// rollovers.js
// EnSky's JavaScript image swapping code
// After discovering about 1 million different ways to implement rollovers
// this collection of scripts seems to do the job in a pretty flexible and extensible
// manner. Hopefully the comments explain how to use the scripts.
// You should strip comments when embedding these scripts in actual pages
// Last Updated: 25-Jul-00




/* functions that implement the rollovers */

// this function loads the rollover images into the browser's cache
// the images to load are defined in the dynImages array
// the cached image objects are stored in the cachedImages array 
// called onload - page has loaded before we start to load the rollover images
function preloadImages() {
	if (document.images) {
		// iterate thru the dynImages array...
		for (var imgName in dynImages) {
			// for each entry in the dynImages array, create an array in the cachedImages array
			// these arrays may contain n image objects, representing n image states
			cachedImages[imgName] = new Array()
			for (var i = 0; i < dynImages[imgName].length; i++) {
				cachedImages[imgName][i] = new Image
				cachedImages[imgName][i].src = imagePath + dynImages[imgName][i]
			}
		}	
	}
	return true
}
		
// this function, called onload, will add references to any named images in layers to 
// global document.images array - copying the MSIE object model
// add if the page uses layers
function NS_flattenImages (documentObj) {
	if (document.layers) {
		var me = NS_flattenImages
		if (!documentObj) {
			documentObj = window.document //top-level document is default value
		}
		/* add references to global document.images array */
		for (var i = 0; i < documentObj.images.length; i++) {
			var img = documentObj.images[i]
			if (img.name && !document.images[img.name]) {
				document.images[img.name] = img
			}
		}
		
		/* recursively search through layers for images */
		for (var i = 0; i <  documentObj.layers.length; i++) {
			me(documentObj.layers[i].document) //recurse
		}
		
	}
	return true
}

// use this function as the onmouseover handler
function roll_over(imgName) {
	var img, rollSrc
	if (document.images && imagesCached) {
		img = document.images[imgName]
		rollSrc = cachedImages[imgName][1].src
		img.src = rollSrc
	}
	return true
}

// use this function as the onmouseout handler
function roll_out(imgName) {
	var img, defaultSrc
	if (document.images && imagesCached) {
		img = document.images[imgName]
		defaultSrc = cachedImages[imgName][0].src
		img.src = defaultSrc
	}
	return true
}

// sample onload handler
function initPage () {
	imagesCached = preloadImages()
	if ( document.layers && (document.layers.length > 0) )
		NS_flattenImages();
}