Attachment 135579 Details for Bug 101139 – MacOS inspired touchpad acceleration patch

[patch] MacOS inspired touchpad acceleration patch

accelonly.patch (text/plain), 2.54 KB, created by Greg Reichow on 2017-11-18 19:33:10 UTC

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Creator: Greg Reichow

Created: 2017-11-18 19:33:10 UTC

Size: 2.54 KB

patch

obsolete

>diff --git a/src/filter.c b/src/filter.c
>index 206695bb..b502d8b2 100644
>--- a/src/filter.c
>+++ b/src/filter.c
>@@ -827,73 +827,25 @@ touchpad_accel_profile_linear(struct motion_filter *filter,
> 	struct pointer_accelerator *accel_filter =
> 		(struct pointer_accelerator *)filter;
> 	const double max_accel = accel_filter->accel; /* unitless factor */
>-	const double threshold = accel_filter->threshold; /* units/us */
>-	const double incline = accel_filter->incline;
> 	double factor; /* unitless */
> 
> 	/* Convert to mm/s because that's something one can understand */
> 	speed_in = v_us2s(speed_in) * 25.4/accel_filter->dpi;
> 
>-	/*
>-	   Our acceleration function calculates a factor to accelerate input
>-	   deltas with. The function is a double incline with a plateau,
>-	   with a rough shape like this:
>-
>-	  accel
>-	 factor
>-	   ^
>-	   |        /
>-	   |  _____/
>-	   | /
>-	   |/
>-	   +-------------> speed in
>-
>-	   The two inclines are linear functions in the form
>-		   y = ax + b
>-		   where y is speed_out
>-		         x is speed_in
>-			 a is the incline of acceleration
>-			 b is minimum acceleration factor
>-
>-	   for speeds up to the lower threshold, we decelerate, down to 30%
>-	   of input speed.
>-		   hence 1 = a * 7 + 0.3
>-		       0.7 = a * 7  => a := 0.1
>-		   deceleration function is thus:
>-			y = 0.1x + 0.3
>+	/* All constants below are based on touchpad accel profile characterization */
>+	double x_factor = 0.003738 + 0.003058 * filter->speed_adjustment;
>+	double power = 1.3 + 0.2 * filter->speed_adjustment;
>+	factor = 2.2 * pow(speed_in * x_factor, power);
> 
>-	  Note:
>-	  * The minimum threshold is a result of trial-and-error and
>-	    has no other intrinsic meaning.
>-	  * 0.3 is chosen simply because it is above the Nyquist frequency
>-	    for subpixel motion within a pixel.
>-	*/
>-	if (speed_in < 7.0) {
>-		factor = 0.1 * speed_in + 0.3;
>-	/* up to the threshold, we keep factor 1, i.e. 1:1 movement */
>-	} else if (speed_in < threshold) {
>-		factor = 1;
>-	} else {
>-	/* Acceleration function above the threshold:
>-		y = ax' + b
>-		where T is threshold
>-		      x is speed_in
>-		      x' is speed
>-	        and
>-			y(T) == 1
>-		hence 1 = ax' + 1
>-			=> x' := (x - T)
>-	 */
>-		factor = incline * (speed_in - threshold) + 1;
>+	/* Mininum factor for slow speeds */
>+	if (factor < 0.17) {
>+		factor = 0.17;
> 	}
>-
>+	
> 	/* Cap at the maximum acceleration factor */
> 	factor = min(max_accel, factor);
> 
>-	/* Scale everything depending on the acceleration set */
>-	factor *= 1 + 0.5 * filter->speed_adjustment;
>-
>-	return factor * TP_MAGIC_SLOWDOWN;
>+	return factor;
> }
> 
> double

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Attachments on bug 101139: 135510 | 135579 | 136584 | 136585 | 136627 | 136628 | 138012 | 138716

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