Lines Matching +full:multi +full:- +full:protocol

4 Multi-touch (MT) Protocol
7 :Copyright: |copy| 2009-2010	Henrik Rydberg <rydberg@euromail.se>
11 ------------
13 In order to utilize the full power of the new multi-touch and multi-user
16 document describes the multi-touch (MT) protocol which allows kernel
19 The protocol is divided into two types, depending on the capabilities of the
20 hardware. For devices handling anonymous contacts (type A), the protocol
22 devices capable of tracking identifiable contacts (type B), the protocol
26    MT protocol type A is obsolete, all kernel drivers have been
29 Protocol Usage
30 --------------
34 packet. Since these events are ignored by current single-touch (ST)
35 applications, the MT protocol can be implemented on top of the ST protocol
48 All drivers mark the end of a multi-touch transfer by calling the usual
53 The main difference between the stateless type A protocol and the stateful
54 type B slot protocol lies in the usage of identifiable contacts to reduce
55 the amount of data sent to userspace. The slot protocol requires the use of
67 the ABS_MT_TRACKING_ID of the associated slot.  A non-negative tracking id
68 is interpreted as a contact, and the value -1 denotes an unused slot.  A
92 Protocol Example A
93 ------------------
95 Here is what a minimal event sequence for a two-contact touch would look
125 zero-contact event reaching userland.
128 Protocol Example B
129 ------------------
131 Here is what a minimal event sequence for a two-contact touch would look
152    ABS_MT_TRACKING_ID -1
162    ABS_MT_TRACKING_ID -1
167 -----------
186 than unity, is related to the contact pressure. For pressure-based devices,
217 direction of the finger ellipse is given by the vector (a - b).
226 In the type B protocol, ABS_MT_TOOL_TYPE and ABS_MT_TRACKING_ID are
232 ---------------
260     of TOUCH and WIDTH for pressure-based devices or any device with a spatial
264     If the resolution is non-zero, the pressure data is in units/gram. See
265     :ref:`input-event-codes` for details.
280     direction, the range -max should be returned.
284     indicate more than a quarter of a revolution. For an upside-down finger,
317     event should be omitted. The protocol currently mainly supports
327     the contact. This is a low-level anonymous grouping for type A devices, and
328     should not be confused with the high-level trackingID [#f5]_. Most type A
340 -----------------
343 better to the MT protocol than others. To simplify and unify the mapping,
378 ellipse should align with the vector (T - C), so the diameter must
383 ---------------
393 --------
403 -----
406 in a finger packet must not be recognized as single-touch events.
411 .. [#f1] Also, the difference (TOOL_X - POSITION_X) can be used to model tilt.