Re: [Spice-devel] [Qemu-devel] spicevmv chardev, guest agents and paravirtual mouse

[Gerd Hoffmann <kraxel@redhat.com>]

   Hi,

>>>> The VDAgentMouseState messages have one problem: They send the pointer
>>>> position as-is, which introduces a dependency on the screen size.
>>
>> Yeah, if we could get rid of that, that would be great. We could even
>> introduce a new mouse message type to the existing spice vdagent protocol
>> and use capabilities to switch between the 2.
>
> I think the typical trick is to scale the coordinates to some large
> resolution. Would there be any issue doing this in vdagent today?

No.  The vdagent actually registers a uinput device with the size 
matching the screen resolution today.  It could also register a tablet 
with a -- say -- 65536 x 65536 resolution and scale.  Even better would 
be to let spice-server or qemu do the scaling and feed vdagent/pvmouse 
with already scaled coordinates, so the vdagent doesn't has to hop 
through the loops Hans described to get the screen resolution coordinates.

qemu already uses a 0 -> 0xffff range internally for absolute input 
coordinates, the pvmouse (or should we better name it pvtablet?) should 
probably pass those values as-is to the guest.

cheers,
   Gerd