On 6/28/2010 6:17 PM, Henrik Rydberg wrote: > Joonyoung Shim wrote: >> On 6/28/2010 5:34 PM, Henrik Rydberg wrote: >>> Joonyoung Shim wrote: >>> [...] >>>> I see, but i have something wondering at your document. >>>> >>>> This is your patch of "Document the MT event slot protocol" >>>> >>>> +Protocol Example A >>>> +------------------ >>>> + >>>> +Here is what a minimal event sequence for a two-contact touch would look >>>> +like for a type A device: >>>> + >>>> + ABS_MT_POSITION_X x[0] >>>> + ABS_MT_POSITION_Y y[0] >>>> + SYN_MT_REPORT >>>> + ABS_MT_POSITION_X x[1] >>>> + ABS_MT_POSITION_Y y[1] >>>> + SYN_MT_REPORT >>>> + SYN_REPORT >>>> >>>> +The sequence after moving one of the contacts looks exactly the same; the >>>> +raw data for all present contacts are sent between every synchronization >>>> +with SYN_REPORT. >>>> >>>> -Usage >>>> ------ >>>> +Here is the sequence after lifting the first contact: >>>> + >>>> + ABS_MT_POSITION_X x[1] >>>> + ABS_MT_POSITION_Y y[1] >>>> + SYN_MT_REPORT >>>> + SYN_REPORT >>>> + >>>> +And here is the sequence after lifting the second contact: >>>> + >>>> + SYN_MT_REPORT >>>> + SYN_REPORT >>>> + >>>> >>>> Here, there is no reporting for ABS_MT_POSITION_X/Y event, because that >>>> is the last contact? >>>> Then, the coordinates of the first contact are x[1] and y[1], right? If >>>> yes, it is some confusing, i think they are x[0] and y[0]. >>> It is a bit confusing I agree, but the document is correct. The empty >>> input_mt_sync() is used when there is no data to report, no lifted fingers, >>> nothing. Just imagine a device which gets polled periodically. >>> >> The thing i wondering is why reports x[1] and y[1] instead of x[0] and >> y[0] after lifting the first contact. I have understood the first >> contact are x[0] and y[0] and the second contact are x[1] and y[1]. > > Yes, after lifting the first contact, what remains is the second contact, which > is the one getting reported. Again, stateless protocol. ;-) > Do you mean to report the coordinates of contact __remaining__? You told me at first, "The position should be the position where the finger left the surface", so i am confusing. -- 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
