Re: [PATCH 6/6] input: Add a detailed multi-touch finger data report protocol (rev2)

[Joon Young Shim <dofmind@gmail.com>]

2009/1/28 Henrik Rydberg <rydberg@euromail.se>:
> In order to utilize the full power of the new multi-touch devices, a
> way to report detailed finger data to user space is needed. This patch
> adds a multi-touch (MT) protocol which allows drivers to report details
> for an arbitrary number of fingers.
>
> The driver sends a SYN_MT_REPORT event via the input_mt_sync() function
> when a complete finger has been reported.
>
> In order to stay compatible with existing applications, the data
> reported in a finger packet must not be recognized as single-touch
> events. In addition, all finger data must bypass input filtering,
> since subsequent events of the same type refer to different fingers.
>
> A set of ABS_MT events with the desired properties are defined. The
> events are divided into categories, to allow for partial implementation.
> The minimum set consists of ABS_MT_TOUCH_MAJOR, ABS_MT_POSITION_X and
> ABS_MT_POSITION_Y, which allows for multiple fingers to be tracked.
> If the device supports it, the ABS_MT_WIDTH_MAJOR may be used to provide
> the size of the approaching finger. Anisotropy and direction may be
> specified with ABS_MT_TOUCH_MINOR, ABS_MT_WIDTH_MINOR and
> ABS_MT_ORIENTATION. Devices with more granular information may specify
> general shapes as blobs, i.e., as a sequence of rectangular shapes
> grouped together by a ABS_MT_BLOB_ID. Finally, the ABS_MT_TOOL_TYPE
> may be used to specify whether the touching tool is a finger or a pen.


Hi Henrik,

I want to know how calculates touch coordinates at user space using a
set of ABS_MT.
If i do dual touch, can i get correct two coordinates through ABS_MT report?


Joonyoung