/*******************************************************************
* File    : JSFX_ImageFadeSwap.js  © JavaScript-FX.com
* Created : 2001/08/31
* Author  : Roy Whittle  (Roy@Whittle.com) www.Roy.Whittle.com
* Purpose : To create a more dynamic image swap using opacity
* History
* Date         Version        Description
* 2001-08-09	1.0		First version
* 2001-08-31	1.1		Got it working with NS6 - You must use opaque
*					GIF's and use a STYLE attrib in the main
*					HTML Page - Thanks Owl.
* 2001-08-31	1.2		Added different FadIn/FadeOut and converted
*					all vars to JSFX name space.
* 2001-09-01	1.3		Make it so you only need one onMouseOver
*					onMouseOut in the main document.
* 2001-09-09	1.4		Allow you to do a "Swap Other Image" so
*					you can swap the same image with different pictures.
* 2001-09-17	1.5		Create the pre-loading object - just like
*					simple rollovers and animated rollovers.
*					allows for a similar interface to all.
* 2001-09-18	1.6		The code contains so much of SimpleRollovers that
*					I added imgOn and imgOff so you can mix rollovers
*					without having to include 2 ".js" files.
* 2002-02-08	1.7		If the ON image is already loaded don't reload it.
*					This should help with the IE bug that reloads images
*					from the server even though they are pre-cached.
*					(will not work for swapping multiple pictures into same Image object)
* 2002-02-13	1.8		Corrected a bug in JSFX.findImg
* 2002-04-23	1.9		Write out the style tag.
* 2002-06-09	1.10		Attempt fix for IE on a Mac
* 2002-08-27	1.11		Fix a bug whereby opacity may go over 100 which
*					may be causing a bug in IE6
* 2002-08-29	1.12		Thanks to piglet (http://homepage.ntlworld.com/thepiglet/)
*					I now have a partial fix for NS7 and Mozilla 1.1.
***********************************************************************/
/****** User may alter these to change the fade effect ********/
var FadeInStep 	= 20;
var FadeOutStep 	= 20;
/****** Don't alter anything else **************/
document.write('<STYLE TYPE="text/css">.imgFader{ position:relative; filter:alpha(opacity=0); -moz-opacity:0.0 }</STYLE>');

if(!window.JSFX)
JSFX=new Object();

JSFX.RolloverObjects=new Array();

JSFX.Rollover = function(name, img)
{
JSFX.RolloverObjects[name]=new Image();
JSFX.RolloverObjects[name].img_src = img;
if(!JSFX.Rollover.postLoad)
JSFX.RolloverObjects[name].src = img;
}
JSFX.Rollover.postLoad = false;
JSFX.Rollover.loadImages = function()
{
var i;
for(i in JSFX.RolloverObjects)
{
r=JSFX.RolloverObjects[i];
r.src=r.img_src;
}
}
JSFX.Rollover.error = function(n)
{
alert("JSFX.Rollover - An Error has been detected\n"
+ "----------------------------------\n"
+ "You must define a JSFX.Rollover in your document\n"
+ "JSFX.Rollover(\""+n+"\",\"your_on_img.gif\")\n"
+ "(check the spelling of your JSFX.Rollovers)");
}
/*******************************************************************
*
* Function    : getImg
*
* Description : In Netscape 4 images could be in layers so we might
*		    have to recurse the layers to find the image
*
*****************************************************************/
JSFX.getImg = function(n, d)
{
var img = d.images[n];
if(!img && d.layers)
for(var i=0 ; !img && i<d.layers.length ; i++)
img=JSFX.getImg(n,d.layers[i].document);
return img;
}
/*******************************************************************
*
* Function    : findImg
*
* Description : gets the image from the document and reports an
*		    error if it cannot find it.
*
*****************************************************************/
JSFX.findImg = function(n, d)
{
var img = JSFX.getImg(n, d);

