XComposite input redirection/transformation proposal

[Daniel Stone]

On Tue, Feb 19, 2008 at 10:36:27AM +0100, Rémi Cardona wrote:
> Kristian Høgsberg a écrit :
> > I don't really think it's that bad - a 3D tri-mesh mirrors the way we
> > do output redirection, that is OpenGL triangles.  I'm sceptical that
> > we'll need more advanced primitives for the foreseeable future, I just
> > don't see a use case.
> 
> Neither do most of us, because experimentations in that area have been 
> very limited. Here's how I see it :
> 
>   - going down the server path means "forcing" a certain type of 
> primitives, that may very well be enough for the next 20 years, but OTOH 
> could prove to be very limited for other unforeseen cases (ie, non 
> linear transforms such as zooms). Should that be the case, we would have 
> to add new primitives to the extension, or even deprecate the extension 
> altogether, yet maintaining it for backwards compatibility.

Not really.  If it turns out to be the wrong path to go down, then we'll
cross that bridge when it comes to it, but as you said, the
experimentation has been limited.  Why not try with what's there and
easiest first, and we can find out later whether or not it was a good
idea, instead of canning it now because it may possibly be not quite
what we really want?

>   - going down the client side is more complicated, everyone seems to 
> agree on that. Yet, it allows clients to decide whatever they want to do 
> with input events, freeing the server of complicated code paths. Also, 
> I'm not really fond of having to tell the server what my windows look 
> like, in a way that may not match on a 1:1 basis with my OpenGL objects.

It doesn't get rid of complicated code paths, just provide more
opportunities for it to go wrong.  It's not perfect at the moment, but
at least it's a known quantity.

> Keith and Barton [1] have already acknowledged that doing fonts in the 
> server was a bad idea and that client-side was better. I'm afraid 
> server-side input-redirection will be a similarly bad idea.

Yes, as we have a well-understood and straightforward way of doing
client-side fonts.  We don't even properly understand the problem space
for proper input redirection at the moment.

Cheers,
Daniel
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