[sorry, got stuck in my outbox for some reason] On Tue, Dec 14, 2010 at 10:10:10AM +0100, Henrik Rydberg wrote: > On 12/14/2010 05:36 AM, Peter Hutterer wrote: > > > On Tue, Dec 14, 2010 at 12:25:26AM +0100, Henrik Rydberg wrote: > >>>> The envelope contacts serve as a way to detect a small area of fingers or a > >> > >>>> large area of fingers. There is nothing inherently problematic with having one > >>>> or three or more such contacts. > >>> > >>> Then I'm more confused :). > >>> > >>> I see one problem: devices that report two touch points, (X1, Y1) and > >>> (X2, Y2), but in reality the touches could be at (X1, Y2) and (X2, Y1) > >>> instead. Using a rectangle helps resolve this issue for panning and > >>> pinching, though not for rotation. > >> > >> > >> If panning and pinching and rotation could all be recovered properly, then the > >> individual contacts could actually have been reconstructed properly in the first > >> place. This is the whole point - there is not enough information available for > >> rotation to be recovered properly. > > > > can you post an example event stream of the MT_ENVELOPE tool? I'm having > > trouble wrapping my head around it. > > > Here is an example for you: You sit in a car. You turn your steering wheel left > or right to follow the road. Now, imagine that 40% of the time, when you turn > left, the car actually turns right. This is the behavior you get from the raw > data. Now, instead soak your gloves in soap. At least now you know that your car > will go straight 100% of the time. The MT_ENVELOPE tool is the soapy glove. > That's all there is to it. > > The synaptics driver patch sent recently contains an example event stream > generator, in case you want to dwell on more details. > > Personally, I am done bending myself backwards to support "old" or "semi-mt" > hardware I never use myself. If somebody cares deeply enough, send a patch. Or > forever hold your peace. thanks, I understood the concept but I was trying to get the actual event stream out of this patch set. I missed the synaptics one, makes sense now. Cheers, Peter -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
