[PATCH libinput] filter: reduce deceleration to minimal speeds only

[Hans de Goede]

Hi,

On 25-06-15 08:08, Peter Hutterer wrote:
> Deceleration at low speeds is intended to enhance precision when moving the
> pointer slowly. However, the adaptive deceleration we used was badly
> calibrated, at slow-but-normal speeds the pointer became too slow to manouver.
>
> We don't want to drop deceleration completely, the subpixel precision it
> provides is useful. And it also helps those that can't move a 1000dpi mouse by
> exactly one unit.
>
> Make the adaptive deceleration steeper so it only kicks in at extremely slow
> motions and defaults to 1 at anything resembling normal movement (i.e. pointer
> moves like the physical device does).
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1227039#c44
>
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>

Looks good to me:

Reviewed-by: Hans de Goede <hdegoede at redhat.com>

Regards,

Hans

> ---
>   src/filter.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/filter.c b/src/filter.c
> index a4142e9..69f78b1 100644
> --- a/src/filter.c
> +++ b/src/filter.c
> @@ -386,7 +386,7 @@ pointer_accel_profile_linear(struct motion_filter *filter,
>   	const double threshold = accel_filter->threshold; /* units/ms */
>   	const double incline = accel_filter->incline;
>
> -	s1 = min(1, 0.3 + speed_in * 4);
> +	s1 = min(1, 0.3 + speed_in * 10);
>   	s2 = 1 + (speed_in - threshold) * incline;
>
>   	return min(max_accel, s2 > 1 ? s2 : s1);
>