/* The following function creates an XMLHttpRequest object... */
function getXmlHttp()
{
	var xmlHttp = null;
	try 
	{
		xmlHttp = new XMLHttpRequest();
	} 
	catch (e) 
	{
		var progIds = ['MSXML2.XMLHTTP', 'Microsoft.XMLHTTP', 'MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0'];
		var success = false;
		for (var iterator = 0; (iterator < progIds.length) && ( ! success); iterator ++) {
			try {
				xmlHttp = new ActiveXObject(progIds[iterator]);
				success = true;
			} catch (e) {}
		}
		if ( ! success ) 
		{
			xmlHttp = false;
		}
	}
	return xmlHttp;
};

function createRequestObject()
{
	return getXmlHttp(); //return the object

//	var request_o; //declare the variable to hold the object.
//	var browser = navigator.appName; //find the browser name
//	if(browser == "Microsoft Internet Explorer")
//	{
//		/* Create the object using MSIE's method */
//		request_o = new ActiveXObject("Microsoft.XMLHTTP");
//	}
//	else
//	{
//		/* Create the object using other browser's method */
//		request_o = new XMLHttpRequest();
//	}
//	return request_o; //return the object
}

/* You can get more specific with version information by using 
	parseInt(navigator.appVersion)
	Which will extract an integer value containing the version 
	of the browser being used.
*/

/* The variable http will hold our new XMLHttpRequest object. */
var http = createRequestObject(); 

/* Function called to get the product categories list */
function getPhotos(pagenumber, rootdir)
{
  if(!http)
  {
    alert("Debugging!");
  }
	/* 
    alert('pagenumber = '+pagenumber);
	  Create the request. The first argument to the open function is the method (POST/GET),    
		and the second argument is the url... 
		document contains references to all items on the page
		We can reference document.form_category_select.select_category_select and we will
		be referencing the dropdown list. The selectedIndex property will give us the 
		index of the selected item. 
	*/
	http.open('get', 'indexedphotos.php?index=' + pagenumber + '&imagedir='+rootdir);
	/* Define a function to call once a response has been received. This will be our
		handleProductCategories function that we define below. */
	http.onreadystatechange = handlePhotos; 
	/* Send the data. We use something other than null when we are sending using the POST
		method. */
	http.send(null);
}

/* Function called to handle the list that was returned from the internal_request.php file.. */
function handlePhotos(){
	/* Make sure that the transaction has finished. The XMLHttpRequest object 
		has a property called readyState with several states:
		0: Uninitialized
		1: Loading
		2: Loaded
		3: Interactive
		4: Finished */
	if(http.readyState == 4){ //Finished loading the response
		/* We have got the response from the server-side script,
			let's see just what it was. using the responseText property of 
			the XMLHttpRequest object. */
		var response = http.responseText;
		/* And now we want to change the product_categories <div> content.
			we do this using an ability to get/change the content of a page element 
			that we can find: innerHTML. */
		document.getElementById('gallerysection').innerHTML = response;
	}
}