var G_ROWS = 3;
var G_COLS = 5;
var G_HEIGHT = 93*3;
var pos = 0;

function isTop()
{
	return pos >= 0;
}

function isBottom()
{
	var e = $("#gallery_thumnails_case>:last");
	var last_child = e.position().top + e.height();
	
	return last_child <= (-pos) + G_HEIGHT;
}

function setArrows()
{
	if(isTop())
		$("#gallery_scrollbar-up").attr("src", "images/scroll_indicator-up_end.gif");
	else
		$("#gallery_scrollbar-up").attr("src", "images/scroll_indicator-up.gif");
	
	if(isBottom())
		$("#gallery_scrollbar-down").attr("src", "images/scroll_indicator-down_end.gif");
	else
		$("#gallery_scrollbar-down").attr("src", "images/scroll_indicator-down.gif");
}

$(document).ready(function()
{
	$("#gallery_thumnails_case_scroll").css({height: G_HEIGHT + "px", overflow: "hidden"});
	$("#gallery_scrollbar-up").css({display: "inline"});
	$("#gallery_scrollbar-down").css({display: "inline"});
	
	setArrows();
	
	$("#gallery_scrollbar-up").click(function() {
		if(isTop())
			return;
		
		pos += G_HEIGHT;
		setArrows();
		
		$("#gallery_thumnails_case").animate({top: "+=" + G_HEIGHT + "px"}, "slow");
	});
	
	$("#gallery_scrollbar-down").click(function() {
		if(isBottom())
			return;
		
		pos -= G_HEIGHT;
		setArrows();
		
		$("#gallery_thumnails_case").animate({top: "-=" + G_HEIGHT + "px"}, "slow");
	});
});