isMac = (navigator.appVersion.indexOf("Mac") != -1);
isIE = (navigator.appName == "Microsoft Internet Explorer")
isNN = (navigator.appName == "Netscape")
isSafari = (navigator.userAgent.indexOf("Safari") != -1);
isWindows = (navigator.appVersion.indexOf("Windows") != -1);
isIE5 = (navigator.appVersion.indexOf("MSIE 5") != -1)

function imageSwap(imgName,imgObj) { 
	if (document.images && preloaded) document.images[imgName].src = imgObj.src		
}

var aImages = new Array()

function preload(imgObj,imgSrc) {
	if (document.images) { 
		aImages[imgObj] = new Image()
		aImages[imgObj].src = imgSrc
	}
}

function msover(imgName) {
	imageSwap(imgName,aImages[imgName + '_over'])
}

function msout(imgName) { 
	imageSwap(imgName,aImages[imgName + ''])
}

var preloaded;
preloaded = false;

function preloadImages() 
{
        preload("btn_send_over","images/btnSendOver.gif");
        preload("btn_send","images/btnSend.gif");
        
        preload("btn_design_over","images/btnDesignOver.gif");
        preload("btn_design","images/btnDesign.gif");
        
        preload("btn_print_over","images/btnPrintOver.gif");
        preload("btn_print","images/btnPrint.gif");
        
        preload("btn_distribution_over","images/btnDistributionOver.gif");
        preload("btn_distribution","images/btnDistribution.gif");
        
        preload("roll_design_over","images/nav/design_over.gif");
        preload("roll_design","images/nav/design.gif");
        
        preload("roll_print_over","images/nav/print_over.gif");
        preload("roll_print","images/nav/print.gif");
        
        preload("roll_distribution_over","images/nav/distribution_over.gif");
        preload("roll_distribution","images/nav/distribution.gif");
        
        preload("roll_environment_over","images/nav/environment_over.gif");
        preload("roll_environment","images/nav/environment.gif");
        
        preload("roll_contact_over","images/nav/contact_over.gif");
        preload("roll_contact","images/nav/contact.gif");

        preload("roll_sub_design_over","images/subnav/design_over.gif");
        preload("roll_sub_design","images/subnav/design.gif");
        
        preload("roll_sub_print_over","images/subnav/print_over.gif");
        preload("roll_sub_print","images/subnav/print.gif");
        
        preload("roll_sub_distribution_over","images/subnav/distribution_over.gif");
        preload("roll_sub_distribution","images/subnav/distribution.gif");

        preload("roll_sub_distribution_link_over","images/subnav/distributionLink_over.gif");
        preload("roll_sub_distribution_link","images/subnav/distributionLink.gif");
                
        preload("roll_sub_environment_over","images/subnav/environment_over.gif");
        preload("roll_sub_environment","images/subnav/environment.gif");
        
        preload("roll_sub_contact_over","images/subnav/contact_over.gif");
        preload("roll_sub_contact","images/subnav/contact.gif");
        
	preloaded = true;
}

function validateContactForm(f) {
	if (isBlank(f.firstname.value)) {
		alert("Please enter your first name");
		f.firstname.focus();
		return false;
	}
	if (isBlank(f.surname.value)) {
		alert("Please enter your surname");
		f.surname.focus();
		return false;
	}
	if (isBlank(f.email_address.value)) {
		alert("Please enter your email address");
		f.email_address.focus();
		return false;
	}
	if (!isEmail(f.email_address.value)) {
		alert("Please enter a valid email address");
		f.email_address.focus();
		return false;
	}	
	if (f.telephone.value!="") {
		if (!isNumber(f.telephone.value)) {
			alert("Please enter numbers only into the telephone field");
			f.telephone.focus();
			return false;
		}
	}
	if (isBlank(f.message.value)) {
		alert("Please enter your message");
		f.message.focus();
		return false;
	}
	return true;
}

function isBlank(v) {
	if ((v.length>0) && (v!=" ")) {
		return false;
	}
	else {
		return true;
	}
}

function isEmail(v) {
	at=v.indexOf('@');
	dot=v.lastIndexOf('.');
	end=v.length;
	subone=v.substring(at+1,dot);
	domainbeforedot=subone.length;
	subtwo=v.substring(dot+1,end);
	domainafterdot=subtwo.length;
   	if (v.indexOf ('@',0) == -1 || v.indexOf ('.',0) == -1  || domainbeforedot < 1 || domainafterdot < 2 ) {
      		return false;
	}
   	else { 
   		return true; 
   	}
}

function isNumber(v) {
    	if (isNaN(v.replace(/ /g,""))) {
    		return false;
    	}
    	else return true;
}