var counter=0;

function image_instance(width, height, name, type, content, tooltip) 
{ 
   this.width = width;
   this.height = height; 
   this.name = name;
   this.type = type;
   this.content = content;
   this.tooltip = tooltip;
} 

function image_load(id) 
{
   var image_detail = document.getElementById('image_detail');
   var image_frame = document.getElementById('image_frame');
   var link_previous = document.getElementById('link_previous');
   var link_next = document.getElementById('link_next');
   var image_content = document.getElementById('image_content');

   if (image.length > 0) 
   {
      counter = id;
      image_frame.src = 
         image_path 
         + image[id].name 
         + ' ('
         + image[id].width
         + ' x '
         + image[id].height
         + ' px).' 
         + image[id].type;
      image_frame.alt = image[id].tooltip;
      image_frame.title = image[id].tooltip;
      image_frame.onload = function() { protect_images(); }

      image_content.innerHTML = image[id].content;   
               
      if (id == 0 && document.getElementById('link_previous')) {
          link_previous.style.visibility = 'hidden';
      } else if (id !=0 && document.getElementById('link_previous')) { 
         link_previous.style.visibility = 'visible';
      }

      if (id == (image.length-1) && document.getElementById('link_next')) {
         link_next.style.visibility= 'hidden';
      } else if (id != (image.length-1) && document.getElementById('link_next')) {
         link_next.style.visibility = 'visible';
      }
   } else {
      image_detail.style.display = 'none';
   }
}

function image_previous() 
{
   counter--;
   image_load(counter);
   return false;
}

function image_next() 
{
   counter++;
   image_load(counter);
   return false;
}

function image_detail_initialize()
{
   var image_detail = document.getElementById('image_detail');
   var image_navigation = document.getElementById('image_navigation');
   var link_previous = document.getElementById('link_previous');
   
   if (image_navigation) 
   {
      image_navigation.style.visibility = 'visible';
   }
   
   if (counter == 0 && link_previous) 
   {
      link_previous.style.visibility = 'hidden'
   }

   if (image.length == 1) 
   {
      link_next.style.visibility = 'hidden'
   }
}