[PATCH 2/2] Allow grabbing clients to accept or reject touches any time

[Peter Hutterer]

On Wed, Sep 14, 2011 at 12:09:02PM -0500, Chase Douglas wrote:
> On 09/14/2011 11:59 AM, Peter Hutterer wrote:
> > On Wed, Sep 14, 2011 at 10:22:36AM -0500, Chase Douglas wrote:
> >> This is potentially both a performance and client complexity
> >> improvement.
> > 
> > this needs more description, especially for the archives (we just talked
> > about this here at the XDC), please add that to the commit message.
> > 
> > and one more thing: if a client can reject a sequence at any time it may be
> > that the sequence already disappeared by the time the reject is processed.
> > (this shouldn't happen unless the client buffers the request but thats been
> > known to happen).
> > 
> > should we allow clients to reject any touch (even invalid ones) without
> > returning a BadValue?
> 
> Hmmm... The same could happen with accept too:
> 
> * Client A owns touch
> * Client B has a touch grab and is listening too
> 
> 1. Client A accepts touch
> 2. TouchEnd sent to client B
> 3. Client B accepts touch (which means, I accept iff I become the owner)
> 4. TouchEnd reaches client B
> 5. Client B gets an error from the touch acceptance because at the time
> the server got the accept request, the touch has already ended for client B
> 
> We probably need to think a bit more about this...

accept is a different case where the client should handle errors
appropriately. reject is more fire-and-forget. same with Ungrab, iirc it
always succeeds even if you don't actually have the grab.

Cheers,
  Peter