/**
 * NAVIGATOR.JS - NAVIGATE USING A <SELECT> ELEMENT IN AN IFRAME
 *
 * Author: Thomas Knierim
 * Contact: webmaster@thebigview.com
 * Implemented: 18-May-2006
 *
 * All Rights Reserved.
 * Unauthorized use, duplication and distribution prohibited.
 */

// synchronise the <SELECT> index with the page being viewed
function set_index() {
  chapters = document.getElementById("chapters");
  page = parent.location.href;
  page = page.substring(page.lastIndexOf('/') + 1);
  for (i = 0; i < chapters.length; i++) {
    if (chapters.options[i].value == page) {
      chapters.selectedIndex = i;
      break;
    }
    chapters.selectedIndex = 1; // default
  }
}
// load a new page according to selected <SELECT> option
function show_chapter() {
  chapters = document.getElementById("chapters");
  selected_item = chapters.selectedIndex;
  page = chapters.options[selected_item].value;
  parent.location.href = page;
}
// switch to next page
function next_page() {
  chapters = document.getElementById("chapters");
  selected_item = chapters.selectedIndex;
  if (selected_item + 1 < chapters.length) {
//    chapters.selectedIndex = selected_item + 1;
    page = chapters.options[selected_item + 1].value;
    parent.location.href = page;
  }
}
// switch to previous page
function previous_page() {
  chapters = document.getElementById("chapters");
  selected_item = chapters.selectedIndex;
  if (selected_item > 1) {
//    chapters.selectedIndex = selected_item - 1;
    page = chapters.options[selected_item - 1].value;
    parent.location.href = page;
  }
}