[PATCH libinput 3/3] filter: move the pointer acceleration profiles back to units/ms

Jonas Ådahl jadahl at gmail.com
Thu Jul 30 23:37:52 PDT 2015


On Fri, Jul 31, 2015 at 04:19:03PM +1000, Peter Hutterer wrote:
> There is no need here to use µs since we're just handling speeds/thresholds,
> not actual events where a ms granularity can be too high.
> 
> Moving back to ms lets us drop a bunch of zeroes that clutter up the code, and
> since the acceleration functions are a bit magic anyway, having the various
> 1000.0 factors in there makes it even less obvious.
> 
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
> ---
>  src/filter.c           | 38 +++++++++++++++++++-------------------
>  tools/ptraccel-debug.c |  4 ++--
>  2 files changed, 21 insertions(+), 21 deletions(-)
> 
> diff --git a/src/filter.c b/src/filter.c
> index 54ae397..f5a3748 100644
> --- a/src/filter.c
> +++ b/src/filter.c
> @@ -77,7 +77,7 @@ filter_get_speed(struct motion_filter *filter)
>   * Default parameters for pointer acceleration profiles.
>   */
>  
> -#define DEFAULT_THRESHOLD 0.0004		/* in units/us */
> +#define DEFAULT_THRESHOLD 0.4			/* in units/ms */
>  #define DEFAULT_ACCELERATION 2.0		/* unitless factor */
>  #define DEFAULT_INCLINE 1.1			/* unitless factor */
>  
> @@ -220,7 +220,7 @@ calculate_velocity(struct pointer_accelerator *accel, uint64_t time)
>  		}
>  	}
>  
> -	return result; /* units/us */
> +	return result * 1000; /* units/ms */

Did you consider changing velocity back to units/ms everywhere, i.e.
calculate_tracker_velocity? Doing it here would mean "velocity" means
different depending on where in the code it is.

Also, I wonder how I could have missed 2/3. Sorry about that.

With the above comment in mind, these three are still Reviewed-by: Jonas
Ådahl <jadahl at gmail.com>


