From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chase Douglas Subject: Re: [PATCH] Input: wacom - Add POINTER and DIRECT device properties Date: Mon, 19 Sep 2011 16:40:46 -0700 Message-ID: <4E77D2FE.8060709@gmail.com> References: <1314892843-1475-1-git-send-email-killertofu@gmail.com> <20110913080911.GA4986@polaris.bitmath.org> <20110914071524.GA3422@polaris.bitmath.org> <20110916105036.GA4455@polaris.bitmath.org> <20110917112114.GA3015@polaris.bitmath.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-yi0-f46.google.com ([209.85.218.46]:34881 "EHLO mail-yi0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751666Ab1ISXkw (ORCPT ); Mon, 19 Sep 2011 19:40:52 -0400 Received: by yie30 with SMTP id 30so4504341yie.19 for ; Mon, 19 Sep 2011 16:40:52 -0700 (PDT) In-Reply-To: <20110917112114.GA3015@polaris.bitmath.org> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Henrik Rydberg Cc: Jason Gerecke , Ping Cheng , Mohamed Ikbel Boulabiar , Linux Input On 09/17/2011 04:21 AM, Henrik Rydberg wrote: > Hi Jason, > >>>> Take Wacom's Intuos and Graphire series for example, those tablets >>>> support both styli and mice. For styli, the default is absolute mode; >>>> while for mice, it is relative. So, only valid property the tablet can >>>> tell the user-land is: I am a tablet, i.e., not a touchscreen. Clients >>>> have to check the tool types to set the default mode to relative >>>> (BTN_TOOL_MOUSE/LENS) or absolute (BTN_TOOL_PEN/AIRBRUSH/RUBBER...). >>> >>> And those modes can be determined using the available axes. However, >>> when all axes are the same, a statement like "I am a tablet" does not >>> exist. In that case, distinguishing between touchscreen, touchpad and >>> tablet becomes a question of interpreting the properties. Such a >>> distinction cannot be achieved using a single bit of information, and >>> that was never the intention. >>> >> It is certainly true that you cannot separate out the different cases >> with a single bit. The more properties and hints we can expose to >> userspace the better. However, at the device level, there's only so >> much information we *can* expose. We know if its a direct input device >> or not. We don't know if its relative or absolute, since that depends >> on the tool in use at any given moment. > > It seems the various arguments we have seen in this thread are all > logical and well founded, but they originate in different assumptions > about the semantics of POINTER and DIRECT. Such a debate does > obviously not satisfy everyone. > > The original intention of the properties are these: > > POINTER - The device needs a visual guide in order to be useful. In > most cirumstances, this is equivalent to not having a screen directly > beneath the surface. > > DIRECT - The input device is to be used as if it was overlaying a > sreen. It could be separate from the screen, but the expected behavior > should be the same. > > From these definitions, it follows that a device could well be both > POINTER and DIRECT. For instance, a multitouch tablet designed to > replace the keyboard would fall into this category. I think these are the clearest definitions I've seen of these properties. It would be good to get them documented in Documentation/input. Henrik, would you be able to do this? -- Chase