From mboxrd@z Thu Jan 1 00:00:00 1970 From: Henrik Rydberg Subject: Re: ABS_MT_TOUCH_MAJOR metric Date: Thu, 22 May 2014 21:46:09 +0200 Message-ID: <537E5401.9000109@euromail.se> References: <537DD98C.5090800@cypress.com> <20140522172353.GA1984@core.coreip.homeip.net> <537E5027.9010705@cypress.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from smtprelay-h21.telenor.se ([195.54.99.196]:53759 "EHLO smtprelay-h21.telenor.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750890AbaEVUBY (ORCPT ); Thu, 22 May 2014 16:01:24 -0400 Received: from ipb1.telenor.se (ipb1.telenor.se [195.54.127.164]) by smtprelay-h21.telenor.se (Postfix) with ESMTP id DF1EEC345 for ; Thu, 22 May 2014 21:41:08 +0200 (CEST) In-Reply-To: <537E5027.9010705@cypress.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Ferruh Yigit , Dmitry Torokhov Cc: "linux-input@vger.kernel.org" Ferruh, > 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? You are right to be confused here. The axes you refer to are, in a way, meaningless because both TOUCH_MAJOR and TOUCH_MINOR (and the corresponding WIDTH_MAJOR and WIDTH_MINOR) are assumed to be measured in surface coordinates, i.e., of the same scale as ABS_X and ABS_Y. Historically, these axes have had specific values anyways, as an indication of how large a touch area can be a the specific device. This is how userland MT applications interpret the data. Strictly speaking, this is incorrect, but that's how it is. Henrik