From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Ferruh Yigit <fery@cypress.com>
Cc: "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
Henrik Rydberg <rydberg@euromail.se>
Subject: Re: ABS_MT_TOUCH_MAJOR metric
Date: Thu, 22 May 2014 10:23:53 -0700 [thread overview]
Message-ID: <20140522172353.GA1984@core.coreip.homeip.net> (raw)
In-Reply-To: <537DD98C.5090800@cypress.com>
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.
--
Dmitry
next prev parent reply other threads:[~2014-05-22 17:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-22 11:03 ABS_MT_TOUCH_MAJOR metric Ferruh Yigit
2014-05-22 17:23 ` Dmitry Torokhov [this message]
2014-05-22 19:29 ` Ferruh Yigit
2014-05-22 19:42 ` Dmitry Torokhov
2014-05-22 19:45 ` Michael Wright
2014-05-22 19:46 ` Henrik Rydberg
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