Is there a chance to set an alpha-mask using XOrg?

[Helge Bahmann]

Am Saturday 06 June 2009 21:03:12 schrieb Leif Bergerhoff:
> Peter Harris wrote:
> > It depends on your toolkit. If you're not using any particular toolkit,
> > the easiest way is to set _NET_WM_WINDOW_OPACITY on your window. See
> > http://webcvs.freedesktop.org/xapps/transset/transSet.c?view=markup for
> > an example.
> >
> > Make sure a composite manager is running (many desktops run one by
> > default these days).
>
> No, I don't want to make use of a toolkit if possible.
>
> As I can see I would have to make use of the composite extension.

no, you need "composite" if you want to write your own compositing manager 
(it's unlikely you really want to do that)

> If I remember correctly, I read about this extension supporting max. 2
> output devices. Right?

no

> This would mean, I'll need another way for setting an image as an
> alpha-mask, since I want to make use of 6 output devices.

to *draw* using transparency, you need either the "render" extension (but use 
cairo if you can, as pointed out), or GL (but note that compositing managers 
and direct rendering do not mix well with DRI1)

to *show* a translucent window, you generally need a compositing manager, and 
either set _NET_WM_WINDOW_OPACITY as suggested (if you want uniform opacity), 
or otherwise create your window using an ARGB visual and provide appropriate 
per-pixel alpha while drawing

Helge Bahmann
-- 
Dipl. Math.
Helge Bahmann
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