impressive is the best software available on linux for showing PDF based presentations.

Macs have the perfect presentation software: while an external beamer shows the slide you are talking about, your notebook shows

• the current slide
• the next slide
• time elapsed for the current slide
• total elapsed time

This is exactly what I need and what impressive is unfortunately missing - the dual monitor feature.

impressive is written in python and uses OpenGL for rendering, so I thought, I'll add the desired feature.

My fork provides a new command line option dual-head. On my notebook I typically run the presentation tool with

/path/to/impressive.py -t None \
  --dual-head 1024x768+1280+31,1280x800+0+0 \
  pres.pdf' 

because

• my notebook has a screen resolution of 1280x800
• typical projector has a resolution of 1024x768
• I use xrandr and big screen, where the display area of the external output is to the right of the notebook display, this leads to horizontal offset of +1280
• OpenGL coordinates use bottom left corner, so we normally would need a vertical offset of +32 (=800-768)
• but I had to adjust it by one pixel to remove an unsightly border at the bottom of the slide - some rounding problems or OpenGL anomaly
• so the leads to the offset of +1280+31 for the external output (projector)

Please note: the new feature is not compatible with all the other options of impressive, that deal with resolution, picture size and screen size detection. Transitions also do not work. This because the implementation of impressive is so complicated, that it is not possible to introduce an implementation for a new cross cutting concern without breaking everything.

I hope, someday I have enough time to refactor the original implementation and implement following ideas:

• a single file is an advantage, but a file of 4000 lines length is probably not
• swap optional stuff like implementation of transitions out, so they can be included with import if needed
• make the whole thing more modular and organize it as a set of functions, that can be tied together with a small wrapper script; everybody could write its own integration script using units like
  • parse PDF
  • render one slide to a rectengular area
  • show text on OSD
  • caching
  • overview mode

More about presentations for geeks can be found on my blog http://blog.geekq.net/2009/03/29/impressive-presentation-for-geeks/.