Re: Drawing on the root window



On Fri, 26 Nov 2004 22:21:02 -0200, Joao Victor said:

> Hmmm that's because you didn't understand very well my problem here...
> what i'm trying to do is similar to this:
> 
> http://www.quinn.echidna.id.au/Quinn/WWW/HISubtleties/AnnotatedCoachMark.gif
> 
> See that red circle painted over the widgets? That's that. Anybody
> knows how to do it?

OK... Now I *fully* understand what you're trying to do, and it *is* a
reasonable thing to try to do when that's the effect you want. Unfortunately,
there's probably no really good way to attack this easily, at least with the X
graphics backend, as it requires a level of cooperation and/or transparency
support that X doesn't usually provide.

One trick you can try is to allocate a *small* window, *without WM
decorations*, and then walk through the window list and gather up the bits for
each window, (look at the source for 'xv' or other programs that can take a
snapshot of other windows for details) and composite them yourself.  Then
having composited the image together, throw it up on the very top of the
stacking order.  I suspect that a number of these steps will require at least
some low-level X hacking, as I don't think gdk/gtk expose the primitives you
need....

You *may* be able to do better if the X server supports some of the newer
rendering and transparency extensions, and if you're using some other back-end
for GTK other than X (like the framebuffer driver), you're on your own - I'm
just an X guy.. ;)

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