On Fri, May 21, 2010 at 11:25:41PM +0200, Henrik Rydberg wrote: > Ping Cheng wrote: > > On Fri, May 21, 2010 at 8:19 AM, Rafi Rubin <rafi@xxxxxxxxxxxxxx> wrote: > [...] > >> Ping: please confirm, are you actually talking about each finger simultaneously sending multiple positions? > > > > You are definitely on the right track. The fingers/touch objects can > > be represented two-dimensionally (x,y) instead of one-dimensionally > > (ABS_MT_TRACKING_ID). I think we can survive with the current MT_BLOB > > definition although some optimization would be helpful, especially for > > filtering. For the sake of Henrik great effort, I'd like to see his > > current patchset gets in the tree before we start another round of > > "suggestions". > > > > Thank you for asking. > > Regarding blobs, I confused myself yesterday. The original intention of the blob > id was in fact to be able to "paint" more generic contact forms. However, no > driver has come close to doing this yet, so it has gotten close to no attention. > Now, to address the question of how to communicate more elaborate contact forms, > it seems one can combine the two goals "one position per slot" and "multiple > positions per contact" by simply repeating the same tracking id for a set of > slots, like this: > > ABS_SLOT 0 > ABS_MT_TRACKING_ID 14 > ABS_MT_POSITION_X x[0] > ABS_MT_POSITION_Y y[0] > ABS_SLOT 1 > ABS_MT_TRACKING_ID 14 > ABS_MT_POSITION_X x[1] > ABS_MT_POSITION_Y y[1] > ABS_SLOT 2 > ABS_MT_TRACKING_ID 14 > ABS_MT_POSITION_X x[2] > ABS_MT_POSITION_Y y[2] > > Not all too different from what you suggested, and there is no blob id involved > at all. And yes, it would require additional parsing power at the user end. > Something for later. This is confusing me now :) How would a device get multiple x/y coordinates for a single contact? I could understand a range of coordinates but that's what we have the ABS_MT_WIDTH_MAJOR/MINOR for. If a touchpoint sends two different x/y coordinates, wouldn't that be two touchpoints, tracked individually and thus with a different tracking ID? I read the example above as _the_ example for using blob IDs to combine multiple contacts into one semantic contact. Cheers, Peter -- 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
