/*
	Name:		Scott Ash JS Menu Image Swap
	Type:		Object
	Created:	12/20/2004
	Modified:	03/02/2005
	Version:	1.1
	Updates:	12/20/2004 (v1.0)
					first release into build of a website. 
				03/02/2005 (v1.1)
					updated swap() and load_array() functions to determine "this.base" based on image
					object attributes in html document. This requires that this module be called on an 
					onload event so that the methods can locate the image objects on the page. Added function
					revert() to force images to default state for browser cache issues. Renamed to Menu 
					Image Swap
	Author:		Scott A. Ash
	Copyright:	Scott Ash
	Functions:	init()
				load_array()
				swap()
				
				.init():
				This is used to initialize the properties of the object. Each property is set 
				one at a time by calling [object].init([a],[b]) and passing it the property name [a]
				and the property setting [b]. Initializing a nonexistant property of the object will
				result in an error message.
				
				.load_array():
				This function requires that the object be initialized before being called. Once called 
				this function loads the specified image files into memory for fast swapping. This 
				function is not necessary for the swap() function to work.
				
				.swap();
				This swaps the image based on an image name passed to it. An image name must be passed
				or the function will return an error alert. The function finds which image to replace
				based on the current url of the referenced image and the object "over" and "dormant" settings.
				
				.revert()
				This method forces all swappable images back to their default state. It is intended to be 
				used on page unload() in the body tag. It takes no parameters but relies on the object being 
				fully created.
					
	Uses:		solo
	Required:	This object must be initialized in the master site script or page head script before 
				being used.
				
	Settings:	None
*/


function sa_image_swap()
{
	// constructor

	function init(item,val)
	{
		// set only legal properties of object
		if(item == "graphics")
			this.graphics = val;
		else if(item == "over")
			this.over = val;
		else if(item == "dormant")
			this.dormant = val;
		else if(item == "base")
			this.base = val;
		else if(item == "types")
			this.types = val;
		else
			alert("ERROR!\nsa_image_swap.init():\n\"" + item + "\" is not a property of this object.");
	}
	
	function load_array()
	{	
		// test for image ability
		var isAllowed = (document.images);
		
		if(isAllowed)
		{
			// create image memory arrays
			this.overs = new Array();
			this.dormants = new Array();
			
			// load images into memory
			for(var i=0;i<this.graphics.length;i++)
			{
				if(document[this.graphics[i]])
				{
					temploc = document[this.graphics[i]].src.split(this.graphics[i]);
					this.base = temploc[0];
					
					this.overs[i] = new Image();
					this.overs[i].src = this.base + this.graphics[i] + this.over + '.' + this.types;
					
					this.dormants[i] = new Image();
					this.dormants[i].src = this.base + this.graphics[i] + this.dormant + '.' + this.types;
				}else
				{
					alert("ERROR!\nsa_image_swap.load_array():\nThe image \"" + this.graphics[i] + "\" cannot be found in the page.");
				}
			}
		}
	}
	
	function swap_image(imgName)
	{
		// test for image swap ability
		var isAllowed = (document.images);
		
		
		if(isAllowed)
		{
			// find image in array
			theImg = 0;	// Netscape and IE don't like variables declared without values (i.e. theImg;)
			flag = 0;
			for(i=0;i<this.graphics.length;i++)
			{
				if(imgName == this.graphics[i])
				{
					theImg = i;	// the image has been found!
					flag = 1;	// set the flag to allow continuation of function
					break;		// break out of the loop to discontinue search
				}
			}
		
			// swap image
			if(flag)
			{
				if(document[imgName].src.indexOf(this.over) != -1)
				{
					document[imgName].src = this.dormants[theImg].src;
				}else
				{
					document[imgName].src = this.overs[theImg].src;
				}
				//alert(document[imgName].src);
			}else
			{
				alert("ERROR!\nsa_image_swap.swap_image():\n\"" + imgName + "\" could not be set.");
			}
		}
	}
	
	function revert()
	{
		// test for image swap ability
		var isAllowed = (document.images);
		
		if(isAllowed)
		{
			// reset images to dormant state for browser back button returns
			for(i=0;i<this.graphics.length;i++)
			{
				if(document[this.graphics[i]])
				{
					// test this function by setting all graphics to a non-dormant state and
					// clicking the browser back/forward button with the alert below activated
					document[this.graphics[i]].src = this.dormants[i].src;
				}
			}
			
			// alert("onunload() called");
		}
	}
	
	// properties
	this.graphics;
	this.over;
	this.dormant;
	this.base;
	this.types;
	
	// created properties
	this.overs;
	this.dormants;
	
	// methods
	this.init = init;
	this.swap = swap_image;
	this.load_array = load_array;
	this.revert = revert;
}