//identifies the current image number by reading the url's query string
function getimgnumber() {
		var search = document.location.search;
		var querystring = search.substring(1, search.length);
		var queryarray = querystring.split("=");
		var imgnumber = queryarray[1];
		return imgnumber;
}

//loads the current image, image title, image info and image width, according to the current url query string
function loadimg() {
	var imgnumber = getimgnumber();
	document.getElementById("currentimg").src = imgfolder + "/" + imgsrclist[imgnumber];
	document.getElementById("currentimg").alt = imgtitlelist[imgnumber];
	document.getElementById("currentimg").width = imgwidthlist[imgnumber];
	document.getElementById("currentimgtitle").innerHTML = imgtitlelist[imgnumber];
	document.getElementById("currentimginfo").innerHTML = imginfolist[imgnumber];
} 	

//advances the image number by 1 (or if at last image, loops to beginning), changes the url query string, and reloads the page
function nexturl() {
	var imgnumber = getimgnumber();
	imgnumber++;
//THIS IS WHERE THE BUG IS.--temporary solution: make the if statement into if else statement. a bit longer, but it works.
	if (imgnumber < imgtotal) {document.location.search = "?imgnumber=" + imgnumber;}
	else {
		imgnumber = 0;
		document.location.search = "?imgnumber=" + imgnumber;
	}
}

//reduces the image number by 1 (or if at first image, loops to last image), changes the url query string, and reloads the page.
function previousurl() {
	var imgnumber = getimgnumber();
	//imgnumber--;
	if (imgnumber == 0) {
		imgtotal--; 
		document.location.search = "?imgnumber=" + imgtotal;
	}
	else {	
		imgnumber--;
		document.location.search = "?imgnumber=" + imgnumber;
	}
}

//in the head of each gallery page, include the following: 
//variables: imgfolder, imgtotal 
//arrays: imgsrclist, imgtitlelist, imginfolist, imgwidthlist