// ISF1.11 :: Image swap-fade 
// *****************************************************
// DOM scripting by brothercake -- http://www.brothercake.com/
//******************************************************
//global object
var isf = { 'clock' : null, 'fade' : true, 'count' : 1 }
/*******************************************************



/*****************************************************************************
 List the images that need to be cached
*****************************************************************************/

isf.imgs = [
	'buttons/udm4-whitebutton88x31.gif',
	'buttons/udm4-greenbutton88x31.gif',
	'buttons/udm4-purplebutton88x31.gif'
	];

/*****************************************************************************
*****************************************************************************/



//cache the images
isf.imgsLen = isf.imgs.length;
isf.cache = [];
for(var i=0; i<isf.imgsLen; i++)
{
	isf.cache[i] = new Image;
	isf.cache[i].src = isf.imgs[i];
}


//swapfade setup function
function swapfade()
{
	//if the timer is not already going
	if(isf.clock == null)
	{
		//copy the image object 
		isf.obj = arguments[0];
		
		//copy the image src argument 
		isf.src = arguments[1];
		
		//store the supported form of opacity
		if(typeof isf.obj.style.opacity != 'undefined')
		{
			isf.type = 'w3c';
		}
		else if(typeof isf.obj.style.MozOpacity != 'undefined')
		{
			isf.type = 'moz';
		}
		else if(typeof isf.obj.style.KhtmlOpacity != 'undefined')
		{
			isf.type = 'khtml';
		}
		else if(typeof isf.obj.filters == 'object')
		{
			//weed out win/ie5.0 by testing the length of the filters collection (where filters is an object with no data)
			//then weed out mac/ie5 by testing first the existence of the alpha object (to prevent errors in win/ie5.0)
			//then the returned value type, which should be a number, but in mac/ie5 is an empty string
			isf.type = (isf.obj.filters.length > 0 && typeof isf.obj.filters.alpha == 'object' && typeof isf.obj.filters.alpha.opacity == 'number') ? 'ie' : 'none';
		}
		else
		{
			isf.type = 'none';
		}
		
		//change the image alt text if defined
		if(typeof arguments[3] != 'undefined' && arguments[3] != '')
		{
			isf.obj.alt = arguments[3];
		}
		
		//if any kind of opacity is supported
		if(isf.type != 'none')
		{
			//copy and convert fade duration argument 
			//the duration specifies the whole transition
			//but the swapfade is two distinct transitions
			isf.length = parseInt(arguments[2], 10) * 500;
			
			//create fade resolution argument as 20 steps per transition
			//again, split for the two distrinct transitions
			isf.resolution = parseInt(arguments[2], 10) * 10;
			
			//start the timer
			isf.clock = setInterval('isf.swapfade()', isf.length/isf.resolution);
		}
		
		//otherwise if opacity is not supported
		else
		{
			//just do the image swap
			isf.obj.src = isf.src;
		}
		
	}
};


//swapfade timer function
isf.swapfade = function()
{
	//increase or reduce the counter on an exponential scale
	isf.count = (isf.fade) ? isf.count * 0.9 : (isf.count * (1/0.9)); 
	
	//if the counter has reached the bottom
	if(isf.count < (1 / isf.resolution))
	{
		//clear the timer
		clearInterval(isf.clock);
		isf.clock = null;

		//do the image swap
		isf.obj.src = isf.src;

		//reverse the fade direction flag
		isf.fade = false;
		
		//restart the timer
		isf.clock = setInterval('isf.swapfade()', isf.length/isf.resolution);

	}
	
	//if the counter has reached the top
	if(isf.count > (1 - (1 / isf.resolution)))
	{
		//clear the timer
		clearInterval(isf.clock);
		isf.clock = null;

		//reset the fade direction flag
		isf.fade = true;
		
