Slide show using java script

/*==================================================*
$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;

if (this.slides.length > 1) {

do {
i = Math.floor(Math.random()*this.slides.length);
} while (i == this.current);
this.goto_slide(i);
}
}



this.next = function() {
// This method advances to the next slide.

if (this.current < this.slides.length - 1) {
this.current++;
} else if (this.repeat) {
this.current = 0;
}

this.update();
}



this.previous = function() {

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;

slides_copy = new Array();
for (i = 0; i < this.slides.length; i++) {
slides_copy[i] = this.slides[i];
}

slides_randomized = new Array();



do {


i = Math.floor(Math.random()*slides_copy.length);

slides_randomized[ slides_randomized.length ] =
slides_copy[i];


for (i2 = i + 1; i2 < slides_copy.length; i2++) {
slides_copy[i2 - 1] = slides_copy[i2];
}
slides_copy.length--;


} while (slides_copy.length);

this.slides = slides_randomized;
}


this.get_text = function() {
return(this.slides[ this.current ].text);
}


this.get_all_text = function(before_slide, after_slide) {

all_text = "";

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) {

if (!text) {
text = this.slides[ this.current ].text;
}

if (this.textarea && typeof this.textarea.value != 'undefined') {
this.textarea.value = text;
}

if (this.textid) {

r = this.getElementById(this.textid);
if (!r) { return false; }
if (typeof r.innerHTML == 'undefined') { return false; }

r.innerHTML = text;
}
}


this.hotlink = function() {


this.slides[ this.current ].hotlink();
}




if (!cookiename) {
cookiename = this.name + '_slideshow';
}

document.cookie = cookiename + '=' + this.current;
}


this.restore_position = function(cookiename) {



if (!cookiename) {
cookiename = this.name + '_slideshow';
}

var search = cookiename + "=";

if (document.cookie.length > 0) {
offset = document.cookie.indexOf(search);
if (offset != -1) {
offset += search.length;
end = document.cookie.indexOf(";", offset);
if (end == -1) end = document.cookie.length;
this.current = parseInt(unescape(document.cookie.substring(offset, end)));
}
}
}


$html = "\n";

// Loop through all the slides in the slideshow
for (i=0; i < this.slides.length; i++) {

slide = this.slides[i];

$html += '

';

if (slide.link) {
$html += '';
}

$html += '';

if (slide.link) {
$html += "<\/a>";
}

if (slide.text) {
$html += "
\n" + slide.text;
}

$html += "<\/P>" + "\n\n";
}

$html = $html.replace(/\&/g, "&" );
$html = $html.replace(/ $html = $html.replace(/>/g, ">" );

return('

' + $html + '

');
}


this.loop = function() {

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 {
this.next();
}

this.play( );
}



this.valid_image = function() {

if (!this.image)
{
return false;
}
else {
return true;
}
}

this.getElementById = function(element_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;
}
}



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.textarea = textareaobject;
this.display_text();
}


this.set_textid = function(textidstr) {

this.textid = textidstr;
this.display_text();
}
}