Re: [g-a-devel] gnome-mag, full screen magnication and composite

[Peter Korn <Peter Korn Sun COM>]

Hi Carlos Eduardo Rodrigues,

I believe the cost of new video cards is coming down so rapidly that the 
best place for most of our magnification investment is around 
COMPOSITE.  Every customer I come in contact with around UNIX 
accessibility compares what we are doing to the state of the art in 
Windows commercial software.  And users have come to expect this level 
of quality, and depend upon the efficiency and productivity that is 
affords them (and are NOT willing to give that up).

I agree that to make good use of COMPOSITE, the magnifier must know 
about most window manager tasks.  I think the best way to do this is to 
build magnification functionality *into* the compositing window 
manager(s) of our desktop(s).  I don't see a lot of value to keeping the 
magnifier separate from the window manager.

All that said, users who don't have the resources for modern graphics 
cards are an important group, and your idea of an OverlayWindow is an 
interesting one.  I'm curious to see where that investigation goes!


Regards,

Peter Korn
Accessibility Architect,
Sun Microsystems, Inc.

> 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.
>
> Thanks,
>