[Spice-devel] [Qemu-devel] paravirtual mouse/tablet

[Alexander Graf]

On 17.01.2011, at 08:48, Gerd Hoffmann wrote:

>>> There are three cases:
>>> 
>>> (1) no pressure supported (i.e. your mouse moving around in the vnc
>>> window and qemu reporting this as tablet coordinates).
>>> (2) just pen/finger present/not present supported.  pressure jumps
>>> between 0 and max (and we can make max == 1 in that case).
>> 
>> Phew - that's one of the bits where touchpads and tablets behave
>> differently IIUC. For touchpads, pressing means movement happens.
>> For tablets, pressing means an actual press, as if you would press
>> your pencil on a sheet of paper. So for tablets, pressure==1
>> basically means click.
> 
> I wouldn't make a difference from the virtual hardware perspective.  If something touches the pad/tablet surface we'll report the position where it happened (and the pressure if supported).  Whenever this is interpreted as click or not is up to the guest.

There is a major difference. "Touching" means on

Touchpad: movement of cursor
Tablet: pressing down a pen

This difference needs to be reflected somehow. Maybe in the future there might even be devices that combine both. Imagine a tablet device that has a capacitive touchpad, but also accepts pen input, so you can draw on it. This would be separate events. Pressing down a pen would be interpreted completely differently from touching something on the device.


Alex