This duplicates the code so we can change it for touchpads without affecting
mice.
Signed-off-by: Peter Hutterer <peter.hutte...@who-t.net>
---
src/filter.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 98 insertions(+), 5 deletions(-)
diff --git a/src/filter.c b/src/filter.c
index 06f07af..6f06ab9 100644
--- a/src/filter.c
+++ b/src/filter.c
@@ -117,6 +117,12 @@ filter_get_type(struct motion_filter *filter)
#define DEFAULT_ACCELERATION 2.0 /* unitless factor */
#define DEFAULT_INCLINE 1.1 /* unitless factor */
+/* Touchpad acceleration */
+#define TOUCHPAD_DEFAULT_THRESHOLD v_ms2us(0.4)
+#define TOUCHPAD_MINIMUM_THRESHOLD v_ms2us(0.2)
+#define TOUCHPAD_ACCELERATION 2.0 /* unitless factor */
+#define TOUCHPAD_INCLINE 1.1 /* unitless factor */
+
/* for the Lenovo x230 custom accel. do not touch */
#define X230_THRESHOLD v_ms2us(0.4) /* in units/us */
#define X230_ACCELERATION 2.0 /* unitless factor */
@@ -470,6 +476,34 @@ accelerator_filter_constant_x230(struct motion_filter
*filter,
return normalized;
}
+static bool
+touchpad_accelerator_set_speed(struct motion_filter *filter,
+ double speed_adjustment)
+{
+ struct pointer_accelerator *accel_filter =
+ (struct pointer_accelerator *)filter;
+
+ assert(speed_adjustment >= -1.0 && speed_adjustment <= 1.0);
+
+ /* Note: the numbers below are nothing but trial-and-error magic,
+ don't read more into them other than "they mostly worked ok" */
+
+ /* delay when accel kicks in */
+ accel_filter->threshold = TOUCHPAD_DEFAULT_THRESHOLD -
+ v_ms2us(0.25) * speed_adjustment;
+ if (accel_filter->threshold < TOUCHPAD_MINIMUM_THRESHOLD)
+ accel_filter->threshold = TOUCHPAD_MINIMUM_THRESHOLD;
+
+ /* adjust max accel factor */
+ accel_filter->accel = TOUCHPAD_ACCELERATION + speed_adjustment * 1.5;
+
+ /* higher speed -> faster to reach max */
+ accel_filter->incline = TOUCHPAD_INCLINE + speed_adjustment * 0.75;
+
+ filter->speed_adjustment = speed_adjustment;
+ return true;
+}
+
static struct normalized_coords
touchpad_constant_filter(struct motion_filter *filter,
const struct normalized_coords *unaccelerated,
@@ -662,15 +696,74 @@ pointer_accel_profile_linear(struct motion_filter *filter,
double
touchpad_accel_profile_linear(struct motion_filter *filter,
- void *data,
- double speed_in, /* units/us */
- uint64_t time)
+ void *data,
+ double speed_in, /* 1000-dpi normalized */
+ uint64_t time)
{
+ struct pointer_accelerator *accel_filter =
+ (struct pointer_accelerator *)filter;
+ const double max_accel = accel_filter->accel; /* unitless factor */
+ const double threshold = accel_filter->threshold; /* units/us */
+ const double incline = accel_filter->incline;
double factor; /* unitless */
speed_in *= TP_MAGIC_SLOWDOWN;
- factor = pointer_accel_profile_linear(filter, data, speed_in, time);
+ /*
+ Our acceleration function calculates a factor to accelerate input
+ deltas with. The function is a double incline with a plateau,
+ with a rough shape like this:
+
+ accel
+ factor
+ ^
+ | /
+ | _____/
+ | /
+ |/
+ +-------------> speed in
+
+ The two inclines are linear functions in the form
+ y = ax + b
+ where y is speed_out
+ x is speed_in
+ a is the incline of acceleration
+ b is minimum acceleration factor
+
+ for speeds up to 0.07 u/ms, we decelerate, down to 30% of input
+ speed.
+ hence 1 = a * 0.07 + 0.3
+ 0.3 = a * 0.07 => a := 10
+ deceleration function is thus:
+ y = 10x + 0.3
+
+ Note:
+ * 0.07u/ms as threshold is a result of trial-and-error and
+ has no other intrinsic meaning.
+ * 0.3 is chosen simply because it is above the Nyquist frequency
+ for subpixel motion within a pixel.
+ */
+ if (v_us2ms(speed_in) < 0.07) {
+ factor = 10 * v_us2ms(speed_in) + 0.3;
+ /* up to the threshold, we keep factor 1, i.e. 1:1 movement */
+ } else if (speed_in < threshold) {
+ factor = 1;
+ } else {
+ /* Acceleration function above the threshold:
+ y = ax' + b
+ where T is threshold
+ x is speed_in
+ x' is speed
+ and
+ y(T) == 1
+ hence 1 = ax' + 1
+ => x' := (x - T)
+ */
+ factor = incline * v_us2ms(speed_in - threshold) + 1;
+ }
+
+ /* Cap at the maximum acceleration factor */
+ factor = min(max_accel, factor);
return factor * TP_MAGIC_SLOWDOWN;
}
@@ -823,7 +916,7 @@ struct motion_filter_interface
accelerator_interface_touchpad = {
.filter_constant = touchpad_constant_filter,
.restart = accelerator_restart,
.destroy = accelerator_destroy,
- .set_speed = accelerator_set_speed,
+ .set_speed = touchpad_accelerator_set_speed,
};
struct motion_filter *
--
2.9.3
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