libevdev/tools/mouse-dpi-tool.c

/*
 * Copyright © 2014 Red Hat, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software
 * and its documentation for any purpose is hereby granted without
 * fee, provided that the above copyright notice appear in all copies
 * and that both that copyright notice and this permission notice
 * appear in supporting documentation, and that the name of Red Hat
 * not be used in advertising or publicity pertaining to distribution
 * of the software without specific, written prior permission.  Red
 * Hat makes no representations about the suitability of this software
 * for any purpose.  It is provided "as is" without express or implied
 * warranty.
 *
 * THE AUTHORS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
 * NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
 * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <libevdev/libevdev.h>
#include <sys/signalfd.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <poll.h>
#include <signal.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#define min(a, b) (((a) < (b)) ? (a) : (b))
#define max(a, b) (((a) > (b)) ? (a) : (b))

struct measurements {
	int distance;
	double frequency;
	uint32_t ms;
};

static int
usage(void) {
	printf("Usage: %s /dev/input/event0\n", program_invocation_short_name);
	printf("\n");
	printf("This tool reads relative events from the kernel and calculates\n "
	       "the distance covered and frequency of the incoming events.\n");
	return 1;
}

static inline uint32_t
tv2ms(const struct timeval *tv)
{
	return tv->tv_sec * 1000 + tv->tv_usec/1000;
}

static inline double
get_frequency(double last, double current)
{
	return 1000.0/(current - last);
}

static int
print_current_values(const struct measurements *m)
{
	static int progress = 0;
	char status = 0;

	switch (progress) {
		case 0: status = '|'; break;
		case 1: status = '/'; break;
		case 2: status = '-'; break;
		case 3: status = '\\'; break;
		default:
			status = '?';
			break;
	}

	progress = (progress + 1) % 4;

	printf("\rCovered distance in device units: %8d at frequency %3.1fHz 	%c",
	       abs(m->distance), m->frequency, status);

	return 0;
}

static int
handle_event(struct measurements *m, const struct input_event *ev)
{
	if (ev->type == EV_SYN) {
		const int idle_reset = 3000; /* ms */
		uint32_t last_millis = m->ms;

		m->ms = tv2ms(&ev->time);

		/* reset after pause */
		if (last_millis + idle_reset < m->ms) {
			m->frequency = 0.0;
			m->distance = 0;
		} else {
			double freq = get_frequency(last_millis, m->ms);
			m->frequency = max(freq, m->frequency);
			return print_current_values(m);
		}

		return 0;
	} else if (ev->type != EV_REL)
		return 0;

	switch(ev->code) {
		case REL_X:
			m->distance += ev->value;
			break;
	}

	return 0;
}

static int
mainloop(struct libevdev *dev, struct measurements *m) {
	struct pollfd fds[2];
	sigset_t mask;

	fds[0].fd = libevdev_get_fd(dev);
	fds[0].events = POLLIN;

	sigemptyset(&mask);
	sigaddset(&mask, SIGINT);
	fds[1].fd = signalfd(-1, &mask, SFD_NONBLOCK);
	fds[1].events = POLLIN;

	sigprocmask(SIG_BLOCK, &mask, NULL);

	while (poll(fds, 2, -1)) {
		struct input_event ev;
		int rc;

		if (fds[1].revents)
			break;

		do {
			rc = libevdev_next_event(dev, LIBEVDEV_READ_FLAG_NORMAL, &ev);
			if (rc == LIBEVDEV_READ_STATUS_SYNC) {
				fprintf(stderr, "Error: cannot keep up\n");
				return 1;
			} else if (rc != -EAGAIN && rc < 0) {
				fprintf(stderr, "Error: %s\n", strerror(-rc));
				return 1;
			} else if (rc == LIBEVDEV_READ_STATUS_SUCCESS) {
				handle_event(m, &ev);
			}
		} while (rc != -EAGAIN);
	}

	return 0;
}

static void
print_summary(struct measurements *m)
{
	int res;

	printf("Estimated sampling frequency: %dHz\n", (int)m->frequency);
	printf("To calculate resolution, measure physical distance covered\n"
	       "and look up the matching resolution in the table below\n");

	m->distance = abs(m->distance);

	/* If the mouse has more than 2500dpi, the manufacturer usually
	   shows off on their website anyway */
	for (res = 400; res <= 2500; res += 200) {
		double inch = m->distance/(double)res;
		printf("%8dmm	%8.2fin	%8ddpi\n",
		       (int)(inch * 25.4), inch, res);
	}
}

int
main (int argc, char **argv) {
	int rc;
	int fd;
	const char *path;
	struct libevdev *dev;
	struct measurements measurements = {0};

	if (argc < 2)
		return usage();

	path = argv[1];
	if (path[0] == '-')
		return usage();

	fd = open(path, O_RDONLY|O_NONBLOCK);
	if (fd < 0) {
		fprintf(stderr, "Error opening the device: %s\n", strerror(errno));
		return 1;
	}

	rc = libevdev_new_from_fd(fd, &dev);
	if (rc != 0) {
		fprintf(stderr, "Error fetching the device info: %s\n", strerror(-rc));
		return 1;
	}

	if (libevdev_grab(dev, LIBEVDEV_GRAB) != 0) {
		fprintf(stderr, "Error: cannot grab the device, something else is grabbing it.\n");
		fprintf(stderr, "Use 'fuser -v %s' to find processes with an open fd\n", path);
		return 1;
	}
	libevdev_grab(dev, LIBEVDEV_UNGRAB);

	printf("Mouse %s on %s\n", libevdev_get_name(dev), path);
	printf("Move the device along the x-axis.\n");
	printf("Pause 3 seconds before movement to reset, Ctrl+C to exit.\n");
	setbuf(stdout, NULL);

	rc = mainloop(dev, &measurements);

	printf("\n");

	print_summary(&measurements);

	libevdev_free(dev);
	close(fd);

	return rc;
}