On Wed, May 19, 2010 at 07:34:04PM -0400, Rafi Rubin wrote: > My understanding is that it would be more like > + SYN_MT_SLOT 0 > + ABS_MT_POSITION_X x > + ABS_MT_POSITION_Y y > + SYN_REPORT > + SYN_MT_SLOT 0 > + ABS_MT_POSITION_X x > + ABS_MT_POSITION_Y y > + SYN_REPORT > + SYN_MT_SLOT 0 > + ABS_MT_POSITION_X x > + ABS_MT_POSITION_Y y > + SYN_MT_SLOT 1 > + ABS_MT_POSITION_X x > + ABS_MT_POSITION_Y y > + SYN_REPORT > > > (2 events from 1 finger, followed by 1 event with both). where does the ABS_MT_BLOB_ID come in then? I thought this was the use-case it was added for. With the example above, you're updating the position for the finger three times, not specifying that there are 3 _simultaneous_ but disparate touches of the same finger. I'm thinking of a palm touch which may (for some hand shapes) gives you two blobs right next to each other but separated by a thin line. So palm + finger gives you three blobs in three slots, two of them linked by contact ID? Cheers, Peter > On 05/19/2010 06:43 PM, Ping Cheng wrote: > >Hi Henrik, > > > >I am trying to link the protocol to the actual multi-touch devices in > >my "mind". Hope it helps you to point out the mismatch between my > >imagination and the protocol. Please see details in line. > > > >Ping > > > >On Tue, May 18, 2010 at 1:10 PM, Henrik Rydberg<rydberg@xxxxxxxxxxx> wrote: > >>This patch adds documentation for the SYN_MT_SLOT event and > >>gives examples of how to use the event slot protocol. > > > >Am I right in thinking that SYN_MT_SLOT represents to the actual touch > >area/finger on the surface? There could be more than one (x,y) (a few > >points that form an irregular shape) that represents one finger. The > >following example shows that slot 0 (finger 1) touched three points on > >the surface while slot 1 (finger 2) only has one point reported: > > > >+ SYN_MT_SLOT 0 > >+ ABS_MT_TRACKING_ID 45 > >+ ABS_MT_POSITION_X x[0] > >+ ABS_MT_POSITION_Y y[0] > >+ ABS_MT_TRACKING_ID 46 > >+ ABS_MT_POSITION_X x[1] > >+ ABS_MT_POSITION_Y y[1] > >+ ABS_MT_TRACKING_ID 47 > >+ ABS_MT_POSITION_X x[2] > >+ ABS_MT_POSITION_Y y[2] > >+ SYN_MT_SLOT 1 > >+ ABS_MT_TRACKING_ID 30 > >+ ABS_MT_POSITION_X x[3] > >+ ABS_MT_POSITION_Y y[3] > >+ SYN_REPORT > > > >If my assumption is correct, i.e., one slot can have more than one > >point, I would think ABS_MT_TRACKING_ID may not have to be a required > >entry inside SYN_MT_SLOT. To the user land clients/drivers, > >SYN_MT_SLOT itself could serve as an ID. So, the following case is > >also a type B ( we know there are two touch areas. But we don't keep > >track of the points inside the areas): > > > >+ SYN_MT_SLOT 0 > >+ ABS_MT_POSITION_X x[0] > >+ ABS_MT_POSITION_Y y[0] > >+ ABS_MT_POSITION_X x[1] > >+ ABS_MT_POSITION_Y y[1] > >+ ABS_MT_POSITION_X x[2] > >+ ABS_MT_POSITION_Y y[2] > >+ SYN_MT_SLOT 1 > >+ ABS_MT_POSITION_X x[3] > >+ ABS_MT_POSITION_Y y[3] > >+ SYN_REPORT > > > >So, an EVIO for X driver to retrieve the number of SLOTs would be very > >helpful. Something like the following would do the work: > > > >input_set_abs_params(input_dev, ABS_MT_SLOT, 0, 12, 0, 0); > > > >which tells the user land clients that they can expect up to 13 touch areas. > > > >>+The main difference between the raw type A protocol and the higher level > >>+type B slot protocol lies in the usage of identifiable contacts. The slot > >>+protocol requires the use of the ABS_MT_TRACKING_ID, > > > >With what I said above, I think ABS_MT_TRACKING_ID is not the unique > >identifier for type B protocol. It is the fact that we can identify > >individual touch areas and use ABS_MT_SLOT to report them that makes > >it a type B event. > > > >>ABS_MT_TRACKING_ID, either provided by the > >>+hardware of computed from the raw data [5]. > > ^^ or (is it?) > > > >I agree with this ABS_MT_TRACKING_ID definition. I would think something like: > > > >input_set_abs_params(input_dev, ABS_MT_TRACKING_ID, 0, 47, 0, 0); > > > >which tells the clients that total of 48 points are tracked, would be helpful. > > > >Another topic that may be irrelevant to this patch is the filter. With > >the use of ABS_MT_TRACKING_ID, a filter can be applied to discard the > >useless repeated points or less than a certain number of points > >movement. > > -- 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
