Use smoothed version of sensor array data to calculate movement and add weight
to prior values when calculating average. This gives more granular and more
predictable movement.
Signed-off-by: Clinton Sprain <clintonsprain@xxxxxxxxx>
---
drivers/input/mouse/appletouch.c | 72 ++++++++++++++++++++++++++++----------
1 file changed, 53 insertions(+), 19 deletions(-)
diff --git a/drivers/input/mouse/appletouch.c b/drivers/input/mouse/appletouch.c
index 2745832..0252bab 100644
--- a/drivers/input/mouse/appletouch.c
+++ b/drivers/input/mouse/appletouch.c
@@ -332,7 +332,11 @@ static void atp_reinit(struct work_struct *work)
static int atp_calculate_abs(int *xy_sensors, int nb_sensors, int fact,
int *z, int *fingers)
{
- int i;
+ int i, k;
+ int smooth[nb_sensors + 8];
+ int smooth_tmp[nb_sensors + 8];
+ int scale = 12;
+
/* values to calculate mean */
int pcum = 0, psum = 0;
int is_increasing = 0;
@@ -344,9 +348,6 @@ static int atp_calculate_abs(int *xy_sensors, int nb_sensors, int fact,
if (is_increasing)
is_increasing = 0;
- continue;
- }
-
/*
* Makes the finger detection more versatile. For example,
* two fingers with no gap will be detected. Also, my
@@ -361,27 +362,60 @@ static int atp_calculate_abs(int *xy_sensors, int nb_sensors, int fact,
*
* - Jason Parekh <jasonparekh@xxxxxxxxx>
*/
- if (i < 1 ||
+
+ } else if (i < 1 ||
(!is_increasing && xy_sensors[i - 1] < xy_sensors[i])) {
(*fingers)++;
is_increasing = 1;
} else if (i > 0 && (xy_sensors[i - 1] - xy_sensors[i] > threshold)) {
is_increasing = 0;
}
+ }
- /*
- * Subtracts threshold so a high sensor that just passes the
- * threshold won't skew the calculated absolute coordinate.
- * Fixes an issue where slowly moving the mouse would
- * occasionally jump a number of pixels (slowly moving the
- * finger makes this issue most apparent.)
- */
- pcum += (xy_sensors[i] - threshold) * i;
- psum += (xy_sensors[i] - threshold);
+ /*
+ * Use a smoothed version of sensor data for movement calculations, to
+ * combat noise without needing to rely so heavily on a threshold.
+ * This improves tracking.
+ *
+ * The smoothed array is bigger than the original so that the smoothing
+ * doesn't result in edge values being truncated.
+ */
+
+ for (i = 0; i < 4; i++)
+ smooth[i] = 0;
+ for (i = nb_sensors + 4; i < nb_sensors + 8; i++)
+ smooth[i] = 0;
+
+ /* Pull base values, scaled up to help avoid truncation errors. */
+
+ for (i = 0; i < nb_sensors; i++)
+ smooth[i + 4] = xy_sensors[i] << scale;
+
+ for (k = 0; k < 4; k++) {
+
+ /* Handle edge. */
+ smooth_tmp[0] = (smooth[0] * 1 + smooth[1]) >> 1;
+
+ /* Average values with neighbors. */
+ for (i = 1; i < nb_sensors + 7; i++)
+ smooth_tmp[i] = (smooth[i - 1] + smooth[i] * 2 + smooth[i + 1]) >> 2;
+
+ /* Handle other edge. */
+ smooth_tmp[nb_sensors + 7] = (smooth[nb_sensors + 7] + smooth[nb_sensors + 6]) >> 1;
+
+ for (i = 0; i < nb_sensors + 7; i++)
+ smooth[i] = smooth_tmp[i];
+ }
+
+ for (i = 0; i < nb_sensors + 8; i++) {
+ if ((smooth[i] >> scale) > 0) { /* Skip individual values if */
+ pcum += (smooth[i]) * i; /* they are small enough to */
+ psum += (smooth[i]); /* be truncated to 0 by our */
+ } /* scale; mostly just noise. */
}
if (psum > 0) {
- *z = psum;
+ *z = psum >> scale; /* Scale down pressure output. */
return pcum * fact / psum;
}
@@ -559,8 +593,8 @@ static void atp_complete_geyser_1_2(struct urb *urb)
if (x && y) {
if (dev->x_old != -1) {
- x = (dev->x_old * 3 + x) >> 2;
- y = (dev->y_old * 3 + y) >> 2;
+ x = (dev->x_old * 7 + x) >> 3;
+ y = (dev->y_old * 7 + y) >> 3;
dev->x_old = x;
dev->y_old = y;
@@ -671,8 +705,8 @@ static void atp_complete_geyser_3_4(struct urb *urb)
if (x && y) {
if (dev->x_old != -1) {
- x = (dev->x_old * 3 + x) >> 2;
- y = (dev->y_old * 3 + y) >> 2;
+ x = (dev->x_old * 7 + x) >> 3;
+ y = (dev->y_old * 7 + y) >> 3;
dev->x_old = x;
dev->y_old = y;
--
1.7.9.5
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