libinput/src/filter-trackpoint.c

/*
 * Copyright © 2006-2009 Simon Thum
 * Copyright © 2012 Jonas Ådahl
 * Copyright © 2014-2018 Red Hat, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#include "config.h"

#include <assert.h>
#include <math.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#include "filter-private.h"
#include "filter.h"
#include "libinput-util.h"

struct trackpoint_accelerator {
	struct motion_filter base;

	struct pointer_trackers trackers;
	double speed_factor;

	double multiplier;
};

double
trackpoint_accel_profile(struct motion_filter *filter,
			 void *data,
			 double velocity,
			 usec_t time)
{
	struct trackpoint_accelerator *accel_filter =
		(struct trackpoint_accelerator *)filter;
	double factor;

	velocity = v_us2ms(velocity); /* make it units/ms */

	/* Just a nice-enough curve that provides fluid factor conversion
	 * from the minimum speed up to the real maximum. Generated by
	 * https://www.mycurvefit.com/ with input data
	 * 0    0.3
	 * 0.1  1
	 * 0.4  3
	 * 0.6  4
	 */
	factor = 10.06254 + (0.3 - 10.06254) / (1 + pow(velocity / 0.9205459, 1.15363));

	factor *= accel_filter->speed_factor;
	return factor;
}

static struct normalized_coords
trackpoint_accelerator_filter(struct motion_filter *filter,
			      const struct device_float_coords *unaccelerated,
			      void *data,
			      usec_t time)
{
	struct trackpoint_accelerator *accel_filter =
		(struct trackpoint_accelerator *)filter;
	struct device_float_coords multiplied;
	struct normalized_coords coords;
	double f;
	double velocity;

	multiplied.x = unaccelerated->x * accel_filter->multiplier;
	multiplied.y = unaccelerated->y * accel_filter->multiplier;

	trackers_feed(&accel_filter->trackers, &multiplied, time);
	velocity = trackers_velocity(&accel_filter->trackers, time);

	f = trackpoint_accel_profile(filter, data, velocity, time);
	coords.x = multiplied.x * f;
	coords.y = multiplied.y * f;

	return coords;
}

static struct normalized_coords
trackpoint_accelerator_filter_constant(struct motion_filter *filter,
				       const struct device_float_coords *unaccelerated,
				       void *data,
				       usec_t time)
{
	struct trackpoint_accelerator *accel_filter =
		(struct trackpoint_accelerator *)filter;
	struct normalized_coords coords;

	coords.x = unaccelerated->x * accel_filter->multiplier;
	coords.y = unaccelerated->y * accel_filter->multiplier;

	return coords;
}

static struct normalized_coords
trackpoint_accelerator_filter_scroll(struct motion_filter *filter,
				     const struct device_float_coords *unaccelerated,
				     void *data,
				     usec_t time,
				     enum filter_scroll_type type)
{
	/* Scroll wheels were not historically accelerated and have different
	 * units than button scrolling. Maintain the status quo and do not
	 * accelerate wheel events.
	 */
	if (type == FILTER_SCROLL_TYPE_WHEEL) {
		return (struct normalized_coords){
			.x = unaccelerated->x,
			.y = unaccelerated->y,
		};
	}

	return trackpoint_accelerator_filter_constant(filter,
						      unaccelerated,
						      data,
						      time);
}

/* Maps the [-1, 1] speed setting into a constant acceleration
 * range. This isn't a linear scale, we keep 0 as the 'optimized'
 * mid-point and scale down to 0 for setting -1 and up to 5 for
 * setting 1. On the premise that if you want a faster cursor, it
 * doesn't matter as much whether you have 0.56789 or 0.56790,
 * but for lower settings it does because you may lose movements.
 * *shrug*.
 *
 * Magic numbers calculated by MyCurveFit.com, data points were
 *  0.0 0.0
 *  0.1 0.1 (because we need 4 points)
 *  1   1
 *  2   5
 *
 *  This curve fits nicely into the range necessary.
 */
static inline double
speed_factor(double s)
{
	s += 1; /* map to [0, 2] */
	return 435837.2 + (0.04762636 - 435837.2) / (1 + pow(s / 240.4549, 2.377168));
}

static bool
trackpoint_accelerator_set_speed(struct motion_filter *filter, double speed_adjustment)
{
	struct trackpoint_accelerator *accel_filter =
		(struct trackpoint_accelerator *)filter;

	assert(speed_adjustment >= -1.0 && speed_adjustment <= 1.0);

	filter->speed_adjustment = speed_adjustment;
	accel_filter->speed_factor = speed_factor(speed_adjustment);

	return true;
}

static void
trackpoint_accelerator_restart(struct motion_filter *filter, void *data, usec_t time)
{
	struct trackpoint_accelerator *accel = (struct trackpoint_accelerator *)filter;

	trackers_reset(&accel->trackers, time);
}

static void
trackpoint_accelerator_destroy(struct motion_filter *filter)
{
	struct trackpoint_accelerator *accel_filter =
		(struct trackpoint_accelerator *)filter;

	trackers_free(&accel_filter->trackers);
	free(accel_filter);
}

static const struct motion_filter_interface accelerator_interface_trackpoint = {
	.type = LIBINPUT_CONFIG_ACCEL_PROFILE_ADAPTIVE,
	.filter = trackpoint_accelerator_filter,
	.filter_constant = trackpoint_accelerator_filter_constant,
	.filter_scroll = trackpoint_accelerator_filter_scroll,
	.restart = trackpoint_accelerator_restart,
	.destroy = trackpoint_accelerator_destroy,
	.set_speed = trackpoint_accelerator_set_speed,
};

struct motion_filter *
create_pointer_accelerator_filter_trackpoint(double multiplier,
					     bool use_velocity_averaging)
{
	struct trackpoint_accelerator *filter;

	assert(multiplier > 0.0);

	/* Trackpoints are special. They don't have a movement speed like a
	 * mouse or a finger, instead they send a stream of events based on
	 * the pressure applied.
	 *
	 * Physical ranges on a trackpoint are the max values for relative
	 * deltas, but these are highly device-specific and unreliable to
	 * measure.
	 *
	 * Instead, we just have a constant multiplier we have in the quirks
	 * system.
	 */

	filter = zalloc(sizeof *filter);
	if (!filter)
		return NULL;

	filter->multiplier = multiplier;

	trackers_init(&filter->trackers, use_velocity_averaging ? 16 : 2);

	filter->base.interface = &accelerator_interface_trackpoint;
	filter->trackers.smoothener =
		pointer_delta_smoothener_create(usec_from_millis(10),
						usec_from_millis(10));

	return &filter->base;
}