touchpad: don't feed 0/0 deltas into the accel filters

[platform/upstream/libinput.git] / src / filter.c

diff --git a/src/filter.c b/src/filter.c
index 7db78ba..5b0b877 100644 (file)
--- a/src/filter.c
+++ b/src/filter.c
@@ -51,8 +51,7 @@ filter_destroy(struct motion_filter *filter)
  * Default parameters for pointer acceleration profiles.
  */
 
-#define DEFAULT_CONSTANT_ACCELERATION 10.0     /* unitless factor */
-#define DEFAULT_THRESHOLD 4.0                  /* in units/ms */
+#define DEFAULT_THRESHOLD 0.4                  /* in units/ms */
 #define DEFAULT_ACCELERATION 2.0               /* unitless factor */
 
 /*
@@ -335,13 +334,13 @@ pointer_accel_profile_smooth_simple(struct motion_filter *filter,
        double threshold = DEFAULT_THRESHOLD; /* units/ms */
        double accel = DEFAULT_ACCELERATION; /* unitless factor */
        double smooth_accel_coefficient; /* unitless factor */
+       double factor; /* unitless factor */
 
-       if (threshold < 1.0)
-               threshold = 1.0;
+       if (threshold < 0.1)
+               threshold = 0.1;
        if (accel < 1.0)
                accel = 1.0;
 
-       velocity *= DEFAULT_CONSTANT_ACCELERATION;
 
        if (velocity < (threshold / 2.0))
                return calc_penumbral_gradient(0.5 + velocity / threshold) * 2.0 - 1.0;
@@ -349,12 +348,12 @@ pointer_accel_profile_smooth_simple(struct motion_filter *filter,
        if (velocity <= threshold)
                return 1.0;
 
-       velocity /= threshold;
-       if (velocity >= accel)
+       factor = velocity/threshold;
+       if (factor >= accel)
                return accel;
 
-       /* Velocity is between 1.0 and accel, scale this to 0.0 - 1.0 */
-       velocity = (velocity - 1.0) / (accel - 1.0);
-       smooth_accel_coefficient = calc_penumbral_gradient(velocity);
+       /* factor is between 1.0 and accel, scale this to 0.0 - 1.0 */
+       factor = (factor - 1.0) / (accel - 1.0);
+       smooth_accel_coefficient = calc_penumbral_gradient(factor);
        return 1.0 + (smooth_accel_coefficient * (accel - 1.0));
 }