function showFirstTime ()
	{
		document.getElementById("loading").style.display = "block";

		document.getElementById("result_image").src =  "images/example_cover.png";
	}
	
	function hideLoading ()
	{
  	document.getElementById("loading").style.display = "none";
  	document.getElementById("show_image").style.display = "block";
	} 
	
	//show bar code
	function showBookCover ()
	{
		
		var cover_color = document.upload_form.cover_color.value;
		var top_title = document.upload_form.top_title.value;
		var main_title = document.upload_form.main_title.value;
		var main_size = document.upload_form.main_size.value;
		var bottom_title = document.upload_form.bottom_title.value;
		var cover_image = document.upload_form.cover_image.value;
		var publisher_title = document.upload_form.publisher_title.value;
		var author_title = document.upload_form.author_title.value;
		
		var parameter = "cover_color=" + escape (cover_color);
				parameter += "&top_title=" + escape (top_title);
				parameter += "&main_title=" + escape (main_title);
				parameter += "&main_size=" + escape (main_size);
				parameter += "&bottom_title=" + escape (bottom_title);
				parameter += "&cover_image=" + escape (cover_image);
				parameter += "&publisher_title=" + escape (publisher_title);
				parameter += "&author_title=" + escape (author_title);
				parameter += "&temp=" + escape (temp);
				parameter += "&rand=" + escape (Math.floor(Math.random()*1000));
		
		document.getElementById("loading").style.display = "block";

		document.getElementById("result_image").src =  "cover.show.php?" + parameter;
	}
	
	
	function disableForm ()
	{

	}
	
	//check form
	function checkForm ()
	{

		if (document.upload_form.cover_color.value == "")
		{
			alert ("Please select color first!");
			document.upload_form.cover_color.focus ();
			return false;
		}
		
		if (document.upload_form.top_title.value == "")
		{
			alert ("Please fill top title!");
			document.upload_form.top_title.focus ();
			return false;
		}
		
		if (document.upload_form.main_title.value == "")
		{
			alert ("Please fill main title!");
			document.upload_form.main_title.focus ();
			return false;
		}
		
		if (document.upload_form.main_size.value == "")
		{
			alert ("Please fill main size!");
			document.upload_form.main_size.focus ();
			return false;
		}
		
		if (isNaN (document.upload_form.main_size.value))
		{
			alert ("Number only please!");
			document.upload_form.main_size.focus ();
			return false;
		}
		
		showBookCover ();
		
		return false;
		
	}