On Wed, Dec 8, 2010 at 3:58 PM, Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote: > 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, No, we are not talking about non-rectangular shape here. Envelop is always a rectangle. By rectangle above, I meant 2 touches. An envelop that includes number of touches offers us more information than a rectangle does. Ping > 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
