Slide Show Engine

The Slide Show Engine is a simple tool for scripting Web-based presentations containing still images and short sound clips. The presentation runs from a text file containing a list of instructions on what to do. This documentation describes the syntax of a script and how to use it.

Scripts are plain text files and implement a very high-level syntax that contains instructions on what the slideshow should do. Each instruction comprises a command keyword followed by some data; the only other feature is comments. In general you can lay out your scripts pretty well any way you please; apart from comments the system pays no regard to line breaks. A comment on the other hand is only cancelled by the end of the line it starts on.

Keyword reference

Testing

Deployment

Registration

Update information

An example

Here's the start of a typical show:

!	Diary.ls

	register "My Name" 12345		! an invalid code !

	title "Potter Heigham, Norfolk, January 1999"

	backdrop "jpg/Background.jpg"
	
	text style "Normal Text"
		font "Serif"
		style bold
		size 16
		colour 0 0 128
		align centre centre
	
	text "Banner" "Welcome to my diary." and return
		and "Sit back and enjoy the show!"
		at 320 240
		font "Serif"
		style bold
		size 36
		colour 0 0 128
		align centre centre
	picture "Sign 1" "jpg/Sign2.jpg" at 320 50 align centre top hidden
	wait 3
	slide "Banner" left rate 16 then continue
	show "Sign 1"

Some of the commands have been split over several lines to improve readability, but you could just as well put them inline, as in

	text style "Normal Text" font "Serif" style bold size 16 colour 0 0 128 align centre centre

Keyword reference

Here's a list of all of the keywords:

backdrop
base
exit
picture
register
remove
show
slide
stop
text
title
wait

Testing

To test your slide show you can use either your browser or run the show as an application. The latter requires you to have a Java Runtime Engine (JRE) installed. This can be obtained from Sun Microsystems at http://java.sun.com/products/index.html.

Now you are able to run any Java program on your computer.

To run your slide show, open a command-line window (DOS prompt) and type the following command (for Windows).

jre -cp .;slides.jar;c:\windows\java\classes\media.zip Slides MyScript.txt

where

c:\windows\java\classes\media.zip is where the files for the media player will have been installed.

MyScript.txt is the name of your script file.

You will probably want to create a batch (.BAT) file containing this command line. There are two supplied with the package; RunD.bat is used for debugging in a DOS window while Run.bat is for double-clicking from Windows Explorer.

Running from the browser is also simple. To detect errors you need to enable the Java Console, which you can find under the Advanced Options in Internet Explorer. Navigator also has a console.

Deployment

Deploying a slide show is simple. Create or locate a directory for the project and place in it the HTML file that your users will start with. This is usually called 'index.htm' or 'index.html'; some systems use 'default.htm'. This page either contains the applet itself or links to one or more other pages containing slideshow applets. Copy slides.jar, your script and the images and audio files to the server, maintaining the same folder structure as your development machine.

The applet that runs the slide show must be located somewhere in your HTML file. Since the program creates its own separate window the applet itself does not need to have any particular size; the examples cause it to appear as a short horizontal bar. Here's the HTML tag for the applet:

The tag defines the name of the applet code (Slides.class) and an archive file that contains it. Then it defines the size of the applet and its alignment. Finally it defines a single parameter, the name of the script to run. The applet tag can be placed anywhere in the body of your HTML.

All that remains to be done is to tell your readers about the slide show. If you want to provide sound you will also need to tell them how to install the appropriate media player.

Registration

Although this software is at present free, we may decide to charge in the future for registration codes. An unregistered script has the word "Unregistered" displayed at the top and bottom of the window while the slideshow is running. To prevent this happening you need a registration number, which is then placed in a register instruction in your script. (There is a hidden feature in the program that will reveal the registration number so we can tell who it belongs to.)

To obtain a valid registration number, send an email to gt@pobox.com, giving your full name and requesting a registration number. Then add a register command as in the example above. At present, registration numbers are free on request.

Update information

March 3, 1999 Audio functions removed owing to Intel no longer offering the Media Player.
January 20, 1999 Various changes, notably to cause the show command to block until the picture has finished loading its image.