function addLoadEvent(func) {
    var oldonload = window.onload;
    if (typeof window.onload != 'function') {
        window.onload = func;
    } else {
        window.onload = function() {
            oldonload();
            func();
        }
    }
}
function RemoveArrow(Arrow){
	$(Arrow).addClassName('hidden');
}
function ShowArrow(Arrow){
	$(Arrow).removeClassName('hidden');
}

function moveSlideshow(elementID,final_x,final_y,interval) {
	var Speed = 40; //higher the number the slower the animation
    if (!document.getElementById) return false;
    
    // if the element does not exist we have nothing to do
    if (!document.getElementById(elementID)) return false;
    var elem = document.getElementById(elementID);
    
    // the slideshow events stack up and the animation is not smooth anymore
    if (elem.movement) {
        clearTimeout(elem.movement);
    }
    
    // current slideshow position
    var xpos = parseInt(elem.style.left);
    var ypos = parseInt(elem.style.top);
		
    if (xpos == final_x && ypos == final_y) {
		if (xpos <= -elem.max_x){
			RemoveArrow('scroll_right');
		}else{
			ShowArrow('scroll_right');
		}
		if (final_x == 0) {
			RemoveArrow('scroll_left');
		}else{
			ShowArrow('scroll_left');
		}
        return true;
    }
	
	if (xpos >= -elem.max_x){
		ShowArrow('scroll_right');
	}
	if (final_x != 0) {
		ShowArrow('scroll_left');
	}
    
    // restrict moving to white area
    if (final_x <= -elem.max_x) {
        final_x = -elem.max_x;
    }
    if (final_x > 0) {
	    final_x = 0;
    }
    
    // animation bit (taken from the book DOM Scripting by Jeremy Keith)
    if (xpos < final_x) {
        var dist = Math.ceil((final_x - xpos)/Speed);
        xpos = xpos + dist;
		
    }
    if (xpos > final_x) {
        var dist = Math.ceil((xpos - final_x)/Speed);
        xpos = xpos - dist;
	}
  
    // again, restrict showing white area
    if (xpos <= -elem.max_x) {
	    xpos = -elem.max_x;
    }
    if (xpos > 0) {
	    xpos = 0;
    }
    // fix the elements position
    elem.style.left = xpos + "px";
    elem.style.top = ypos + "px";
    
    // and set up the event again after an interval
    var repeat = "moveSlideshow('"+elementID+"',"+final_x+","+final_y+","+interval+")";
    elem.movement = setTimeout(repeat,interval);
}

function prepareSlideshow() {
	// first lets make sure the browser understands the DOM methods we will be using
  	if (!document.getElementsByTagName) return false;
  	if (!document.getElementById) return false;
  	
	// Make sure the elements exist
  	if (!document.getElementById("slideshow")) return false;
  	var slideshow = document.getElementById("slideshow");
  	var wrapper = document.getElementById("slideshow_wrapper");
  	wrapper.style.overflow = "hidden";
	wrapper.style.height = "240px";
  	
  	// prepare the navigation bit we will be using
  	// left
  	var navigation = document.createElement("ul");
  	navigation.setAttribute("id", "navigation");
  	var li = document.createElement("li");
  	var scroll_left = document.createElement("a");
  	scroll_left.setAttribute("id", "scroll_left");
  	scroll_left.href ="#";
  	var text = document.createTextNode("Left");
  	scroll_left.appendChild(text);
  	li.appendChild(scroll_left);
  	navigation.appendChild(li);
  	slideshow.insertBefore(navigation, wrapper);
  	
  	//right
  	var li = document.createElement("li");
  	var scroll_right = document.createElement("a");
  	scroll_right.setAttribute("id", "scroll_right");
  	scroll_right.href ="#";
  	var text = document.createTextNode("Right");
  	scroll_right.appendChild(text);
  	li.appendChild(scroll_right);
  	navigation.appendChild(li);
  	slideshow.insertBefore(navigation, wrapper);
	
	var slideshow_set = document.getElementById("slideshow_set");
	slideshow_set.style.top = 0+"px";
	slideshow_set.style.left = 0+"px";
	
