screen annotation
Joel Dice
joel.dice at gmail.com
Fri Sep 7 10:49:54 PDT 2012
Hi all,
I'm interested in writing an application which allows a user to draw on
their desktop (e.g. highlight, circle, or underline an area of interest).
The closest thing I've found that already exists is
http://www.home.unix-ag.org/simon/gromit/, but that only provides opaque
annotations, whereas I'd like to allow semi-transparent (i.e.
alpha-blended) annotations which can be "clicked through" such that input
events in highlighted areas are passed through to the windows below as if
the highlights weren't there.
I thought of a couple of ways to implement this:
1. Create a full-screen window with an alpha channel that's completely
transparent by default and draw the annotations on that. The tricky parts
are keeping the window in the foreground, hiding it from the window
manager, and passing mouse and keyboard events through to the appropriate
windows.
2. Implement a compositing manager which draws the annotations on top of
everything else. I'm not sure how this would work if there's already a
compositing manager running.
Has anyone tried doing something like this already? Any advice on the
above strategies or some other approach?
Thanks.
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