Emulating a laser pointer over X windows

an fvwm implementation

Lucio Chiappetti IASF Milano 14 Sep 09 14:59
Introduction Operation Download Updates

Introduction

I do not know about you, but to me it happens sometimes to make a presentation (typically I use Latex-Beamer generated PDF) or a demo (e.g. of some web site).
If I do the presentation locally, with the PC connected to a projector, it is easy to highlight items in the presentation with a laser pointer. This is usually (more or less barely) more visible than trying to move the mouse pointer around the screen.

Nowadays it also occurs sometimes to make the presentation in a videoconference. In this case one cannot use a laser pointer, so I looked for a way to have something like a bright and large screen cursor which I could move around the screen with my local mouse.

What I describe here is the solution which works for me in my specific environment (i.e. a Linux workstation with X, and using the fvwm window manager). I also give some (untested) hints I received while trying to find my solution.

Here are some snapshots of "pointers" of different shape (all red) superimposed over various windows.


Principles of operation

Since I am not so skilled in X programming to write new cursors (and also because such cursors may work in the root window, but will not necessarily be able to override the cursors defined by a specific application, like the Acrobat reader or Firefox), I decided to use instead semi-transparent icons which I associate to a generic application (I currently use an xterm ... but one can use anything since the application will never be opened, but only used in iconized form) and can then move around.

I therefore need a way to

Implementation

Since I normally use
fvwm as my window manager of choice, it was natural for me to look for a solution under such context.
This does not mean that somebody else can adapt a similar logical solution to other window managers ... but that's entirely up to you.

Alternate implementations

I received two alternate (and window-manager independent) suggestions to solve this problem, which I haven't tested since I was already half-way my solution which does not require to install anything but just exploits fvwm.

Command interface


Download and installation


Update history

S/w V1.0 and web page established on 10 Sep 2009
Web page last updated on 14 Sep 09 14:59

Bugs

More a(n unavoidable) feature: once the "move" operation is initiated on the icon, the usage of the mouse and keyboard is inhibited (because they are grabbed by the window manager) until one clicks to terminate the move.

The way I handle styles is possibly clumsy.

Contacts

I have no time to actively mantain this software other than for my own use. However I will be glad to receive communication of problems (or improvements) to it at my e-mail address lucio in domain lambrate.inaf.it.

Acknowledgment

In addition to the untested alternate solutions quoted above, I gratefully acknowledge a lot of useful suggestions by Thomas Adam which were essential to make the present one work.