On Thu, May 22, 2014 at 10:29:43PM +0300, Ferruh Yigit wrote: > On 05/22/2014 08:23 PM, Dmitry Torokhov wrote: > > Hi Ferruh, > > > > On Thu, May 22, 2014 at 02:03:40PM +0300, Ferruh Yigit wrote: > >> Hi, > >> > >> What is the metric of ABS_MT_TOUCH_MAJOR / ABS_MT_WIDTH_MAJOR events? > >> > >> The Linux documentation > >> <https://www.kernel.org/doc/Documentation/input/multi-touch-protocol.txt> says: > >> "The length of the major axis of the contact. The length should be given > >> in surface units. ..." > >> > >> What does "surface units" means, is it millimeter or pixels? > > It is whatever unit the device reports, similarly to ABS_MT_POSITION_X > > and ABS_MT_POSITION_Y. Userspace can use EVIOCGABS to map device units > > onto common units. > > > > From include/uapi/linux/input.h (struct input_absinfo): > > > > * Resolution for main axes (ABS_X, ABS_Y, ABS_Z) is reported in > > * units per millimeter (units/mm), resolution for rotational axes > > * (ABS_RX, ABS_RY, ABS_RZ) is reported in units per radian. > > > > Hope this helps. > > > Hi Dmitry, > > I understand this works for Dmitry ABS_X, ABS_Y, > touchscreen reports between 0..A, screen resolution is 0..B, a mapping > can be done 0..A -> 0..B > > But for ABS_MT_TOUCH_MAJOR how this scaling can be done, > touchscreen reports between 0..A, do we know the min/max values for > application side? I believe in normal (all?) cases we'd use the same resolution iand limits for ABS_MT_TOUCH_MAJOR/MINOR and ABS_X/Y and kernel not report any mix/max on ABS_MT_TOUCH_MAJOR/MINOR. Thanks. -- Dmitry -- 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
