function preLoadImages()
{
	if (document.images) //object not available in older browsers
    {
      preload_image_object = new Image();
      // set image url
      image_url = new Array();
      image_url[0] = "/images/arrow_hover.png";
      image_url[1] = "/images/bullets_hover.png";

      var i = 0;
      for(i=0; i<=1; i++) 
      	preload_image_object.src = image_url[i];
    }
}
function SubmitForm(formId)
{
	$(formId).submit();
}
function GetRadioBtnVal(btn)
{
	var cnt = -1;
	for (var i=btn.length-1; i > -1; i--) {
		if (btn[i].checked) {cnt = i; i = -1;}
	}
	if (cnt > -1) return btn[cnt].value;
	else return null;
}
function ChangeProductSize(sizeComboBox, productID)
{
	location.href = 'view-product.php?id=' + productID + '&size=' + sizeComboBox.value;
}
function AddWatermark(textBox, text)
{
	textBox.value = text;
	textBox.addClass("watermark");
	textBox.addEvent("focus", RemoveWatermark);
}
function RemoveWatermark()
{
	this.removeEvent("focus", RemoveWatermark);
	this.value = "";
	this.removeClass("watermark");
}
function showPopup(url, width, height, left, top)
{
	newWindow = window.open(url, 'name', 'height=' + height + ', width=' + width + ', left=' + left + ' , top=' + top);
	if (window.focus)
	{
		newWindow.focus()
	}
	return false;
}
function toggleInvoiceRowVisiblities()
{
	var display = !$("chkSameAddresses").checked;
	var toggleRows = $("invoiceDetailsTable").getElementsByClassName("toggleRow");
	for (var i = 0; i < toggleRows.length; i++)
	{
		toggleRows[i].style.display = display ? "" : "none";
	}
}

function ValidateCheckoutForm(f)
{
	if(!ValidEmail(f.Email.value))
		alert('Please enter a valid email address');
	else if(f.Telephone.value == '')
		alert('Please enter a telephone number');
	else if(f.DeliveryName.value == '')
		alert('Please enter a delivery name');
	else if(f.DeliveryAddress.value == '')
		alert('Please enter a delivery address');
	else if(f.DeliveryPostcode.value == '')
		alert('Please enter a delivery postcode');
	else if(!f.SameAddresses.checked && f.InvoiceName.value == '')
		alert('Please enter a invoice name');
	else if(!f.SameAddresses.checked && f.InvoiceAddress.value == '')
		alert('Please enter a invoice address');
	else if(!f.SameAddresses.checked && f.InvoicePostcode.value == '')
		alert('Please enter a invoice postcode');
	else if(!f.Agree.checked)
		alert('You must agree to our Terms and Conditions to checkout');
	else
		return true;
	return false;
}

function ValidEmail(email) {
	AtPos = email.indexOf("@")
	StopPos = email.lastIndexOf(".")
	if (email == "")
		return false;
	
	if (AtPos == -1 || StopPos == -1)
		return false;
	
	if (StopPos < AtPos)
		return false;
	
	if (StopPos - AtPos == 1)
		return false;
	
	return true
}