/*==================================================*
   $Id: slideshow.js,v 1.16 2003/10/14 12:39:00 pat Exp $
   Copyright 2000-2003 Patrick Fitzgerald
   http://slideshow.barelyfitz.com/
  
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
  
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
  
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   *==================================================*/
  
  // There are two objects defined in this file:
  // "slide" - contains all the information for a single slide
  // "slideshow" - consists of multiple slide objects and runs the slideshow
  
  //==================================================
  // slide object
  //==================================================
  function slide(src,link,text,target,attr) {
    // This is the constructor function for the slide object.
    // It is called automatically when you create a new slide object.
    // For example:
    // s = new slide();
  
    // Image URL
    this.src = src;
  
    // Link URL
    this.link = link;
  
    // Text to display
    this.text = text;
  
    // Name of the target window ("_blank")
    this.target = target;
  
    // Custom duration for the slide, in milliseconds.
    // This is an optional parameter.
    // this.timeout = 3000
  
    // Attributes for the target window:
    // width=n,height=n,resizable=yes or no,scrollbars=yes or no,
    // toolbar=yes or no,location=yes or no,directories=yes or no,
    // status=yes or no,menubar=yes or no,copyhistory=yes or no
    // Example: "width=200,height=300"
    this.attr = attr;
  
    // Create an image object for the slide
    if (document.images) {
      this.image = new Image();
    }
  
    // Flag to tell when load() has already been called
    this.loaded = false;
  
    //--------------------------------------------------
    this.load = function() {
      // This method loads the image for the slide
  
      if (!document.images) { return; }
  
      if (!this.loaded) {
        this.image.src = this.src;
        this.loaded = true;
      }
    }
  
    //--------------------------------------------------
    this.hotlink = function() {
      // This method jumps to the slide's link.
      // If a window was specified for the slide, then it opens a new window.
  
      var mywindow;
  
      // If this slide does not have a link, do nothing
      if (!this.link) return;
  
      // Open the link in a separate window?
      if (this.target) {
  
        // If window attributes are specified,
        // use them to open the new window
        if (this.attr) {
          mywindow = window.open(this.link, this.target, this.attr);
    
        } else {
          // If window attributes are not specified, do not use them
          // (this will copy the attributes from the originating window)
          mywindow = window.open(this.link, this.target);
        }
  
        // Pop the window to the front
        if (mywindow && mywindow.focus) mywindow.focus();
  
      } else {
        // Open the link in the current window
        location.href = this.link;
      }
    }
  }
  
  //==================================================
  // slideshow object
  //==================================================
  function slideshow( slideshowname ) {
    // This is the constructor function for the slideshow object.
    // It is called automatically when you create a new object.
    // For example:
    // ss = new slideshow("ss");
  
    // Name of this object
    // (required if you want your slideshow to auto-play)
    // For example, "SLIDES1"
    this.name = slideshowname;
  
    // When we reach the last slide, should we loop around to start the
    // slideshow again?
    this.repeat = true;
  
    // Number of images to pre-fetch.
    // -1 = preload all images.
    //  0 = load each image is it is used.
    //  n = pre-fetch n images ahead of the current image.
    // I recommend preloading all images unless you have large
    // images, or a large amount of images.
    this.prefetch = -1;
  
    // IMAGE element on your HTML page.
    // For example, document.images.SLIDES1IMG
    this.image;
  
    // ID of a DIV element on your HTML page that will contain the text.
    // For example, "slides2text"
    // Note: after you set this variable, you should call
    // the update() method to update the slideshow display.
    this.textid;
  
    // TEXTAREA element on your HTML page.
    // For example, document.SLIDES1FORM.SLIDES1TEXT
    // This is a depracated method for displaying the text,
    // but you might want to supply it for older browsers.
    this.textarea;
  
    // Milliseconds to pause between slides.
    // Individual slides can override this.
    this.timeout = 3000;
  
    // Hook functions to be called before and after updating the slide
    // this.pre_update_hook = function() { }
    // this.post_update_hook = function() { }
  
    // These are private variables
    this.slides = new Array();
    this.current = 0;
    this.timeoutid = 0;
  
    //--------------------------------------------------
    // Public methods
    //--------------------------------------------------
    this.add_slide = function(slide) {
      // Add a slide to the slideshow.
      // For example:
      // SLIDES1.add_slide(new slide("s1.jpg", "link.html"))
    
      var i = this.slides.length;
    
      // Prefetch the slide image if necessary
      if (this.prefetch == -1) {
        slide.load();
      }
  
      this.slides[i] = slide;
    }
  
    //--------------------------------------------------
    this.play = function(timeout) {
      // This method implements the automatically running slideshow.
      // If you specify the "timeout" argument, then a new default
      // timeout will be set for the slideshow.
    
