/*==================================================* $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) { // 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; // 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; } } } //================================================== // 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"); // 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; // 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.update = function() { // This method updates the slideshow image on the page // Make sure the slideshow has been initialized correctly if (! this.valid_image()) { return; } // Convenience variable for the current slide var slide = this.slides[ this.current ]; // Load the slide image if necessary slide.load(); // Update the image. this.image.src = slide.image.src; // 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.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.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))); } } } //================================================== // 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; } } }