Generating Slides from Enhanced Media Content

Extended Abstract

Hauke Christoph Matthias Runge
February, 25th 2003
 

Summary

This document describes the representation of a multi-functional slide sheet presentation using the Scalable Vector Graphics (SVG) format and its generation from a complex XML document via XSLT.


Introduction

The 'Knowledge Factory', or wwr-project (referred as 'wwr' [2]), is a venture, run by twelve German universities. It aims to generate multimedia enhanced lectures for Computer Engineering (Technical Informatics). Unlike other projects in Germany, wwr is not targeted solely at students. It is specifically designed to allow for a differentiation between the content provided for lecturers and their target audience. That is, the content provided for lecturers contains didactic hints or anecdotes, which may not be included in the students’ version.

Having established the purpose of wwr, the next goal was to provide script, online and slide versions of the lectures/presentations. It is necessary to differentiate between online and paper versions, because the online version allows for the inclusion of animation, sounds etc., which, of course, cannot be included in script versions. In order to compensate for its “technological shortcomings”, the script version is designed to include static pictures and special text-elements.

The content in wwr is written in XML-notation. This notation contains detailed information about the content of a document/presentation [1].

Transformation from XML to SVG
Figure1: Visualisation of conception


Slide Presentation using SVG

The members of wwr needed a way to demonstrate the contents of their presentations (within lectures, symposiums, etc.) as slides. The features of SVG, combined with the fact that the wwr’s content is XML-text based (on wwr’s own XML Schema) influenced the design team’s decision to utilise SVG. Using SVG also made it possible to develop a product that is platform independent – something that is crucial if wwr’s slide format is to achieve broad acceptance.


Requirements

To ensure these acceptance, there also had to be imposed high demands upon the viewing tool. This new tool had to be as functional and comfortable as possible. This aim led the design team to produce the following minimal requirements for a new viewing tool:
  1. Platform independency
  2. Full screen view
  3. Consistent layout
  4. The ability to scroll through a document step-by-step, forwards and backwards
  5. The ability to navigate by keyboard, mouse and/or context menu
  6. The ability to jump to specific slides (e.g. 'go to'-function)
  7. The freedom to allow individuals to adapt the presentation to best meet their needs and preferred style of presentation (e.g. context menu, special text-decorations, etc.)
  8. The ability to use different skins (e.g. usage of CSS)
  9. The ability to use hyperlinks
  10. To contain a paint-function and allow for the usage of individual markers
  11. To be capable of generating an automated slide show
Screenshot
Figure2: Modified contextual menu


Transformation from XML-Document to SVG

Focussing upon the process of XSL-Transformations, it was necessary for the design team to keep its design objectives in mind. In order to ensure that the transformed documents can be presented in any format (as a slide show, as script, or online) an attribute called ‘target’ was introduced. As within wwr, creation of presentations is left to individual academic staff, all they need do is to define the target, be it slide, script, or online, at the time of creating their presentation.
It was decided that the best way to develop an XSL-Transformation is a modular approach. The Advantages of a modular system are obvious: better overview, easy debugging, the ease with which enhancements can be implemented, etc.


Example:

<list target="slide" ordered="no">
	<litem><text>line #1 of a list</text></litem>
	<litem><text>second item in list</text></litem>
</list>

The above XML-input clearly describes output that is formatted as a list, in which each member of the list is marked with a bullet [&9702;]. This list is translated to text within the SVG-slide using code which follows the format detailed below:

<text x=".." y="..">&9702; line #1 of a list</text>
<text x=".." dy="..(+..*fontsize)">&9702; second item in list</text>
Instead of looking at the implementation of specific tags, let us consider the slide implementation itself. The approach is a simple one - displaying one sheet after another. For this purpose, it is necessary to save, load and change variables - say: counting! The pure language of SVG does not cater for such an operation, so it is necessary to resort to the ECMA-script-engine, which allows for the showing and hiding of individual slides. Each slide is assigned a number as a unique identifier and is displayed once the value of the counting variable reaches that number.


Outlook

The viewing tool designed by the design team has proven to be capable of dealing with marked-up XML-content for lectures and automatically generating multi-functional slide presentations. This type of presentation is highly customizable to meet the needs of the individual. The tool was designed to meet a demand expressed by the staff of wwr and will be widely used both within wwr and by institutions affiliated with wwr.


References

[1] "The Use of XML for the Development of an Adaptive Multimedia Teaching and Learning System", U. Lucke, D. Tavangarian, H.-R. Vatterott, Proceedings of the World Congress on Networked Learning in a global Environment, ICSC Academic Press, Canada / The Netherlands, 2002.
[2] wwr-Project (WissensWerkstatt Rechensysteme): authors being active members www.wwr-project.de
[3] Federal Ministry of Education and Research (BMB+F): initiator/supporter of wwr-project www.bmbf.de
[4] Institute of Computer Engineering (ITI): author's field of work www.iti.uni-luebeck.de
[5] University of Luebeck: author's employer www.uni-luebeck.de
[6] World Wide Web Consortium (W3C): developer of specifications for XML, XSLT, SVG etc. www.w3.org


Authors

surname name email further contact information

Christoph Hauke christoph@iti.uni-luebeck.de more
Runge Matthias runge@iti.uni-luebeck.de more

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