gnome-mag, full screen magnication and composite

Carlos Eduardo Rodrigues Diógenes cerdiogenes at
Mon Jun 19 06:57:21 PDT 2006

Hi guys,

I was thinking about gnome-mag and full screen magnification. The only
way that we can achieve this feature today is throw composite, but I
really doubt if we must use this technology, so I want to here what our
community members have in mind about this.

If we use composite in gnome-mag we must have a window-manager like code
in it to manage windows that come and goes, windows overlap, so we must
track a lot of events and use clip lists, I don't know if the server can
generate clip list to us, to render only the window parts the will be
showed in the screen. I think that we can make a good job on this to
maintaim the magnifier responsive in the case that the user don't have a
good video card, but we still with a memory problem, because with
composite each window is maintained in off-screen memory. This is not a
big problem to new video cards, but I think that we could, and must do
this work in older hardware.

Another solution that is hitting my head is that we could change a bit
the server, so we put the magnifier window in top of all others,
something like the OverlayWindow in composite, and paint the contents of
all windows below it in a pixmap with the same properties of the root
window using the same algorithm that is already used in the server.

I think that this second solution is better, but maybe there are reasons
to doesn't try it there I don't realize here. I'm very motivated to try
this, so if there isn't any good arguments to forget this possibility I
will start to play.

Carlos Eduardo Rodrigues Diógenes
Projeto xLupa -

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