var titles = new Array();
var photos_min_index = 0;
var current_image;

function GetParameterFromUrl(name) {
   var url = window.location.href;
   var paramsStart = url.indexOf("?");
   if(paramsStart != -1){
      var paramString = url.substr(paramsStart + 1);
      var tokenStart = paramString.indexOf(name);
      if(tokenStart != -1){
         paramToEnd = paramString.substr(tokenStart + name.length + 1);
         var delimiterPos = paramToEnd.indexOf("&");
         if(delimiterPos == -1){
            return paramToEnd;
         }
         else {
            return paramToEnd.substr(0, delimiterPos);
         }
      }
   }
   else
     return -1;
};

function show_start_image(){
  var image_index = GetParameterFromUrl("image");
  if (image_index == -1) {image_index = 0;};
  imgchange(image_index);	 
};

function imgchange(index)
{
  if (index < 0){
    if (index == -1)
	{ 
	  if (current_image > photos_min_index) 
        current_image = current_image - 1;
	  else
	    current_image = photos_max_index;
	}		
    else if (index == -2)
	{
	  if (current_image < photos_max_index)	
        current_image = current_image + 1;
	  else	
	    current_image = photos_min_index;
	}	
  }
  else
    current_image = index;
  document.mainform.img.src     = current_image + ".jpg";
  document.mainform.title.value = titles[current_image];
};