Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758290Ab2EDNns (ORCPT ); Fri, 4 May 2012 09:43:48 -0400 Received: from smtprelay-b12.telenor.se ([62.127.194.21]:56691 "EHLO smtprelay-b12.telenor.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756713Ab2EDNnr (ORCPT ); Fri, 4 May 2012 09:43:47 -0400 X-SENDER-IP: [85.230.168.62] X-LISTENER: [smtp.bredband.net] X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ar6CAKbco09V5qg+PGdsb2JhbABFijCnDgSBIBkBAQEBNzSCCQEBBAE6HCMFCwgDRhQlChqIGwm7DBOLGoR9YwSVfYYGg1WJUg X-IronPort-AV: E=Sophos;i="4.75,531,1330902000"; d="scan'208";a="105449777" From: "Henrik Rydberg" Date: Fri, 4 May 2012 15:48:31 +0200 To: "benjamin.tissoires" Cc: Dmitry Torokhov , Jiri Kosina , Stephane Chatty , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/5] input: Introduce MT_CENTER_X and MT_CENTER_Y Message-ID: <20120504134831.GA8263@polaris.bitmath.org> References: <1336136030-18503-1-git-send-email-benjamin.tissoires@gmail.com> <1336136030-18503-5-git-send-email-benjamin.tissoires@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1336136030-18503-5-git-send-email-benjamin.tissoires@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1190 Lines: 26 Hi Benjamin, Stephane, > Microsoft published a new version of their multitouch specification. > They introduced a new multitouch field: MT_CENTER_X|Y. I would like a bit of elaboration here, since I am not convinced the mapping should be directly translated to the MT protocol. Clearly, the basic idea to be able to model an assymmetric tool is good. Without an angle description, however, there seems to be a mismatch in the degrees of freedom. In win8, one can place the hot spot in a corner of the rectangle, but one cannot make the rectangle into an ellipse in that direction. In linux, one can put the ellipse in the wanted direction, but the hot spot is always in the center. To first order, both models allow for finger-rotation information, but in different ways. Adding more parameters requires a bit more thought. Perhaps one should use the newly found win8 parameters to reshape the pointing ellipse to start with. Thanks, Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/