/*** Stop emails because the image was named incorrectly ***/
if(!img)
{
alert("JSFX.findImg - An Error has been detected\n"
+ "----------------------------------\n"
+ "You must define an image in your document\n"
+ "<IMG SRC=\"your_image.ext\" NAME=\""+n+"\">\n"
+ "(check the NAME= attribute of your images)");

return(new Image());
}
return img;
}

JSFX.ImageFadeRunning=false;
JSFX.ImageFadeInterval=30;

/*******************************************************************
*
* Function    : imgFadeIn
*
* Description : This function is based on the turn_on() function
*		      of animate2.js (animated rollovers from www.roy.whittle.com).
*		      Each image object is given a state.
*			OnMouseOver the state is switched depending on the current state.
*			Current state -> Switch to
*			===========================
*			null		->	OFF.
*			OFF		->	FADE_IN
*			FADE_OUT	->	FADE_IN
*			FADE_OUT	->	FADE_OUT_IN (if the new image is different)
*			FADE_IN_OUT->	FADE_IN (if the image is the same)
*****************************************************************/
JSFX.imgFadeIn = function(img, imgSrc)
{
if(img)
{
if(img.state == null)
{
img.state = "OFF";
img.index = 0;
img.next_on    = null;
}

if(img.state == "OFF")
{
/*** Vers 1.7 only load the ON image once ever ***/
if(img.src.indexOf(imgSrc) == -1)
img.src=imgSrc;

img.currSrc = imgSrc;
img.state = "FADE_IN";
JSFX.startFading();
}
else if( img.state == "FADE_IN_OUT"
|| img.state == "FADE_OUT_IN"
|| img.state == "FADE_OUT")
{
if(img.currSrc == imgSrc)
img.state = "FADE_IN";
else
{

img.next_on = imgSrc;
img.state="FADE_OUT_IN";
}
}
}
}
/*******************************************************************
*
* Function    : imgFadeOut
*
* Description : This function is based on the turn_off function
*		      of animate2.js (animated rollovers from www.roy.whittle.com).
*		      Each image object is given a state.
*			OnMouseOut the state is switched depending on the current state.
*			Current state -> Switch to
*			===========================
*			ON		->	FADE_OUT.
*			FADE_IN	->	FADE_IN_OUT.
*			FADE_OUT_IN	->	FADE_IN. (after swapping to the next image)
*****************************************************************/
JSFX.imgFadeOut = function(img)
{
if(img)
{
if(img.state=="ON")
{
img.state="FADE_OUT";
JSFX.startFading();
}
else if(img.state == "FADE_IN")
{
img.state="FADE_IN_OUT";
}
else if(img.state=="FADE_OUT_IN")
{
img.next_on == null;
img.state = "FADE_OUT";
}
}
}
/*******************************************************************
*
* Function    : startFading
*
* Description : This function is based on the start_animating() function
*	        	of animate2.js (animated rollovers from www.roy.whittle.com).
*			If the timer is not currently running, it is started.
*			Only 1 timer is used for all objects
*****************************************************************/
JSFX.startFading = function()
{
if(!JSFX.ImageFadeRunning)
JSFX.ImageFadeAnimation();
}

/*******************************************************************
*
* Function    : ImageFadeAnimation
*
* Description : This function is based on the Animate function
*		    of animate2.js (animated rollovers from www.roy.whittle.com).
*		    Each image object has a state. This function
*		    modifies each object and (possibly) changes its state.
*****************************************************************/
JSFX.ImageFadeAnimation = function()
{
JSFX.ImageFadeRunning = false;
for(i=0 ; i<document.images.length ; i++)
{
var img = document.images[i];
if(img.state)
{
if(img.state == "FADE_IN")
{
img.index+=FadeInStep;

if(img.index > 100)
img.index = 100;

if(img.filters)
img.filters.alpha.opacity = img.index;
else
img.style.MozOpacity = img.index/101;

if(img.index == 100)
img.state="ON";
else
JSFX.ImageFadeRunning = true;
}
else if(img.state == "FADE_IN_OUT")
{
img.index+=FadeInStep;
if(img.index > 100)
img.index = 100;

if(img.filters)
img.filters.alpha.opacity = img.index;
else
img.style.MozOpacity = img.index/101;


if(img.index == 100)
img.state="FADE_OUT";