      // Make sure we're not already playing
      this.pause();
    
      // If the timeout argument was specified (optional)
      // then make it the new default
      if (timeout) {
        this.timeout = timeout;
      }
    
      // If the current slide has a custom timeout, use it;
      // otherwise use the default timeout
      if (typeof this.slides[ this.current ].timeout != 'undefined') {
        timeout = this.slides[ this.current ].timeout;
      } else {
        timeout = this.timeout;
      }
  
      // After the timeout, call this.loop()
      this.timeoutid = setTimeout( this.name + ".loop()", timeout);
    }
  
    //--------------------------------------------------
    this.pause = function() {
      // This method stops the slideshow if it is automatically running.
    
      if (this.timeoutid != 0) {
  
        clearTimeout(this.timeoutid);
        this.timeoutid = 0;
  
      }
    }
  
    //--------------------------------------------------
    this.update = function() {
      // This method updates the slideshow image on the page
  
      // Make sure the slideshow has been initialized correctly
      if (! this.valid_image()) { return; }
    
      // Call the pre-update hook function if one was specified
      if (typeof this.pre_update_hook == 'function') {
        this.pre_update_hook();
      }
  
      // Convenience variable for the current slide
      var slide = this.slides[ this.current ];
  
      // Determine if the browser supports filters
      var dofilter = false;
      if (this.image &&
          typeof this.image.filters != 'undefined' &&
          typeof this.image.filters[0] != 'undefined') {
  
        dofilter = true;
  
      }
  
      // Load the slide image if necessary
      slide.load();
    
      // Apply the filters for the image transition
      if (dofilter) {
  
        // If the user has specified a custom filter for this slide,
        // then set it now
        if (slide.filter &&
            this.image.style &&
            this.image.style.filter) {
  
          this.image.style.filter = slide.filter;
  
        }
        this.image.filters[0].Apply();
      }
  
      // Update the image.
      this.image.src = slide.image.src;
  
      // Play the image transition filters
      if (dofilter) {
        this.image.filters[0].Play();
      }
  
      // Update the text
      this.display_text();
  
      // Call the post-update hook function if one was specified
      if (typeof this.post_update_hook == 'function') {
        this.post_update_hook();
      }
  
      // Do we need to pre-fetch images?
      if (this.prefetch > 0) {
  
        var next, prev, count;
  
        // Pre-fetch the next slide image(s)
        next = this.current;
        prev = this.current;
        count = 0;
        do {
  
          // Get the next and previous slide number
          // Loop past the ends of the slideshow if necessary
          if (++next >= this.slides.length) next = 0;
          if (--prev < 0) prev = this.slides.length - 1;
  
          // Preload the slide image
          this.slides[next].load();
          this.slides[prev].load();
  
          // Keep going until we have fetched
          // the designated number of slides
  
        } while (++count < this.prefetch);
      }
    }
  
    //--------------------------------------------------
    this.goto_slide = function(n) {
      // This method jumpts to the slide number you specify.
      // If you use slide number -1, then it jumps to the last slide.
      // You can use this to make links that go to a specific slide,
      // or to go to the beginning or end of the slideshow.
      // Examples:
      // onClick="myslides.goto_slide(0)"
      // onClick="myslides.goto_slide(-1)"
      // onClick="myslides.goto_slide(5)"
    
      if (n == -1) {
        n = this.slides.length - 1;
      }
    
      if (n < this.slides.length && n >= 0) {
        this.current = n;
      }
    
      this.update();
    }
  
  
    //--------------------------------------------------
    this.goto_random_slide = function(include_current) {
      // Picks a random slide (other than the current slide) and
      // displays it.
      // If the include_current parameter is true,
      // then 
      // See also: shuffle()
  
      var i;
  
      // Make sure there is more than one slide
      if (this.slides.length > 1) {
  
        // Generate a random slide number,
        // but make sure it is not the current slide
        do {
          i = Math.floor(Math.random()*this.slides.length);
        } while (i == this.current);
   
        // Display the slide
        this.goto_slide(i);
      }
    }
  
  
    //--------------------------------------------------
    this.next = function() {
      // This method advances to the next slide.
  
