This changes how the touch packets for Intuos5 and 3rd-gen Bamboo
are interpreted, so that proper values for the MAJOR and MINOR
axes are reported. Instead of using the amplitude field (data[6]),
we use the size field (data[5]) and do some calculation to
transform it from a scaled-down area into axis lengths.
Note that even though we assume a circular contact, both MAJOR and
MINOR are reported since the resolution of the X and Y axes differ.
---
Changes from v1:
* Changed name from "Use touch size for ABS_MT_TOUCH_MAJOR"
* Also populate ABS_MT_TOUCH_MINOR to avoid some userspace
assumptions.
* Experimentally determined the calculations necessary to produce
proper values instead of simply using the raw value in data[5].
drivers/input/tablet/wacom_wac.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/drivers/input/tablet/wacom_wac.c b/drivers/input/tablet/wacom_wac.c
index 004bc1b..940caf3 100644
--- a/drivers/input/tablet/wacom_wac.c
+++ b/drivers/input/tablet/wacom_wac.c
@@ -25,6 +25,11 @@
#define WACOM_INTUOS_RES 100
#define WACOM_INTUOS3_RES 200
+/* Scale factor relating reported contact size to logical contact area.
+ * 2^14/pi is a good approximation on Intuos5 and 3rd-gen Bamboo
+ */
+#define WACOM_CONTACT_AREA_SCALE 5215
+
static int wacom_penpartner_irq(struct wacom_wac *wacom)
{
unsigned char *data = wacom->data;
@@ -1036,11 +1041,21 @@ static void wacom_bpt3_touch_msg(struct wacom_wac *wacom, unsigned char *data)
if (touch) {
int x = (data[2] << 4) | (data[4] >> 4);
int y = (data[3] << 4) | (data[4] & 0x0f);
- int w = data[6];
+ int a = data[5];
+
+ // "a" is a scaled-down area which we assume is roughly
+ // circular and which can be described as: a*C=(pi*r^2).
+ int x_res = input_abs_get_res(input, ABS_X);
+ int y_res = input_abs_get_res(input, ABS_Y);
+ int logical_diameter = 2 * int_sqrt(a * WACOM_CONTACT_AREA_SCALE);
+ int physical_diameter = logical_diameter / ((x_res + y_res) / 2);
+ int logical_width = physical_diameter * x_res;
+ int logical_height = physical_diameter * y_res;
input_report_abs(input, ABS_MT_POSITION_X, x);
input_report_abs(input, ABS_MT_POSITION_Y, y);
- input_report_abs(input, ABS_MT_TOUCH_MAJOR, w);
+ input_report_abs(input, ABS_MT_TOUCH_MAJOR, logical_width);
+ input_report_abs(input, ABS_MT_TOUCH_MINOR, logical_height);
}
}
@@ -1520,7 +1535,9 @@ int wacom_setup_input_capabilities(struct input_dev *input_dev,
input_mt_init_slots(input_dev, features->touch_max);
input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR,
- 0, 255, 0, 0);
+ 0, features->x_max, 0, 0);
+ input_set_abs_params(input_dev, ABS_MT_TOUCH_MINOR,
+ 0, features->y_max, 0, 0);
input_set_abs_params(input_dev, ABS_MT_POSITION_X,
0, features->x_max,
@@ -1625,7 +1642,10 @@ int wacom_setup_input_capabilities(struct input_dev *input_dev,
input_set_abs_params(input_dev,
ABS_MT_TOUCH_MAJOR,
- 0, 255, 0, 0);
+ 0, features->x_max, 0, 0);
+ input_set_abs_params(input_dev,
+ ABS_MT_TOUCH_MINOR,
+ 0, features->y_max, 0, 0);
}
input_set_abs_params(input_dev, ABS_MT_POSITION_X,
--
1.7.10.2
--
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