On Wed, Dec 08, 2010 at 03:43:51PM -0800, Ping Cheng wrote: > On Wed, Dec 8, 2010 at 9:43 AM, Chase Douglas > <chase.douglas@xxxxxxxxxxxxx> wrote: > > On 12/07/2010 03:29 AM, Henrik Rydberg wrote: > >> Some touch devices are capable of detecting the envelope or hull > >> of the touches, but not the touches themselves. This patch adds > >> the MT_TOOL_ENVELOPE touch type to be used for such devices. > >> > >> Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx> > >> --- > >> Hi all, > >> > >> This patch represents an MT solution for those devices that can detect > >> and report some effects of dual touch, but cannot report individual > >> contacts. Synaptics and elantech are two examples. Having the drivers > >> report the bounding rectangle of the touches is useful in userland, > >> since the information makes it possible to implement zooming > >> gestures. At the same time, it would be confusing to send these > >> envelope points as fingers, since they clearly are not. As a remedy, > >> introduce MT_TOOL_ENVELOPE, which tells applications that care about > >> details that these are not real fingers, at the same time as it allows > >> gesture applications based on MT data to function without > >> modification. > > > > Is it assumed that the envelop has only two touches comprising it? Or is > > it any number of touches? If it's any number of touches, how does one > > know how many touches it is? > > Those are good questions. Specifying how many touches are in the > envelop makes sense. It also covers rectangle as a special case of > envelop. I have a feeling that trying to accomodate non-rectangular, more than 2 point shapes without using native MT data is over-engineering the problem... Do we have examples other than older generation Elantechs and Synaptics that need envelope notion? -- Dmitry -- 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
