On 01/30/2012 01:23 PM, Jussi Pakkanen wrote: > On 01/30/2012 10:35 AM, Henrik Rydberg wrote: >> +INPUT_PROP_SEMI_MT: >> +------------------ >> +Some touchpads, most common between 2008 and 2011, can detect the presence >> +of multiple contacts without resolving the individual positions; only the >> +number of contacts and the corresponding bounding box is known. For such >> +touchpads, the semi-mt property should be set. > > A "corresponding bounding box" usually means "a bounding box that > contains all touches on the touchpad". I've been told (though I have not > checked it myself) that there are devices that don't do this. They only > report a bounding box for some subset of touches. If this is the case, > it should be documented here. Yeah, I thought Henrik's definition was correct for a long time, but when Derek Foreman (I think) proposed some patches for the latest synaptics devices I took a closer look at my semi-mt synaptics trackpad. The coordinates it gave were locations based on two of the touches. When three touches are on the touchpad, it gave a bounding box of two of the touches, and there's no way to tell which two. -- 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
