filter: add two helper functions to convert between speeds

This makes it more obvious where we're using units/us and units/ms as input
variable and what the output is. Clutters up the code, but still better than
dealing with us/ms differently per function, and still better than carrying
all the 1000.0 multiplications/divisions manually.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>

diff --git a/src/filter.c b/src/filter.c
index 9aaf1f42ab5fdfd713df3d9fdd1b43fa489df5ca..425bc795c1c476ee0992b6c45dad957ded8bd675 100644 (file)
--- a/src/filter.c
+++ b/src/filter.c
@@ -36,6 +36,20 @@
 #include "libinput-util.h"
 #include "filter-private.h"
 
+/* Convert speed/velocity from units/us to units/ms */
+static inline double
+v_us2ms(double units_per_us)
+{
+       return units_per_us * 1000.0;
+}
+
+/* Convert speed/velocity from units/ms to units/us */
+static inline double
+v_ms2us(double units_per_ms)
+{
+       return units_per_ms/1000.0;
+}
+
 struct normalized_coords
 filter_dispatch(struct motion_filter *filter,
                const struct normalized_coords *unaccelerated,
@@ -77,8 +91,8 @@ filter_get_speed(struct motion_filter *filter)
  * Default parameters for pointer acceleration profiles.
  */
 
-#define DEFAULT_THRESHOLD 0.0004               /* in units/us */
-#define MINIMUM_THRESHOLD 0.0002               /* in units/us */
+#define DEFAULT_THRESHOLD v_ms2us(0.4)         /* in units/us */
+#define MINIMUM_THRESHOLD v_ms2us(0.2)         /* in units/us */
 #define DEFAULT_ACCELERATION 2.0               /* unitless factor */
 #define DEFAULT_INCLINE 1.1                    /* unitless factor */
 
@@ -86,7 +100,7 @@ filter_get_speed(struct motion_filter *filter)
  * Pointer acceleration filter constants
  */
 
-#define MAX_VELOCITY_DIFF      0.001 /* units/us */
+#define MAX_VELOCITY_DIFF      v_ms2us(1) /* units/us */
 #define MOTION_TIMEOUT         ms2us(1000)
 #define NUM_POINTER_TRACKERS   16
 
@@ -332,8 +346,12 @@ accelerator_set_speed(struct motion_filter *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 = DEFAULT_THRESHOLD - speed_adjustment / 4000.0;
+       accel_filter->threshold = DEFAULT_THRESHOLD -
+                                       v_ms2us(0.25) * speed_adjustment;
        if (accel_filter->threshold < MINIMUM_THRESHOLD)
                accel_filter->threshold = MINIMUM_THRESHOLD;
 
@@ -412,8 +430,8 @@ pointer_accel_profile_linear_low_dpi(struct motion_filter *filter,
 
        max_accel /= dpi_factor;
 
-       f1 = min(1, 0.3 + speed_in * 10000.0);
-       f2 = 1 + (speed_in * 1000.0 - threshold * dpi_factor * 1000.0) * incline;
+       f1 = min(1, 0.3 + v_us2ms(speed_in) * 10.0);
+       f2 = 1 + (v_us2ms(speed_in) - v_us2ms(threshold) * dpi_factor) * incline;
 
        factor = min(max_accel, f2 > 1 ? f2 : f1);
 
@@ -435,8 +453,8 @@ pointer_accel_profile_linear(struct motion_filter *filter,
        const double incline = accel_filter->incline;
        double factor; /* unitless */
 
-       f1 = min(1, 0.3 + speed_in * 10 * 1000.0);
-       f2 = 1 + (speed_in * 1000.0 - threshold * 1000.0) * incline;
+       f1 = min(1, 0.3 + v_us2ms(speed_in) * 10);
+       f2 = 1 + (v_us2ms(speed_in) - v_us2ms(threshold)) * incline;
 
        factor = min(max_accel, f2 > 1 ? f2 : f1);
 
@@ -493,8 +511,8 @@ touchpad_lenovo_x230_accel_profile(struct motion_filter *filter,
 
        speed_in *= TP_MAGIC_SLOWDOWN / TP_MAGIC_LOW_RES_FACTOR;
 
-       f1 = min(1, speed_in * 5 * 1000.0);
-       f2 = 1 + (speed_in  * 1000.0 - threshold * 1000.0) * incline;
+       f1 = min(1, v_us2ms(speed_in) * 5);
+       f2 = 1 + (v_us2ms(speed_in) - v_us2ms(threshold)) * incline;
 
        factor = min(max_accel, f2 > 1 ? f2 : f1);