A problem arises when "presentation graphics" software such as Microsoft PowerPoint is used to prepare lectures which are subsequently published on the Web. The alternatives are:
Using HTML as the source format has the additional advantage that the new "Web Authoring" software packages can be used, instead of proprietary presentation graphics packages. It also eliminates the pain of having two versions of the document: one for the actual lecture and a derived version for publication on the Web. One particular advantage of this is that the original document can contain hyperlinks, which can be ignored when the material is being used as part of a presentation.
The use of a web browser as a presentation graphics tool has some disadvantages. The HTML must be authored in such a way that scrolling is not used - our students report that this is very distracting. Best practice seems to be to configure the browser to use a specified (large) font size, with appropriately sized graphic images, and to make each "slide" of the presentation a separate HTML page. In reality, this is simply cajoling the browser into reluctantly accepting a role it was not designed for.
However, as mentioned earlier the problem at Bendigo, as in most universities is that lecture rooms with PC (or Mac) screen projection hardware are very scarce. The need then arises for a system whereby presentations written in HTML can be displayed where the only technology available is an Overhead projector (OHP). What is required is a software utility which can format and print HTML documents in an appropriate style for use on an OHP.
This paper describes the first prototype of such a tool, "ohpmlps". It takes as input an HTML file, written in a defined subset, which we call "OHPML". An OHPML document is perfectly legal HTML, and displays correctly on any Web browser. OHPML simply defines which markups are appropriate to an OHP presentation, and adds some extra interpretation rules. For example, in ordinary HTML the <hr> markup generates a horizontal line. In OHPML, it is used to signal the end of a "slide", and therefore generates a new page of output.
The prototype ohpmlps compiler was written using a standard C/yacc/lex approach, and generates PostScript output. It currently implements most of the markups defined in OHPML, and has proven already to be a very useful tool. There are man potential directions for future development of ohpmlps which we detail in the paper. The transparencies (or slides, as appropriate) used in presentation of this paper will be authored using OHPML and ohpmlps. The prototype ohpmlps software (source code) is available for downloading from the Web page http://ironbark.bendigo.latrobe.edu.au/staff/pscott/ohpmlps/ohpmlps.html