var agent = navigator.userAgent.toLowerCase();	
var ff = agent.indexOf("firefox") != -1?1:0;

function ShowPreviousImage()
{
    current_slide--;		        
    if (current_slide < 1)
    {
        current_slide = number_of_slides;
    }                
    
    SetImage();
    SetSlideNumber();                
}

function ShowNextImage()
{
    current_slide++;		        
    if (current_slide > number_of_slides)
    {
        current_slide = 1;
    }
    
    SetImage();	            
    SetSlideNumber();
}

function ShowNavigation(fade)
{   
    if (fade)
    {
        if (opacity < max_opacity)
        {
            opacity = opacity + inc_opacity;
            SetOpacity(opacity);                        
            SetSlideNumber();                        
            var timer = setTimeout('ShowNavigation()', timeout);
        }
        else
        {
            clearTimeout(timer);
        }
    }
    else
    {
        opacity = max_opacity;
        SetOpacity(opacity);                    
        SetSlideNumber();
    }                
}

function HideNavigation(fade)
{
    if (fade)
    {
        if (opacity > min_opacity)
        {
            opacity = opacity - inc_opacity;	
            SetOpacity(opacity);
            var timer = setTimeout('HideNavigation()', timeout);
        }
        else
        {
            clearTimeout(timer);
        }
    }
    else
    {
        opacity = min_opacity;
        SetOpacity(opacity);
    }
}

function SetSlideNumber()
{
    document.getElementById('slide_number').innerHTML = 'Slide: ' + current_slide + ' of ' + number_of_slides;
}

function SetImage()
{
    document.getElementById('slide_image').innerHTML = '<img src="' + image_loc + prefix + current_slide + '.jpg" />';
} 

function SetOpacity(opacity)
{
    if (ff)
    {
        document.getElementById('slide_prev').style.MozOpacity = '.' + opacity;
        document.getElementById('slide_next').style.MozOpacity = '.' + opacity;
        document.getElementById('slide_number').style.MozOpacity = '.' + opacity;		    
    }
    else
    {
        document.getElementById('slide_prev').style.filter = 'alpha(opacity=' + opacity + ')';
        document.getElementById('slide_next').style.filter = 'alpha(opacity=' + opacity + ')';
        document.getElementById('slide_number').style.filter = 'alpha(opacity=' + opacity + ')';		    
    }
}