function mouseX(evt) {
        evt = evt || window.event;
if (evt.pageX) return evt.pageX;
else if (evt.clientX)
   return evt.clientX + (document.documentElement.scrollLeft ?
   document.documentElement.scrollLeft :
   document.body.scrollLeft);
else return null;


}
function mouseY(evt) {
    evt = evt || window.event;
if (evt.pageY) return evt.pageY;
else if (evt.clientY)
   return evt.clientY + (document.documentElement.scrollTop ?
   document.documentElement.scrollTop :
   document.body.scrollTop);
else return null;
}

var xVal;
var yVal;

function photoNav(evt)
{
    var thisx = mouseX(evt);
    var thisy = mouseY(evt);
    
    //document.getElementById('tracker').innerHTML = thisx + " " + thisy;
    var photo = document.getElementById('mainphoto');
    var photodiv = document.getElementById('mainphotodiv');
    xVal = thisx - photodiv.offsetLeft;
    yVal = thisy - photodiv.offsetTop;
    
    
    
    //width = photo.offsetRight - photo.offsetLeft;
    
    if (xVal > 0 && xVal < photo.width/2 && (yVal > 0 && yVal < photo.height))
    {
        //document.getElementById('tracker').innerHTML = "Prev " + photo.width;
    }
    else if (xVal > 0 && xVal > photo.width/2 && xVal < photo.width && (yVal > 0 && yVal < photo.height))
    {
        //document.getElementById('tracker').innerHTML = "Next";
    }
    else
    {
        //document.getElementById('tracker').innerHTML = "";
    }
}

function photoNavLocation(nextID, prevID)
{
    var photo = document.getElementById('mainphoto');
    
   
    if (xVal > 0 && xVal < photo.width/2 && (yVal > 0 && yVal < photo.height))
    {
        if (prevID == 0)
        {
            document.location.href = "/";
        }
        else
        {
            document.location.href = "?viewBlog=" + prevID;    
        }
        
    }
    else if (xVal > 0 && xVal > photo.width/2 && xVal < photo.width && (yVal > 0 && yVal < photo.height))
    {
        if (nextID == 0)
        {
            document.location.href = "/";
        }
        else
        {
            document.location.href = "?viewBlog=" + nextID;    
        }
    }
}

document.onmousemove = photoNav;