var agent = navigator.userAgent.toLowerCase();
var mac = (agent.indexOf("mac") != -1);
var ie = ((agent.indexOf("msie") != -1) && (agent.indexOf('opera')==-1));

var gImage=0;
function next ()
{
	gImage++;
	SetPrevNext ();
}

function prev ()
{
	gImage--;
	SetPrevNext ();
}

function GetHtmlName(p)
{
	var htmlname = p.filename;
	htmlname = "pages/" + htmlname.substr (0, htmlname.length - 3) + "htm";
	return htmlname;
}

function SetPrevNext ()
{
	SetCell (document.getElementById("leftcell"), gImage-1, "prev", false);
	SetArrow (document.getElementById("leftarrow"), gImage-1, "LeftArrow", "prev", "Previous Picture");
	SetCell (document.getElementById("rightcell"), gImage+1, "next", false);
	SetArrow (document.getElementById("rightarrow"), gImage+1, "RightArrow", "next", "Next Picture");

	var f = parent.frames["TopFrame"];
	f.frameElement.src = GetHtmlName (gPhotos[gImage]);
	
	SetCell (document.getElementById("preload"), gImage+1, "next", true);
}

function SetCell(cell,index, proc, preload)
{
	if(index < 0 || index >= gPhotos.length)
	{
		cell.innerHTML = "&nbsp";
	}
	else
	{
		var p = gPhotos[index];
		var htmlname = GetHtmlName (p);
		if (preload)
		{
			cell.innerHTML = "<IMG src='images/" + p.filename + "' height=0 width=0 style='border:0pt solid white'>";
		}
		else
		{
			cell.innerHTML = "<A onclick='" + proc + "()' name=" + index + " target='TopFrame' href='" + htmlname + "'>" +
				"<IMG src='thumbnails/" + p.filename + "' height='" + p.ThumbHeight + "' width='" + p.ThumbWidth + "' style='border:0pt solid white'><br></A>";
		}
	}
}

function SetArrow(cell,index,imagenamebase, proc, alttext)
{
	var filename;
	var onclick;
	if(index < 0 || index >= gPhotos.length)
	{
		filename = imagenamebase + "Gray.gif";
		onclick = "";
		alttext = "";
	}
	else
	{
		filename = imagenamebase + ".gif";
		var p = gPhotos[index];
		var htmlname = GetHtmlName (p);
		onclick="onclick='" + proc + "()' name=" + index + " target='TopFrame' href='" + htmlname + "'";
	}
	
	cell.innerHTML = "<br><A " + onclick + "><IMG src='" + filename + "' height=37 width=49 style='border:0pt solid white' alt='" + alttext + "'><br></a>";
}

SetPrevNext ();