On Sun, Dec 28, 2008 at 11:58:57PM +0100, Henrik Rydberg wrote: > 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. To clarify: the MT_TOUCH_MAJOR is to track a touchpoint over time, and the BLOB_ID to compile a arbitrarily shaped touchpoint within the same event? Would it make sense to allow specification of a blob as bit/bytemask? There are a few devices that can do detection of multi-color non-rectangular touchpoints, especially camera-based systems. Limiting these to a sequence of rectangles means dropping information that may be useful for certain tasks (e.g. fingerprint detection). OTOH, a rectangle as bounding box with an accompanying (optional) bytemask can pass this data on to prospective clients. 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
