/*==================================================*
	 $Id: slideshow.js,v 1.8 2003/08/23 16:54:31 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;
	
	  // 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();
	  }
	
	  //--------------------------------------------------
	  this.load = function() {
	  // This function loads the image for the slide
	
	    if (!document.images) { return; }
	
	    if (this.image.src != this.src) {
	      this.image.src = this.src;
	    }
	  }
	
	  //--------------------------------------------------
	  this.hotlink = function() {
	  // This function jumps to the slide's link.
	  // If a window was specified for the slide, then it opens a new window.
	
	    if (this.target) {
	
	      // If window attributes are specified, use them to open the new window
	      if (this.attr) {
	        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)
	        window.open(this.link, this.target);
	      }
	
	    } else {
	      // Open the hotlink 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.
	  this.textarea;
	
	   // Milliseconds to pause between slides
	  this.timeout = 6000;
	
	  // 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"))
	  
	    // If this version of JavaScript does not allow us to
	    // change images, then we can't do the slideshow.
	    if (!document.images) { return; }
	  
	    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 function implements the automatically running slideshow.
	  
	    // Make sure we're not already playing
	    this.pause();
	  
	    // If a new timeout was specified (optional)
	    // set it here
	    if (timeout) {
	      this.timeout = timeout;
	    }
	  
	    // After the timeout, call this.loop()
	    this.timeoutid = setTimeout( this.name + ".loop()", this.timeout);
	  }
	
	  //--------------------------------------------------
	  this.pause = function() {
	  // This function stops the slideshow if it is automatically running.
	  
	    if (this.timeoutid != 0)
	    {
	      clearTimeout(this.timeoutid);
	      this.timeoutid = 0;
	    }
	  }
	
	  //--------------------------------------------------
	  this.update = function() {
	  // This function updates the slideshow image on the page
	
	    // Convenience variables
	    var slide = this.slides[ this.current ];
	    var dofilter = (this.image.filters && this.image.filters[0]);
	
	    // Make sure the slideshow has been initialized correctly
	    if (! this.valid_image()) { return; }
	  
	    // 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();
	
	    // Pre-fetch the next slide image(s) if necessary
	    if (this.prefetch > 0) {
	      for (i = this.current + 1;
	           i <= (this.current + this.prefetch) && i < this.slides.length;
	           i++) {
	        this.slides[i].load();
	      }
	    }
	  }
	
	  //--------------------------------------------------
	  this.goto_slide = function(n) {
	  // This function 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.next = function() {
	  // This function 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 function 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.get_text = function() {
	  // This function 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) {
	      this.textarea.value = text;
	    }
	  
	    // If a text id has been specified,
	    // then change the contents of the HTML element
	    if (this.textid) {
	
	      // Make sure we don't cause an error
	      // for browsers that do not support getElementById
	      if (!document.getElementById){ return false; }
	      r = document.getElementById(this.textid);
	      if (!r) { return false; }
	
	      // Update the text
	      r.innerHTML = text;
	
	    }
	  }
	
	  //--------------------------------------------------
	  this.hotlink = function() {
	  // This function 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 function 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 function is for internal use only.
	  // This function 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)
	    {
	      // Stop the slideshow
	      this.pause;
	  
	      // Display an error message
	      window.status = "Error: slideshow image not initialized for " + this.name;
	          
	      return 0;
	    }
	    else {
	      return 1;
	    }
	  }
	
	  //--------------------------------------------------  
	  // 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 function 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 function 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 function is deprecated; you should use
	  // the following code instead:
	  // s.textid = "mytextid";
	  // s.update();
	    this.textid = textidstr;
	    this.display_text();
	  }
	}