	// to get the max y position of the gallery image track we need to count all
	// the li items and multiply that number with 308
	var li = slideshow_set.getElementsByTagName("div");
	slideshow_set.max_x = ((li.length-3) * 308); //the 3 is the number of image to scroll by
	slideshow_set.max_y = li.length * 308;
	
	// need the width of the gallery so that they do not scroll vertical
	var width = li.length * 308;
	slideshow_set.style.width = width + "px";
	
	
	// Attach onmouseover event for left
  	scroll_left.onclick = function() {
		// get the current position of the gallery element
		var slideshow_set = document.getElementById("slideshow_set");
		var x = parseInt(slideshow_set.style.left);
		if (x % 308 == 0) {			
    		moveSlideshow("slideshow_set",x+924,0,10);
		}else{			
			moveSlideshow("slideshow_set",x+924+((x % 308)*-1),0,10);
		}
		return false;
	}
	
	// Attach onmouseover event for right
  	scroll_right.onclick = function() {
		// get the current position of the gallery element
		var slideshow_set = document.getElementById("slideshow_set");
		var x = parseInt(slideshow_set.style.left);
    	if (x % 308 == 0) {
    		moveSlideshow("slideshow_set",x-924,0,10);
		}else{			
			moveSlideshow("slideshow_set",x-924+((x % 308)*-1),0,10);
		}
		return false;
	}
	//Drag.init(slideshow_set, null, -slideshow_set.max_x, 0, 0, 0);
	
	//set slide show all they way to the left off screen
	slideshow_set.style.left = -slideshow_set.max_x-924 + "px";
	slideshow_set.style.display = "block";
	//move the slide show onto the first item
	var x = parseInt(slideshow_set.style.left);
	moveSlideshowFirst("slideshow_set",x+slideshow_set.max_x+924,0,10);
	

}

function moveSlideshowFirst(elementID,final_x,final_y,interval) {
	var Speed = 40; //higher the number the slower the animation
    if (!document.getElementById) return false;
    
    // if the element does not exist we have nothing to do
    if (!document.getElementById(elementID)) return false;
    var elem = document.getElementById(elementID);
    
    // the slideshow events stack up and the animation is not smooth anymore
    if (elem.movement) {
        clearTimeout(elem.movement);
    }
    
    // current slideshow position
    var xpos = parseInt(elem.style.left);
    var ypos = parseInt(elem.style.top);
		
    if (xpos == final_x && ypos == final_y) {		
		if (final_x == 0) {
			RemoveArrow('scroll_left');
		}
        return true;
    }
    
    // animation bit (taken from the book DOM Scripting by Jeremy Keith)
    if (xpos < final_x) {
        var dist = Math.ceil((final_x - xpos)/Speed);
        xpos = xpos + dist;
    }
    if (xpos > final_x) {
        var dist = Math.ceil((xpos - final_x)/Speed);
        xpos = xpos - dist;
    }
  
    // fix the elements position
    elem.style.left = xpos + "px";
    elem.style.top = ypos + "px";
    
    // and set up the event again after an interval
    var repeat = "moveSlideshowFirst('"+elementID+"',"+final_x+","+final_y+","+interval+")";
    elem.movement = setTimeout(repeat,interval);
}

//addLoadEvent(prepareSlideshow);


// the dragging bit
var Drag = {

	obj : null,

	init : function(o, oRoot, minX, maxX, minY, maxY, bSwapHorzRef, bSwapVertRef, fXMapper, fYMapper)
	{
		o.onmousedown	= Drag.start;

		o.hmode			= bSwapHorzRef ? false : true ;
		o.vmode			= bSwapVertRef ? false : true ;

		o.root = oRoot && oRoot != null ? oRoot : o ;

		if (o.hmode  && isNaN(parseInt(o.root.style.left  ))) o.root.style.left   = "0px";
		if (o.vmode  && isNaN(parseInt(o.root.style.top   ))) o.root.style.top    = "0px";
		if (!o.hmode && isNaN(parseInt(o.root.style.right ))) o.root.style.right  = "0px";
		if (!o.vmode && isNaN(parseInt(o.root.style.bottom))) o.root.style.bottom = "0px";
	
		o.minX	= typeof minX != 'undefined' ? minX : null;
		o.minY	= typeof minY != 'undefined' ? minY : null;
		o.maxX	= typeof maxX != 'undefined' ? maxX : null;
		o.maxY	= typeof maxY != 'undefined' ? maxY : null;