		//reset the counter
		isf.count = 1;
	}

	//set new opacity value on element
	//using whatever method is supported
	switch(isf.type)
	{
		case 'ie' :
			isf.obj.filters.alpha.opacity = isf.count * 100;
			break;
			
		case 'khtml' :
			isf.obj.style.KhtmlOpacity = isf.count;
			break;
			
		case 'moz' : 
			//restrict max opacity to prevent a visual popping effect in firefox
			isf.obj.style.MozOpacity = (isf.count == 1 ? 0.9999999 : isf.count);
			break;
			
		default : 
			//restrict max opacity to prevent a visual popping effect in firefox
			isf.obj.style.opacity = (isf.count == 1 ? 0.9999999 : isf.count);
	}
};



dw_Rotator.restartDelay = 500; // delay onmouseout before call to rotate
dw_Rotator.col = []; 

// arguments: image name, rotation speed, path to images (optional), 
// target, i.e. name of window to direct url's to onclick (optional)
function dw_Rotator(name, speed, path, tgt) {
    this.name = name; this.speed = speed || 4500; // default speed of rotation
    this.path = path || ""; this.tgt = tgt;
    this.ctr = 0; this.timer = 0; this.imgs = []; this.actions = [];
    this.index = dw_Rotator.col.length; dw_Rotator.col[this.index] = this;
    this.animString = "dw_Rotator.col[" + this.index + "]";
}

dw_Rotator.prototype.addImages = function() { // preloads images
    var img;
    for (var i=0; arguments[i]; i++) {
        img = new Image();
        img.src = this.path + arguments[i];
        this.imgs[this.imgs.length] = img;
    }
}

dw_Rotator.prototype.addActions = function() {
    var len = arguments.length; // in case an argument's value is null
    for (var i=0; i < len; i++) 
        this.actions[this.actions.length] = arguments[i]; 
}

dw_Rotator.prototype.rotate = function() {
    clearTimeout(this.timer); this.timer = null;
    if (this.ctr < this.imgs.length-1) this.ctr++;
    else this.ctr = 0;
    var imgObj = document.images[this.name];    
    if (imgObj) {
		<!-- define swapfade (image-object, 'new src', 'seconds'[, 'new alt text']) -->
        swapfade(imgObj, this.imgs[this.ctr].src, '1');
		<!--         imgObj.src = this.imgs[this.ctr].src; -->
        this.timer = setTimeout( this.animString + ".rotate()", this.speed);
    }
}

// Start rotation for all instances 
dw_Rotator.start = function() {
    var len = dw_Rotator.col.length, obj;
    for (var i=0; i<len; i++) {
        obj = dw_Rotator.col[i];
        if (obj && obj.name ) // check for empty instance created by dw_random.js
            obj.timer = setTimeout( obj.animString + ".rotate()", obj.speed);
    }
}

// called onclick of images
dw_Rotator.doClick = function(n) {
    var obj = dw_Rotator.col[n]; 
	if ( !document.images || !obj ) return true;
    if ( obj.actions && obj.actions[obj.ctr] ) {
        if ( typeof obj.actions[obj.ctr] == "string" ) { // url
            if ( obj.tgt ) { // open in separate window
                // add features here if you want, i.e., chrome, size, position, ...
                var win = window.open(obj.actions[obj.ctr], obj.tgt);
                if ( win && !win.closed ) win.focus();
            } else {
                window.location = obj.actions[obj.ctr];
            }
        } else { // function pointer 
            obj.actions[obj.ctr](); // execute function
        }
    }
    return false;
}

// for stopping/starting onmouseover/out
dw_Rotator.pause = function(n) {	
    dw_Rotator.clearTimers(n);
}

dw_Rotator.clearTimers = function(n) {
    var obj = dw_Rotator.col[n]; 
    if ( obj ) {
        clearTimeout( obj.timer ); obj.timer = null;
    }
}

dw_Rotator.resume = function(n) {
    dw_Rotator.clearTimers(n);
    var obj = dw_Rotator.col[n]; 
    if ( obj ) {
        obj.timer = setTimeout( obj.animString + ".rotate()", dw_Rotator.restartDelay );
    }
}