      // Increment the image number
      if (this.current < this.slides.length - 1) {
        this.current++;
      } else if (this.repeat) {
        this.current = 0;
      }
  
      this.update();
    }
  
  
    //--------------------------------------------------
    this.previous = function() {
      // This method goes to the previous slide.
    
      // Decrement the image number
      if (this.current > 0) {
        this.current--;
      } else if (this.repeat) {
        this.current = this.slides.length - 1;
      }
    
      this.update();
    }
  
  
    //--------------------------------------------------
    this.shuffle = function() {
      // This method randomly shuffles the order of the slides.
  
      var i, i2, slides_copy, slides_randomized;
  
      // Create a copy of the array containing the slides
      // in sequential order
      slides_copy = new Array();
      for (i = 0; i < this.slides.length; i++) {
        slides_copy[i] = this.slides[i];
      }
  
      // Create a new array to contain the slides in random order
      slides_randomized = new Array();
  
      // To populate the new array of slides in random order,
      // loop through the existing slides, picking a random
      // slide, removing it from the ordered list and adding it to
      // the random list.
  
      do {
  
        // Pick a random slide from those that remain
        i = Math.floor(Math.random()*slides_copy.length);
  
        // Add the slide to the end of the randomized array
        slides_randomized[ slides_randomized.length ] =
          slides_copy[i];
  
        // Remove the slide from the sequential array,
        // so it cannot be chosen again
        for (i2 = i + 1; i2 < slides_copy.length; i2++) {
          slides_copy[i2 - 1] = slides_copy[i2];
        }
        slides_copy.length--;
  
        // Keep going until we have removed all the slides
  
      } while (slides_copy.length);
  
      // Now set the slides to the randomized array
      this.slides = slides_randomized;
    }
  
  
    //--------------------------------------------------
    this.get_text = function() {
      // This method returns the text of the current slide
    
      return(this.slides[ this.current ].text);
    }
  
  
    //--------------------------------------------------
    this.get_all_text = function(before_slide, after_slide) {
      // Return the text for all of the slides.
      // For the text of each slide, add "before_slide" in front of the
      // text, and "after_slide" after the text.
      // For example:
      // document.write("<ul>");
      // document.write(s.get_all_text("<li>","\n"));
      // document.write("<\/ul>");
    
      all_text = "";
    
      // Loop through all the slides in the slideshow
      for (i=0; i < this.slides.length; i++) {
    
        slide = this.slides[i];
      
        if (slide.text) {
          all_text += before_slide + slide.text + after_slide;
        }
    
      }
    
      return(all_text);
    }
  
  
    //--------------------------------------------------
    this.display_text = function(text) {
      // Display the text for the current slide
    
      // If the "text" arg was not supplied (usually it isn't),
      // get the text from the slideshow
      if (!text) {
        text = this.slides[ this.current ].text;
      }
    
      // If a textarea has been specified,
      // then change the text displayed in it
      if (this.textarea && typeof this.textarea.value != 'undefined') {
        this.textarea.value = text;
      }
  
      // If a text id has been specified,
      // then change the contents of the HTML element
      if (this.textid) {
  
        r = this.getElementById(this.textid);
        if (!r) { return false; }
        if (typeof r.innerHTML == 'undefined') { return false; }
  
        // Update the text
        r.innerHTML = text;
      }
    }
  
  
    //--------------------------------------------------
    this.hotlink = function() {
      // This method calls the hotlink() method for the current slide.
    
      this.slides[ this.current ].hotlink();
    }
  
  
    //--------------------------------------------------
    this.save_position = function(cookiename) {
      // Saves the position of the slideshow in a cookie,
      // so when you return to this page, the position in the slideshow
      // won't be lost.
    
      if (!cookiename) {
        cookiename = this.name + '_slideshow';
      }
    
      document.cookie = cookiename + '=' + this.current;
    }
  
  
    //--------------------------------------------------
    this.restore_position = function(cookiename) {
    // If you previously called slideshow_save_position(),
    // returns the slideshow to the previous state.
    