JSFX.ImageFadeRunning = true;
}
else if(img.state == "FADE_OUT")
{
img.index-=FadeOutStep;
if(img.index < 0)
img.index = 0;

if(img.filters)
img.filters.alpha.opacity = img.index;
else
img.style.MozOpacity = img.index/101;


if(img.index == 0)
img.state="OFF";
else
JSFX.ImageFadeRunning = true;
}
else if(img.state == "FADE_OUT_IN")
{
img.index-=FadeOutStep;
if(img.index < 0)
img.index = 0;

if(img.filters)
img.filters.alpha.opacity = img.index;
else
img.style.MozOpacity = img.index/101;

if(img.index == 0)
{
img.src = img.next_on;
img.currSrc = img.next_on;
img.state="FADE_IN";
}
JSFX.ImageFadeRunning = true;
}
}
}
/*** Check to see if we need to animate any more frames. ***/
if(JSFX.ImageFadeRunning)
setTimeout("JSFX.ImageFadeAnimation()", JSFX.ImageFadeInterval);
}
/*******************************************************************
*
* Function    : hasOpacity
*
* Description : Tests if the browser allows Opacity
*
*****************************************************************/
JSFX.hasOpacity = function(obj)
{
if(document.layers)
return false;

if(window.opera)
return false;

if(navigator.userAgent.toLowerCase().indexOf("mac") != -1)
return false;

return true;
}
/*******************************************************************
*
* Function    : fadeIn /fadeOut
*
* Description : Detects browser that can do opacity and fades the images
*		    For browsers that do not support opacity it just does an image swap.
*		    (I only know about NS4 but maybe IE on a Mac also ?)
*		    For these functions to work you need to name the image
*			e.g. for an image named "home" you need
*			<IMG .... NAME="home">
*		    and you need 2 images, the on and the off image
*****************************************************************/
JSFX.fadeIn = function(imgName, rollName)
{
if(rollName == null)
rollName=imgName;

/*** Stop emails because the rollover was named incorrectly ***/
if(!JSFX.RolloverObjects[rollName])
{
JSFX.Rollover.error(rollName);
return;
}

var img = JSFX.findImg(imgName, document);
if(JSFX.hasOpacity(img))
JSFX.imgFadeIn(img, JSFX.RolloverObjects[rollName].img_src);
else
{
if(img.offSrc==null)
img.offSrc=img.src;
img.src=JSFX.RolloverObjects[rollName].img_src;
}
}
JSFX.fadeOut = function(imgName)
{
var img = JSFX.findImg(imgName, document);
if(JSFX.hasOpacity(img))
JSFX.imgFadeOut(img);
else
img.src=img.offSrc;
}
/*******************************************************************
*
* Function    : imgOn /imgOff
*
* Description : Included these functions so you can mix simple and
*		    fading rollovers without having to include 2 ".js" files
*
*****************************************************************/
JSFX.imgOn = function(imgName, rollName)
{
if(rollName == null)
rollName=imgName;

/*** Stop emails because the rollover was named incorrectly ***/
if(!JSFX.RolloverObjects[rollName])
{
JSFX.Rollover.error(rollName);
return;
}
var img = JSFX.findImg(imgName,document);
if(img.offSrc==null)
img.offSrc=img.src;
img.src=JSFX.RolloverObjects[rollName].img_src;
}
JSFX.imgOff = function(imgName)
{
var img = JSFX.findImg(imgName,document);
img.src=img.offSrc;
}