Re: Transparent background in window?

[John Cupitt ng-london org uk]

Brett Granger wrote:
> But I am not interested in non-rectangular windows via the shape 
> extension (which I have used quite a bit) -- I am interested in 
> translucent rectangular (alpha-blended) top level windows, preferably 
> with minimal modification to X or to GTK.  There have been previous 
> discussions on this list (or was it the app-devel list?) about this, 
> indicating that it is possible with DirectFB or perhaps faked using a 
> patch from Owen.  Seems like it ought to be possible to create something 
> using the render extension, but performance might be an issue?  I'm 
> working in a remote display environment, so DirectFB might not really be 
> feasible...
> 
> --Brett

Hi, I don't know if this is any help, but the liquid theme on Qt fakes 
this by:

- before mapping a window, it grabs the area of the screen the
   window will occupy

- all painting to the window is done to an offscreen pixmap

- on an expose event, the offscreen pixmap is copied to the
   client, blended with the underlying window, and then
   pasted back to the display

This does not work if the window underneath is changing, and is also 
slow :-( but it does look rather nice.

John



========================================================== 
Fabric of Vision 
Dress and Drapery in Painting 

19 June - 8 September 2002 

For information and tickets: 
http://www.nationalgallery.org.uk/exhibitions/fabric/