[RFC XI 2.1 - xf86-input-evdev 2/3] Add experimental XI 2.1 multitouch support

Daniel Stone daniel at fooishbar.org
Thu Dec 2 07:28:58 PST 2010


On Thu, Dec 02, 2010 at 10:06:01AM -0500, Chase Douglas wrote:
> On 12/01/2010 05:07 PM, Peter Hutterer wrote:
> > On Fri, Nov 19, 2010 at 10:58:20AM -0500, Chase Douglas wrote:
> >> Can you provide more detail? I don't see the parallel yet.
> >>
> >> If you're thinking that each touch axis valuator could have it's own
> >> direct/dependent mode, I don't really understand what that would mean.
> > 
> > well, I guess 20 years ago they didn't think that having devices that are
> > both absolute and relative was unlikely :)
> > 
> > same thing here. best example I can think of right now is a MT tablet that
> > has a touchstrip like the Intuos3. the latter would be relative to the
> > pointer position.
> We could support this through per-axis modes, but I think that would get
> hairy. We would have to enforce the X and Y axes to be the same mode.
> Then we would need some sort of distinction between the strip valuators
> and the touchscreen valuators. They both may support pressure data, for
> example, with different resolutions and such. And what would be the mode
> of the non-positional axes like pressure?

Well, seeing that the only relevant axes for direct/dependent are x & y,
I don't think we have to worry about this.

> Instead, we could create separate input devices for the strip and the
> touchscreen. The strip would be a dependent device, and would usually be
> attached to the same MD as the touch screen. However, it could also be
> attached to a different MD, allowing for more interesting mixing and
> matching of input devices.

We could make the mode in the touch class a bitmask of direct and
dependent, and let the driver tell us at touch creation time whether the
touch should be direct or dependent?

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