diff options
Diffstat (limited to 'Documentation/input/multi-touch-protocol.rst')
| -rw-r--r-- | Documentation/input/multi-touch-protocol.rst | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/Documentation/input/multi-touch-protocol.rst b/Documentation/input/multi-touch-protocol.rst index 307fe22d9668..47d3dcb5d44b 100644 --- a/Documentation/input/multi-touch-protocol.rst +++ b/Documentation/input/multi-touch-protocol.rst @@ -260,6 +260,10 @@ ABS_MT_PRESSURE of TOUCH and WIDTH for pressure-based devices or any device with a spatial signal intensity distribution. + If the resolution is zero, the pressure data is in arbitrary units. + If the resolution is non-zero, the pressure data is in units/gram. See + :ref:`input-event-codes` for details. + ABS_MT_DISTANCE The distance, in surface units, between the contact and the surface. Zero distance means the contact is touching the surface. A positive number means @@ -275,14 +279,14 @@ ABS_MT_ORIENTATION max should be returned; when aligned with the X axis in the negative direction, the range -max should be returned. - Touch ellipsis are symmetrical by default. For devices capable of true 360 + Touch ellipses are symmetrical by default. For devices capable of true 360 degree orientation, the reported orientation must exceed the range max to indicate more than a quarter of a revolution. For an upside-down finger, range max * 2 should be returned. Orientation can be omitted if the touch area is circular, or if the information is not available in the kernel driver. Partial orientation - support is possible if the device can distinguish between the two axis, but + support is possible if the device can distinguish between the two axes, but not (uniquely) any values in between. In such cases, the range of ABS_MT_ORIENTATION should be [0, 1] [#f4]_. @@ -352,7 +356,7 @@ The range of ABS_MT_ORIENTATION should be set to [0, 1], to indicate that the device can distinguish between a finger along the Y axis (0) and a finger along the X axis (1). -For win8 devices with both T and C coordinates, the position mapping is:: +For Win8 devices with both T and C coordinates, the position mapping is:: ABS_MT_POSITION_X := T_X ABS_MT_POSITION_Y := T_Y @@ -379,7 +383,7 @@ Finger Tracking --------------- The process of finger tracking, i.e., to assign a unique trackingID to each -initiated contact on the surface, is a Euclidian Bipartite Matching +initiated contact on the surface, is a Euclidean Bipartite Matching problem. At each event synchronization, the set of actual contacts is matched to the set of contacts from the previous synchronization. A full implementation can be found in [#f3]_. |