Slides Viewer for an LCD Projection Panel
||Slides Viewer for an LCD Projection Panel
||Dr S. W. Moore
The laboratory now has an LCD projection panel for electronic display
of slides. It offers a resolution of 640x480 with medium
contrast and a small range of colours. This can be neatly combined
with a portable computer for the roving lecturer.
To make best use of the LCD display a careful choice of neatly
rendered fonts is required. Colour also needs to be wisely chosen,
particularly since many portables only offer a 4~bit deep display.
Slides could be generated in LaTeX and displayed with ghostview.
Unfortunately ghostview makes a poor job of rendering postscript fonts
when only a limited number of pixels are available. Alternatively,
slides could be prepared in HTML and displayed with netscape. Alas
netscape only works with mono or 8~bits per pixel displays.
Furthermore, a complex distributed hypertext environment is not
required. None the less, HTML has the attraction that material could
easily be supplied via the web for later perusal.
Notes on Requirements
- An X based slides viewer which displays HTML from local files and allows
rapid movement between slides.
- Hypertext links could be ignored but a new delimiter may be
used to identify slide boundaries within a HTML file.
- Traversing slides should be achieved using keyboard control
(e.g.\ space, right arrow and down arrow to move forward; left and up
arrow for moving backwards) and/or mouse buttons.
- It must be possible to insert GIF (or possibly PPM) images in
the usual HTML manner.
- Neatly rendered X screen fonts should be used and it should be possible
to specify font choice (e.g.\ for a particular hardware configuration)
in a configuration file. Colours should also be specified in the
- It should be written in tcl/tk, and if necessary C, to assist
- Each slide should be displayed full screen. Consequently any
menus must be popup. Since the left and right mouse buttons may be
used for turning pages, the popup menu should be activated with the
- It must be possible for the HTML based slide file to be viewed in a
conventional and convenient manner using netscape.
- The position and size of the slide viewer window should be able to be
set using the command line option -geometry to assist accurate
- By using a private colour map, a fade effect could be achieved
when moving between slides.
- Electronic equivalents of a highlighter and a pen.
- Answering questions at the end of a long presentation often
requires quick selection of previous slides. A tiled overview of the
slides would be a useful selection technique.
- Animation of a number of GIF images both forward, backward and
at varying speed.
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