[Xevie] My current design efforts

[Deron Johnson]

Hi Keith,

I wanted to update you on my current design efforts in the area of
the event pathway. I'm currently investigating an approach which
has the X server sending events to the Display Server to do the pick
and the Display Server sends the events back to the X server to do the
grab processing and event propogation. If the event is destined for an
X window, the event is sent to the event client. But if the event is
destined for a 3D object, the event is sent back to the Display Server
for further propogation. This approach avoids the need to export window
geometry information to the Display Server and it has no race conditions
because all of the grab processing is done in one place (in the X 
server). The down side of this approach is that there is extra latency
for 3D object events (the time it takes to ship the post-grab-processing
event back to the Display Server). I am currently trying to characterize
whether this latency is significant.

Shared memory picking in the X server could provide an optimization for
this design, but it's just an optimization; it's not central to the
design. And it's looking like it will probably require a large 
implementation effort in our scene graph library (Java3D). So I'll 
probably only go that route if the non-shared-memory-picking approach
has too great a latency.

But I still wanted to know why you said that you wanted to support
systems that don't support shared memory. What type of systems are
you talking about?