      //Get cookie code by Shelley Powers
    
      if (!cookiename) {
        cookiename = this.name + '_slideshow';
      }
    
      var search = cookiename + "=";
    
      if (document.cookie.length > 0) {
        offset = document.cookie.indexOf(search);
        // if cookie exists
        if (offset != -1) { 
          offset += search.length;
          // set index of beginning of value
          end = document.cookie.indexOf(";", offset);
          // set index of end of cookie value
          if (end == -1) end = document.cookie.length;
          this.current = parseInt(unescape(document.cookie.substring(offset, end)));
          }
       }
    }
  
  
    //--------------------------------------------------
    this.noscript = function() {
      // This method is not for use as part of your slideshow,
      // but you can call it to get a plain HTML version of the slideshow
      // images and text.
      // You should copy the HTML and put it within a NOSCRIPT element, to
      // give non-javascript browsers access to your slideshow information.
      // This also ensures that your slideshow text and images are indexed
      // by search engines.
    
      $html = "\n";
    
      // Loop through all the slides in the slideshow
      for (i=0; i < this.slides.length; i++) {
    
        slide = this.slides[i];
    
        $html += '<P>';
    
        if (slide.link) {
          $html += '<a href="' + slide.link + '">';
        }
    
        $html += '<img src="' + slide.src + '" ALT="slideshow image">';
    
        if (slide.link) {
          $html += "<\/a>";
        }
    
        if (slide.text) {
          $html += "<BR>\n" + slide.text;
        }
    
        $html += "<\/P>" + "\n\n";
      }
    
      // Make the HTML browser-safe
      $html = $html.replace(/\&/g, "&amp;" );
      $html = $html.replace(/</g, "&lt;" );
      $html = $html.replace(/>/g, "&gt;" );
    
      return('<pre>' + $html + '</pre>');
    }
  
  
    //==================================================
    // Private methods
    //==================================================
  
    //--------------------------------------------------
    this.loop = function() {
      // This method is for internal use only.
      // This method gets called automatically by a JavaScript timeout.
      // It advances to the next slide, then sets the next timeout.
      // If the next slide image has not completed loading yet,
      // then do not advance to the next slide yet.
  
      // Make sure the next slide image has finished loading
      if (this.current < this.slides.length - 1) {
        next_slide = this.slides[this.current + 1];
        if (next_slide.image.complete == null || next_slide.image.complete) {
          this.next();
        }
      } else { // we're at the last slide
        this.next();
      }
      
      // Keep playing the slideshow
      this.play( );
    }
  
  
    //--------------------------------------------------
    this.valid_image = function() {
      // Returns 1 if a valid image has been set for the slideshow
    
      if (!this.image)
      {
        return false;
      }
      else {
        return true;
      }
    }
  
    //--------------------------------------------------
    this.getElementById = function(element_id) {
      // This method returns the element corresponding to the id
  
      if (document.getElementById) {
        return document.getElementById(element_id);
      }
      else if (document.all) {
        return document.all[element_id];
      }
      else if (document.layers) {
        return document.layers[element_id];
      } else {
        return undefined;
      }
    }
    
  
    //==================================================
    // Deprecated methods
    // I don't recommend the use of the following methods,
    // but they are included for backward compatibility.
    // You can delete them if you don't need them.
    //==================================================
  
    //--------------------------------------------------
    this.set_image = function(imageobject) {
      // This method is deprecated; you should use
      // the following code instead:
      // s.image = document.images.myimagename;
      // s.update();
  
      if (!document.images)
        return;
      this.image = imageobject;
    }
  
    //--------------------------------------------------
    this.set_textarea = function(textareaobject) {
      // This method is deprecated; you should use
      // the following code instead:
      // s.textarea = document.form.textareaname;
      // s.update();
  
      this.textarea = textareaobject;
      this.display_text();
    }
  
    //--------------------------------------------------
    this.set_textid = function(textidstr) {
      // This method is deprecated; you should use
      // the following code instead:
      // s.textid = "mytextid";
      // s.update();
  
      this.textid = textidstr;
      this.display_text();
    }
  }