function set_active_class(obj, store_target) {
	
	if (!store_target.prev_el)
	{
		store_target.prev_el = obj;
		for (var i=0; i<=store_target.getElementsByTagName('a').length-1; i++) {
			store_target.getElementsByTagName('a')[i].className = "";
		}
		
		
	} else {
		store_target.prev_el.className = '';
		store_target.prev_el = obj;
	}

	obj.className += "active";
	
	return false;
}

function get_slideshow_active_el(obj) {
	
	for (var i=0; i<=obj.getElementsByTagName('a').length-1; i++) {
		if (obj.getElementsByTagName('a')[i].className == "active") {
			return i;
		}
	}
	
	return false;
}

function hideShowImageOpacity(id, obj, millisec) { 
	
    //speed for each frame 
    var speed = Math.round(millisec / 100); 
    var timer = 0; 
	var opacStart = 100;
	var opacEnd = 0;
    
    for(i = opacStart; i >= opacEnd; i--) { 
        setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed)); 
        timer++; 
    }

    setTimeout(function(){document.getElementById(id).src = obj.target;}, millisec);
    
    for(i = opacEnd; i <= opacStart; i++) { 
        setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed)); 
        timer++; 
    }

    return false;
    
}

//change the opacity for different browsers 
function changeOpac(opacity, id) { 
    var object = document.getElementById(id).style; 
    object.opacity = (opacity / 100); 
    object.filter = "alpha(opacity=" + opacity + ")"; 
}

function showStartImagesAuto() {
	if (document.getElementById('slideshow_box')) {
		autoSlideShow = setInterval ("showStartImages()", 5000);
	}
}

function showStartImages () {

	var cur_selected_image = get_slideshow_active_el(document.getElementById('slideshow_box'));
	var counter = cur_selected_image;
	counter++;
		if (counter == document.getElementById('slideshow_box').getElementsByTagName('a').length) {
		counter = 0;
	}

	object = document.getElementById('slideshow_box').getElementsByTagName('a')[counter];
	hideShowImageOpacity('target_image', object, 500); 
	set_active_class(object, object.parentNode);

}