/******************************************************************* 
* 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=60;

/*******************************************************************
*
* 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;
}