//<script language="JavaScript" type="text/JavaScript">

// Routines to randomly change an Image on a Web page.

// Created by Francis E Bauer  9/19/2004



  var NumImages = 6;            // Actual number of Images in Random Image directory.

  

  var ImageDir = "randomimg"; // Random Image directory.

  var FileMask = "image_";       // Image filename prefex.

  var FileType = ".jpg";         // Image filename suffix.

  var FieldName = "ShowImage";   // Image field name on Web page.

  var PrevImgPtr = 0;            // Previous Image presented.

  var ImageUpdateID = null;      // Image interval ID.



  function ImagePtr () { // Return an integer between 1 and NumImages

    return Math.round ( 1 + Math.random() * ( NumImages - 1 ) );

  }



  function RandomImage() { // Change "FieldName" image at random.

    var ImgPtr = ImagePtr();

    while ( PrevImgPtr == ImgPtr ) // If previous "image" is the same, get new "image"

	  ImgPtr = ImagePtr();

    document.images[FieldName].src = ImageDir + "/" + FileMask + ImgPtr + FileType;

    PrevImgPtr = ImgPtr;

  }

  

  function ShowRandom () { // Start random image presentation every n seconds.

    var RandomInterval = 2000;  // 2 seconds (2000 ms)

    if ( ImageUpdateID == null )

	  ImageUpdateID = setInterval("RandomImage()",RandomInterval);

  }

  

  function StopRandom() { // Stop random image presentation.

    if ( ImageUpdateID != null ) {

	  clearInterval(ImageUpdateID);

	  ImageUpdateID = null;

	}

  }

//</script>// JavaScript Document