// IXF1.11 :: Image cross-fade 
// *****************************************************
// DOM scripting by brothercake -- http://www.brothercake.com/
//******************************************************
//global object
var ixf = { 'clock' : null, 'count' : 1 }
ixf.antBoton = null;

//crossfade setup function
function crossfade() {
    //if the timer is not already going
    if(ixf.clock == null) {
        //copy the image object 
        //alert("he recibido el id " + arguments[0]);
        ixf.obj = document.getElementById(arguments[0]);
        
        //copy the image src argument 
        ixf.src = document.getElementById(arguments[1]).src;
        
        //store the supported form of opacity
        if(typeof ixf.obj.style.opacity != 'undefined') {
            ixf.type = 'w3c';
        }
        else if(typeof ixf.obj.style.MozOpacity != 'undefined') {
            ixf.type = 'moz';
        }
        else if(typeof ixf.obj.style.KhtmlOpacity != 'undefined') {
            ixf.type = 'khtml';
        }
        else if(typeof ixf.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
            ixf.type = (ixf.obj.filters.length > 0 && typeof ixf.obj.filters.alpha == 'object' && typeof ixf.obj.filters.alpha.opacity == 'number') ? 'ie' : 'none';
        }
        else {
            ixf.type = 'none';
        }
        
        //change the image alt text if defined
        ixf.obj.alt = document.getElementById(arguments[1]).alt;
        
        //if any kind of opacity is supported
        if(ixf.type != 'none') {
            //create a new image object and append it to body
            //detecting support for namespaced element creation, in case we're in the XML DOM
            ixf.newimg = document.getElementsByTagName('body')[0].appendChild((typeof document.createElementNS != 'undefined') ? document.createElementNS('http://www.w3.org/1999/xhtml', 'img') : document.createElement('img'));
            
            //set positioning classname
            ixf.newimg.className = 'idupe';
            
            //set src to new image src
            ixf.newimg.src = ixf.src
            
            //move it to superimpose original image
            ixf.newimg.style.left = ixf.getRealPosition(ixf.obj, 'x') + 'px';
            ixf.newimg.style.top = ixf.getRealPosition(ixf.obj, 'y') + 'px';
            
            //copy and convert fade duration argument 
            // para mas rapidez cambio 1000 por 100 y pruebo
            ixf.length = parseInt(arguments[2], 10) * 100;
            
            //create fade resolution argument as 20 steps per transition
            // lo cambio a 5 para que vaya mas rápido
            ixf.resolution = parseInt(arguments[2], 10) * 2;
            
            //start the timer
            ixf.clock = setInterval('ixf.crossfade()', ixf.length/ixf.resolution);
        }
        
        //otherwise if opacity is not supported
        else {
            //just do the image swap
            ixf.obj.src = ixf.src;
        }
        
    }
    
    // cambiamos el boton
    if(typeof arguments[3] != 'undefined' && arguments[3] != '') {
        if (ixf.antBoton == null) {
            ixf.antBoton = document.getElementById(arguments[4]);
        }
        ixf.antBoton.className = "foto_numero";
        ixf.antBoton = arguments[3];
        ixf.antBoton.className = "foto_numero_seleccionado";
    }
};


//crossfade timer function
ixf.crossfade = function() {
    //decrease the counter on a linear scale
    ixf.count -= (1 / ixf.resolution);
    
    //if the counter has reached the bottom
    if(ixf.count < (1 / ixf.resolution)) {
        //clear the timer
        clearInterval(ixf.clock);
        ixf.clock = null;
        
        //reset the counter
        ixf.count = 1;
        
        //set the original image to the src of the new image
        ixf.obj.src = ixf.src;
    }
    
    //set new opacity value on both elements
    //using whatever method is supported
    switch(ixf.type) {
        case 'ie' :
            ixf.obj.filters.alpha.opacity = ixf.count * 100;
            ixf.newimg.filters.alpha.opacity = (1 - ixf.count) * 100;
            break;
            
        case 'khtml' :
            ixf.obj.style.KhtmlOpacity = ixf.count;
            ixf.newimg.style.KhtmlOpacity = (1 - ixf.count);
            break;
            
        case 'moz' : 
            //restrict max opacity to prevent a visual popping effect in firefox
            ixf.obj.style.MozOpacity = (ixf.count == 1 ? 0.9999999 : ixf.count);
            ixf.newimg.style.MozOpacity = (1 - ixf.count);
            break;
            
        default : 
            //restrict max opacity to prevent a visual popping effect in firefox
            ixf.obj.style.opacity = (ixf.count == 1 ? 0.9999999 : ixf.count);
            ixf.newimg.style.opacity = (1 - ixf.count);
    }
    
    //now that we've gone through one fade iteration 
    //we can show the image that's fading in
    ixf.newimg.style.visibility = 'visible';
    
    //keep new image in position with original image
    //in case text size changes mid transition or something
    ixf.newimg.style.left = ixf.getRealPosition(ixf.obj, 'x') + 'px';
    ixf.newimg.style.top = ixf.getRealPosition(ixf.obj, 'y') + 'px';
        
    //if the counter is at the top, which is just after the timer has finished
    if(ixf.count == 1) {
        //remove the duplicate image
        ixf.newimg.parentNode.removeChild(ixf.newimg);
    }
};



//get real position method
ixf.getRealPosition = function() {
    this.pos = (arguments[1] == 'x') ? arguments[0].offsetLeft : arguments[0].offsetTop;
    this.tmp = arguments[0].offsetParent;
    while(this.tmp != null) {
        this.pos += (arguments[1] == 'x') ? this.tmp.offsetLeft : this.tmp.offsetTop;
        this.tmp = this.tmp.offsetParent;
    }
    
    return this.pos;
};