		o.xMapper = fXMapper ? fXMapper : null;
		o.yMapper = fYMapper ? fYMapper : null;

		o.root.onDragStart	= new Function();
		o.root.onDragEnd	= new Function();
		o.root.onDrag		= new Function();
	},

	start : function(e)
	{
		var o = Drag.obj = this;				
		
		if (o.movement) {
        	clearTimeout(o.movement); //clear any scroll animations
    	}
				
		e = Drag.fixE(e);
		var y = parseInt(o.vmode ? o.root.style.top  : o.root.style.bottom);
		var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );
		o.root.onDragStart(x, y);

		o.lastMouseX	= e.clientX;
		o.lastMouseY	= e.clientY;

		if (o.hmode) {
			if (o.minX != null)	o.minMouseX	= e.clientX - x + o.minX;
			if (o.maxX != null)	o.maxMouseX	= o.minMouseX + o.maxX - o.minX;
		} else {
			if (o.minX != null) o.maxMouseX = -o.minX + e.clientX + x;
			if (o.maxX != null) o.minMouseX = -o.maxX + e.clientX + x;
		}

		if (o.vmode) {
			if (o.minY != null)	o.minMouseY	= e.clientY - y + o.minY;
			if (o.maxY != null)	o.maxMouseY	= o.minMouseY + o.maxY - o.minY;
		} else {
			if (o.minY != null) o.maxMouseY = -o.minY + e.clientY + y;
			if (o.maxY != null) o.minMouseY = -o.maxY + e.clientY + y;
		}

		document.onmousemove	= Drag.drag;
		document.onmouseup		= Drag.end;
		

		return false;
	},

	drag : function(e)
	{
		e = Drag.fixE(e);
		var o = Drag.obj;
		
		//deactivate the links while dragging
		var GalItems = $A($$('a.GalLink'));
		GalItems.invoke('writeAttribute', 'onclick', 'DoGalLink();return false;');

		var ey	= e.clientY;
		var ex	= e.clientX;
		var y = parseInt(o.vmode ? o.root.style.top  : o.root.style.bottom);
		var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );
		var nx, ny;
		
		if (o.minX != null) ex = o.hmode ? Math.max(ex, o.minMouseX) : Math.min(ex, o.maxMouseX);
		if (o.maxX != null) ex = o.hmode ? Math.min(ex, o.maxMouseX) : Math.max(ex, o.minMouseX);
		if (o.minY != null) ey = o.vmode ? Math.max(ey, o.minMouseY) : Math.min(ey, o.maxMouseY);
		if (o.maxY != null) ey = o.vmode ? Math.min(ey, o.maxMouseY) : Math.max(ey, o.minMouseY);
		
		
		nx = x + ((ex - o.lastMouseX) * (o.hmode ? 1 : -1));
		ny = y + ((ey - o.lastMouseY) * (o.vmode ? 1 : -1));
		
		if (o.xMapper)		nx = o.xMapper(y)
		else if (o.yMapper)	ny = o.yMapper(x)

		Drag.obj.root.style[o.hmode ? "left" : "right"] = nx + "px";
		Drag.obj.root.style[o.vmode ? "top" : "bottom"] = ny + "px";
		Drag.obj.lastMouseX	= ex;
		Drag.obj.lastMouseY	= ey;

		Drag.obj.root.onDrag(nx, ny);
		return false;
	},

	end : function()
	{
			
		document.onmousemove = null;
		document.onmouseup   = null;
		Drag.obj.root.onDragEnd(	parseInt(Drag.obj.root.style[Drag.obj.hmode ? "left" : "right"]), 
									parseInt(Drag.obj.root.style[Drag.obj.vmode ? "top" : "bottom"]));
		Drag.obj = null;
	},

	fixE : function(e)
	{
		if (typeof e == 'undefined') e = window.event;
		if (typeof e.layerX == 'undefined') e.layerX = e.offsetX;
		if (typeof e.layerY == 'undefined') e.layerY = e.offsetY;
		return e;
	}
};

function DoGalLink(){
	//activate the links
	var GalItems = $A($$('a.GalLink'));
	GalItems.invoke('writeAttribute', 'onclick', '');
}