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 -- 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
