( styleStrings[' + y + '] )'; }
			eval( 'changeStyle(' + funcStr + ');' ); break;
		}
	}
}