[PATCH libinput v2] evdev-mt-touchpad: Switch to smooth simple acceleration code from filter.c

[Peter Hutterer]

On Tue, Jul 01, 2014 at 02:53:18PM +0200, Hans de Goede wrote:
> The old touchpad accel code was clamping touchpad acceleration between
> 0.2 and 0.4, and on the test devices I have the constant_factor ended up
> such that in practice the accel was almost always 0.2, so rather than having
> a velocity based acceleration curve, in essence it was just always using an
> acceleration of 0.2 .
> 
> This commit introduces actual velocity based acceleration based on the
> recently added smooth simple acceleration code from filter.c .
> 
> Before feeding motion events to filter.c, they first get adjusted for touchpad
> resolution. For touchpads where the driver does not provide resolution info,
> scale based on the diagonal-size in units instead.
> 
> While at it rename's tp_init_accel's dispatch parameter from touchpad to tp
> to be consistent with all other functions.
> 
> Since the acceleration is also used for scrolling also adjust the scroll
> start threshold for these changes.
> 
> Note that switching to the smooth simple accel code, as an added bonus gives
> the tp code an accel profile with a threshold and a speed parameter, which
> is exactly what is needed for the upcoming configuration interface support.
> 
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>

merged, with  the x/y swap you mentioned on IRC and two typo fixes. thanks.

Cheers,
   Peter
 
> --
> 
> Changes since v1:
> -Use resolution info where available instead of always scaling by diagonal
> ---
>  src/evdev-mt-touchpad.c | 78 +++++++++++++++++--------------------------------
>  src/evdev-mt-touchpad.h |  4 ---
>  2 files changed, 26 insertions(+), 56 deletions(-)
> 
> diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
> index 9e858f1..e5289b9 100644
> --- a/src/evdev-mt-touchpad.c
> +++ b/src/evdev-mt-touchpad.c
> @@ -28,9 +28,7 @@
>  
>  #include "evdev-mt-touchpad.h"
>  
> -#define DEFAULT_CONSTANT_ACCEL_NUMERATOR 100
> -#define DEFAULT_MIN_ACCEL_FACTOR 0.20
> -#define DEFAULT_MAX_ACCEL_FACTOR 0.40
> +#define DEFAULT_ACCEL_NUMERATOR 1200.0
>  #define DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR 700.0
>  
>  static inline int
> @@ -46,27 +44,6 @@ tp_hysteresis(int in, int center, int margin)
>  		return center + diff + margin;
>  }
>  
> -static double
> -tp_accel_profile(struct motion_filter *filter,
> -		 void *data,
> -		 double velocity,
> -		 uint64_t time)
> -{
> -	struct tp_dispatch *tp =
> -		(struct tp_dispatch *) data;
> -
> -	double accel_factor;
> -
> -	accel_factor = velocity * tp->accel.constant_factor;
> -
> -	if (accel_factor > tp->accel.max_factor)
> -		accel_factor = tp->accel.max_factor;
> -	else if (accel_factor < tp->accel.min_factor)
> -		accel_factor = tp->accel.min_factor;
> -
> -	return accel_factor;
> -}
> -
>  static inline struct tp_motion *
>  tp_motion_history_offset(struct tp_touch *t, int offset)
>  {
> @@ -464,11 +441,11 @@ tp_post_twofinger_scroll(struct tp_dispatch *tp, uint64_t time)
>  
>  	tp_filter_motion(tp, &dx, &dy, time);
>  
> -	/* Require at least three px scrolling to start */
> -	if (dy <= -3.0 || dy >= 3.0)
> +	/* Require at least five px scrolling to start */
> +	if (dy <= -5.0 || dy >= 5.0)
>  		tp->scroll.direction |= (1 << LIBINPUT_POINTER_AXIS_SCROLL_VERTICAL);
>  
> -	if (dx <= -3.0 || dx >= 3.0)
> +	if (dx <= -5.0 || dx >= 5.0)
>  		tp->scroll.direction |= (1 << LIBINPUT_POINTER_AXIS_SCROLL_HORIZONTAL);
>  
>  	if (dy != 0.0 &&
> @@ -665,9 +642,10 @@ tp_init_slots(struct tp_dispatch *tp,
>  	return 0;
>  }
>  
> -static void
> -calculate_scale_coefficients(struct tp_dispatch *tp)
> +static int
> +tp_init_accel(struct tp_dispatch *tp, double diagonal)
>  {
> +	struct motion_filter *accel;
>  	int res_x, res_y;
>  
>  	if (tp->has_mt) {
> @@ -682,35 +660,31 @@ calculate_scale_coefficients(struct tp_dispatch *tp)
>  						    ABS_Y);
>  	}
>  
> -	if (res_x <= 0 || res_y <= 0) {
> -		tp->accel.x_scale_coeff = 1.0;
> -		tp->accel.y_scale_coeff = 1.0;
> -	} else if (res_x > res_y) {
> -		tp->accel.x_scale_coeff = res_y / (double) res_x;
> -		tp->accel.y_scale_coeff = 1.0f;
> +	/*
> +	 * Not all touchpads report the same amount of units/mm (resolution).
> +	 * Normalize motion events to a resolution of 10 units/mm as base
> +	 * (unaccellerated) speed. This also evens out any differences in x
> +	 * and y resolution, so that a circle on the touchpad does not turn
> +	 * into an elipse on the screen.
> +	 */
> +	if (res_x > 1 && res_y > 1) {
> +		tp->accel.y_scale_coeff = 10.0 / res_x;
> +		tp->accel.x_scale_coeff = 10.0 / res_y;
>  	} else {
> -		tp->accel.y_scale_coeff = res_x / (double) res_y;
> -		tp->accel.x_scale_coeff = 1.0f;
> +	/*
> +	 * For touchpads where the driver does not provide resolution, fall
> +	 * back to scaling motion events based on the diagonal size in units.
> +	 */
> +		tp->accel.x_scale_coeff = DEFAULT_ACCEL_NUMERATOR / diagonal;
> +		tp->accel.y_scale_coeff = DEFAULT_ACCEL_NUMERATOR / diagonal;
>  	}
> -}
> -
> -static int
> -tp_init_accel(struct tp_dispatch *touchpad, double diagonal)
> -{
> -	struct motion_filter *accel;
> -
> -	calculate_scale_coefficients(touchpad);
> -
> -	touchpad->accel.constant_factor =
> -		DEFAULT_CONSTANT_ACCEL_NUMERATOR / diagonal;
> -	touchpad->accel.min_factor = DEFAULT_MIN_ACCEL_FACTOR;
> -	touchpad->accel.max_factor = DEFAULT_MAX_ACCEL_FACTOR;
>  
> -	accel = create_pointer_accelator_filter(tp_accel_profile);
> +	accel = create_pointer_accelator_filter(
> +			pointer_accel_profile_smooth_simple);
>  	if (accel == NULL)
>  		return -1;
>  
> -	touchpad->filter = accel;
> +	tp->filter = accel;
>  
>  	return 0;
>  }
> diff --git a/src/evdev-mt-touchpad.h b/src/evdev-mt-touchpad.h
> index 7afb3c4..051a7eb 100644
> --- a/src/evdev-mt-touchpad.h
> +++ b/src/evdev-mt-touchpad.h
> @@ -152,10 +152,6 @@ struct tp_dispatch {
>  	struct motion_filter *filter;
>  
>  	struct {
> -		double constant_factor;
> -		double min_factor;
> -		double max_factor;
> -
>  		double x_scale_coeff;
>  		double y_scale_coeff;
>  	} accel;
> -- 
> 2.0.0