>  }
>  
>  static double
> @@ -256,11 +256,11 @@ calculate_acceleration(struct pointer_accelerator *accel,
>  static struct normalized_coords
>  accelerator_filter(struct motion_filter *filter,
>  		   const struct normalized_coords *unaccelerated,
> -		   void *data, uint64_t time)
> +		   void *data, uint64_t time /* in us */)
>  {
>  	struct pointer_accelerator *accel =
>  		(struct pointer_accelerator *) filter;
> -	double velocity; /* units/us */
> +	double velocity; /* units/ms */
>  	double accel_value; /* unitless factor */
>  	struct normalized_coords accelerated;
>  	struct normalized_coords unnormalized;
> @@ -397,23 +397,23 @@ create_pointer_accelerator_filter(accel_profile_func_t profile,
>  double
>  pointer_accel_profile_linear_low_dpi(struct motion_filter *filter,
>  				     void *data,
> -				     double speed_in, /* in device units (units/us) */
> -				     uint64_t time)
> +				     double speed_in, /* in device units (units/ms) */
> +				     uint64_t time /* in us */)
>  {
>  	struct pointer_accelerator *accel_filter =
>  		(struct pointer_accelerator *)filter;
>  
>  	double s1, s2;
>  	double max_accel = accel_filter->accel; /* unitless factor */
> -	const double threshold = accel_filter->threshold; /* units/us */
> +	const double threshold = accel_filter->threshold; /* units/ms */
>  	const double incline = accel_filter->incline;
>  	double factor;
>  	double dpi_factor = accel_filter->dpi_factor;
>  
>  	max_accel /= dpi_factor;
>  
> -	s1 = min(1, 0.3 + speed_in * 10000.0);
> -	s2 = 1 + (speed_in * 1000.0 - threshold * dpi_factor * 1000.0) * incline;
> +	s1 = min(1, 0.3 + speed_in * 10.0);
> +	s2 = 1 + (speed_in - threshold * dpi_factor) * incline;
>  
>  	factor = min(max_accel, s2 > 1 ? s2 : s1);
>  
> @@ -424,19 +424,19 @@ double
>  pointer_accel_profile_linear(struct motion_filter *filter,
>  			     void *data,
>  			     double speed_in, /* 1000-dpi normalized */
> -			     uint64_t time)
> +			     uint64_t time /* in us */)
>  {
>  	struct pointer_accelerator *accel_filter =
>  		(struct pointer_accelerator *)filter;
>  
>  	double s1, s2;
>  	const double max_accel = accel_filter->accel; /* unitless factor */
> -	const double threshold = accel_filter->threshold; /* units/us */
> +	const double threshold = accel_filter->threshold; /* units/ms */
>  	const double incline = accel_filter->incline;
>  	double factor;
>  
> -	s1 = min(1, 0.3 + speed_in * 10 * 1000.0);
> -	s2 = 1 + (speed_in * 1000.0 - threshold * 1000.0) * incline;
> +	s1 = min(1, 0.3 + speed_in * 10);
> +	s2 = 1 + (speed_in - threshold) * incline;
>  
>  	factor =  min(max_accel, s2 > 1 ? s2 : s1);
>  
> @@ -446,8 +446,8 @@ pointer_accel_profile_linear(struct motion_filter *filter,
>  double
>  touchpad_accel_profile_linear(struct motion_filter *filter,
>                                void *data,
> -                              double speed_in,
> -                              uint64_t time)
> +			      double speed_in,
> +			      uint64_t time /* in us */)
>  {
>  	/* Once normalized, touchpads see the same
>  	   acceleration as mice. that is technically correct but
> @@ -468,7 +468,7 @@ double
>  touchpad_lenovo_x230_accel_profile(struct motion_filter *filter,
>  				      void *data,
>  				      double speed_in,
> -				      uint64_t time)
> +				      uint64_t time /* in us */)
>  {
>  	/* Keep the magic factor from touchpad_accel_profile_linear.  */
>  	const double TP_MAGIC_SLOWDOWN = 0.4;
> @@ -488,13 +488,13 @@ touchpad_lenovo_x230_accel_profile(struct motion_filter *filter,
>  	const double max_accel = accel_filter->accel *
>  				  TP_MAGIC_LOW_RES_FACTOR; /* unitless factor */
>  	const double threshold = accel_filter->threshold /
> -				  TP_MAGIC_LOW_RES_FACTOR; /* units/us */
> +				  TP_MAGIC_LOW_RES_FACTOR; /* units/ms */
>  	const double incline = accel_filter->incline * TP_MAGIC_LOW_RES_FACTOR;
>  
>  	speed_in *= TP_MAGIC_SLOWDOWN / TP_MAGIC_LOW_RES_FACTOR;
>  
> -	s1 = min(1, speed_in * 5 * 1000.0);
> -	s2 = 1 + (speed_in  * 1000.0 - threshold * 1000.0) * incline;
> +	s1 = min(1, speed_in * 5);
> +	s2 = 1 + (speed_in - threshold) * incline;
>  
>  	speed_out = min(max_accel, s2 > 1 ? s2 : s1);
>  
> diff --git a/tools/ptraccel-debug.c b/tools/ptraccel-debug.c
> index b0867db..1496763 100644
> --- a/tools/ptraccel-debug.c
> +++ b/tools/ptraccel-debug.c
> @@ -147,12 +147,12 @@ print_accel_func(struct motion_filter *filter)
>  	printf("# set ylabel \"raw accel factor\"\n");
>  	printf("# set style data lines\n");
>  	printf("# plot \"gnuplot.data\" using 1:2\n");
> -	for (vel = 0.0; vel < 0.003; vel += 0.0000001) {
> +	for (vel = 0.0; vel < 3.0; vel += .0001) {
>  		double result = pointer_accel_profile_linear(filter,
>                                                               NULL,
>                                                               vel,
>                                                               0 /* time */);
> -		printf("%.8f\t%.4f\n", vel, result);
> +		printf("%.4f\t%.4f\n", vel, result);
>  	}
>  }
>  
> -- 
> 2.4.3
> 
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