[Telepathy] Vino-telepathy for a single window?

[Benjamin M. Schwartz]

Robert McQueen wrote:
> Dafydd Harries wrote:
>> Presumably it's using XGetImage, which doesn't handle occluded regions
>> properly. It's possible to do this properly using XComposite + XDamage.
>> XComposite lets you redirect the drawing offscreen so you can copy the
>> contents regardless of occlusion, and XDamage will tell you when it changes so
>> you can update.
> 
> This is a Vino thing rather than a Telepathy thing, but it would be
> bloody useful... :D
> 
> We actually looked into this at the beginning of the year at LCA - we'd
> also quite like the ability to share one application because it
> alleviates the need to modify each and every application to support
> collaborative stuff, and addresses (some of) the privacy/security
> concerns of whole-desktop sharing.
> 
> I believe libvncserver (inside Vino) already uses damage and composite
> internally, to get a pixbuf for the root window. So I think its not too
> hard to modify it to look at one particular window, but the devil is in
> the details. There are a lot of them. :(

Indeed.  For Sugar, if we ever do this, it will probably be by forcibly
sandboxing each activity in a Xephyr or similar, which should make the
problem trivial, or nearly so.

For the record, I've given up on the single-app feature for the moment,
and instead just whipped up a whole-desktop sharing activity, "Watch Me"
[1].  It's just x11vnc running in view-only mode, tunneled over a stream
tube to a client built on gtk-vnc-python (same codebase as Gnome's
Vinagre).  I'm using x11vnc instead of Vino because Vino is hard to invoke
(it relies on gnome-session and gconf).

Watch Me makes absolutely no attempt to be compatible with Empathy.
That's something I'd like to fix.  I get the feeling that it would require
explicit support in the Sugar shell, though, at least for connecting to an
Empathy server.

--Ben

[1] http://bemasc.net/~bens/WatchMe-1.xo

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