[g-a-devel] comosite based magnifier design

["Carlos Eduardo R. Diógenes" <cerdiogenes yahoo com br>]

Hi,

I was thinking about a composite based magnifier and
have some ideas how it can be implemented, but I'd
like to argue about it before starting coding the
solution this way.

First, I don't think that is a good solution have all
the screen magnified, because the amount of space
needed to store magnifications above 4x. If I'm not
wrong, this was percepted in gnome-mag too.

I think that a good way to implement it (a composite
based magnifier) is divide the actual gnome-mag
implementation in two process that colaborate through
shared memory.

One process (proc1) will track the changes in the
screen and composite the actual screen in the shared
memory (with no magnification). I think that this is a
complex task, because this need to be made as fastest
as possible and the cost to composite is high (the
problem is bigger when you have many windows), and
putting all this logic (verify created, moved,
resized, exposed windows) to keep the screen in the
shared memory updated in a separated process will
simplify the things and make updates easy.

The second process will do something very similar of
what gnome-mag is doing, the only difference is that
this other process (proc2) will not have anymore to
take the screen from the video memory, but from the
shared memory (maybe there is a need to be a flag to
indicate that proc1 is updating the image) and will
not have anymore to track damage events too.

Questions, sugestions or criticals are very welcome,

Thanks,
Carlos.


	



	
		
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